AUFA, Muhammad (2026) Detection of β-Lactamase Resistance Genes in Enterobacteriaceae Isolated from Bottlenosed Dolphin (Tursiops truncatus). Undergraduate thesis, Fakultas Sains dan Matematika.

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Abstract

Antibiotic resistance in Enterobacteriaceae has emerged as a serious global concern, not
only in clinical settings but also within marine ecosystems. This study aimed to detect β
lactamase resistance genes in Enterobacteriaceae isolated from bottlenose dolphins
(Tursiops truncatus). A total of 47 bacterial isolates were obtained and subsequently
identified using MALDI-TOF MS, resulting in 18 species, of which 7 belonged to the
Enterobacteriaceae family, namely Escherichia coli, Hafnia alvei, Citrobacter freundii,
Citrobacter brakii, Providencia stuartii, Serratia marcescens, and Proteus vulgaris.
Antibiotic susceptibility testing (AST) using the Kirby-Bauer disk diffusion method
revealed that all isolates were resistant to penicillin and cephalothin, while most isolates
remained sensitive to meropenem, except for Serratia marcescens, which showed
intermediate susceptibility. Molecular detection of β-lactamase resistance genes (blaTEM,
blaSHV, blaCTX-M, blaOXA) was performed using PCR. The results indicated that only
E. coli carried the blaTEM gene, whereas other resistance genes were not detected in the
tested isolates. These findings demonstrate that bottlenose dolphins may serve as carriers
of Enterobacteriaceae harboring β-lactam resistance determinants, highlighting their
potential role as sentinel species for monitoring antimicrobial resistance in marine
environments. The absence of other β-lactamase genes may be associated with genetic
variability among marine-associated isolates, potential primer-target mismatches,
suboptimal PCR optimization, and the absence of appropriate positive controls, rather than
indicating a complete failure of PCR amplification.
Keywords: β-lactamase, antibiotic resistance, bottlenose dolphin, Enterobacteriaceae

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