Review #1: General Microbiology 1 Difference between
Eukaryote/Prokaryote Eukaryote: sexual reproduction - example: Algae, fungi Prokaryote: asexual division - example: Bacteria
Eukaryote + Prokaryote: - Are organisms
- They contain all enzymes required for replication/division
- Plus possess the biological equipment necessary for their production of metabolic energy
2 Light Microscope : - Used in bacteriology
- Examination of un/stained smears
Electron Microscope: - Detailed structure of pro/eukaryotic observed - 2 Types: TEM/SEM
-
TEM : Good for minute particles/viruses-
SEM : Good for 3-D images of surface of micro.org by use of shadowing technique or freeze-dryingspecimens
Darkfield Illumination: - Performed on dark microscope
-
Creating a darkfield contrasting against the highlighted edge of specimen-
Used of observing spirochetes-
Ex: Treponnema pallidumPhase-phase microscope: - Different phases are converted into different intensities so that some structures appear darker than others
- Killed and stained org must be used
Confocal Microscope:
-
Laser light beams-
Provide 3-D image from thick fluorescent specimen - Useful in cell biologyAuto Radiograph
-
Radio active atom cells fixed on a slide-
Converts w/photographic emulsion therefore tracks appear in a developed film-
Useful in following replication of DNA using Tritum labeled thymidine as tracer- In Situ hybridization
- Employes labeled nucleic acid probes used to detect presence viral, bacterial + funcgi nucleic acid in cells/tissues
3 Difference between Gram (+)ve and Gram (-)ve cells:
Gram (+)ve Gram (-)ve
• Teichoic acid • Thick
• Peptidoglycan • Blue Gram stain
• Outer membrane containing LPS • Thin
• Peptidoglycan • Red Gram stain
• Endotoxin symptoms (fever, shock) Nature of Gram simple stain
bacteria classified on basis of staining reaction
stain allows clinician to determine whether org is round or rod-shaped
1. Cells stained w/crystal violet 2. Treated w/Gram’s iodine
3. Decolorization w/acetone or alcohol
4 Acid Fasting Stains
-
Aka: Ziell Neelsen Staining-
Used in bacteria that resist decolorization with acid or alcohol after being stained with strong carbol fuschin-
therefore resulting in their inability to stainAcid fastness inability to stain due to: High concentration of Lipids called:
• Mycolic acids granules (Lipid-A) (metachromatic granules) 5 What gives bacteria their shape and
provides rigid support: •• Peptidoglycan layer in cell wallNot in human cells therefore • Good target for anti-bacterial drugs
• Eg: Penicllin, Cephalosporin inhibiting cell wall synthesis
Type of polysaccharide capsule helpful in serological typing of bacteria and
determinant to virulence:
Polymerized D-glutamic acid Capsule in all gram (-)ve except: - Anthrax Bacillus
Function of a capsule:
•
Capsule protects organism from environmental hazards•
Serves as antiphagocytic surface•
Provides specific adherenceLysosome Enzyme:
-
Present in human tears, mucus, saliva-
Can cleave peptidoglycan backbone-
Contributes to natural resistance of host to microbial infectionLipopolysaccharide (LPS):
•
Consist of Lipid-A complex lipids•
Endotoxin of gram (-)ve bacteria firmly bound to cell surface• Released only when cell lysed
•
Target for antibiotics and pyrogenic activity (Fever induction)Purified form of Endotoxin • Found in outer membrane of gram (-)ve bac
6 Flagella:
•
Mainly in gram (-)ve•
Organ of locomotion/motility • H-antigen•
Found in UTI•
Major function: mediate adherence of bacteria to to other bacteria/cellsFor serological classification:
-
Flagellar proteins used are called H-antigen - Flagellar are organs of motility-
Flagella cell wall = O-antigen - Capsular called = K-antigenPili:
-
aka: Fimbriae-
found mainly in Gram (-)ve - 2 Types: Ordinary pili & Sex pili - Function: Adhesion7 Spore forming organisms: Clostridium, Bacillus (Both Gram (+)ve )
- Clostridium (anaerobic), Bacilllus (aerobic)
Spores are:
-
Single internal spore produced under unfavorable conditions such as nutrition depletion)- Resistant to cold, heat, dyring, chemical agents possess multiplayer protective coating
8 Mechanism of gene transfer
Conjugation
-
- requires cell to cell contactplasmids are transferred-
bacterial conjugation requires F-factor - F-factor (Fertility) Transduction - Phage mediated (infected bacteria)
-
Virulent phage (assemble/release new viruses) - Temperature phage (may enter productive cycle orenter bacteria DNA and reside there) 2 Types:
1) Generalized Transduction
-
Do not require lysogeny and any gene may be transferred by infecting bacterial DNA 2) Specialized Transduction - Requires lysogeny- Only bacterial genes next to insertional site are transferred
Transformation:
-
Uptake of donor DNA by recipient cells - Most primitive mode of gene transfer Recombination - Donor DNA that does not carry info needed for its own replication must recombine w/recipient DNA to become established
Lysogenic conversion - New properties are conferred on bacterial cell by products of prophage genes
9 Antimicrobial Chemotherapy
1.
By inhibition of cell wall synthesis - Penicillin, Bacitracin, Vancomycin2.
By inhibition of cell membrane function - Amphotreicin-B3.
By inhibition of protein synthesis - Chloramphenicol, Tetracycline4.
By inhibition of nucleic acid synthesis - Quinolones, Rifampin, CirpoBacterial Plasmids: - carry genes for antibiotic resistance - carry genes for synthesis of pilli and - genes that code for exotoxins
- genes essential for growth of host cells are NOT carried
For most antibiotics: - Susceptibility + resistant break points based on level of drug in serum/blood
- Not in urine or other fluids 10 Methods of Sterilization: Physical agents
-
Dry heat (oven: 160 degee celcius) - Moist heat (autoclave: 121 degree celcius) - Radiation (UV light)- Filteration (candles, asbestos pads) - Ultrasonic vibrations
Chemical agents
- Alcohol (70% concentration) - Phenol
- Heavy metal ions - Oxidizing agents - Detergents (soaps)
11 In Vitro (outside the body)
anti-septic/anti-biotic susceptibility testing depends on:
-
-
Type of medium usedQuantity of organism (inoculum)-
Incubation periodReview #2: Immunology
1 Immunity defn: Resistence by the host towards injury caused by micro.org and/or products
Types of immunity: • Acquired – adaptive • Passive – natural
• Local – destruction at local level • Herd – control of disease in body
Measurement of immunity: - Agglutination, Precipitation, Complement fixation - Testing level of antibodies
Immune Response: Primary, Secondary
Humoral (Antibody mediated) response Cellular (Cell mediated) response Immunogenicity deponds on: - foreigness, chemical nature/size
Immune reponse altered by: - amount of immunogen, time of exposure, mode of administration and duration of exposure
2 Antigen / Antibody: - response depends on:
• dose, route, timing, administration Antibodies: - Ab are produced in response to Ag
- Abs are immunoglobulins
Classes of Immunoglobulins:
IgG - Secondary response
- Crosses placenta
- Mainly in internal secretions (blood, CSF)
IgM - Primary response
-
Presence in fetus intrauterine infectionIgA
-
Secretory immunoglobulin- Present in external secretions
• Tears, saliva, sweat, breast milk, GI secretions, Mucous secretion of respiratory tract, Urogenital tract
IgD
-
Present in traces only- Found on surface of B lymphocyte - Marker for B mature cells
IgE
-
Allergic / antiparasitic responsesAbnormal immunoglobulins - Cryoglubulins, Bence Jones proteins 3 Auto-immune diseases: Chronic thyroiditis + Grave’s Disease
Hemolytic anemia
Thrombocytopenia & granulocytopenia Immune deficiencies: Abnormal immune response
Could be congenital or acquired • B-cell (Ab) – recurrent infections • T-cell – Acquired immuno def syndrome Location of cells:
•
B-cells:•
T-cell:follicles funtn: markers of foreign pathogen
paracortex funtn: defense against intracellular patho Cells that attack (protozons): CD4 T-cells
4 Activation cells: o B-cells o T-cells o Macrophages o NK cells o ABO-incompatibility o Rh blood group IL-1 C3
gamma-interferon from T-cells
Type II hypersensitivity rxns (kill tumor cells) Transplant rejection/Type II hypersensitivity only RBC’s
Class I antigen: (HLA-A/B/C)
Class II antigen: (HLA-D) CD8 cytotoxic T-cells recognized these antigensCD4 helper T-cells & macrophage recognize these 5 Transplant success requirements: • ABO blood group compatibility
• Absence of anti-HLA cytotoxic Abs in recip.
