Co-occurrence of genes encoding carbapenem resistance and aminoglycoside resistance in clinical isolates of Enterobacterales.

INTRODUCTION

This study aimed to detect the co-occurrence of carbapenem resistance genes along with aminoglycoside-modifying enzyme (AME) genes in clinical Enterobacterales isolates to understand the distribution of multiple resistance genes among clinical isolates.

METHODS

This prospective study was conducted for six months (November 2024 to April 2025) in the department of microbiology of a tertiary care hospital. A total of 30 blood culture isolates were identified as resistant to both carbapenem and aminoglycoside antibiotics using the automated VITEK 2 compact system. The genes responsible for carbapenem resistance (blaNDM , blaOXA-48 , blaKPC , blaIMP , and blaVIM ) were detected by multiplex real-time PCR, and the aminoglycoside-modifying enzyme genes [APH(3')-Ia, APH(2")-Ib, AAC(3)-IIc, AAC(6')-Ib, and ANT(3")-I] were detected by the conventional polymerase chain reaction method. All the clinical data, patient demographics, and molecular findings were entered in an MS Excel spreadsheet version 14.0.4734.1000 and analyzed using GraphPad/PRISM software version 10.5.0.

RESULTS

Of the 30 Enterobacterales isolates, Klebsiella pneumoniae was the most common isolate (66.7%). Molecular detection revealed blaNDM in 40% isolates and blaOXA48 in 10% isolates. The majority of the AME genes were in combination. The most common combination of the AME gene was AAC(6')-Ib+ AAC(3)-IIc+ ANT(3")-I + APH(3')-I detected in 4 (13.3%) isolates. The most common combination of carbapenem and aminoglycoside resistant genes was blaNDM + blaOXA48 + AAC(6')-Ib+ AAC(3)-IIc+ ANT(3")-I+ APH(3')-I (13.3%). The blaOXA-48 gene had a statistically significant association with AAC(6')-Ib, ANT(3")-I, and APH(3')-I (p <0.05).

CONCLUSION

The Co-occurence of carbapenem resistance and aminoglycoside-modifying enzyme genes in clinical Enterobacterales isolates limits the therapeutic option.