Micro Cheat Sheet
(PASS Videos)
Staining Clues
- Gram (+) cocci – staph/strep - Gram (-) cocci – Niserria/Moraxella
- Gram (+) rods – Bacillus, Clostridium, Listeria, Cornybacterium - Gram (+) Branching rods – Nocardia, Actinomyces
Exotoxins (G-) Exotoxin (G+ &G-)
LPS/LOS A-B Component
Lipid A (toxic) A = Toxin B = Binding Increased # Macrophages Nickolsky’s Sign
Increased # Cytokines
Virulence
- Gram (-) pilli or fimbriae - Gram (+) teichoic acid - IgA proteus
- Capsules largest capsule is in Neiserria
- Antiphagocytic Surface (Ex: S.pyogenes – M protein ; N. gonorrhea – pili ; S. aureus – protein A
Neurotoxins
- C. tetani painful spasms - C. botulinum flaccid paralysis
Evade Killing
- Mycobacterium TB – “cord factor” (macrophages cannot breakdown bacteria so T cells surround and create granulomas)
- Listeria – jumps from cell to cell
Media
- MacConkey’s – ferments lactose
- EMB – eosin methylin blue – fecal stool (E.coli) - Buffer Charcoal Yeast Agar – legionella
- Chocolate agar – Neiserria, Haemopolis o X factor = Heme ; V factor = NAD
***Anytime you see this, choose Chocolate agar
- TCBS – Vibrio cholera – ferments sucrose turns orange
***Staph. pyogenes = Staph. aureus (Old name for it) ***Strep. pyogenes is #1 cause for:
o Lymphangitis (see red line going up arm), Impetigo, Necrotizing fasciitis, crysipelas (no blanching), and Scarlet Fever ( rash that spares palms and soles)
Skin Infections
- Cellulitis: flat, red, blanches
- Mastitis: cellulitis around the breast (mother’s should continue to breast feed) - Balanitis: infection at the head of the penis
- Periorbital cellulitis: infants, trauma (little kid with swollen eye) o S. aureus
- Orbital Cellulitis: proptosis, older pt. o S. pneumonia
- Carbuncle: nodular induration with infection
- Furuncle: hair follicle in the middle of the carbuncle; no pus - Carbunculosis: deep skin infection
o S. aureus
- Furunculosis: many infections of the hair shafts o Common areas – nap of neck, chest, legs - Fasciitis: inflammation of the fascia
o Plantar or necrotizing
- Folliculitis: infection of the hair shaft - Blepharitis: infection of the eyelid
Mouth Flora
- S. pyogenes (GAS) - S. pneumonia
- H. influenza IgA protease - N. catarrhalis o N. gonorrhea o N. meningitides - Peptococcus - Peptostreptococcus - Fusobacterium
o “Trench Mouth”- pus from gums
o Vincent’s Angina – painful ulcers at the back of the neck - Actinomyces
o Draining fistulas o Sulphur granules - S. viridians
o S. mutans ferments glucose Dental
Subacute bacterial endocarditis o S. sanguis
o S. salivarius
Stomach Flora
- H. pylori use campylobacter-like test to diagnose (positive turns green)
Urease (+) Bugs “P PUNCHeS B”
- Proteus - Pseudomonas - Ureoplasma - Nocardia - Cryptococcus - H. pylori - S. saprophyticus - Brucellosis Curved Rods - Vibrio - Camphlobacter - Listeria - H.pylori
Small Intestinal Flora
- 95% E.coli processes vit. K production of factors 2, 7, 9, 10 in liver
Small Intestinal Infections
- Cholecystitis
- Ascending Cholangitis - Appendicitis
- Spontaneous bacterial peritonitis - Abdominal abscess
***If there is a perforation, blame anaerobes put in a draining site
E.coli makes...
