ESBL- A continuous diagnostic challenge to clinical microbiology laboratories.

ABSTRACT

Objectives: Extended spectrum beta lactamase (ESBL) producers have posed a great threat to the use of many classes of antibiotics, particularly cephalosporins. Their detection has proved to be difficult for many laboratories because the resistant ESBL producing organisms appear to be susceptible by in vitro routine testing but result in treatment failure.The present study aims to detect the prevalence of ESBLs in organisms like E.coli and Klebsiella spp. which are responsible for many serious infections. Method: Isolates were screened for ESBL production using cefotaxime, ceftazidime and ceftriaxone by disk diffusion method. Isolates showing resistance to one or more than one of these drugs were futher subjected to Phenotypic Confirmatory Test (PCT) using CAZ/CAZ-CAC as per CLSI guidelines. Results: Of the 230 isolates, 116 (50.43%) tested positive by initial screening method. But on PCT only 94 tested positive. Out of 94 ESBL producers, 59 (62.76%) were E.coli and 35(37.23%) were Klebsiella spp. Of the various clinical samples urine 90(39%) showed maximum number of ESBL producers (32, 34%), followed by pus (27, 29%). Out of 230, 126 (54.7%) were females and 104 (45.2%) were males with a male to female ratio of 0.821 showing female preponderance. This study also showed increasing resistance to fluoroquinolones among ESBL producers. Conclusion: The results of our study show that there is an increased prevalence of ESBL producers in our tertiary care centre and also an increased resistance to fluoroquinolones among ESBL producers. Hence infections caused by E.coli and Klebsiella spp. which are prime producers of ESBL have to be considered seriously and proper screening methods and antibiotic policies have to be drawn to confine their spread.