Effectiveness of Combination Drugs in Extended Spectrum Beta Lactamases Producing Gram Negative Isolates- Experience in a Tertiary Care Hospital of Uttarakhand

Resistance by virtue of production of ESBL in gram negative bacteria is an emerging problem leading to therapeutic failure when β-lactam drugs are used. However, their presence may be missed while using routine disc diffusion methods for antibiotic susceptibility testing. All isolates of E. coli, K. pneumoniae, K. oxytoca and P. mirabilis were studied for ESBL production by CLSI recommended Phenotypic confirmatory test (PCT ) and Double disk approximation test (DDAT). Out of 10,055 clinical samples,1738 study isolates were obtained of which 1196 were E. coli (68.82%), 465 K. pneumoniae (26.75%), 17 K. oxytoca (0.97%) and 60 P. mirabilis (3.46%). 43.10% (749 out of 1738) study isolates were confirmed to be ESBL producers. The best sensitivity was found for Tigecycline (100%) followed by Polymyxin B (91%) and Imipenem (81%). To conclude, we found a very high prevalence of ESBL producers (43.10 %) in our hospital especially from the IPD wards. KEYWORDS; Extended Spectrum Beta Lactamases, ESBL, Phenotypic confirmatory test, PCT, Double disk approximation test, DDAT *Corresponding author PRATIMA GUPTA Department of Microbiology, Himalayan Institute of Medical Sciences, HIHT University, Dehradun Int J Pharm Bio Sci 2012 July; 3(3): (B) 251260 This article can be downloaded from www.ijpbs.net B 252 INTRODUCTION The discovery of penicillin changed the course of history and forever altered the treatment of bacterial infections. Since then the introduction of every new antimicrobial is soon followed by discovery of its resistance. In Gram negative pathogens, β-lactamase production remains the most important contributing factor to β-lactam resistance which is chiefly due to plasmid mediated Extended Spectrum β-Lactamase (ESBL) production. They can be found in a variety of Enterobacteriaceae species, however, the majority of ESBL producing strains are K. pneumoniae, K. oxytoca and E. coli . Resistance by virtue of production of ESBL in gram negative bacteria is an emerging problem leading to therapeutic failure when βlactam drugs are used. However, their presence may be missed while using routine disc diffusion methods for antibiotic susceptibility testing and special methodology is required to detect their presence. Hence, the following study was conducted to estimate the burden of these highly drug resistant gram negative bacteria in clinical specimens received in the Bacteriology laboratory at our tertiary care center to guide the clinicians in prescribing appropriate antibiotic therapy. MATERIALS AND METHODS The present study was carried out from 1 March 2009 to 28 February 2010. All isolates of E. coli, K. pneumoniae, K. oxytoca and P. mirabilis obtained from clinical samples like blood, pus, CSF, ascitic fluid, pleural fluid, urine etc. were included in the study. Particulars of patient, relevant clinical history and reports of investigations were recorded after taking written informed consent. The study was approved by the ethics committee of the institution.