• Close matches for HLA-A/B/D bet/n donor/recipient Transplant donors Siblings are best donors sources
6 Graft types:
o Autograft o Isograft o Allograft o Xenograft
Transfer of tissue from self-self, best survival Between identical twins
Between unrelated individuals
Between one species to another (pig vavles) Corneal transplant: Best overall allograft survival rate
7 Complement fixation rxn: ~Hemolysis test: (-)ve Presence of bacteria (+)ve No presence of bacteria Testing of complement system: C3 is the 1st step in complement system
~Classical pathway
~Alternative pathway Low C4 or C2 is activatedLow factor B if activated
8 Latex agglutination rxn: Antibody to capsular antigen is attached to beads 9 Examples of hypersensitivit Rxns:
Type-I Eczema, hives, asthma, hypersensitivity to bee sting (involves: IgE)(eryth. Lesions w/in 30min)
Type-II Goodpasture’s syndrome, Myasthenia gravis
- Cells coated by specific IgG/IgE Abs are destroyed by cells (eg: NK/esoinphils)
Type-III Serum sickness, SLE
- Circulating immunocomplexs, IgG/IgM deposit in target tissue activate complement system
Type-IV (delayed type) Poison ivy, nickel(metal) contact, soap, tuberculin, dermatitis - Skin test needs to be performed
10 In acute inflammation: Accumulation of polymorh nuclear cells (PML) Patients deficient in C8 have increased
Inability to response to self-antigen Aka: Tolerance
HLA-27 is a risk factor for Ankylosing spondylitis arthritis Review #3/4: Bacteriology
Staphylococcus
Acute endocarditis Abscesses
Post-op wound infect. Toxic shock syndrome --- Catheter-prosthetic device infections
--- UTI in young women
- Gram (+)ve spherical cells
- Arranged in grape-like-clusters (pigmented colonies)
-
Normal flora : Skin, mucous membranes-
Manifestations : abscess, septicemia, pneumonia in lungs/liver-
Stains : Hemolysis of RBC on blood agar- Catalase (+)ve – all staph
- Coagulase (-)ve…except staph. aureus - Types:
• Staph. Aureus
Exotoxin: Coagulase (+),Entertoxin Beta-hemolysis Enterotoxin caused food poisoning • Staph. Epidermis
Coagulase (-) No hemolysis
Susceptible to novobiocin
Catheter-prosthetic device infections • Staph. Saprophyticus
Coagulase (-) No hemolysis
Resistant to novobiocin
-
PenicillinTx:- Hospitals have higher risks of carrying antibiotic resistant staph.
Enterotoxins - Cause food poisoning
- Heat stable toxins - Resistant to gut enzymes
- S/S: Nausea/vomitting, ab-pain, diarrhea Coagulase - Best correlate of pathogenicity
- Coverts fibrinogen to fibrin (clot) - Allow org to adhere
Hemolysis
-
Alpha partial breakdown of RBC-
Beta complete breakdown of RBC-
Gamma no breakdown of RBCQ Pneumococci can be typed by: Swelling of the capsule in the presence of type specific antiserum
Q The coagulase test, in which the bacteria causes plasma to
clot is used to distinguish Staph. Aureas from Staph. Epidermis Q Each of the following concerning staph. Aureas is correct
except:
Treatment should include Beta-Lactamase resistant Penicillin
Q Staph. which is part of normal floral of human skin: S. Albus
Streptococcous - Gram (+)ve cocci, Catalase (+)
- Types: Group A, B, D, S.Viridens, S. Pneumoniae
Group A - Capsule of group A strep have
• Hair-like pill that consist of protein-M and lipoteichoic acid that aid in attachment to epithelial cells
- Aka Strep. Pyogenes
• Catalase (-), Beta-hemolytic
• Remain in throat/skin causing sore throat Toxins – produced by group A Streptolysin .O: - Subsurface blood agar
- Hemolysis in anaerobic conditions Strep. S: - Responsible for beta-hemolysis Streptokinase
-
Fibrinolysin (plasmaplasminogen)- Associated with virulence
- IV tx of pulmonary emboli/thromb. Streptodornase - Liquefaction of pus
Hyaloronidase - Halornic acid
- Hydrolyses ground substance of
connective tissue therefore helps spread infection
Strep Exotoxin A-C - Causes fever
- Produce rash of scarlet fever
- Inhibit liver clearance therefore creating shock
Sore Throat C/F: - Onset of fever, sore throat, malaise, headache, nasopharyngitis, tonsilar abscess
- All may spread to middle ear, mastoid meninges Dz: Strep. Pyoderma Local infection of superficial layer of skin (IMPEDIGO)
Infective Endocarditis Strep may settle on normal or previously deformed heart valves producing endocarditis
Sub-acute endocarditis - Involves abnormal vales (congenital deformities, rheumatic fever, artherosclerotic lesions)
- Transient bacteriaemia when Strep accidentally reaches blood (usually seen after dental extractions)
- In these case, prophylactic treatment is used Post Strep. A - Rheumatic fever, Glomerulo-nephritis
- Latent period of 1-4 weeks due to hypersensitivity response Acute Glomerulonephritis - Develops 3 weeks after strep infection
- Nephritogenic stains involves basement membrane - Blood/protein in urine
- W/edema, hypertension, urea/nitrogen retension Rheumatic fever - Damage to heart muscles/valves
- S/s: fever, malaise, evidence of all parts of heart inflamed (endo/myo/pericardium) leading to thickness of valves (deformities)
-
Prophylactic penicillin prevents pharyngitisTx: Group B – Strep. Agalactie - Gram (+), Catalase (-), Beta-hemolytic- In vagina
-
Neonatal meningitis/septicemiaDz:-
Pathogenesis: ~(+) cAMP test~Infection assoc/w/ premature rupture of membrane
Group D: Strep. Faecalis
(Enterococcous) -- Gram (+), Catalase (-), Enterococcus, variable hemolysisTransmission: during medical procedures (GI/Ug) in blood stream onto previous damaged heart valves causing endocarditis
- In colon, urethra, female genitals
-
Lab: grows with 6.5 NaCl (& in presence of bile)-
Urinary/biliary tract infections, endocarditis w/damaged heart Dz: valves Viridans Streptococci - no group
- S. Sanguis, S. mutans
- Gram (+), Catalase (-), alpha hemolysis
-
In oropharynx-
Spread by dental work, poor dental hygiene into blood and damaged heart valves-
Sub-acute bacterial endocarditis, dental carriesDz: - Prevention: Prophylactic penicillin Strep. Pneumoniae
- no group -
-
Gram (+), Catalase (-), Lancet-shaped cocciTransmission via: resp. droplets-
Pathogenesis: IgA helps in colonizationTeichoic acid present for attachment Polysaccharide cap. virulence factor
- In upper respiratory tract (dz is caused in lower resp)
-
Lab: - (+) Quellung Rxn (Swelling of capsule in presence of antiserum leading to pneumonia) - Inhibited by optochin- lysed by bile
Toxin of Strep.pneum. Pneumolysin O – released by capsule
- similar to Strep. O
- when reaches alveoli (lower resp) - damages cells w/cholesterol - damages resp. epithelium
- inhibits leukocutes and complement fixation - outpouring of fluid, RBC, WBC causing CNS
inflammation
Dz: Bacterial pneumonia, adult meningitis, Otitis media & sinusitis in children
Q The principle toxin of Strep. Association with virulence is: Streptokinase Q Acute glomerulonephritis is associated with: Strep. Pyogenes
Q Which organism causes subacute bacterial endocarditis: Alpha-hemolytic strep (Strep. Viridans) Q Pneumococci differentiated from Step. Viridans is by: Bile solubility
Q Subacute bacterial endocarditis caused by a member of viridian of Strep. Which one is the source of the organism in the this infection:
