DETERMINATION OF DRUG RESISTANT STRAINS CAUSING URINARY TRACT INFECTIONS WITH MIC AND DISK DIFFUSION METHODS

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www.wjpr.net Vol 4, Issue 09, 2015.

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DETERMINATION OF DRUG RESISTANT STRAINS CAUSING

URINARY TRACT INFECTIONS WITH MIC AND DISK DIFFUSION

METHODS

Afsaneh Karami*1, saideh Mazloom Zadeh2, Ala Rastin3, mehdi ojagh faghihi4, Afroozeh Karami5

1

Department of Infectious Disease, Zanjan University of Medical Sciences, Zanjan, IR Iran.

2.

Epidemiology and Biostatistics Department, Zanjan University of Medical Sciences,

Zanjan, IR Iran.

3

Shahid Beheshti Hospital. Zanjan University of Medical Sciences, Zanjan, IR Iran.

4

Vali-e-asr Hospital, zanjan University of Medical Sciences, Zanjan, IR Iran.

5

Zanjan University of Medical Sciences, Zanjan, IR Iran.

ABSTRACT

Introduction: Urinary tract infection (UTI) is one of the most prevalent bacterial infections. Wide ranges of antibiotics are used for

treatment of UTI. Studies revealed that the antimicrobial therapies are

not effective many times and excessive use of antibiotics could result

in development of multidrug resistance organisms. Determination of

causative strains for infection and especially the pattern of antibiotic

resistance in each area are essential to find a proper antibiotic for the

first-line therapy and consequently preventing from more drug

resistance by prescribing the better drugs. Materials and Methods:

This cross sectional study was performed from 2011 to 2012 on the

organisms collected from urine culture of UTI patients who were

hospitalized at Vali-ye-Asr Hospital in Zanjan, Iran. To define the type of strains the

organisms were cultured in differential medium and the type of strain was determined by

adding anti serum and using tables for the type of strains. After determination of the strains of

each organism for collected urine cultures, the drug resistance was assessed using MIC

(Minimum Inhibitory Concentration) and disc diffusion methods. Results: among 223

patients, 58.7% were female, and their mean age was 64 ± 0.18 years old. The most common

organisms were Escherchia coli (44.8%) and streptococcus (15.7%). The disk diffusion test

Volume 4, Issue 9, 298-310. Research Article ISSN 2277– 7105

Article Received on 30 June 2015,

Revised on 24 July 2015, Accepted on 18 Aug 2015

*Correspondence for Author

Dr. Afsaneh Karami

Department of Infectious Disease, Zanjan

University of Medical Sciences, Zanjan, IR Iran.

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showed highest resistance of vancomycin (83.3%), Nalidixic Acid (83%) and Ampicillin

(80.7%). With the MIC method highest resistance was from Ampicillin, cephalexine,

co-tromoxazole (each one with 92.4% resistancy). In disk diffusion method the most common

Resistancy were in patients over 60 years old , and in MIC method resistancy was more

common in 41-60 years old patients with vancomycin , cefixime , Gentamicin and

co-Amoxiclave. In male patients Resistancy with ceftriaxone and Gentamicine and in female

with vancomycin and co-Amoxiclave were the heighest. With underlyind diseases resistancy

to co-trimoxazole, Ampicillin, co-Amoxiclave, cefixime, cephalexin, ceftriaxone,

Nitrofurantoin, Gentamicin and ciprofloxacin was heighest, and in MIC method to

ciprofloxacin and co-trimoxazole was more common. And the differences were statistically

significant. The highest sensitivity of disk method was from nitrofurantoin with 84.7%

sensitivity, and the highest specitivity was from nalidixic Acid (89.2%). The Correlation

between MIC and disk diffusion method for diagnosis of nitrofurantoin, ofloxacin, nalidixic

acid resistancy was observed. Conclusions: Because of high sensitivity of Nitrofurantoin,

Imipenem and Gentamicin, with disk diffusion and MIC methods, it seems that these drugs

are preffered for treatment and prevention of Urinary tract infections. As Gentamicin,

cephalexin and co-trimoxazole showed high resistancy, it’s recommended to avoid using of

them for those infections.

