Characterization Of Β-Lactamases and Multidrug Resistance Mechanisms in Enterobacterales from Hospital Effluents and Wastewater Treatment Plant

Abstract

Antimicrobial resistance presents a global challenge to the fight against infections in modern time. It is projected that, close to 2.4 million people are likely to die globally by the year 2050 due to infections linked to antibiotic resistance. Antimicrobials indiscriminately discharged into wastewater promote the emergence of antibiotic resistance, facilitated by selective pressure and transfer of resistance genes. This study aimed to determine the antimicrobial resistance profiles of enteric bacteria from wastewater and to establish the prevalence of plasmid borne β-lactamases and other mechanisms conferring multiresistance. Enteric bacteria, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, and Citrobacter species (n = 126) from hospital effluents and proximate wastewater treatment plant in the city of Pecs, Hungary, were assayed for susceptibility to four antimicrobial classes. The β-lactamase encoding genes harbored in plasmids were genotyped and the plasmid DNA was subjected to the next generation sequencing. A multidrug resistance phenotype was found in 72% (n = 58) of E. coli isolates, 70% (n = 43) of Klebsiella species isolates, and 40% (n = 25) of Enterobacter and Citrobacter species. 86% (n = 50) of E. coli, 77% (n = 33) of Klebsiella species and 25% (n = 4) of Citrobacter species isolates phenotypically expressed extended spectrum β- lactamase (ESBL). ESBL genes, blaCTX-M-27 and blaTEM-1 were found in E. coli, while Klebsiella species harbored blaCTX-M-15, blaCTX-M-30, or blaSHV-12. Genes coding for aminoglycoside modifying enzymes, adenylyltransferases (aadA1, aadA5), phosphotransferases (aph(6)-1d, aph(3")-Ib), acetyltransferases (aac(3)-IIa), (aac(6)-Ib), sulfonamide/trimethoprim resistant dihydropteroate synthase (sul), and dihydrofolate reductase (dfrA) were also identified. Mobile genetic elements namely; plasmids and integrons acquired via horizontal gene transfer are vehicles for multiresistance in enteric bacteria from wastewater. Monitoring wastewater from human sources for acquired resistance in clinically important bacteria may provide a cheaper alternative in regions facing challenges that limit clinical surveillance.