Rare Salmonella strain detected in Metro Manila pork

Researchers warn of multidrug resistant Salmonella in swine meat, highlighting urgent food safety concerns and the need for stronger surveillance in the Philippines.

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Rare Salmonella strain detected in Metro Manila pork

Pathology porciNews Asia

A new study has found 13 Salmonella enterica serovars in pork sold across Metro Manila, the Philippines’ biggest market, raising urgent food safety concerns. Researchers analyzed 110 isolates from abattoirs and wet markets, identifying Rissen, Typhimurium monophasic variant, Anatum, and Derby as the most common.

The standout discovery was serovar Soerenga, reported for the first time in the Philippines and Asia. It was isolated from a wet market pork chop, underscoring the risk of rare strains entering the food chain.

Different contamination patterns across markets

The study revealed Rissen dominated abattoir samples, while Anatum was more frequent in wet markets. This suggests contamination pathways differ between slaughterhouses and retail environments.

Researchers warn that wet markets, with open handling and limited sanitation, may play a critical role in spreading Salmonella. The findings highlight the need for stricter hygiene measures in post‑harvest settings.

Genes linked to virulence and resistance

Genetic analysis showed high frequencies of virulence genes, including hilA (75.45%), avrA (73.64%), and mgtC (72.73%). These genes enhance the bacteria’s ability to invade hosts and survive inside cells.

Resistance genes were also widespread. bla_TEM was present in 44.55% of isolates, matching phenotypic resistance to β‑lactams. The most common resistances were to ampicillin (39.81%), trimethoprim/sulfamethoxazole (36.11%), and ampicillin/sulbactam (34.26%). Alarmingly, 14.81% of isolates showed multidrug resistance, spanning β‑lactams, aminoglycosides, and folate pathway inhibitors.

What the findings mean for consumers

The dominance of Rissen, Derby, and Typhimurium monophasic variant mirrors global patterns, where these serovars are linked to human infections and multidrug resistance. Their persistence in swine reservoirs raises concerns about zoonotic transmission.

Meanwhile, Anatum’s prevalence in wet markets points to contamination during handling rather than farm‑level persistence. The detection of rare serovar Soerenga adds urgency to surveillance efforts, as emerging strains may carry unpredictable risks.

Strengthening surveillance and regulation

The study highlights the value of microarray‑based serotyping as a reliable, cost‑effective tool for monitoring Salmonella. Its findings call for tighter regulation, improved sanitation, and stronger surveillance in the Philippine pork industry.

Researchers stress that without decisive action, multidrug‑resistant Salmonella could spread more widely, posing a growing threat to consumers and public health.