β -Lactamase-Producing Multidrug-Resistant Bacterial Pathogens from Tracheal Aspirates of Intensive Care Unit Patients at National Institute of Neurological and Allied Sciences, Nepal

Abstract

The widespread use of tracheal intubation and mechanical ventilation to support the critically ill patients increases the risk of development of tracheobronchitis and bronchopneumonia. This cross-sectional study was conducted with an aim to isolate and identify bacterial pathogens from tracheal aspirates producing extended-spectrum β -lactamase (ESBL), AmpC β -lactamase, and metallo- β -lactamase (MBL) from August 2011 to April 2012 at National Institute of Neurological and Allied Sciences (NINAS), Kathmandu, Nepal. ESBL was detected by combined disk assay using cefotaxime and cefotaxime with clavulanate, AmpC β -lactamase by inhibitor-based method using cefoxitin and phenylboronic acid, and MBL by Imipenem-EDTA combined disk method. 167 bacterial strains were isolated from 187 samples and majority of them were Acinetobacter spp. followed by Klebsiella pneumoniae with 32.9% and 25.1%, respectively. 68.8% of isolates were multidrug resistant (MDR) and Acinetobacter spp. constituted 85.4%. ESBL, AmpC β -lactamase, and MBL were detected in 35 (25%), 51 (37.2%), and 11 (36.7%) isolates, respectively. Pseudomonas spp. (42.8%) were the predominant ESBL producer while Acinetobacter spp. were the major AmpC β -lactamase producer (43.1%) and MBL producer (54.5%).