Table of Contents
ISRN Microbiology
Volume 2014, Article ID 953417, 9 pages
Research Article

Prevalence and Genetic Characterization of Carbapenem- and Polymyxin-Resistant Acinetobacter baumannii Isolated from a Tertiary Hospital in Terengganu, Malaysia

1Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
2Faculty of Agriculture, Biotechnology and Food Sciences, Universiti Sultan Zainal Abidin, 20400 Kuala Terengganu, Malaysia
3Faculty of Medicine and Health Sciences, Universiti Sultan Zainal Abidin, 20400 Kuala Terengganu, Malaysia
4Department of Pathology, Hospital Sultanah Nur Zahirah, 20400 Kuala Terengganu, Malaysia

Received 5 December 2013; Accepted 9 February 2014; Published 19 March 2014

Academic Editors: B. Ayo, K. Leung, and C. Pazzani

Copyright © 2014 Soo-Sum Lean et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Nosocomial infection caused by Acinetobacter baumannii is of great concern due to its increasing resistance to most antimicrobials. In this study, 54 nonrepeat isolates of A. baumannii from the main tertiary hospital in Terengganu, Malaysia, were analyzed for their antibiograms and genotypes. Out of the 54 isolates, 39 (72.2%) were multidrug resistant (MDR) and resistant to carbapenems whereas 14 (25.9%) were categorized as extensive drug resistant (XDR) with additional resistance to polymyxin B, the drug of “last resort.” Pulsed-field gel electrophoresis analyses showed that the polymyxin-resistant isolates were genetically diverse while the carbapenem-resistant isolates were clonally related. The 14 XDR isolates were further investigated for mutations in genes known to mediate polymyxin resistance, namely, pmrCAB, and the lipopolysaccharide biosynthesis genes, lpxA, lpxC, lpxD, and lpsB. All 14 isolates had a P102H mutation in pmrA with no mutation detected in pmrC and pmrB. No mutation was detected in lpxA but each polymyxin-resistant isolate had 2–4 amino acid substitutions in lpxD and 1-2 substitutions in lpxC. Eight resistant isolates also displayed a unique H181Y mutation in lpsB. The extent of polymyxin resistance is of concern and the novel mutations discovered here warrant further investigations.