Detection and Characterization of Extended‐Spectrum Beta‐Lactamase‐Producing <i>Escherichia coli</i> in Raw Seafood From the Coastal Area of Bangladesh

The emergence of antimicrobial resistance (AMR) and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) in seafood represents a significant public health concern. In this study, we screened 102 raw seafood samples, comprising shrimp (n = 42), sea fish (n = 36), and crabs (n = 24), to detect ESBL-EC. E. coli was isolated and identified through culture-based methods, staining procedures, biochemical assays, and polymerase chain reaction (PCR) analysis. The AMR properties of E. coli isolates were evaluated using the disc diffusion test, while ESBL-EC was identified phenotypically through the double-disc synergy test and confirmed at the genetic level using PCR. PCR analysis revealed that 42.2% (43/102) of the samples were contaminated with E. coli, with sea fish showing the highest (p < 0.05) prevalence (63.9%, 23/36), followed by crabs (37.5%, 9/24) and shrimp (26.2%, 11/42). All the isolates exhibited phenotypic resistance to ampicillin, followed by ceftazidime (95.3%), ciprofloxacin (55.8%), azithromycin (39.5%), cefotaxime (37.2%), and streptomycin (16.3%). Notably, 69.8% (30/43) of E. coli isolates exhibited phenotypically multidrug resistance. Moreover, 18.6% (8/43) of the isolates showed ESBL-producing characteristics, higher in shrimp than in sea fish and crabs. ESBL-related gene, bla_TEM, was detected in 75% (6/8), bla_SHV in 87.5% (7/8), and bla_CTX-M in 50% (4/8) of the ESBL-EC isolates. Regular surveillance of seafood for antimicrobial-resistant bacteria, particularly ESBL-producing strains, is recommended due to their potential public health implications.