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Introduction: OXA-48, a carbapenem-hydrolysing class D ß-lactamase, and its variant, OXA-181, are increasingly reported worldwide. This study aimed to describe the prevalence and distribution of OXA-48 and OXA-181 carbapenem-resistant Enterobacteriaceae (CRE) in a tertiary medical centre in Malaysia. Materials & Methods: A total of 13,098 Enterobacteriaceae isolates from various clinical samples were sent to our laboratory between January 2011 and December 2012. Of these, 90 demonstrated reduced susceptibility to at least one carbapenem and were included in this study. Only 88 isolates were successfully subcultured on blood agar (BA). Another 2 isolates failed to grow and were excluded. Of the 88, 2 isolates had the same identification number (repetitive isolates); therefore, 1 isolate was excluded from further analyses. Only 87 isolates were subjected to molecular detection of the blaOXA-48 and blaOXA-181 genes by polymerase chain reaction. Results: Eighty-seven non-repetitive isolates grew following subculture on BA. Of these, 9 (10.34%) were positive for OXA-48 (7 Klebsiella pneumoniae, 2 Escherichia coli). Each isolate originated from different patients. All patients had a history of treatment with at least one cephalosporin and/or carbapenem prior to the isolation of OXA-48 CRE. OXA-181 was detected in one (1.15%) out of the 87 isolates; Conclusions: The prevalence of OXA-48 and OXA-181 CRE among all Enterobacteriaceae isolates in our institution is 0.069% and 0.008%, respectively. Nevertheless, our findings suggest that OXA-48 and OXA-181 carbapenemases appear to be important and possibly under-recognised causes of carbapenem resistance in Malaysia. [ABSTRACT FROM AUTHOR]

Background: New Delhi metallo-β-lactamase-1 (NDM-1) is a relatively recent carbapenemase enzyme that inactivates all β-lactam antibiotics with the exception of aztreonam. This study aims to ascertain the baseline prevalence and antibiotic susceptibility patterns of NDM-1-producing Enterobacteriaceae in a tertiary medical center in Malaysia. Methods: Over a period of one year, all Enterobacteriaceae isolates from all clinical specimens with reduced susceptibility to at least one carbapenem and resistance to at least one third generation cephalosporin were subjected to antibiotic susceptibility testing by disk diffusion and molecular detection of the NDM-1 gene by single-target PCR followed by gel electrophoresis. Results: A total of 13,098 Enterobacteriaceae isolates were screened and 63 (0.48%) had reduced susceptibility to at least one carbapenem. Of this 63, 18 (29%) were NDM-1-positive. Of this 18, 16 (89.0%) were Klebsiella pneumoniae, one (5.5%) was Escherichia coli and one (5.5%) was Klebsiella ornithinolytica. Reduced susceptibility to at least one aminoglycoside was seen in 17 (94%) of the NDM-1-positive isolates. All 18 (100%) had reduced susceptibility to ertapenem and were resistant to all the second and third generation cephalosporin antibiotics tested. Conclusion: The prevalence of NDM-1-producing Enterobacteriaceae among all the Enterobacteriaceae isolates in our institution is low (0.14%) and screening for the NDM-1 gene is best performed using ertapenem-impregnated disks. [ABSTRACT FROM AUTHOR]