Antibiotic Sensitivity and Phenotypic Detection Of ESBL producing E.Coli Strains Causing Urinary Tract Infection In a Community Hospital, Chennai, Tamil Nadu, India

Urinary Tract Infection (UTI) forms the largest single group of hospital acquired infections and account for about 40-50% of the total nosocomial infections. In spite of the wide spread availability of antibiotics, UTI remains to be one of the most common infectious diseases diagnosed. Further world wide data shows that there is an increasing resistance among UTI pathogens to conventional drugs. Resistance have emerged even to newer more potent antimicrobial agents. Therefore, the aim of the present study is to determine the prevalence and susceptibility of extended spectrum beta – lactamase in urinary isolates of Escherichia coli (E. coli) in a community hospital, Sundaram Medical Foundation, Chennai, South India. A total number of 562 urine samples suspicious of UTI were analyzed and it was found that 115 cultures were positive for E. coli infection. The study period ranges from March to April 2012. Antimicrobial susceptibility testing was determined to commonly used antibiotics using the modified Kirby-Bauer’s disc diffusion method. ESBL detection was done by the screening method of double disc synergy test and then confirmed by the phenotypic confirmatory test with combination disc as recommended by the Clinical Laboratory Standards Institute (CLSI) and the minimum inhibitory concentration (MIC) method using the E-test strips (AB Biodisk, Sweden). The prevalence of ESBL E. coli was 34.8%. The ESBL producing isolates were significantly resistant to Ampicillin (100%), norfloxacin (98%) and Nalidixic acid (100%) and third generation of cephalosporins (100%) as compared to non-ESBL producers. Multidrug resistance was significantly higher (63.2%) in ESBL positive isolates than non-ESBL isolates (26.3%). Knowledge of the prevalence of ESBL and resistance pattern of bacterial isolates in a geographical area will help the clinicians to formulate the guidelines for antibiotic therapy to avoid inappropriate use of extended spectrum cephalosporins. In conclusion the study of ESBL producing E. coli can be treated with beta lactamase inhibitors like Augmentin and Tazobactum / Pippercillin to some extent. As carbapenems like Imipenem and Ertapenem sensitivity is high, therefore these drugs are the only choice for the treatment of severe or life threatening infections caused by ESBL producing organisms. In order to prevent the outbreaks of this life threatening ESBL producers, certain infection control measures have to be followed. Adequate precautions have to be taken to minimize the risk of cross contamination among patients. Contact precautions by cohort patients during outbreaks and also promoting meticulous hand hygiene practices.