UP biologists uncover drug-resistant Salmonella in Metro Manila chicken

Biologists at the University of the Philippines Diliman - College of Science’s Institute of Biology are urging nationwide surveillance of foodborne pathogens after uncovering high levels of multidrug-resistant (MDR) Salmonella in chicken sold at Metro Manila wet markets.

Using whole-genome sequencing and phenotypic antimicrobial-resistance testing, the Pathogen-Host-Environment Interactions Research Laboratory team analyzed Salmonella isolates from the country’s second most-consumed meat. They identified six major serovars — Infantis, Brancaster, Anatum, London, Uganda, and Derby — all carrying diverse virulence factors and 50 antimicrobial-resistance genes (ARGs) spanning 12 drug classes. More than 45 percent of isolates exhibited multidrug resistance, and numerous resistance-spreading plasmids were detected.

“Our study suggests a need for proper surveillance of contaminating bacteria as well as regulations on antimicrobial use at the farm level, as infections from MDR Salmonella, especially among vulnerable populations and from highly virulent serovars (types of Salmonella), can lead to life-threatening, systemic, and untreatable manifestations,” the team said.

The biologists further emphasized that there is a clear and significant risk of MDR Salmonella variants spreading within wet markets and food animal value chains, as well as the potential for cross-contamination and undetected transmission in kitchens and homes.

Salmonellosis — marked by fever, abdominal pain, diarrhea, and nausea — typically appears 6–72 hours after exposure and can last up to seven days. MDR Salmonella is recognized globally as a leading cause of diarrheal outbreaks, and the Philippines’ large poultry industry makes local surveillance critical.

To combat this threat, the team called for multi-sectoral policies enforcing responsible antibiotic use, public and farmer education on antimicrobial resistance (AMR), support for alternative treatments, and ongoing pathogen surveillance.

“Mitigating this concern requires multi-sectoral policies, regulations, and standards — especially regarding proper antibiotic use, increased awareness of AMR and MDR at the farm, clinical, and community levels, and support for research and development of antimicrobial alternatives, and surveillance of foodborne pathogens and resistance,” they concluded.

Supported by the Department of Agriculture-Biotechnology Program Office, the study highlights the urgent need to safeguard food safety and public health against the growing challenge of MDR Salmonella.