KEYWORDS: Microbial Sensitivity Tests; Disk Diffusion Antimicrobial Tests; Urinary Tract Infections; Organism, Microbial Sensitivity Tests; Drug Resistance, Bacterial

1. INTRODUCTION

Urinary tract infection (UTI) which specified as urinary system infection is one of the most

prevalent bacterial infections.[1] It is the second common infection after respiratory

infections,[2] Both the lower and upper urinary tracts can be involved by UTI.[1] Some

different conditions are considered for UTI including UTI, Asymptomatic bacteriuria,

Symptomatic UTI, Uncomplicated UTI, Complicated UTI, Recurrent UTI and Urosepsis.[3]

Symptomatic UTI is determined by the specific symptoms of UTI with a significant

bacteriuria with a quantitative count of ≥105

CFU/ml in a urine sample,[4,5] The presence of

bacteria in the urine without the symptoms of UTI is considered as

Asymptomaticbacreriuria,[4] Uncomplicated UTI is distinguished by a symptomatic bladder

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is due to the structural and functional disorders such as organ transplantation, diabetes or

renal failure are considered as complicated UTI.[6, 7]

Almost 150 million individuals throughout the world experience the UTI at least once during

their lifetime.[8] The prevalence of UTI in United States is about more than eight million per

year and almost all of the patients with UTI undergone antibiotic therapy and a restricted

numbers of them should be hospitalized.[9, 10]

In all age groups the prevalence of UTI are higher among women than men with the ratio of 8

women per one man.[11] By age 24 one out of three women will face with UTI and 50% of

women experience UTI during their life,[10] It was shown that the rate of UTI incidence is

higher in elderly men and women especially after the age of 85,[12, 13] In addition, UTI is one

of the usual diseases among children with the prevalence of 2-8% during childhood.[14]

The Escherichia coli (E coli)is the main cause of the UTI. After that Enterobacteraciae

including Klebsiella, Providentia and Proteus mirabilis species are at the second place.

Methicillinresistant Staphylococcus aureus and Enterococcus as gram positive organisms are

of little importance.[15, 16]

Wide ranges of antibiotics are used for treatment of UTI. Amoxicillin, ampicillin, and

sulfonamides are not proper options for UTI treatment since the E coli is resistance to

them.[17-19] Amoxicillin/clavulanic and nitrofurantoin are still effective although

nitrofurantoin shouldn’t prescribe for patients with renal failure.[20] According to

International Clinical Practice Guidelines for the Treatment of Acute Cystitis, for the

treatment of uncomplicated UTIs treating with trimethoprim-sulfamethoxazole (TMP-SMX)

for three days and nitrofurantoin for five days are suggested as the first-line therapy.[21, 22] If

first-line therapies are not possible beta-lactams, such as amoxicillin/clavulanic acid and

cefaclor for 3-7 days is recommended.[19, 21] In a study by Falagas et al., it was revealed that

fosfomycintrometamol is another effective choice for treatment of UTIs. However, the

previous therapies are a little more effective,[23] Fluoroquinoloneis one of the most common

antibiotics for UTI, but resistance to these antibiotics is high and they shouldbe used after

performing the sensitivity test.[15] TMP-SMX, fluoroquinolones and nitrofurantoin are useful

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Many of the antimicrobial therapies are not effective sometimes and excessive useof

antibiotics could result in development of multidrug resistance organisms. Since due to acute

symptoms of UTI the antibiotic therapy will be started before receiving the result of urine

culture and antibiogram, determination of causative strains for infection and especially the

pattern of antibiotic resistance in each area is essential to find a proper antibiotic for the

first-line therapy and consequently preventing from more drug resistance by prescribing the better

drugs.