Oropharynx Q A culture of a skin lesion from a patient with pyoderma
(impetigo) shows numerous colonies surrounded by zone of beta-hemolysis on blood agar. A gram stain smear shows gram (+)ve cocci. If you catalase test (-)ve, which of the following organism is to be isolated:
Step. Pyogenes
Q What is the most common infection due to Beta-hemolytic
strep.: Strep. Sore throat
Q 45-yr-old male w/alcohol abuse, periodontal disease, fever/chills, pneumonia with lung consolidation. CXR shows cavity in right lower lung; what type of bacteria involved:
Anaerobic bacteria b/c organism is elsewhere + causing disease elsewhere (mixed infection)
Neisseria - Gram (-)ve cocci occur in pairs
- Oxidase (+)
-
Capsule prevents phagocytosis-
Endotoxin: produces shock - Non-motile (kidney shapped)- 2 types: N. gonorrhea, N. meningitides - found associated with or inside PMN cells Culture: ~ferment carbohydrates producing acids only ~requires 5-10% CO2
N. Gonorrhea
- STD
-
- Ferment GLUCOSE onlyHave pili (attachment/resist phagocytosis)- IgA protease hydrolyzes secretory IgA for adherence - Protein I – extends thru cell membrane
- Protein II – functions in adhesion and attachment - LOS – toxicity in infection due to endotoxic effects - Chocolate agar
Dz:
-
Attack: mucous membrane of genitor-urinary tract, eye, rectum, throat with tissue invasion followed by inflammation and fibrosis•
Males – urethritis with yellow creamy pus and painful urination•
Females – infection in endocervix extending to cervix and vagina with mucopurulent dischargeGonococcal bacteriaemia - Leads to skin lesions, hemorrhagic, pustules
- On hands, forearms, feet, legs, supportive arthritis in knee, ankle and wrists
Gonaococcal ophthalmia - Infection of eye of newborn
- Acquired during passage thru an infected birth canal
-
If untreated may lead to blindness N. Meningitis - Ferments glucose AND maltose
-
Nasopharynx port of entry & may reach bloodstream producing bacteriaemia causing pharyngitis-
Pathogenesis : ~ Polysaccharide capsule~ IgA protease allows colonization ~ Endotoxin
~ Pili and outer membrane protein II for virulence
- Lab: Latex agglutination (beads)
Q Which doesn’t influence virulence of N. gonorrhea: Genus specific protein
Q Neisseria are all: Oxidase (+)ve
Q Effective vaccines presently in use against meningococceal
disease contains which as primary immunogenic agent: Capsular polysaccharide
Q Neisseria meningitis: Differs from other species of neisseria by family of various sugars, oxidase (+)ve, grows in 5-10% CO2, prosses endotoxin
Q N. gonorrhea: Has pilli if pathogenic, produces penicillin, is
oxidase (+)ve, grows best under 10% CO2, may cause blindness in newborns + stertility in women
Q Frequent bacteria responsible for pharyngitis: Neisseria meningitis Q Organism most likely to cause conjunctivitis/eye infection in
new born if appropriate preventative measures are not taken: N. gonorrhea
E.Coli - Lactose fermenter
-
Reservoir: Colon, colonizing vagina/urethra (urogenital epithelium)-
Normal flora : Intestine - Hospital acquired infection- Tx: Ampicillin, Cephalosporins, Rehydration - Prevention: ~Limit use of urinary catheter ~Eat only hot cooked food, drink only boiled water/beverages in risk countries - Imp. For sampling water
- Many Clinical features:
1 UTI - Urinary Tract Infection, Biliary tract infection
-
: Urinary frequency, dysuria, hematuriaC/F2 EPEC (Enteropathogenic)
some form of diarrhea
- Watery diarrhea in infants in developing countries ETEC (Enterotoxigenic) - Traveller’s diarrhea
- Heat Labile: Stimulates cAMP
- Heat Stable: stimulates guanylate cyclase, fimbriae EHEC (Enterohemorrhagic) - Severe diarrhea results in acute renal failure EIEC (Enteroinvasive) - Invade human epi cells and cause diarrhea
EAEC (Enteroaggressive) - Causes acute/chronic diarrhea in develop.countries 3 SEPSIS - E.coli reaches blood stream and causes sepsis
- Newborns susceptible b/c lack IgM Abs - May occur secondary to sepsis
4 Meningitis - in infants
Q Organism commonly characterized by its O, K, H antigen + ability to ferment lactose:
E.Coli Q Organism most likely responsible for UTI: E.Coli Q In the intestinal tract the organism that is lactose fermenting is: E.coli
Klebsiella pneumoniae • Gram (-), non-motile • Lactose-fermenter
•
Reservoir : Resp. tract & feces•
Causes : Bacterial pneumonia, UTI, Bacteremia; Hospital acquired infection•
: Upper lobe cavitation with thick mucousDz•
Associated with : Alcoholics•
Capsule : impedes phagocytosis•
Endotoxin : Causes fever, shock assoc/w/septicemia • No exotoxinTx: • Not susceptible to Penicillin
Q Klebsiella p. has the following features except: Susceptible to penicillin
Proteus - Gram (-), Motile (flagella)
-
Urease (+) / H-antigen (+)- Produce infection in UTI only when bacteria leaves intestinal tract - S/s: bacteriaemia, pneumonia, UTI, diarrhea
-
Lad: smear not useful but PPA test (+)Shigella - Gram (-) rod, Non-lactose fermenting, non-motile
-
Normal Flora : Intestine (Ileum, Colon)-
Transmission : Fecal/oral spread, person-to-person & Fingers, food, feces, flies-
Pathogenesis : Infection limited to intestinal tract b/c no blood stream invasion-
Endotoxin : irritation to bowel wall-
Exotoxin : Type-1: affects gut/CNS; also inhibits sugar and amino acid absorption in SI-
Enterotoxin : Diarrhea-
Neurotoxin : fatal nature of Sh. Dysenteriae in CNS C/F: Fever, watery diarrhea, malena, dehydration, acidosis Sh. Dysentriae - Most servere diseaseSh. Sonnei - Most common in USA
Q Exotoxin that function as a neurotoxin and enterotoxin Shigella dysentriae Q Which species of Shigella is responsbible for basically
dysentery in the US:
S. Sonnei
Salmonella - Gram (-) bacilli, Motile
- H-antigen (+)
-
Transmission : Oral route, animal/animal products-
Causes : Enteritis, systemic infection, Enteric fever-
Produces: H2S which produces black stool-
Carrier: Gall Bladder, biliary tract-
Antigenic structure includes: Capsular K-antigen but is referred to as Vi- antigen which may interfere with agglutination-
Lab: Triple Sugar Iron agar, Rapid slide agglutination, Widal test, Tube agglutination-
Multiple-drug resistantTx:-
Source of Infection: ~Food/drink (Water/Milk/Cheese) ~Meat/products/eggsSal. Typhi (D) - Most important classification type
Enteric Fever (Typhoid) • reaches SI then lymphatics then blood stream to organs, including intestine then multiply in intestine and finally excreted in stool
• Incubation period: 10-14 days
• Peyer’s patches may be seen due to necrosis Enterocolitis (gastroenteritis) C/F: Nausea/headache, vomiting, perfuse diarrhea
S. paratyphi Most common casue of non-typhoid fever and cause of osteomyelitis in pts with sickle cell disease
Q Salmonella food poisoning: S. Typhimurium
Q Early in course of Typhoid fever, Salmonella typhi is isolated
from: Blood
Q Which of the following Typhoid antigens is to be most immunogenic:
V1
Q Outbreak of Typhoid fever occurred in a local high school due
to: Cook in school cafeteria
Q Which organism produces disease resembling Salmonellosis: Campylobcter jejuni Q Salmonella & Shigella are differentiated in the lab by: Motility
