Extended spectrum β-lactamases and ampc β-lactamases producing strains of escherichia coli: a challenge to therapeutics in current era of antibiotics

Objective: To determine the prevalence and presumptive antibiogram of ESBL and AmpC beta lactamases producing strains of E. coli isolated from different clinical specimens from a Tertiary Care Hospital of Punjab.
Material and Methods: Study was done from January 2014 to June 2014. A total 2069 various clinical samples received in Microbiology Department of GGSMCH, Faridkot were processed. Escherichia coli was the predominant bacteria and was identified as per CLSI. The antibiotic sensitivity pattern of E.coli was tested by Kirby Bauer’s disc diffusion method. The isolates found resistant to one or more 3rd generation cephalosporins as per CLSI guidelines were further processed for confirmation by combination disc technique. All Escherichia coli isolates were tested for cefoxitin susceptibility (30μg). Isolates with zone of inhibition ≤ 18 mm were taken to be putative AmpC producers and further processed for confirmation by Boronic acid disc potentiation method.
Results: Of the 298 GNB isolates, predominant was E.coli (51%) followed by Pseudomonas (26.8%), Citrobacter (12%), Klebsiella (4.7%), Acinetobacter (3.7%) and Proteus (1%).
E.coli showed dreadful resistance to third generation cephalosporins (91%) as compared to other GNB isolates (57%). ESBL positivity was found to be 43% and AmpC β-lactamases (9.1%) among E.coli isolates.
Conclusion: The study concludes that there is a high prevalence of ESBL producing E.coli in our hospital. So, along with detection of ESBL, detection of AmpC β-lactamases is also important. Strategies to keep a check on the emergence of such drug resistant microorganisms by hospital environmental surveillance and laboratory monitoring should form an important aspect of Hospital Infection control policy guidelines.