Antibiotic resistance in uropathogenic Escherichia coli isolated from urinary tract infections out-patients in Kermanshah

Address for the Correspondence: Dr. P. Mohajeri, Assistant Professor of Medical Bacteriology, Department of Microbiology, Faculty of Medicine, School of Medicine, Kermanshah University of Medical Sciences, Shirudi Shahid Blvd, Daneshgah Street, Postal Code 67148-69914, Kermanshah, Iran. E-mail: p_mohajeri@yahoo.com Antibiotic resistance in uropathogenic Escherichia coli isolated from urinary tract infections out-patients in Kermanshah Orig ina l Ar t ic le


MATERIALS AND METHODS
The study is a retrospective analysis of all E. coli isolates recovered from urine samples admitted to Kermanshah Central lab between March 2011 and 2012 were included.This public clinical laboratory is one of big labs located in west of Iran, where patients across the province visit regularly.All patients with pyuria (>10 white blood cells/L), acute voiding symptoms and signifi cant bacteriuria (>10 5 colony forming units [CFU]/ml) from a freshly voided mid-stream urine specimen were included in the microbiological analysis.Only one specimen per patient was included in the study.
Antimicrobial susceptibility of isolates was tested by Kirby-Bauer disk diffusion method following the defi nition of Clinical and Laboratory Standards Institute (CLSI) interpretive breakpoint. [6] pure culture of the organism, which had been freshly grown on blood agar, was suspended in normal sterile saline and the turbidity of the suspension is adjusted to an equivalent 0.5 McFarland standard. [7]e bacterial suspension was inoculated on Mueller-Hinton agar (Merck) as per guidelines for disc diffusion technique.Antibiotic impregnated disks (MAST Company) were applied to the Mueller-Hinton agar plates.The plates were incubated aerobically at 37°C for 18-24 h and colony counts were expressed in CFU/ml of urine.Zone sizes of inhibition were read and interpreted for susceptibility in accordance with the currently recommended CLSI criteria for urinary tract isolates of Enterobacteriaceae.Antibiotic concentrations in the diffusion discs used for antimicrobial susceptibility testing are: amikacin (30 g), amoxicillin (10 g), ceftizoxim (30 g) cephalexin (30 g), chloramphenicol (30 g), co-trimoxazole (1.25/23.75g), gentamicin (10 g), nitrofurantoin (300 g), norfl oxacin (10 g), tetracycline (30 g), coamoxicylin (30 g), cephalothin (30 g), amikacin (30 g) (MAST, Merseyside, U.K). Quality control was performed once weekly using test strains E. coli ATCC 25 922, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853.Data processing and statistical analysis were performed using SPSS software (version 16.0, SPSS, Inc., Chicago, IL).The results were analyzed using the descriptive statistics.The Chi-square and Fisher's exact tests were applied for categorical variables.All statistical tests were two-tailed and P < 0.05 was considered to be statistically signifi cant.Extended-spectrum B-lactamase (activity) was detected by phenotypic confi rmation with ceftazidime and ceftazidime-clavulanate disks, as recommended by the CLSI.
There was no significant difference in resistance rates for all antibiotics tested in the strains from males and females. [8]

DISCUSSION
Microbial infection of the urinary tract is one of the most common infectious diseases world-wide.Today, antimicrobial resistance is increasing and antimicrobial resistance patterns varies over time and in different geographical regions, antibiotic treatment of infections should be based on local experience of sensitivity and resistance patterns.The present study provides the information about the resistance prevalence in uncomplicated UTI and allows comparison of the community in Kermanshah, Iran with other parts of the country.In this study, out of 20,742 patients from who urine samples were taken, nearly 5.92% had a UTI.This is possibly because UTI symptoms are not a reliable indicator of infection.The total growth positive rate (5.92%) observed in this study was very lower in comparison to the fi nding of Saffar et al. ( Iran [8] .4] In the present study, as in previous report from Iran by Kashef et al., UTI occurred more in females than in males, which 85.2% of all patients were female. [14]is is as a result of shorter and wider urethra in women, therefore bacteria have less distance to travel and get to the bladder to cause infection.Furthermore the female urethra is contaminated from the vagina and its proximity to the perineum and anus, so gut bacteria are likely to cause urinary infection. [13]Almost 59-69% of the UPECs were resistant to co-amoxiclave, amikacin, co-trimoxazole, tetracycline and cephalotin and nearly half of them were resistant to nalidixic acid and cephalexin, indicating that empiric treatment with these antibiotics is inadequate for UTI in out-patients in our region.Resistance rats to ampicillin is (9.4%) in the present study.This result, lower than that obtained by other studies (84-100%), may be to un-usage of ampicillin in empirical treatment in recent years in our area. [14]It seems un-usage of antibiotic in special period of time can be cause of the decrease in resistance of bacteria against antibiotic.In our study, amikacin and co-trimoxasole are not good choice for the empirical treatment of UTI in our region.Many of the factors may contributed to such high rates of resistance to above antimicrobial agents explained by the easy access to drugs even without a prescription or inadequate dosage of these antibiotics used during selfmedication.Hence empirical therapy with these antibiotics seems inadequate and should be avoided.Unfortunately, antibiotics co-amoxiclave of new antibiotics that expensively in price, but high used in our region.The resistance 68.6% for antibiotics were not unexpected.In our study showed that these isolates were low resistant to Ampicilin, nitroforantoein, cloramphenicol, gentamicin and ceftizoxim.These antibiotics effective for the treatment of infections caused by UPEC isolated.

CONCLUSION
this study confi rms that E. coli is still the most common uropathogen isolated.Augmentin and amikacin are not as a fi rst choice for treatment of UTI in Kermanshah area.Ampicillin and nitrofurantoin may be considered as a fi rst choice empiric agent in outpatients.Antibiotic resistance pattern of organisms changing rapidly over a short period therefore these fi nding also reinforce the need for ongoing investigation to show trends in antibiotic resistance, which can help effective empiric therapies.