Q 6-wk-old infant with 10 days cough/choking; WBC –20% lymphocytes, vomits x2, encapsulated gram (-) ve rods on which media:
Triple sugar iron agar or Urease agar
Pseudomonas - Gram (-) rods, aerobic, Motile
- Oxidase (+) / H-antigen (+) - Produce pigment
P. aeroginosa
-
Fruity odor with greenish-blue color pus (pyocyanin) - Have pili-
Commonly seen in infant patients with cystic fibrosis, wounds, burns, lumbar puncture, endotracheal tube- Most common cause of death with cystic fibrosis pts
-
Exotoxin produced when mucus membrane/skin disrupted (as in when urinary catheters are used) b/c it inhibits protein synthesis (similar to diphtheria toxin)-
Endotoxin : causes inflammation, shock w/septicemia Q Organism most common bacterial pathogen to complilcate(+)ve management of patients with cystic fibrosis:
P. aeruginosa
Acinetobacter - Gram (-), aerobic
- Found in soil/water/skin/mucous membrane - Appearance like Neisseria but Oxidase (-)
Actinomyces - Actonomyces, anaerobe
- Sulphur granules
- Draining sinus tracts in jaw, throat, abdomen - Yellow flecks of material in drainage fluid
Virbrio - Gram (-) rods, motile (polar flagellum=very mobile) - H-antigen (+) / LPS Capsule (O-antigen)
- Found in surface water
-
Enterotoxin (heat labile) watery diarrhea - Oxidase (+)-
: CholeraDz-
Culture: ~Grows on selective medium (TCBS) ~Grows at high alkaline pH (8.5-9.5)-
Pathogenesis : Killed in acidic mediums, does not reach blood stream-
C/F: Rice-water-stool-
TetracyclineTx:Q Vibrio cholera needs: Marked tolerance for alkaline pH grows at high Ph 8.5-9.5
Q Cholera enterotoxin All
Campylobacter
C. Jejuni C. Coli
-
Gram (-), comma (S) shaped rods, Motile - H-antigen (+)- Oxidase (+) / Catalase (+) - Non-fermenters
- Similar to Neiserria due to Co2 requirement - Common cause of bacterial enteritis (invasive)
-
Due ingestion of contaminated poultry, milk, water causing decreased gastric acidity, increasing chance of infection-
Culture : grows at 42 degree cent.-
Reservoir : Human feces-
Transmission : Fecal/oral, chicken-
: ErythromycinTxC.Jejuni - Similar to Salmonella
- Ulcerative colitis (w/malena) & pseudomembranous colitis
Helicobacter - Gram (-) spiral shaped
-
Multiple flagella H-antigen (+) - Oxidase (+), Catalase (+), Urease (+)-
Culture : Grows at neutral pH-
Associated with gastritis, duodenal (peptic) ulcers/carcinoma, gastrointestinal lymphomas arising from MALT in stomach - Found deep in mucus layer near epithelial surface-
Pathogenesis : Produces protease modifying gastric mucosa (causing ulcer) which requires biopsy for diagnosis-
: Detect urease activity Lab-
; Triple Therapy for 14 daysTxYersenia - Gram (-), short, safety-pin appearance
- Catalase (+), Oxidase (+)
-
Endotoxin : ~Bubonic plague by bite ~ Lymph node enlargement ~ Primary pneumonic plague-
Transmission : Inhalation of droplets causing sepsis/death-
: Lymphadenopathy, high fever, hypotension, renal failureS/SY.Peptis - Produces plague (black death)
Y.Pseudotuberculosis - Respiratory pneumonia
Y.enterocolitis - Contaminates blood during transfusion - Triggers ankylosing spondylitis
- Diarrheal disease
Pasturella - Gram (-), small rods
-
Reservoir : Mouths of animals (cats/dogs)-
Transmission : By bites-
Diagnosis : Wound infection – Cellulitis w/lymphadenitis-
Exotoxin : Capsule spreading within skin rapidly-
: AmoxicillinTxHaemophilus
(“blood loving”) -
-
Gram (-) coccobacillusCapsule : Virulent factor-
Exotoxin : none-
Normal Flora : Upper respiratory tract w/possible extension into middle ear and sinuses-
Transmission : Respiratory tract (person-to-person) especially in children (5mo –5 yr)-
: Isolated by bloodLab-
: Inspiratory stridor, lateral neck x-ray revelas thumbprintS/s-
Culture : ~Brain heart infusion agar w/blood~Growth requires X(blood)+V(NAD) factor
-
Immunization Capsular vaccineH. Influenzae B Common cold (most virulent of all)
H. ducreyi -STD (Chancroid) w/ Ulcers on genitalia, inflame/tenderness
-Diff/Diag: Syphilus, Herpes Simplex
H. Influenzae A-F Flu
Dz: Meningitis (very common among children and if left untx may be fatal), Pneumonia, Empyema, Epiglottitis, Cellulitis
Secondary Dz: Chronic bronchitis, otitis media, sinusitis
Q 4-yr-old with respiratory distress with 103.8oF fever; drools, difficulty swallowing, stridor.
CXR shows epiglottis swelling. Infant has never had a vaccine:
Bodetella B. Pertusis
Whooping cough disease
- Gram (-), non-motile
-
Morphology : Resembles H. Influenzae-
Capsule : present-
: Blood isolationLab-
Exotoxin : Irritate surface cells producing cough/ lymphocytosis-
Transmission : Respiratory route (person-to-person)-
Pathogenesis : Adhere/multiply on epi-surface of trachea, bronchi and interfere with ciliary axn-
: Untx leads to necrosis of epithelium with PMN infiltration and Dz peribronchial inflammation therefore resulting in interstitial pneumonia-
Secondary Dz : Bact. Pneumonia with atelectasis and decreased O2 in blood leading to tertiary dz of convulsions in infants-
Immunization : DPT containing killed bordetella bact. Different Stages Catarrhal:
Paroxsymal
- Mild coughing/sneezing - Shed large # of org - Not very ill
- Incubation: 1-2 weeks
- Exploxive coughing w/ “Whoop” upon inhalation - Rapid exhaustion w/vomiting, cyanosis, convulsions - Incubation: 2-4 weeks
Q ADP-ribosyl transferase which effects G-regulatory protein
causes increase cAMP levels: Pertussis toxin
Q Paroxysms of cough known as Whooping cough which
organism involved: Bordatella pertussis
Brucella • Gram (-), Oxidase (+), Urease (+)
• Typically infest animals
•
S/S: Malaise, fever, weakness, aches, sweats, GI & Nervous symptoms, lymphadenopathy• Acute infection leading to chronic
-
Serology : 1st week increased IgM4th week increased IgG B. melintensis
Brucellosis Infects goat
- Fever, acute bacteriaemia, non-motile, gram (-) - Isolation in blood
-
Transmission : ~Intestinal tract (infected milk/products) ~Mucous membrane~Skin (contact w/inf animals
-
Spreads via lymphatic channel, thoracic duct, blood stream-
affects paraenchymal organs leading to abscess in Dz:liver/spleen/bone marrow
-
Secondary : Osteomyelitis, meningitis, cholecystitis B. arbortus - Increased Co2 for growth
- Mild dz
- Non caseating granuloma
- In pregnant animals, infection reaches placenta causing: Placentitis & Abortion
- However not in humans Q 16-yr-old girl with enlarged lymph node (Right axilla). Blood
count – normal; Granulomas w/neutrophils + necrotic debris. Which org:
Brucella Henselae (also responsible for cat scratch disease) (??bartonella)
Legionella
Water loving pathogen
- Gram (-) long rods - Catalase (+), Oxidase (+)
-
Normal flora : Sputum-
Culture: Yeast agar (fails to grow on ordinary media must be supplemented with iron and cysteine (Silver stain), slow growing org. Seen best with immunofluorescence-
Transmission: Inhalation of aerosols generated from air conditioner, shower heads-
: ~Outbreak of pneumonia (pneumophilia)Dz ~Lobular, segmental, patchy pulmon.infiltrations-
Incidence: ~Higher risk in males > 55 yr~Smokers, Diabetics, Pts w/chronic bronchitis, transplant pts or immunosupp.