2. MATERIALS AND METHODS

This is a cross sectional study and was performed from 2011 to 2012. Organisms were

collected from urine culture of patients who diagnosed with UTI and hospitalized at

Vali-ye-Asr Hospital in Zanjan, Iran. The clinical symptoms of patients were fever, chills, suprapubic

tenderness, frequent urination, dysuria and gastrointestinal symptoms such as vomiting and

diarrhea, sepsis and septic shockandthe diagnosis was confirmed by an infectious disease

specialists. The urine culture was performed by midstream clean catch method. Positive result

for women was determined by equal to or more than 102 organisms and for men by equal to

or more than 103 organisms. After determination of the strains of each organism for collected

urine cultures, the drug resistance was assessed using disc diffusion and MIC (Minimum

Inhibitory Concentration) methods. Antimicrobial susceptibility was evaluated for 13

antibiotics including Ciprofloxacin, Nitrofurantoin, Ampicillin, Ofloxacin, Cotrimoxazole,

Cephalexin, Gentamicin, Ceftriaxone, Nalidixic acid, Imipenem, Ceftizoxime, Co-amoxiclav

and Vancomycin.

To define the type of strains the organisms were cultured in differential medium and the type

of strain was determined by adding anti serum and using tables for the type of strains.

Macrotube method was used for MIC. First of all the stock solution was prepared which

required the antibiotic weight (mg) [Volume (ml) × concentration (µg/ml)/Assay potency

(µg/mg)] and the volume of diluent (ml) [Weight (mg) × Assay potency)/Concentration].

To prepare the microbial suspension from isolated colonies ofmedium with 18-24 h

incubation, they directlyinoculated to liquid Muller Hilton to provide a turbidity similar to 0.5

McFarland (to prepare the McFarland 0.5 mL of barium chloride dihydrate solution [Bacl2 &

2H20] was added to 99.5 mL of 1% Sulfuric acid and the OD of the solution was assessed at

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of antibiotics was added to the tubes with screw caps and 1 mL of microbial suspension was

included. Thus, by doubling the volume, the final concentration of the antibiotic in each tube

is half of the initial calculated concentration. Then thetubes wereincubatedfor16-20hoursat

35°C moist and at the end the resultswere read. The read numbers of MIC were reported

according to the Clinical and Laboratory Standards Association (CLSI) guideline. Drug

resistance was calculated using the disk diffusion method too. A questionnaire was prepared

and the demographic futures of the patients and the results of MIC and antibiogramwith disc

were recorded in it.

2.1. STATISTICAL ANALYSIS

Data were analyzed using Spss version 18. Chi square test, frequency distribution tables and

measures of central tendency and dispersion were used to analyze the data.

3. RESULTS

From positive urine cultures, 224 cases which was confirmed of urinary tract infection were

selected. Bacterial resistance was done for all samples with two disk diffusion and MIC test

methods. The percent of female and male gender was 58.7:41.3 and the age range was about

64 ± 0.18. The most isolated organism was E. coli (44.8%) and Streptococcus (15.7%).

3.1. GENDER

Antibiotic susceptibility test has been performed on all the samples and result was different

based on the gender of patients. Disk diffusion test result can be seen in Table 1 and MIC

result are available in Table 2. In disk diffusion method most resistance to ceftriaxone and

gentamicin were seen in male subjects. Also in MIC method this resistance were belonged to

female subjects to vancomycin and co-amoxiclav antibiotic.

