Nearly 50% of isolates of Salmonella enterica from chicken meat collected from Metro Manila markets are resistant to three or more types of antibiotics

08 Apr 2026

Antimicrobial resistance (AMR) occurs when medicines used to treat infections no longer work effectively, often due to their overuse and misuse. It is a complex and growing problem driven by inappropriate use in human medicine, poor agricultural practices, and environmental pollution, and is now considered a major global public health threat.

Salmonella enterica is one of the most common foodborne pathogens worldwide. It is classified into two types: typhoidal, which causes typhoid fever, and non-typhoidal (NTS), which can lead to food poisoning and, in some cases, severe infections. NTS spreads through animals, food, and the environment, with poultry and poultry products being major sources. A growing concern is the emergence of NTS that are resistant to multiple antibiotics, making infections harder to treat.

In this study, we characterized NTS from chicken meat through whole-genome sequencing. Chicken samples, supplied by local farms to slaughterhouses, were collected from public wet markets in San Juan, Quezon City, Malabon, and Muntinlupa in Metro Manila.

Our findings revealed that our 95 isolates from the chicken cut samples belong to 15 distinct NTS “strains,” with Salmonella Infantis being the most common. By testing 15 different antibiotic classes, we found that 73.68% of our NTS were resistant to at least one antibiotic, and 45.26% were resistant to three or more antibiotic classes.

We also identified the genes responsible for these resistance traits, some of which can transfer between bacteria, accelerating the spread of antibiotic resistance. Additionally, we found genes that enhance the ability of NTS to infect humans and animals.

These findings highlight a potential public health risk, as NTS in chicken meat can spread throughout the entire farm-to-fork continuum, from farms to consumers. This study provides essential baseline data that can guide the development of targeted control strategies to curb antibiotic resistance and support future public health initiatives.

Authors: Michael Joseph M. Nagpala (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman | Microbiology Division, Institute of Biological Sciences, University of the Philippines Los Baños), Jonah Feliza B. Mora (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman), Rance Derrick N. Pavon (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman) and Windell L. Rivera (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman)

Read the full paper: https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1496685/full

Image by Julia Filirovska from Pexels

Nearly 50% of isolates of Salmonella enterica from chicken meat collected from Metro Manila markets are resistant to three or more types of antibiotics

Antimicrobial resistance (AMR) occurs when medicines used to treat infections no longer work effectively, often due to their overuse and misuse. It is a complex and growing problem driven by inappropriate use in human medicine, poor agricultural practices, and environmental pollution, and is now considered a major global public health threat.

Salmonella enterica is one of the most common foodborne pathogens worldwide. It is classified into two types: typhoidal, which causes typhoid fever, and non-typhoidal (NTS), which can lead to food poisoning and, in some cases, severe infections. NTS spreads through animals, food, and the environment, with poultry and poultry products being major sources. A growing concern is the emergence of NTS that are resistant to multiple antibiotics, making infections harder to treat.

In this study, we characterized NTS from chicken meat through whole-genome sequencing. Chicken samples, supplied by local farms to slaughterhouses, were collected from public wet markets in San Juan, Quezon City, Malabon, and Muntinlupa in Metro Manila.

Our findings revealed that our 95 isolates from the chicken cut samples belong to 15 distinct NTS “strains,” with Salmonella Infantis being the most common. By testing 15 different antibiotic classes, we found that 73.68% of our NTS were resistant to at least one antibiotic, and 45.26% were resistant to three or more antibiotic classes.

We also identified the genes responsible for these resistance traits, some of which can transfer between bacteria, accelerating the spread of antibiotic resistance. Additionally, we found genes that enhance the ability of NTS to infect humans and animals.

These findings highlight a potential public health risk, as NTS in chicken meat can spread throughout the entire farm-to-fork continuum, from farms to consumers. This study provides essential baseline data that can guide the development of targeted control strategies to curb antibiotic resistance and support future public health initiatives.

Authors: Michael Joseph M. Nagpala (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman | Microbiology Division, Institute of Biological Sciences, University of the Philippines Los Baños), Jonah Feliza B. Mora (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman), Rance Derrick N. Pavon (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman) and Windell L. Rivera (Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman)

Read the full paper: https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1496685/full

Image by Julia Filirovska from Pexels