-
S/s: Fever, chills, malaise, non-prod-cough, hypoxia, diarrhea, delirium, leukocytosis, hyponatremia, hematuria,bronchopneumonia
-
Lab: Isolation by bronchial washings since it is difficult with sputum/smearsQ Alcoholic + smoker, dyspnea, headache, muscle pain, fever,
chills; which organism involved: Legionella pneumophillia
Gardenella Vaginalis
-
: Vaginosis (non-specific / bacterial vaginitis)Dz-
Pathogenesis : Clue cells yielded with absence of common causes of vaginitis (eg: yeast, trichomonas)-
: Vaginal discharge will have “fishy odor” containing Lab anaerobes and pH will be > 4.5-
: MetronidazoleTxCalymmatobacterium
aka Donovania
- Related to Klebsiella
- Causes: Granuloma Inguinale - Rare STD of genital ulcers
Whipples Disease
Tropheryma Whippelli
- S/s: Fever, pain of abdomen, diarrhea, wt.loss, polyarthritis - Gram (+)
Corynebacterium
Diphtheria
- Gram (+)ve club-shaped rod, aerobic, non-filamentous - Exotoxin produced
-
resp. dropletsT:-
Manifestation sore throats, resp. infections-
C/F: Lymphadenopathy/edema of entire neck, difficulty swallowing-
Path:• Inhibits protein synthesis by ADP-ribosylation of EF2
-
Stain: blood samples will not be helpful b/c it does not enter bloodstream-
Virulence test: Eleks test-
Prevention : w/toxoid (active) immunization DPT-
Pencillin, Erythromycin (inhibits growth of bacteria)Tx: Q Corynebacterium diphtheria: Child should be given toxoidQ All are correct about corneybacteria except: C. Diptheria toxoid shouldn’t be given to kids under 3 years b/c incidence of complication is too high
Clostridium - Gram (+) bacilli, Motile - H-antigen (+) with flagella
-
Culture : Grows under anaerobic conditions-
Reservoir : Found in intestinal tractC. Tetani - Transmission: Puncture wounds/trauma (produces tetanus) - Extreme muscle spasm
- Blocks release of inhibitory mediators at spinal synapses
C.Botulinum - Produced in poorly preserved food (canned beans) - Symptoms: Weakness, dizziness, blurred vision - Muscle paralysis
Infant botulism - Household dust ingested
- Causing constipation, limpness diplopia/dysphagia (floppy baby) - Toxin produced in gut
Wound botulism - Traumatic implantation of spores - In Vivo production of toxin - Tx: Penicillin
- Blocks release of Ach at myoneural junction in flaccid paralysis - Heat labile
C.Perfringenes - Non-motile
- Found in soil, human colon - Dz: Gas gangrene (myonecrosis)
Alpha-toxin of C.p - Disrupts membranes hemolyzing RBC, damaging platelets
Entertotoxin - Causes food poisoning
-
Disruption of ion-transport watery diarrhea and crampsCl. difficile - Pseudomembranous colitis - Yellow plaques on colon - Production of lecthinase
Q Causes muscle paralysis: Botulinum toxin
Q The most important for preventive function of the antibody stimulated by Tetanus:
To neutralize the toxin of the pathogen Q All correct about Clostridium Perferinges except: Gram (-)ve rod that does not ferment lactose Q Which concerning immunization against disease caused by
clostridrium is correct: Immunization with tetnus toxoid induces effective protection against tetnus Q What organism causes gas gangrene: C. Perfringes
Q Each is true concerning wound infection caused by
perfringens except: Organism grows only in human cell culture
Q Causes muscle spasms: Tetanus toxin
Q Causes nyonecrosis: Clostridium alpha-toxin
Virulence tests
-
In Vitro Elk’s test (neutralization test / horse serum)-
In Vivo inoculation and observationListeria Monocytogenes
Perinatal human listeriosis Listeria meningitis
- Gram (+)ve rod
-
Oral – GI tractT:-
Motility: 22o – yes 37o no-
Manifestation early intrauterine sepsis/death/meningitis in neonates/adult transplant patients-
Path: Invades mononuclear cells-
Stain: Beta-hemolysis in blood agar and CSF culture-
AmpicillinTx:Q 28 yr-old preg. Women with fever, headache, myalgia, pain
and spontaneous abortion: Listeria monocystogenes
Q Neonate with widespread granulomas in uterus: Listeria monocystogenes commonly acquired from uterus
Bacillus Anthrax
Woolsorter’s disease
- Gram (+)ve rod, spore-forming, aerobic - Polypeptide capsule of D-glutamic acid - Resistant to heat
-
Skin/mouth/inhalationT:-
Manifestations: Skin ulcers/malignant pus, pneumonia in people working with animal (hides), soil,-
PencillinTx:-
Prevention: Immunization with live vaccineQ Bacillus Anthrax: Causes Woolsorters disease
Mycobacteria - No gram stain, Rod shaped, aerobic, non-spore - Not easily stained and if stained- resist decolorization - Therefore: Acid fast bacilli
Many Types - M. Tuberculosis, M. Avium, M. Bovis, M. Leprae, M. Ulcerans, M. Balnei, M. Butyricum, M. Phelei, M. Sterocori and atypical mycobacteria
M. Tuberculosis
-
Catalase (-), Aerobic, Acid Fast bacilli-
Cell wall with mycolic acids (increased lipid content) induces delayed hypersensitivity (resistance to inf)-
Culture : ~Slow growth (3-6 wks), ~Produces Niacin~Salt solution required
M.tub.Hominis Respiratory Tuberculosis (most common) M.tub.Bovis Intestinal
-
Transmission: Inhalation – reaching alveoli where it fully establishes and proliferates-
Lesions: Exudative type•
Ac. Inflame.rxn, edema w/fluid, PMN, Peyer’s Patches with obstruction in terminal ileum• (+) Tuberculin test (leads to hypersensitivity and resistence to recurrent episodes)
Productive type
• Chronic granuloma in Central (multinuc.giant cells), Midzone (Pale epi-cells), Peripheral (Fibroblasts) - Tx: drug resistance common especially in immune.supp pt.
Tuberculin test - (+)ve test does not prove presence of active dz therefore isolation of organism needed for diagnosis
M.avium, M.kansosii, M.smegmaus, M.scrofulaceum
- Opportunistic in nature - Slow growth in culture
Pulmonary symptoms
-
M.Kanasii (photochromoge), M.Avium- Aids, cancer, chrong lung disease patients (imm.sup) - Disseminated TB in Aids patient
Lymphadenitis symp - M.Scrofulaceum
- Children affected (painless cervical adenopathy)
Gastrointestinal symp - M.Avium
- Immunocompromised patients
Soft Tissue - M.Ulcerans
- Seen in tropical fishing persons
Swimming pool granuloma - M.Marinum
Rapid Growing - M.Fortuitum
Q AIDS patient with chronic cough, has been running low grade fever. CXR is unremarkable. Sputum demonstrates acid fast organisms. CD4 + T-cells 500/mL. Which causative agent:
M. Avium Complex Q Disfiguring lesions with loss of sensation to touch. Scrapings
from skin lesions show which org: M. Leprae
Spirochetes - Motile (H-antigen (+))
- Treponema, Borrelia, Leptospira
Lyme’s disease - Borrelia burgdorferi
- Spirochetes in synovial fluid - S/s: arthritis, inflammation of joints Q Polyarthritis in knees with cough. Sphirochete shows lyme
disease which organism involved:
B. bergdorferi
Q Global eradication of lyme disease is unlikely b/c: Can be maintained by tick vector
Mycoplasma - Rickettsia, Chlamydia, Lymphogranuloma Vereneum
M.pneumoniae
-
Acquired infection contracted in military stations and crowdedsituations
-
Dz: produces interstitial pneumonia assoc.w/erthema multiforme and bullous myringitis- Requires sterols
Rickettsia - Respiratory pathogen transmitted w/o vector
- Transmission: Inhalation by individuals who have an association with the birthing process in sheep, cows, goats or milk industry - Coxiella burnetti (shovel feces of sheep)
Chlamydia trachomatis
C.pneumoniae
- Infertility in women with scarred fallopian tubes
-
Contracted when newborn passes thru birth canal- Produces pneumonia w/abrupt onset of tachypnea, wheezing, hyperaeration, eosinophilia and lack of fever, maybe association with coronary artery dz leading to interstitial pneumonia
-
Transmission : droplets infection-
: Cold agglutinins not associatedLab-
: DoxycyclineTxC. Trachomatis - Associated with conjunctivitis Q 19 yr-old pt. w/weakness, malaise, dry cough. 100oF;
bronchial lavage are slow growing. Org: Mycoplasma pneumoniae
Q Persistent urethritis: Chlamydia
Q Sexually active femaile experiences lower ab-pain, no rash on labia; Smear shows scanty neutrophils. What lab results show:
Inclusion bodies due to Chalmydia Q Pt. collapses, loss of consciousness, severe lower ab-pain,
nausea, shock, ectopic pregnancy. Which organism: Chlamydia Q 4-yr-old infant with chlamydia trachomonis. Blindness in this
Q Maculopapular rash, shock + renal failure 3 days after returning from camping trip in east USA. Which org responsible for symptoms:
Rickettsia ricketsii (aka: Rocky mountain spotted fever) due to ticks
Nocardia - Gram (-), aerobic
- Predominantly respiratory pathogen
- Seen in patients with defects in cellular immunity - Ex: Heart transplantation
- Produces micro abscesses in lung with granulomas
N.asteroids - Partially acid fast
Review #5: Virology Measles Virus
aka Rubeola
-
: Child with fever, sore throat & ulcerative lesion on soft S/spalate (Kopliks spots).-
From Paramyxovirus family,-
Transmission: inhalation - Vaccine preventable4-yr-old male with fever, sore throat, unusal irritability. P/E shows 10-15 small, gray which shallow ulcerative lesions along posterior margin of soft palate. Pharyngeal walls-red. No lesions on gums. Child is of dark complexion with no obvious rashes.