- 90% of vit. K - Biotin – cofactor
- Folate – for rapidly dividing cells and for purine/pyrimidine synthesis
o All pregnant mothers should be on folate 30-90 days prior to conception
E.coli Helps your body absorb…
- Vit. B12 use Schilling’s Test to determine B12 deficiency o Procedure: give B12 I.M. then give B12 radio-labeled) o If B12 is found in urine, then B12 deficiency
Then give radio-labeled intrinsic factor. If in urine, then deficiency and rule out pernicious anemia
Distal ileum and Colonic flora
- Proteus – 2nd line in UTI - Klebsiella – 3rd line in UTI - Serratia marscencens
- Citrobacter – infant with meningitis with cerebral abscesses - Acenetobacter – immunosurpressed pt. on ventilator - E.coli
Big MaMa Anaerobes
- Bacteroides fragilis – obligate anaerobe of GI - S. bovis – big cause of colon cancer
- C. melanogosepticus – less big cause of colon cancer - C. difficile – pseudomembrane colitis
- GBS - E.coli
- Listeria monocytogenes – really old/really young
BUZZWORDS
- Staph gram (+) in clusters
Aureus Epidermitis Saprophyticus Gold pigment White Pigment n/a Β – lactamase Deep to Skin Skin
Coagulase + Novobiocin Sensitive Novobiocin Resistant MSA – ferments mannitol
#1 Osteomyelitis Prosthetic devices UTI; honeymoon cystitis
- S. aureus
o Catalse + - breaks down H2O2
o Β – lactamase – always “garage door”
o Coagulase & staphlokinase – eats through clots o MCC of Acute Endocarditis
o MCC of osteomylitis
o MCC of death in burn pt. in first week After first week is pseudomonas o Toxins:
Scalded Skin Syndrome – Exfoliating (Nikolski Sign), red rash all over body except for palms and soles
Toxic Shock Syndrome – Traid (high fever, hypotension, rash); retained tampon, palms and soles
Lecithinase – causes skin infections (subcutaneous fat)
Enterotoxin – causes food poisoning (dairy products- gastroenteritis; Fast- 2-6 hours)
- Enzymes Continued:
o Lipase (breaks down fat) – panniculitis, folliculitis, mastitis
o Elastase (breaks down elastin) – Bullous Emphysema (pneumatocelle) Comes from neutrophils
A1Antitrypsin (liver) – inhibits elastase Panacinar (panlobular) – aging
Centriacinar (centrilobular) – smoking Distal (periceptal) - bullous
o Collagenase (skin & bone – breaks peptide bonds) MCC of osteomyolitis (2nd
is Salmonella) Type IV (BM)
Type III (endothelium – arteries affected) Type II (CT)
- S. epidermidis o Catalase + o White pigment
o Resides under the skin
o MCC of Shunt infections and central line infections o Tx: Vancomycin
Linezolid for vancomycin resistance
Keep pt in a negative pressure room
- S. saphrophyticus o Catalase + o No pigment
o Frequent cause of UTI
Ages 5-10 and 18-24 (post coital UTI, no circumcision) E.Coli is MCC of UTI’s
- Strep gram + cocci in chains
o Lancfield Groups – A, B, C, D o Types of helolysis:
α hemolysis – partial (green zone) β hemolysis – complete (clear zone) γ hemolysis – no hemolysis (red zone)
o Streptokinase – responsible for the β hemolysis (clear zone) Breaks clots – converts plasminogen to plasmin
If ANY past Strep infection, it will NOT work use tPA…
Converts plasminogen to plasmin – breaks clots
Binds fibrinogen – will not clot again
- Thrombolytics
o Urokinase – opens fistulas and grafts o Streptokinase – Beta hemolytic – acute MI
o Tissue Plasminogen Activator (tPA) – acute MI, acute Stroke (within 3hrs) ***Antidote for all three = aminocaproic acid
- S. pneumonia (pneumococcus) o Gram + diplococcic
o Alpha hemolysis (green zone) o 80 Strains
o Pneumococcal vaccine (pneumovax) covers 23 strains (98% coverage) Who should be on it:
>65y/o ; >2y/o with Sickle Cell (spleen-encapsulated organisms)
End Organ Failure
PSGN (post strepto glomerulo nephritis) - skin and throat can cause this
o Strain 12
- S. pyogenes (GAS)
o Beta hemolytic (clear zone) o 70 Strains
o MCC for throat infections
Can lead to rheumatic fever o 2nd
MCC of Skin infections
- S. agalactiae (GBS)
o MCC of neonatal Sepsis o Beta hemolytic (clear zone)
- S. viridians (GDS – mutans, saguis, salivarius) o Alpha hemolytic (green zone)
o MCC of Subacute Bacterial Endocarditis Septic emboli to brain
Roth Spots – emboli to retina
Osler nodes – emboli to fingers (painful) Splinter hemorrhages – emboli to nail beds
Pitting on nail beds = psoriasis ; spooning on nail beds = iron deficiency
Janeway lesions – emboli to toes
o Previous Damage to heart valve predispose to SBE
this is why dentists ask if have a past history of rheumatic fever; damage to valves
o Tx: Amoxicillin
- Enterococcus (faecalis, faeceum) o Anaerobic
o λ hemolytic (red zone)
o likes immunocompromised pt o Nitrite Negative UTI
o Tx: Vancomycin
MOA: cell wall inhibitor (inhibits phospholipid carrier [irreversible]) and Tx for all gram +
Toxicity: Red Man Syndrome, Intense histamine release (not allergic), ototoxicity, nephrotoxicity (tubules and interstitium)
Used for: MRSA, S. epidermidis, and enterococcus
If MSSA, then switch over to napacillin
- Meningitis o 0-2 month GBS E.coli Lysteria o 2mo-10years
S. pneumoniae N. meningitides o 10-21years N. meningitides S. pneumoniae o >21years S. pneumonia - Cornybacterium Diptheriae o Chinese Letters
o Toxin that ADP-ribosylates EF-2
Affects translocation of protein synthesis o Toxin may also cause Heart Block
o Intracellular pathogen
o Cells die, slough off, and mix with mucus, forming a grey membrane in posterior pharynx
o Do NOT scrape: will hemorrhage profusely o DPT: 2m, 4m, 6m, 18m, 5-6y
o TX: antitoxin first; antibiotic (toxin is hurting the pt, not the bug)
- ADP-ribosylators
o Gs: Vibrio Cholera, ETEC o Gi: Bordatella pertussus
o EF2: C. diptheriae, pseudomonas
- Cause Heart Blocks o Lyme Disease o Legionella o Typhoid Fever o Diptheria o Chaga’s Disease
What parts of the body does it like to chew on? Ganglia no release of VIP (relaxing hormone) lower esophageal sphincter remains