3.2. AGE

The age range of patients was about 64.8 ± 0.18 (Min = 19, Max = 102). The result of the

MIC and disk diffusion test on samples based on age parameter of patients has been shown in

Tables 3 and 4. In disk diffusion method most drug resistance were found in people over 60

years old and in MIC, the greatest resistance to were seen at the age of 60-41 years to

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[image:6.595.69.534.108.766.2]

303 Table 1. Frequency of Antibiotic Resistance in the Disk Diffusion Method based on Age Parameter

20 ≤ 21-40 41-60 61-80 81 ≥ P value

Ciprofloxacin 0.135

Sensitive 2 (0.9) 9 (4) 29 (13) 37 (16.6) 8 (3.6)

Intermediate 0 (0) 1 (0.4) 0 (0) 2 (0.9) 1 (0.4)

Resistant 1 (0.4) 12 (5.4) 25 (11.2) 71 (31.8) 25 (11.2)

Cotrimoxazole 0.633

Sensitive 1 (0.4) 7 (3.1) 16 (7.2) 25 (11.2) 6 (2.7)

Intermediate 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)

Resistant 2 (0.9) 15 (6.7) 38 (17) 85 (38.1) 28 (12.6)

Nitrofurantoin 0.010

Sensitive 2 (0.9) 14 (6.3) 40 (17.9) 85 (38.1) 14 (6.3)

Intermediate 0 (0) 1 (0.4) 0 (0) 5 (2.2) 2 (0.9)

Resistant 1 (0.4) 7 (3.1) 14 (6.3) 20 (9) 18 (8.1)

Ampicillin 0.899

Sensitive 0 (0) 4 (1.8) 10 (4.5) 18 (8.1) 9 (4)

Intermediate 0 (0) 0 (0) 1 (0.4) 1 (0.4) 0 (0)

Resistant 3 (1.3) 18 (8.1) 43 (19.3) 91 (40.8) 25 (11.2)

Ofloxacin 0.956

Sensitive 1 (0.4) 6 (2.7) 18 (8.1) 28 (12.6) 10 (4.5)

Intermediate 0 (0) 1 (0.4) 1 (0.4) 3 (1.3) 0 (0)

Resistant 2 (0.9) 15 (6.7) 35 (15.7) 79 (35.4) 24 (10.8)

Cephalexin 0.601

Sensitive 2 (0.9) 7 (3.1) 17 (7.6) 23 (10.3) 9 (4)

Intermediate 0 (0) 0 (0) 1 (0.4) 1 (0.4) 0 (0)

Resistant 1 (0.4) 15 (6.7) 36 (16.1) 86 (38.6) 25 (11.2)

Gentamicin 0.817

Sensitive 1 (0.4) 8 (3.6) 28 (12.6) 44 (19.7) 15 (6.7)

Intermediate 0 (0) 2 (0.9) 1 (0.4) 5 (2.2) 2 (0.9)

Resistant 2 (0.9) 12 (5.4) 25 (11.2) 61 (27.4) 17 (7.6)

Ceftriaxone 0.435

Sensitive 1 (0.4) 4 (1.8) 17 (7.6) 18 (8.1) 5 (2.2)

Intermediate 0 (0) 1 (0.4) 1 (0.4) 2 (0.9) 0 (0)

Resistant 2 (0.9) 17 (7.6) 36 (16.1) 90 (40.4) 29 (13)

Nalidixic 0.43

Sensitive 0 (0) 4 (1.8) 14 (6.3) 14 (6.3) 4 (1.8)

Intermediate 0 (0) 0 (0) 0 (0) 1 (0.4) 1 (0.4)

Resistant 3 (1.3) 18 (8.1) 40 (17.9) 95 (42.6) 29 (13)

Imipenem 0.630

Sensitive 2 (0.9) 9 (4) 27 (12.1) 38 (17) 14 (6.3)

Intermediate 0 (0) 1 (0.4) 1 (0.4) 2 (0.9) 0 (0)

Resistant 1 (0.4) 12 (5.4) 26 (11.7) 70 (31.4) 20 (9)

co-amoxiclav 0.678

Sensitive 2 (0.9) 9 (4) 23 (10.3) 42 (18.8) 14 (6.3)

Intermediate 1 (0.4) 2 (0.9) 4 (1.8) 7 (3.1) 2 (0.9)

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Cefixime 0.803

Sensitive 2 (0.9) 5 (2.2) 15 (6.7) 13 (5.8) 8 (6.3)