Q Disease: Measles
Q Lesions found on mouth known as: Koplik’s spots
Q Causative agent: Paramyxovirus
Q Transmission of disease by: Inhalation of droplets
Q Another name for disease: Rubeloa
Q Example of arthropod-bone viruses causing encephalitis in
humans including all except: Measles virus
Mumps - Involves Salivary glands(Parotids)
- Vaccine preventable Rabies Virus
Rabdovirus
- Rod or Bullet shaped - Negri bodies diagnostic - Virus destroyed by UV radiation
-
Culture : Multiplies in muscle & conn. Tissue - Infection of the CNS- Incubation 21-60 days. Isolation by Saliva for rabies virus. Q Which virus belongs to rhabdovirus group that resembles a
bullet, flat at one end? Rabies
Infection spread by vector Rabies
Inf.prod vesicular lesions Aseptic meningitis Resp. infection
Infe in throat or intestine
Blood Saliva Vessicle fluid CSF
Throat swab
Throat swab + feces
Q Rabies source of specimen for virus isolation: Saliva
Q Colorado tick fever cultured on: Blood
Q Influenzae specimen isolated on: Throat swab
Q HSV specimen isolvated on: Vessicle fluid
EBV - Nasopharngeal carcinoma
- Burkitt’s lymphoma.
Q Burkitts + Nasopharyngeal carcinoma: EBV
HPV (Papilloma virus) Cervical carcinoma
Q Cervical carcinoma: HPV
Herpes Simplex I oral lesions (painful) II genital lesions (painful) Herpes zoster
aka Shingles •• affects nervous systemdorsal nerve root of trunk involved Q A viral org. was isolated from a painful blister on the lip of a
teenager girl. Agent was found to be double-stranded, linear DNA and was enveloped. The patient had similar sore 2 months ago:
Herpes Simples I (HSV)
RSV - Cause of pneumonia & bronchiolitis in infants. - Only respiratory viruses
- ****Rota viruses do not cause respiratory viruses Coxsackie Group B, type 1-6: aseptic meningitis
Coxsackie Comm... cause of myocarditis and pericarditis Q The illness which often results infection w/Poliovirus,
Coxsackievirus and Echovirus is: Aseptic meningitis Rhinovirus Do not cause gastroenteritis
Rhinovirus - Common cold in fall and winter - Winters disease - Reservoir is school children.
- Transmission: Inhalation droplets Adenovirus Virus responsible for cold in spring and summer. Live vaccine -Oral Polio Vaccine (OPV)
-Produces lasting intestinal immunity Live vaccine in AIDS MMR
Q Which strategy like to induce lasting intestinal mucosal
immunity to poliovirus: Oral vaccination w/live vaccine Q 9-mo-old infant is brought to health dept. for second dose of
OPV (oral polio virus) 2 weeks after 1st vaccine. Child has
mild diarrhea and decision is made to defer 2nd dose.
Bacterial exam of stool is unremarkable but a small, single strand positive RNA virus is isolated. Same agent in sewage effluent previous week. Viral isolated not affected by either:
Poliovirus
Varicella Primary disease of children
Q Varicella is: Primary disease of children
Rotavirus Common cause of diarrhea in children / ELISA for diagnosis Q 6-months child with persistent cough + fever, physical exam
and CXR suggests pneumonia. Which org is lease likely to cause infection:
Rotavirus
Cytomegalovirus (CMV) - Comm. Cause of diarrhea
- S/s: Infant not responding to sound (showing neural deficits) due to periventricular calcification
Q A newborn infant has multiple, hemorrhagic cutaneous lesions and does not respond to SOUND. Head CT scan shows periventricular calcification:
Cytomegalovirus (CMV)
HIV Structure - Multi-shaped but not bullet shaped
Q Structural features of HIV including all Except: Bullet-shaped virion Norwalk Virus Most comm.. cause of gastroenteritis in adults
HAV - Incubation period of 15-45 days
- Travelor’s risk; not chronic - Transmission via fecal/oral route - In vitro + extensive antigenic variation
- Common in day care centers, jail, corrective centers
HBV • Hepatocellular carcinoma (chronic disease)
• Polyarteritis nodosa patients affected • Transmission via accidental needle stick HCV
Flavi virus
- Hepatocellular carcinoma
- Post-transfusion, chronic hepatitis - Person-to-person contact
- No protective antibodies
- Associated with cryoglobulins & membranoproliferative glomerulonephritis
HDV • Super infection in patients with active HBV
• HbsAg therefore chronic disease • No protective antibodies
HEV - No chronic state
- Contamination
- Transmission: fecal/oral route
Flavi-virus HCV, HGV
Q The only hepatitis virus that can be grown In vitro is: HAV Q Transmission is primarily by the fecal-oral route: HAV Q Infected individuals do not become carriers: HAV Q Male gender and early infancy are risk factors for chronic
infection: HBV
Q Patient with jaundice. P/E reveals nodular, enlarged liver. CT of ab shows cirrhotic liver w/large mass. Ct-guided biopsy reveals malignant tumor derived from hepatic parenchymal cells:
HBV
Q Hepatocellular carcinoma: HBV/HCV
Q Which hepatitis virus belongs to FLAVI virus group: HCV Q Most infected persons become carriers: HCV Q Autonomous replication as well as transmission from patient to
patient can be accomplished by all Hepatitis viruses except: HDV Q Transmission of this virus also have an active HBV infection: HDV
arborV type of encephalitis Altered mental status, headache. Mosquito-infested swamp, gram stain & culture of CFS is –ve.
