Prevalence of Extended-Spectrum Beta-Lactamase/Carbapenemase Genes and Quinolone-Resistance Determinants in Klebsiella pneumoniae Clinical Isolates from Respiratory Infections in Myanmar.

In recent years, nosocomial infections due to multidrug resistant Klebsiella pneumoniae strains have been increasing, associated with growing trend of resistance to beta-lactams and fluoroquinolones (FQs) worldwide. In this study, prevalence of beta-lactamase genes and resistance mechanisms to FQ were analyzed in 191 clinical K. pneumoniae isolates derived from respiratory tract infections in a teaching hospital in Yangon, Myanmar. The major extended-spectrum beta-lactamase gene was blaCTX-M, which was detected in 33% of isolates, with CTX-M-15 being dominant. Fourteen isolates (7.3%) harbored carbapenemase genes that were genotyped as blaNDM-1, blaNDM-5, or blaNDM-7. The most common plasmid-mediated quinolone resistance (PMQR) gene was aac6'-Ib-cr (51.8%), followed by qnrB (41.9%), oqxAB (23%), and qnrS (15.2%). In quinolone-resistance determining region of GyrA, eight different types of mutation were identified for FQ-resistant isolates, with double mutations at two positions (S83F, D87A) being most common (54.6%). Isolates with double mutations (three patterns) showed higher minimal inhibitory concentration to levofloxacin (LVX) (≥64 μg/mL) than those with a single mutation. PMQR gene profiles, including aac6'-Ib-cr and any other gene(s), were generally related to higher resistance level to LVX. K. pneumoniae isolates with different profiles of beta-lactamase genes and FQ-resistance determinants were mostly classified into ST15 or its single-locus variant (SLV). The most common NDM gene, blaNDM-5, was detected in ST975 (ST15-SLV) isolates and an ST4000 isolate. The present study revealed the wide spread of FQ-resistant K. pneumoniae clinical isolates acquiring various FQ-resistance determinants and beta-lactamases that were presumably derived from a single clonal lineage in a hospital in Myanmar.