Intermediate 0 (0) 0 (0) 0 (0) 3 (1.3) 0 (0)

Resistant 1 (0.4) 17 (7.6) 39 (17.5) 94 (42.2) 26 (11.7)

Vancomycin 0.401

Sensitive 1 (0.4) 6 (2.7) 7 (3.1) 11 (4.9) 4 (1.8)

Intermediate 0 (0) 0 (0) 2 (0.9) 5 (2.2) 0 (0)

Resistant 2 (0.9) 16 (7.2) 45 (20.2) 94 (42.2) 30 (13.5)

Data are presented as No. (%)

3.3. Having a History of Disease or Previous Use of Antibiotics

In patients with history of a disease drug resistance were seen to cotrimoxazole, ampicillin,

co-amoxiclav, cefixime, cephalexin, ceftriaxone, nitrofurantoin, gentamicin and ciprofloxacin

in in disc diffusion method and to cotrimoxazole and ciprofloxacin in MIC method. In

patients with a history of antibiotic use difference was only significant for ciprofloxacin in

MIC method.

As the result of this study the drug sensitivity of each organism that achieved with MIC

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[image:8.792.0.792.92.241.2]

305 Table 3. Drug Sensitivity for Each Organism in disk diffusion Method

Organism ciprofloxacin Ofloxacin Nalidixic acid Ceftriaxone Cefixime Cephalexin Co-amoxiclav Ampicillin Imipenem Cotrimoxazole Nitrofurantoin Gentamicin Vancomycin

S R S R S R S R S R S R S R S R S R S R S R S R S R

Escherchia

coli _(35.4)53

64 (64.6) 28 (28.3) 69 (69.7)

15(15.2) 84 (84.8) 25 (25.3) 74 (74.7) 22 (22.2) 57 (57.8) 27 (27.3) 72 (72.7) 43 (43.4) 56 (56.6) 13 (13.1) 86 (86.8) 40 (40.6) 59 (59.4) 23 (23.2 76 (76.8) 76 (76.8) 23 (23.2) 49 (49.5) 50 (50.5)

2 (2) 97 (98)

streptococcus 8 (3.6) 27 (12.1) 6 (17.1) 29 (82.9)

5 (14.3) 30 (85.7) 2 (5.7) 33 (94.3) 2 (5.7) 33 (94.3)

7 (20) 28 (80) 19 (54.3) 16 (45.7) 16 (45.7) 19 (53.4)

7 (20) 28 (80) 6 (17.1) 29 (82.9) 24 (68.6) 11 (31 .4) 5 (14.3) 30 (85.7) 12 (34.3) 23 (65.7)

staphylococcus 10 (47.6) 11 (52.4) 7 (33.3) 14 (66.7)

3 (14.3) 18 (85.7) 1 (4.8) 20 (95.2) 6 (28.6) 15 (71.4) 10 (47.6) 11 (52.4) 12 (57.1) 9 (42.9) 5 (23.8) 16 (76.2) 9 (42.9) 12 (57.1) 7 (33.3) 14 (66.7) 14 (66.7) 7 (33.3) 10 (47.6) 11 (52.4) 13 (61.9) 7 (33.3)

Seratia 6

(36.4) 7 (63.6) 2 (18.2) 9 (81.8)

3 (27.3) 8 (72.7) 4 (36.4) 7 (63.6) 2 (18.2) 9 (81.8) 2 (18.2) 9 (81.8) 3 (27.3) 8 (72.7) 1 (9.1) 10 (90.9) 5 (45.5) 6 (54.5) 5 (54.5) 6 (45.5) 9 (81.8) 2 (18.2) 7 (63.6) 6 (36.4)

0 (0) 11 (100)

pseudomonas 8 (61.5) 5 (38.5) 7 (53.8) 6 (46.2)

0 (0) 13

(5.8) 2 (15.4) 11 (84.6) 2 (15.4) 11 (84.6) 2 (15.4) 11 (84.6) 1 (7.7) 12 (92.3)

