Detection of carbapenem resistance genes and cephalosporin, and quinolone resistance genes along with oqxAB gene in Escherichia coli in hospital wastewater: a matter of concern

Aims: This study was performed to detect the presence of Escherichia coli resistant to cephalosporins, carbapenems and quinolones in hospital wastewater.

Methods and results: Wastewaters from a rural (H1) and an urban (H2) hospital were tested for E. coli resistant to cephalosporins, carbapenem and quinolones. Genes coding for chromosomal and plasmid-mediated resistance and phylogenetic grouping was detected by multiplex polymerase chain reaction (PCR) and for genetic relatedness by rep-PCR. Of 190 (H1 = 94; H2 = 96) E. coli examined, 44% were resistant to both cephalosporins and quinolones and 3% to imipenem. ESBLs were detected phenotypically in 96% of the isolates, the gene blaCTX-M coding for 87% and blaTEM for 63%. Quinolone resistance was due to mutations in gyrA and parC genes in 97% and plasmid-coded aac-(6')-Ib-cr in 89% of isolates. Only in one carbapenem-resistant E. coli, NDM-1 was detected. Nearly 67% of the isolates belonged to phylogenetic group B2. There was no genetic relatedness among the isolates.

Conclusions: Hospital wastewater contains genetically diverse multidrug-resistant E. coli.

Significance and impact of the study: This study stresses the need for efficient water treatment plants in healthcare settings as a public health measure to minimize spread of multidrug-resistant bacteria into the environment.