Prevalence of Extended-Spectrum β-lactamases in Enterobacteriaceae Isolated from Polluted Wild Fish

Antibiotic resistance is becoming a major public health concern worldwide. In marine animals, pollution is associated with the emergence of extended-spectrum β-lactamase (ESBL)-expressing bacteria, resulting in antibiotic resistance. However, the prevalence of these bacteria in wild fish has not been reported.

Accordingly, in this study, we explored the influence of pollution oxidative stress on the incidence of ESBL-expressing Enterobacteriaceae in the gut of wild fish species from the Red Sea coastal region of Jeddah City, Saudi Arabia. Additionally, we evaluated the incidence of varied ESBL genes contributing to the ESBL+ phenotype.

Antibiotic susceptibility tests were performed using cephalosporins and carbapenems against ESBL- and carbapenem-resistant Enterobacteriaceae (CRE)-producing bacteria. Frequent genes contributing to the ESBL+ phenotype were analyzed. Primers targeting ESBLs (e.g., blaCTX, blaSHV, blaTEM, and blaOXA) were used in polymerase chain reaction assays to detect the ESBL+ phenotype.

Screening results from the polluted site revealed ESBL-resistant Klebsiella pneumoniae B8 and CRE-resistant Morganella morganii A4. The evolution of the blaCTX-M gene in M. morganii was a consequence of aquatic pollution. The other isolates Acinetobacter pittii and Providencia rettgeri were found in the clean reference site. The isolate M. morganii showed resistance to most mutual antibiotics and expressed some β-lactamase genes.

Our findings provide useful data for selecting marine molecular genomic biomarkers caused by aquatic pollution.