Saudi Journal of Kidney Diseases and Transplantation

: 2009  |  Volume : 20  |  Issue : 2  |  Page : 251--253

Antimicrobial susceptibility pattern of urinary tract pathogens

Zakieh Rostamzadeh Khameneh, Ali Taghizadeh Afshar 
 Department of Microbiology, Medical Sciences University of Urmia, Iran

Correspondence Address:
Zakieh Rostamzadeh Khameneh
Department of Microbiology, Medical Sciences University of Urmia, Urmia


Microbial drug resistance is a major problem in the treatment of infectious diseases worldwide. The purpose of this survey is to determine the prevalence of the type of bacterial agents that cause urinary infection and to assess the antimicrobial sensitivity pattern in the Urmia Medical University, Iran. In the period between 2005 and 2006, urine cultures collected were analyzed. Positive culture was defined as growth of a single bacterial species with colony count of > 100,000 CFU/mL. Stratification was done according to age-group and gender. Statistical tests used included chi-square to evaluate differences between susceptibility rates. A total of 803 urine culture positive patients were studied of whom 81.6% were females and 18.4% were males. The common micro-organisms isolated were E. coli (78.58%), Klebsiella (5.48%), Proteus and Staphylococcus. About 89% of the E. coli isolated showed sensitivity to cephtizoxin, 83.9% to gentamycin and 83.2% to ciprofloxacin; the highest resistance was shown to ampicillin and co­trimoxazole. Surveys of this nature will give a clear idea about the bacteriologic profile in a given institution as well their antibiotic sensitivity profile. This will act as a guide to commencing empirical antibiotic treatment in patients with urinary infections until such time culture reports are available.

How to cite this article:
Khameneh ZR, Afshar AT. Antimicrobial susceptibility pattern of urinary tract pathogens.Saudi J Kidney Dis Transpl 2009;20:251-253

How to cite this URL:
Khameneh ZR, Afshar AT. Antimicrobial susceptibility pattern of urinary tract pathogens. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2022 Jan 19 ];20:251-253
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With the advent of newer and powerful antibiotics, the medical society was hopeful to be able to manage microbial infections more effectively. In the initial few years, advances made in life style changes, diagnostic tech­niques as well as hygienic level of the society, resulted in a significant reduction in the pre­valence of infectious diseases worldwide. [1] The microbes that continued causing infections despite usage of these newer antibiotics re­presented a new form of infectious diseases caused by drug resistance. It is expected that in course of time, microbes will become more resistant because of their new mutants. [2] Urinary tract infections are the second most common infections after infections of the respiratory tract, [3] and constitute a great proportion of prescription of antibiotics. Antibiotic treatment that are of duration shorter than required, and also treatment administered without considering the microbiologic and antibiotic sensitivity data result in more resistance in bacterial strains. Antibiotic resistance patterns vary in different areas. [4] In order to apply an appropriate the­rapeutic strategy in each region, we must have data on the most common pathogens and also their sensitivity to different antibiotics. This study was undertaken to study these data in the Urmia Medical University, Iran

 Materials and Methods

This descriptive study was performed on 803 patients with urinary tract infections referred to a laboratory attached to the Urmia Medical University, Iran during the years 2005 and 2006. Urine samples were collected according to the midstream method and in sterile con­tainers. We cultured them on blood agar and EMB environments. After 24-hours incubation at 37 degrees Celsius, the colonies were coun­ted and samples with colony count more than 100,000/mL were considered positive. A con­firmation test was performed for identifying the organism. The sample was then cultured in muler Hilton bras environment (antimicrobial sensitivity test). The disc diffusion test (using Kirby-baur method) on muler Hilton agar was used to assess the sensitivity pattern. After incubation and diameter measurements, we determined the growth rate of the sensitive, semi-sensitive and resistant micro-organisms. The data were analyzed by Spss software.


A total of 803 patients were studied of whom, 81.6% were female (655) and 18.2% were male. Most of the study patients were more than 35-years of age. Overall, E. coli was the most common micro-organism isolated in all age-groups and both sexes followed by Kleb­siella and Proteus [Table 1]. No significant difference was found between the bacteria isolated and age of the patients (p > 0.05). E. coli showed higher sensitivity to ceftizoxim (89.54%), gentamycin (83.9%), ciprofloxacin (83.2%) and greater resistance to ampicillin and co-trimoxazole [Table 2].

Klebsiella strains showed high sensitivity to ciprofloxacin and gentamycin. The most effec­tive drugs for pseudomonas were amikacin and ciprofloxacin. Staphylococcus strains were more sensitive to vancomycin, gentamycin and ciprofloxacin.


Our results demonstrate that drug resistance of E.Coli to many antibiotics is high with the maximum prevalence of resistance being to drugs that have been used for a long time, such as ampicillin and co-trimoxazole. Our results are similar to one other study that has been conducted in Iran. They have reported E. Coli resistance to ampicillin of 96.8% and to co­trimoxazole of 70%; [5] however, the surveys conducted in Russia [6] and Argentina [7] have shown relatively lesser resistance. The results of our study about co-trimoxazole are similar to results of a survey conducted in Holland, [8] but the drug resistance of E.Coli has reduced from 79% to 62% over the last few years in that country. Partial resistance of E. Coli to ampicillin and co-trimoxazole has been repor­ted in a survey from the USA, [9] which is less than the prevalence in our study. We also found less drug resistance of E. Coli to nitro­furantion and nalidix acid in comparison to ampicillin and co-trimoxazole.

A survey conducted by Chritiaens and col­leagues [10] has demonstrated that Staphylo­coccus saprophyticus (9%) and Proteus (4%) were the main organisms isolated, after E. Coli. Our results are different from results of that survey. A survey conducted by Papapetro­poulon and colleagues [11] on germ-negative ba­cilli has demonstrated the prevalence of Pro­teus to be 10% and Klebsiella to be 8.7%. A study from Brazil has reported the prevalence of E. Coli to be 71.6%, Klebsiella to be 6.4% and Proteus to be 6.1%. [1]

E. Coli is the most common micro-organism causing urinary tract infection in both men and women of all age-groups. It is still sensitive to many drugs, but this is getting reduced each year to some commonly used drugs because of empirical use. Surveys conducted in different parts of Iran and on different patient-groups with urinary tract infection, have demonstrated that many of E. Coli strains are still sensitive to nalidixic acid. The prevalence of this sensi­tivity varies from 73 to 78%. In the USA and other Western countries, the sensitivity is higher and less than 5% of E. Coli strains are resistant to this drug. [1] In our study, the sensi­tivity was less than the other surveys, both in Iran and other parts of the world, and the absolute resistance of E. Coli to nalidixic acid was very low. Klebsiella, the second most common micro-organism in our study, showed a high degree of sensitivity to nalidixic acid. Therefore, we can use nalidixic acid as an appropriate drug for treatment of urinary tract infections, but we should note that 36% of the E. Coli strains had partial resistance to this drug and irrational prescriptions may cause higher resistance to nalidixic acid in the future.


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