Genetic Diversity of Carbapenemases-producing Isolates at a Tertiary Teaching Hospital in Western India.

BACKGROUND

is an alarming pathogen in hospital-acquired infections, particularly in the intensive care units (ICUs). Carbapenemases production and biofilm formation contribute significantly to the pathogenicity of the organism. Carbapenem resistance in is primarily due to the production of carbapenemases.

AIM

The study was conducted to detect the presence of carbapenemase-encoding genes in along with their ability to form biofilm. In addition, this study also investigated the association between biofilm formation and carbapenemase genes harboring isolates.

MATERIALS AND METHODS

One hundred and forty isolates of were collected from the various specimens. Of these, this study included 36 isolates that were carbapenem-resistant, metallo-β-lactamases (MBLs) producing, and extensively drug-resistant (XDR) obtained from ICUs. Identification and antibiotic susceptibility determination was done using VITEK 2. Further, the isolates were confirmed by detecting the OXA-51 carbapenemase gene intrinsic to . Polymerase chain reaction was performed to detect carbapenemase-encoding genes, and biofilm formation was examined using the tube method.

RESULTS

The OXA-51 gene was present in all isolates ( = 36). showed highest sensitivity against colistin (100%) and minocycline (25%). Out of 36 isolates, acquired carbapenemase encoding genes were detected in 35 (97.22%) isolates, as follows: OXA-23 (35/36, 97.22%), NDM (18/36, 50%), IMP (1/36, 2.78%), and VIM (28/36, 77.78%). In 33 (91.67%) isolates, oxacillinase (OXA) and MBL genes coexisted. Among the 36 isolates, 30 (83.33%) formed biofilm.

CONCLUSION

The study highlights that colistin and minocycline are the viable antibiotics for treating carbapenem-resistant MBL-producing XDR infections. OXA-23 is the commonest carbapenemase gene, and VIM is the most frequently found MBL gene prevalent in our hospital and contributes to carbapenem resistance in . The study also showed a higher frequency of co-occurrence of multiple carbapenemase genes in single isolates, and most of these isolates formed biofilm. However, no statistically significant association was found between biofilm formation and carbapenemase genes in . This study emphasizes the molecular diagnostic value of carbapenemase gene detection to reduce the resistance rate in isolates.