0 (0) 13 (100)

8 (61.5)

4 (30.8)

0 (0) 13 (100) 1 (7.7) 12 (92.3) 6 (46.2) 7 (53.8)

0 (0) 13 (100)

klebsiella 6 (42.9) 8 (57.1) 4 (28.6) 10 (71.4)

4 (28.6) 10 (71.4) 4 (28.6) 10 (71.4) 4 (28.6) 10 (71.4) 4 (28.6) 10 (71.4) 6 (42.9) 8 (57.1) 2 (14.3) 12 (85.7)

7 (50) 7 (50) 4 (28.6) 10 (71.4) 10 (71.4) 3 (21.4)

7 (50) 7 (50) 0 (0) 14 (100)

Others* 11

(42.3) 15 (57.7) 6 (23,1) 20 (76.9)

4 (15.3) 22 (84.7) 3 (11.5) 23 (88.5) 3 (11.5) 23 (88.5) 2 ( 11.6) 24 ( 88.4) 3 (11.5) 23 (88.5) 1 (3.8) 25 (98.2) 8 (30.8) 18 (69.2) 6 ( 23.1) 20 (76.9) 17 (82.3) 9 (17.7) 6 (23,1) 20 (76.9) 1 (3.8) 25 (96.2)

*Includes Edwardsiella, Acinetobacter, Citrobacter, Enterobacter, Mvrganla, Providencia, Proteus, and yeast

Data are presented as No. (%)

Table 4.Drug Sensitivity for Each Organism in MIC Method

Organism ciprofloxacin Ofloxacin Nalidixic acid Ceftriaxone Cefixime Cephalexin Co-amoxiclav Ampicillin Imipenem Cotrimoxazole Nitrofurantoin Gentamicin Vancomycin

S R S R S R S R S R S R S R S R S R S R S R S R S R

Escherchi a coli 11 (11.1) 88 (88.9) 19 (19.2) 80 (80.8) 10 (10.1) 89 (89.9) 9 (9.1) 90 (90.9)

3 (3) 96 (97)

1 (1) 98 (99)

10 (10.1)

89 (90.9)

2 (2) 97 (98) 16 (16.1)

83 (83.9)

2 (2) 97 (98) 65 (65.7) 34 (34.3) 27 (27.3) 72 (82.7)

0 (0) 99 (100) streptococ cus 12 (34.3) 23 (65.7) 15 (42.9) 20 (57.1) 14 (40) 21 (60) 11 (31.4) 24 (68.8) 11 (31.4) 23 (65.7) 6 (17.1)

) (82.9)92 23 (65.7) 12 (34.3) 01 (28.6)

) )(71.4)92 14 (40) 21 (60) 9 (25.7) 96 (74.3) ) 27 (22.6) 8 (12.4) 09 (10.5) ) 23 (17.6) 24 (68.6) 11 (31.4) staphyloc occus 9 (42.9) 13 (57.1) 7 (33.3) 14 (66.7)

8 (38) 13 (62) 5 (23.8) 16 (76.2) 2 (9.5) 19 (88.5) 10 (47.6) 11 (52.4) 12 (57.1) 9 (42.9) 5 (23.8) 16 (76.2) 9 (42.9) 12 (57.1) 7 (33.3) 14 (66.7) 14 (66.7) 7 (33.3) 10 (47.6) 11 (52.4) 13 (61.9) 8 (38.1)

Seratia 4 (36.4) 7 (63.6) 2 (18.2) 9 (81.8) 3 (27.3) 8 (72.7) 4 (36.4) 7 (63.6) 2 (18.2) 7 (63.6) 2 (18.2) 9 (81.8) 3 (27.3) 8 (72.7)

1 (9.1) 10 (90.9) 5 (54.5) 6 (45.5) 5 (54.5) 6 (45.5) 9 (81.8) 2 (18.2) 7 (63.6) 4 (36.4)

