Date of Completion

2025

Document Type

Thesis

Degree Name

Bachelor of Science in Life and Health Sciences

Keywords

Enterobacteriaceae, antimicrobial resistance, chicken intestines, multidrug resistance, food safety

Abstract

Enterobacteriaceae are gram-negative bacteria typically present in the gastrointestinal tracts of both humans and animals, and are commonly associated with infections, including urinary tract infections, sepsis, and pneumonia. The widespread and often unregulated use of antibiotics in poultry industry has played a significant role in the emergence of antimicrobial-resistant strains, further worsening the global antimicrobial resistance (AMR) crisis. This study investigated antimicrobial-resistant Enterobacteriaceae in chicken intestines collected from Kadiwa Public Market in Dasmariñas City, Cavite. A total of 40 bacterial isolates were collected from chicken intestinal samples collected from five vendors and cultured on MacConkey and Salmonella- Shigella agar. Based on colony morphology and preliminary identification, the most prevalent genera isolated were Escherichia, Enterobacter, and Klebsiella, along with potential pathogens such as Salmonella and Shigella. Gram staining confirmed five gram-negative isolates, which were further subjected to MR-VP biochemical testing and showed MR-positive and VP-negative results, consistent with the biochemical profiles of Escherichia coli, Salmonella, and Shigella. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method using five antibiotics, revealed complete sensitivity to gentamicin and meropenem, while resistance was observed against piperacillin. Three isolates that exhibited multidrug resistance were further analyzed through 16S rRNA gene sequencing, identifying two isolates as Raoultella ornithinolytica (Enterobacteriaceae) and one as Pseudomonas lundensis (Pseudomonadaceae). These findings underscore the presence of antimicrobial-resistant bacteria in poultry and emphasize the need for strengthened surveillance and improved food safety practices.

First Advisor

Nicole B. Marin

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