Pig germs build drug resistance

Researchers collaborating with Biotec have found that a bacterium carried by pigs has become resistant to antibiotics and caused death in laboratory mice during experimental testing. The number of human infections is also likely to increase, the researchers warned. Speaking at a seminar organised by the National Centre for Genetic Engineering and Biotechnology (Biotec), Parichart Boueroy, a researcher from the Faculty of Public Health at Kasetsart University, said her team collected Streptococcus suis (S. suis) bacteria from infected patients to study virulence, focusing on strains found only in Thailand. The strains are ST 233 and ST 104, which fall under the country's dominant Serotype 2 strain, accounting for 93.4% of cases nationwide. The bacterial sub-strains were injected into mice to test virulence. The study found that the mortality rates of ST 233 and ST 104 in mice were 80% to 100% within 48 hours of infection due to septicaemia, a severe bloodstream infection. Similar results were seen with S. suis Serotype 14, while S. suis Serotype 31 caused intermediate mortality after 42 hours. Anusak Kerdsin, a leading molecular microbiologist at Kasetsart University's Faculty of Public Health, said the country's first case of S. suis was detected in two patients living in Bangkok in 1987, followed by a cluster of 10 fatalities in Lamphun province in 2000. Mr Anusak said that since 1987, 1,798 people have been infected with the deadly bacterial strains. The disease prevalence is around 0.97 per 100,000 population. Mr Anusak said that consuming dishes containing raw pork is the main cause of S. suis infection in humans in Thailand. Serotype 2 is the predominant strain causing human infections, followed by Serotype 4 (5.2%). He also found the strains have undergone a dynamic shift over time. The study found an association between ST1, ST104, ST233, and ST1688 and meningitis, sepsis, and infective endocarditis. He said the study also discovered that CC233 and CC1688 are the predominant strains resistant to penicillin and ceftriaxone. "We need further study on why the country is a major hub of S. suis," he said. "But at least our study will help raise awareness about the dangers of consuming raw meat. Although the bacteria is harmful to health, it can easily be destroyed by heat." He added the research would help pig farmers adopt a hygienic approach to farming to prevent disease transmission from animals to people. Subscribe to our newsletters for daily updates, breaking news and exclusive content.