A Study on Antibiotic Resistance Pattern and AMPC β-Lactamase Production in Clinical Isolates of Klebsiella pneumoniae from Northeast India

We determined the antibiotic resistance pattern and AmpC β-lactamase production in Klebsiella pneumoniae isolates recovered from various clinical specimens at a tertiary care referral hospital in Northeast India. A total of 112 consecutive, non-duplicate isolates of K. pneumoniae isolates were recovered between January and June, 2009. The resistance pattern of the K. pneumoniae isolates to different antibiotics was determined by the Kirby-Bauer disc diffusion method. An isolate with a with a zone diameter of less than 18 mm for cefoxitin was considered as screening positive isolate for AmpC β-lactamase production. Production of AmpC β-lactamase was further confirmed by employing AmpC disc test and boronic acid disc test. By disc diffusion testing, 87.6%.of K. pneumoniae isolates was found to be multi-drug resistant (MDR, i.e. resistant to three or more antibiotics). Out of 43 screening positive isolates for AmpC β-lactamase production, 55.81% showed positive results in AmpC disc test and 62.79% showed positive results in boronic acid disc test. Understanding of antibiotic resistance pattern of important bacterial pathogen is essential to establish an appropriate antimicrobial regime. Since, inability to detect AmpC β-lactamase production in bacterial pathogens may lead to therapeutic failure, it is essential to detect AmpC β-lactamases in clinical laboratory on a daily basis.