Viruses DNA or RNA never both
Q Child w/sickle cell anemia/ She has been tired lately and may have come down w/virus. She is very pale and severely anemic. Bone marrow aspirate contains no erythroid precursor cells:
Parvovirus
Virus measurement Electron microscopy
Cultivation of virus - Fertile eggs (chick embryo) - Results in death of embryo - Production of pocks/plaques
- Chorio-allantoic membrane involved
ECLIPSE period - Viral replication after interaction with host, phase of growth cycle
Mode of Transmission
Person to person Fecal/oral route Arthropod vecor
Influenza, measles, pox Rotavirus, Hep. A Arbovirus
HIV, CMV, HBV, Rubella All have increased congenital risk factors
Review #6: Parasitology A Protozoa
- ingest solid pieces of food thru a small mouth called the cytostome - reproduce asexually; undergo DNA replicat’n
- when exposed to new environments; such as temperature changes, transit down the intestinal tract or chemical agents… they secrete a protective coat and shrink into a round armored form called cyst - It is this cyst form that is infective when ingested by humans
- Following ingestion it converts back into motile form called trophozoite Avoid contaminated food and drink
B Intestinal protozoa
- 5 that cause diarrhea
• Entamoeba histolytica causes a bloody diarrhea
• Giardia lamblia & Cyclospora cayetanensis cause a non-bloody diarrhea
• Cryptosporidium & Isospora belli cause severe diarrhea in individuals w/defective immune systems (such as AIDS)
C Free-living meningitis-causing amoebas - Naegleria fowleri and Acanthameoba - Live in fresh water and moist soils
- Infection common during summer months when people swim in pools and lakes - Although large exposure, infection is rare
- When It does occur, organisms penetrate nasal mucosa thru cribriform plate into brain and spinal fluid causing meningoencephalitis
D Infection in AIDS patients
- Cryptosporidium and Isospora cause severe, chronic diarrhea - Toxoplasma gondii and Pneumocystis carinii
- Ineffective immune system sets them up for certain infections that seldom affect immunocompetent patients
1 Entamoeba histolytica – aka: Amoeba
C/F - Asymptomatic carriage Intestinal amebiasis (acute or chronic)
- Bloody diarrhea when trophozoites invade intestinal mucosa causing erosions - Abdominal pain, cramps
Extra-intestinal amebiasis
- Liver abscesses followed by spread thru diaphragm into lung - Further causing pulmonary abscesses and often death
Dx
-
Fecal (stool) exam for cysts & trophozoites w/RBCs w/in cytoplasm - Sigmoidoscopy-
Abdominal CT for liver abscesses Tx - MetrondiazoleMorphology
n’ stuff •• Oocyst (pseudohyphae)Trophozoite: motile + ingests RBCs in cytoplasm • Homosexual men commonly are asymptomatic carriers Q 27 yr IV drug user, diff swallowing. White plagues along
tongue and oral mucosa budding yeast – pseudohyphae
Q Entamoeba histolytica can cause: Abscess in the liver and lungs 2 Giardia lamblia
C/F
-
Foul smelling, greasy diarrhea ( ↑ fat content ) Steatorrhea - Abdominal gassy distention- Duodenum/jejunum involvement b/c parasite adheres to lining interfering intestinal fat absorption - Does not invade intestinal wall (only adheres) therefore no blood in stool
Dx
-
Fecal (stool) exam for cysts & trophozoites - Immunoassay to detect for org in stool Tx - MetrondiazoleMorphology • Oocyst
• Trophozoite: flagellated 3 Cyclospora cayetanesis
C/F - Watery diarrhea + Nausea/vomiting
Dx
-
Stool exam for oocysts that fluoresce under UV light Tx - Trimethoprim/sulfamethoxazoleMorphology
n’ stuff • Oocyst Oocysts from stool contaminate fruit/vegetables 4 Cryptospoidium
C/F - Watery diarrhea + vomiting + abdominal pain (no blood) - Involves: brush border of small intestine
-
↑ incidence in AIDS pt: > 50 stools/day, ↑ fluid loss (up to 3-17 liters of stool/day) Dx-
Fecal exam for oocysts-
Biopsy small intestine lining - ELISA for detection of AntigenTx
-
Usually self-limiting No effective therapy Morphologyn’ stuff •• Oocysts is infective agent ( contains 4 sporozoites)Life cycle occurs w/in epithelial cells • Animals and humans are equally infected
• Outbreaks of diarrhea from contaminated water sources and infants in daycare centers • Sporadic cases in travelers
C/F - Painful vaginal itching
- Burning and pain on urination (micturation) - Yellow-green malodorous discharge - Urethra+vaginal involvement in females - Urethra+prostate gland involvement in males Dx
-
Examination of vaginal discharge highly motile-
Urine exam ↑ # presentTx - Metrondiazole – to patients sexual partner Morphology
n’ stuff •• Sexually transmittedNo oocyst – only flagellated trophozoite ( highly motile)
6 Naegleria fowleri
C/F
-
Acute meningitis fatal (95%) within one week- Fever, headache, stiff neck, nausea, vomiting, short hx of swimming earlier - Sudden deadly infection in AIDS/transplant patients
Dx
-
CSF exam for motile amoeba and ↑ neutrophil count, low glucose & ↑ protein (identical to bacterial meningitis, however Gram stain will show no bacteria)-
WBC ↑ count suggests infection Tx - Amphotericin B (anti-fungal drug) Morphologyn’ stuff •• AmoebaLives in freshwater lakes
Q what is the treatment of cryptococcers neoformans? amphoteran B – for cryptococal meningitis – reaches CSF
7 Acanthamoeba species
C/F
-
Chronic, slow granulomatous brain infection fatal w/in one year - Over weeks: fever, headache, seizures, focal neuro-signs-
Corneal infection (Keratitis) assoc.w/contact lens (cleaned in non-sterile solutions) Dx-
CSF + brain tissue for cysts + mature trophozoites- Corneal scrapings
Tx
-
Multiple antifungal drugs (prognosis ↓ ) - Corneal transplant or antimicrobial drugs Morphologyn’ stuff
•
• Amoeba cyst in brainCase of chronic meningoencephalitis• Lives in freshwater lakes, soil, swimming pools
Q healthy pt. w/ contacts – dev ulcerative lesion of eye acanthamoeba – freshwater lakes 8 Toxoplasma gondii (Torch org.)
C/F - Congenitally acquired
•
Still birth chorioretinitis, blindness, seizures, mental retardation/syndromes•
Normal infants chorioretinitis (which may lead to blindness) in adolescence - Immunocompromised patients•
↑ susceptibility•
Infection includes encephalitis presenting as brain mass, chorioretinitis, lymph node-liver-spleen enlargement, pneumonia- Most infections: Benign and asymptomatic
- Symptomatic disease: involves cell destruction, reproduction, cyst formation Dx
-
Serology ↑ IgM + IgG-
Biospy from lymph nodes, brain, myocardium, body fluids (including CSF, amniotic or bronchoalveolar lavage fluid) can be examined for organisms-
CT scan mass in brain - Examination of retinaTx - Sulfadiazine/Clindamycin Morphology
n’ stuff • Transmission Ingestion of oocysts in raw port
Inhalation of oocysts from cat feces (80% of cats infected) Pregnant women should avoid cats
• Oocyst (infective) + Trophozoites
• Found in birds, humans but essentially in cats
Q 30yr old vet, usits ob exam—mild cervical lymphadenopathy, px-spiranycin – child
beses of hydrocephalus cerebral calcification toxoplasma gondi Q Which of the following infections agents cannot complete its entire life cycle in the
human without resorting to stages in other living organisms: Toxoplasma gondii 9 Pneumocystis carinii
C/F - Interstitial pneumonia w/fever + dry cough b/c invades lungs at early stage
-
↑ association in AIDS patients (CD4 count < 200) causing PCPDx
-
Silver stain ‘Flying saucer’ appearing fungi in any of following: • Saline induced sputum• Bronchoalveolar lavage w/bronchoscope • Bronchial wall biopsy
-
X-ray interstitial pneumonia w/diffuse infiltrates Tx - Trimeth/sulfamethazoleMorphology
N’ stuff •
•
Flying-saucer appearing fungusTransmission in early age by resp.route that usually remains latent Q Which of the following statements are untrue of pneumocystiscarinii:
Diagnosis is made by the serology; microscopy is of no value
10 Malaria
Org Plasmodium falciparum, P. vivax, P. ovale, P. malariae C/F - High fever & shaking chills: episodic
- Sweating (due to RBC rupture releasing merozoites) - Anemia
- Hepatosplenomegaly/splenomegaly
- Brain lung and/or kidney damage w/P. falciparum 1) Tertian malaria
1. episodes occur every 48 hours (P. vivax + P.ovale) 2. Benign: incubation period: 7-10 days
3. Malignant: Black water fever (resulting from kidney damage) 2) Quartan malaria
1. episodes occur every 72 hours (P.malariae) 3) P. Falciparum
1. irregular episodes occur every 36-48 hrs 2. Most common and deadly
Dx
-
Blood smear Trophozoites (diamond-ring shaped) Tx - Chloroquine + Primaquine (P.ovale + P.vivax)- Chloroquine (P.malariae + non-chloroquine resistant P.falciparum) - Quinine (Chloroquine resistant P.falciparum)
Prophylaxis tx
- Chloroquine - DOC
- Mefloquine (if choloroquine resistance present) Radical cure Primaquine
Morphology
n’ stuff •
•
