Antimicrobial resistance, Extended-Spectrum β-Lactamase production and virulence genes in Salmonella enterica and Escherichia coli isolates from estuarine environment

Abstract

The impact of antimicrobial resistance (AMR) on global public health has been widely documented. AMR in the environment poses a serious threat to both human and animal health but is frequently overlooked. This study aimed to characterize the association between phenotype and genotype of AMR, virulence genes and Extended-Spectrum β-Lactamase (ESBL) production from estuarine environment. TheSalmonella(n= 126) andE.coli(n= 409) were isolated from oysters and estuarine water in Thailand. The isolates ofSalmonella(96.9%) andE.coli(91.4%) showed resistance to at least one antimicrobial agent. Multidrug resistance (MDR) was 40.1% ofSalmonellaand 23.0% ofE.coli. Resistance to sulfamethoxazole was most common inSalmonella(95.2%) andE.coli(77.8%). The common resistance genes found inSalmonellaweresul3(14.3%), followed byblaTEM(11.9%), andcmlA(11.9%), while mostE.coliwereblaTEM(31.5%) andtetA(25.4%). The ESBL production was detected inSalmonella(1.6%,n= 2) of which one isolate was positive toblaTEM-1. EightE.coliisolates (2.0%) were ESBL producers, of which three isolates carriedblaCTX-M-55and one isolate wasblaTEM-1. Predominant virulence genes identified inSalmonellawereinvA(77.0%),stn(77.0%), andfimA(69.0%), while those inE.coliisolates werestx1(17.8%),lt(11.7%), andstx2(1.2%). Logistic regression models showed the statistical association between resistance phenotype, virulence genes and ESBL production (p< 0.05). The findings highlighted that estuarine environment were potential hotspots of resistance. One Health should be implemented to prevent AMR bacteria spreading.