Detection of multi-drug resistance and AmpC β-lactamase/extended-spectrum β-lactamase genes in bacterial isolates of loggerhead sea turtles (Caretta caretta) from the Mediterranean Sea.

Sea turtles are useful sentinels to monitor the dissemination of antimicrobial resistance (AMR) in the marine coastal ecosystems. Forty Gram negative bacteria were isolated from wounds of 52 injured Caretta caretta, living in the Mediterranean Sea. Bacteria were identified using 16S rRNA gene sequencing and tested for susceptibility to 15 antibiotics. In addition, NGS amplicon sequencing was performed to detect the presence of AmpC β-lactamase genes (bla _AmpC ) and extended-spectrum β-lactamase (ESBL) genes (bla _CTX-M, bla _SHV, bla _TEM ). Seventy-five percent of the isolates (30/40 isolates) exhibited multidrug resistance (MDR) phenotypes and 32.5% (13/40 isolates) were confirmed to be positive for at least one gene. The variants of ESBLs genes were bla _CTX-M-3, bla _TEM-236 and bla _SHV-12 . Variants of the bla _AmpC β-lactamase gene i.e., bla _ACT-24 , bla _ACT-2 , bla _ACT-17 , bla _DHA-4 and bla _CMY-37 , were also detected. In addition, 4 isolates were found simultaneously harboring CTX and AmpC genes while 2 strains harbored 3 genes (bla _{ACT-2+TEM-236+SHV-12} , and bla _{CTX-M-3+ACT-24+TEM-236} ).
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