Female anopheles mosquitoP.vivax + P.ovale Hypnozoites=dormant in liver • African Americans resistant to: P.vivax (lack RBC membrane antigen duffy a/b)
P.falciparum (↑ incidence of sickle cell anemia trait)11 Leishmania
C/F Cutaneous leishmaniasis
- L.tropica (incubation: 2 wks – 2 months)
- single ulcer (red papule) at site of bite (aka: Oriental sore) - heals in one year leaving depigmented scar
Diffuse cutaneous
- non-ulcerative nodular bite site (usually near nose) - no immediate tx required
Mucocutaneous
- L.braziliensis ((incubation: 2 wks – 2 months) - ulcers on mucus membranes after first ulcer heals
- ulcers erode nasal septum, soft palate and lips (can last 20-40 yrs) Visceral leishmaniasis (aka: Kala-azar)
- L.donovani (incubation: weeks to 1 yr) - common in young, mal-nourished children
- fever, chills, sweating, diarrhea, anemia, anorexia, weight loss, hepatosplenomegaly, kidney damage - fatal (usually)
Dx - Look for protozoa in: • Blood smear
• Biopsy of skin lesions, spleen, liver, bome marrow - Leishmanin skin test
• Negative in immunocompromised patients
• R/o diffuse cutaneous & active visceral leishmaniasis - Serological test
• Aldehyde test Tx - Arsenical drug
- Amphotericin B (Mucocutaneous leismania) Morphology
n’ stuff
-Promastigote: Flagellated sandfly (bite)
-Amastigote: non-flagellated in phagocytic cells of reticuloendothelial system -Zoonotic: carried by rodents, dogs & foxes
-Vector: Sand flies
Q Leishmania donovanum produces: Amastigotes which are seen in the human reticuloendothelial system
12 African Trypanosoma
Trypanosome rhodesiense & gambiense C/F African Sleeping Sickness
- Hard, red painful skin ulcer at site of tsetse fly bite (heals in 2 wks)
- Intermittent Fever (due to variable surface glycoproteins), headache, lymph node swelling - CNS symptoms: daytime drowsiness, difficulty walking, slurred speech, coma, death
• West African Sleeping sickness
Slow progessing fevers, late neurological symptoms • East African Sleeping sickness
More severe, rapid cycling of fevers, neuro-symptoms and death within weeks-to-months
Dx
-
Blood, spinal fluid, lymph nodes Visualize trypomastigotes-
Serology ↑ IgMMorphology
N’ stuff •• Tsetse fly bitesContaminated blood transfusion
• Trypomastigote: motile, flagellated; in blood, lymph nodes, CNS • Trypomastigote & epimastigote: in tsetse flies
• As antibodies are formed by the human body against a particular VSG, the trypanosome will produce a progeny with a different VSG causing recurrent feveres
Q In which of the following infections would you not expect to
find intracellular amstigote forms: Trypansoma brucei rhodesience 13 American Trypanosoma
Trypanosome cruzi C/F Chagas’ disease
- Chagoma: hardened red area at site of parasite entry - Ac. Chagas’ dz: fever, malaise & swollen lymph nodes
• Meningoencephalitis
• Acute myocarditis w/tacchycardia, EKG changes
- Intermediate dz: low levels of parasites in blood w/positive antibodies against T.cruzi but no symptoms (most people remain in this phase for life)
- Chronic Chagas’ dz: Cardiomyopathy (dilated heart, heart failure, arrhythmias) along with megacolon (causing constipation/ab pain) and megaesophagus (difficulty+pain swallowing, vomiting of food) Dx
-
Blood, spinal fluid, lymph nodes Visualize trypomastigotes-
Xenodiagnosis (ac. Dz) 40 lab grown reduvid bugs are allowed to feed on a patient; one month later bug’s intestinal contents are examined for the parasitesTx - Nitrofurtimo (acute dz)
- No tx for chronic manifestations Morphology
N’ stuff •• Trypomastigote: motile, flagellated; in blood (extracellular)Amastigote: intracellular & non-motile – present in macrophages of lymph nodes, heart, brain • Trypomastigote & epimastigote: in kissing bug
• As antibodies are formed by the human body against a particular VSG, the trypanosome will produce a progeny with a different VSG causing recurrent feveres
• Kissing bug (reduvid bug) defecates on human skin while feeding • Trypomastigotes present in feces tunnel into skin
• Contaminated blood transfusion 14 Balantidium Coli
C/F - diarrhea ( by consuming contaminated food, water, pig feces) - most patients: asymptomatic
Dx - Fecal exam: Identify trophozoites or cysts in stool Tx - Tetracycline
Morphology
N’ stuff •• Ciliated trophozoitesLargest parasitic protozoan in intestine 15 Isospora/Microsporidia
C/F - Severe diarrhea
- Malabsorption in AIDS patients Dx - Fecal exam: Identify oocysts in stool
- Biopsy - Eosinophilia
Tx - Trimeth/sulfamethazole
- Abendalzole can treat microsporidia Morphology
N’ stuff •• Ciliated trophozoitesLargest parasitic protozoan in intestine
Q 24 yr AIDS pt. – chronic ab pain, low greade fever, darrihea, malabsorption,
Intestinal Nematodes (Roundworms)
1 Ascaris lumbricoides
C/F - Asymptomatic - Abdominal cramping
- Dry cough + fever while larvae are in lungs
- Children may become malnutritioned as worm competes for food Dx
-
Fecal exam for eggs (ova)-
Sputum may reveal larvae - EosinophiliaTx - Mebendazole (paralyzes worm & prevents it from migrating out of SI) - Albendazole
Morphology
N’ stuff •• Adult attains a length of 20-30 cmIngests eggs
• If treated incorrectly, worm will migrate out of GI tract 2 Necator americanus (aka Hookworm)
C/F - Diarrhea, abdominal pain, weight loss - Iron deficiency anemia
- Itching at site of skin penetration + rash - Occasional cough with blood sputum Dx
-
Fecal exam for eggs-
Sputum larvae - EosinophiliaTx - Mebendazole
- Albendazole Morphology
N’ stuff •• Adults about 1cm lengthLarvae penetrate thru skin
• Ancyclostoma duodenale is another species of hookworm 3 Strongyloides stercoralis
C/F - Vomiting, diarrhea, anemia, weight loss
- Occasionally fatal due to massive autoinfection in immunocompromised hosts Dx
-
Fecal exam for larvae (no eggs present)-
Enterotest swallow long nylong string and later pull out – might show larvae-
Sputum larvae- Eosinophilia Tx - Thiabendazole
- Albendazole Morphology
N’ stuff •• Larvae penetrate skinAutoinfection • Adult females 2 mm long
Q Which of the following diseases can be prevented by avoiding contact of naked skin with soil:
Stongyloids infection 4 Trichinella spiralis
C/F - Fever, abdominal pain, diarrhea
- Muscle aches as larvae might migrate to skeletal muscles - Severe cases: larvae might migrate to heart and brain Dx - Serologic tests
- Biopsy: Muscle
- Increase levels of muscle enzymes circulating in blood - Eosinophilia
Morphology
N’ stuff
•
• ↑Ingestion of encysted larvae (often found in raw pork) assoc.w/port (always cook or freeze prior to consumption) • Cysts in skeletal muscle5 Trichuris trichiura (aka: Whipworm)
C/F - Diarrhea + Abdominal pain Dx
-
Fecal exam eggs- No eosinophilia
Tx - Mebendazole
- Albendazole Morphology
N’ stuff •• Eggs must incubate in moist soil for 3-6weeks before they become infectedTransmission via ingestion of eggs • Eggs look like a football with polar bumps on each end
• Adults whip-shaped (3-5 cm length)
Q A young child is admitted to your care. You find that he is anemic with a very low lever of serum iron you order a stool specimen to be examined for ova and parasites. The laboratory informs you that the feces contains egg of Trichuris, Ascaris and Hookworm. The correct treatment would be:
Mebendazole and iron replacement
Q Which one of the following parasitic nematodes does not cause a pneumonitis in the
human: Trichuris trichuria (Whipworm)
6 Enterobius vermicularis (aka Pin worm)
C/F - Severe perianal itching Dx - Scotch-tape test
-
Perineum examination at night may show adult worms with eye - No eosinophiliaTx - Mebendazole & Albendalzole Morphology
N’ stuff •• Female migrates to perianal area at night to lay eggsTransmission via ingestion of eggs • Adult worms 1 cm long
Blood and Tissue Nematodes (Roundworms)
1 Onchocerca volvulus
C/F - Skin nodules (containing adult worms) - Pruitic rash w/darkened pigmentation - Dry scaly skin (aka Lizard skin)
- River Blindness b/c microfilariae migrate thru eye Dx - Skin Biopsy for microfilariae
Tx - Ivernectin (kills microfilarial stage) Morphology
N’ stuff •• Filariae (threadlike adult roundworms)Give birth to live offspring called microfilariae transmitted by black fly • Vector = black fly (in rivers, streams; disease known as river blindness) • Common in Africa and Central/South America
• Disease caused by allergic rxn to both microfilariae & dead worms 2 Wuchereria bancrofti
C/F - Filarial Fever (febrile episodes w/headache and swollen lymph nodes) - Elephantiasis
• Following repeat infections, fibrous tissue form around dead filariae in lymph n. • Plugging the lymphatic sys. Resulting in swelling of legs + genitals
• Thick scaly skin covers edematous lower extremities --> look like elephant legs Dx - Microfilaria in blood drawn at night
- Biopsy - Serology
