Detection of clinically relevant carbapenemase encoding genes in carbapenem-resistant Enterobacter cloacae complex and Klebsiella pneumoniae isolated from farmed freshwater fish

Abstract

Aims: The present study was aimed to detect clinically relevant carbapenemase encoding genes in carbapenem-resistant Enterobacter cloacae complex (CR-ECC), Klebsiella pneumoniae (CR-KP), and Serratia plymuthica (CR-SP) isolated from farmed freshwater fish.

Methods and results: Out of 243 spatially diverse freshwater fish samples analysed, 5.3% were contaminated with CR-ECC, 1.6% with CR-KP, and 0.4% with CR-SP. The CR-ECC was further identified as E. asburiae (38.5%), E. mori (23.1%), E. cloacae (15.4%), E. hormaechei (15.4%), and E. kobei (7.7%) by 16S rRNA gene sequencing. The CR-ECC were resistant to carbapenems and cefoxitin, whereas CR-KP and CR-SP were multi-drug resistant (MDR). The CR-ECC harboured the carbapenemase gene blaIMI alone or in combination with blaTEM, blaEBC, blaCIT, blaACC, and tet(E). Whereas, CR-KP harboured carbapenemase gene, blaNDM-5 along with blaOXA-48, blaSHV, blaOXA-1, blaCTX-M-15, tet(A), sul1, and qnrB. No carbapenemase-encoding genes were detected in CR-SP. The MLST analysis showed that CR-KP belonged to ST231 and ST1561 lineages, while CR-ECC did not show exact match with any reported STs. The plasmid replicons predominantly detected were IncF and IncI1. Broth mating assays of CR-KP and CR-ECC with recipient Escherichia coli J53 indicated that blaNDM-5 was transferable but not blaIMI.

Conclusion: This study highlights the low-level contamination of carbapenem-resistant Enterobacterales (CRE) harbouring clinically relevant carbapenemase-encoding genes in farmed freshwater fish from India. The CR-ECC of fish origin did not show the potential to spread carbapenem resistance.