The emergence and global dissemination of extended-spectrum β-lactamase (ESBL)-producing
Escherichia coli (ESBL-
E. coli) represent a major public health concern. However, the characterization and capacity for horizontal gene transfer (HGT) of ESBL-
E. coli in captive black bears remain substantially understudied. In
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The emergence and global dissemination of extended-spectrum β-lactamase (ESBL)-producing
Escherichia coli (ESBL-
E. coli) represent a major public health concern. However, the characterization and capacity for horizontal gene transfer (HGT) of ESBL-
E. coli in captive black bears remain substantially understudied. In the present study, 19 ESBL-
E. coli strains were successfully identified (13.38%, 19/142). A total of 11 sequence types (STs) were identified from 19 ESBL-
E. coli strains using MLST. This included eight known types (ST10, ST2690, ST208, ST695, ST4160, ST540, ST3865 and ST2792) and three new STs. Antimicrobial susceptibility testing demonstrated that all 19 ESBL-
E. coli exhibited high resistance to KZ (100.00%), CRO (78.95%), and CTX (73.68%). Polymerase chain reaction (PCR) screening for 14 β-lactam antibiotic resistance genes (ARGs) and their variants revealed that
blaCTX-M was the most prevalent, followed by
blaSHV,
blaTEM, and
blaDHA. Furthermore, eight β-lactamase variants were detected, including five
blaCTX-M variants (
blaCTX-M-15,
blaCTX-M-3,
blaCTX-M-14,
blaCTX-M-55, and
blaCTX-M-27) and one variant each of
blaSHV-1,
blaTEM-1, and
blaDHA-14. Conjugation assays revealed that eight ESBL-
E. coli strains were capable of conjugative transfer. Five plasmid types (IncFII, IncW, IncFrepB, IncY, and IncHI1) and three mobile genetic elements (MGEs) (
IS26,
ISEcp1, and
trbC) were identified as co-transferred with
blaCTX-M. ESBL-
E. coli poses a potential threat to captive black bears and may lead to further transmission. Consequently, the implementation of continuous surveillance and targeted interventions is imperative to prevent the transmission of ESBL-
E. coli.
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