0 (0) 11 (100) pseudomo nas 8 (61.5) 5 (38.5) 7 (53.8) 6 (46.2)

0 (0) 13 (100) 2 (15.4) 11 (84.6) 2 (15.4) 11 (84.6) 2 (15.4) 11 (84.6) 1 (7.7) 12 (92.3)

0 (0) 13

(100) 8 (61.5)

4 (30.8)

0 (0) 13 (100) 1 (7.7) 12 (92.3) 6 (46.2) 7 (53.8)

0 (0) 13 (100)

klebsiella 6 (42.9) 8 (57.1) 4 (28.6) 10 (71.4) 4 (28.6) 10 (71.4) 4 (28.6) 10 (71.4) 4 (28.6) 10 (71.4) 4 (28.6) 10 (71.4) 6 (42.9) 8 (57.1) 2 (14.3) 12 (85.7)

7 (50) 7 (50) 4 (28.6) 10 (71.4) 10 (71.4) 4 (28.6)

7 (50) 7 (50) 0 (0) 14 (100)

Others* 13

(50) 13 (50) 8 (30.7) 18 (69.3) 4 (15.3) 22 (84.7) 6 (23.1) 20 (76.9) 4 (15.3) 22 (84.7) 5 (19.2) 21 (80.8) 4 (15.3) 22 (84.7) 6 (23.1) 20 (76.9) 12 (46.1) 14 (53.9) 6 (23.1) 20 (76.9) 23 (88.4) 3 (11.6) 10 (38.4) 16 (61.6) 2 (7.7) 24 (92.3)

*Includes Edwardsiella, Acinetobacter, Citrobacter, Enterobacter, Mvrganla, Providencia, Proteus, and yeast

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306 4. DISCUSSION

The prevalence of urinary tract infection is more common in women and as the other studies and

implementation the same results can be seen at the present study.[26-18] In this study that

performed at Ahwaz, Iran, E. coli in women, and Pseudomonas in men was the most common

isolated organism. In a study performed in Hong Kong, the rate of resistance to ampicillin,

nalidixic acid, ciprofloxacin and trimethoprim-sulfamethoxazole in women over 51 years was

more than women 50-18 years old.[29] In another study in Brazil, the rate of resistance to

quinolones reported 25% in men and 9% in women.[30]

In a study performed in South America, enterococci and streptococci were the most common

isolated organisms in women (responsible for 5.2% and 2.8% of infections) and only 8 S.

saprophyticus was isolated.[31] The difference in the organism and drug resistance in both sexes

in other studies may be related to pervious disease and risk factors predisposing to infection and

different consumption patterns for antibiotics in different communities.

The age range of the patients participate in this study was 65.8 ± 0.18 and the most drug resistant

in MIC method were seen in patients over 60 years old but this resistance in MIC methods was in

41-60 years old and to vancomycin, cefixime, gentamicin and co-amoxiclav. In Andrade et al.

study the age range was 42 years,[31] In another study in Spain with the age range of 54.1 the

resistant to ciprofloxacin in patients younger than 40 years old was 6.7% and in patient older

than 60 years old was 33.9%.[32] Shaban et al. reported the 5% resistance to ciprofloxacin in

adults and 13% and 14% resistance to amikacin and co-amoxiclav respectively in men over 50

years old.[33] Regarding the increasing use of antibiotics with ageing result of the above studies

would be expected.

In present study 84.3% of the participants had a background of another disease and drug resistant

was more in such patients. In a study by Ladhani et al. the patients with renal problems had

62.5% more resistance in compare with patients without other disease.[34] A 5 years study in

England showed that resistant to trimethoprim has been increased from 24.1 to 31.6 in children

under 15 years old.[35]

In conclusion due to the high sensitivity of nitrofurantoin, gentamicin and imipenem, with disk

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307

tract infections. Since gentamicin, cephalexin and cotrimoxazole showed high resistance, it is

recommended that the use of these drugs avoided in the treatment and prevention of these

infections.

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