INTERACTIVE: Rising antibiotic resistance detected in livestock bacteria

By SHYAFIQ DZULKIFLI

PETALING JAYA: Malaysia’s livestock have been found to carry bacteria that are increasingly resistant to multiple antibiotics, including those considered critical for human health, according to the Department of Veterinary Services (DVS).

Surveillance data in 2024 show that Salmonella and E. coli bacteria found in poultry, pigs, and dairy cattle remain highly resistant to several commonly used antibiotics, including ampicillin, chloramphenicol, and tetracycline.

The department expressed concern over the growing resistance to third-generation cephalosporins, including cefotaxime and ceftiofur, which the World Health Organization (WHO) lists as critically important antimicrobials (CIAs) for human use.

“From 2022 to 2024, we observed an increase in resistance to cefotaxime and ceftiofur, which are the third generation of cephalosporins, in Salmonella spp. isolated from broilers, pigs and dairy cattle.

“These trends are worrying because these antibiotics are often used for treating serious infections in humans like sepsis, pneumonia and meningitis,” DVS said. 

E. coli isolates showed higher resistance to the third-generation cephalosporins cefotaxime and ceftiofur in poultry and pigs compared to Salmonella.

Among poultry, E. coli from broilers recorded the highest resistance levels, at 26% for cefotaxime and 18% for ceftiofur. 

In layer chickens, resistance was lower, at 10% and 8% respectively.

For Salmonella, isolates from pigs showed the highest resistance, with 8% for both cefotaxime and ceftiofur. 

In poultry, Salmonella from broilers recorded 3% resistance to cefotaxime, while those from layers showed 3% resistance to ceftiofur.

The department added that the presence of drug-resistant bacteria in food-producing animals poses a risk to humans, as these microbes can spread through the food chain via contaminated meat or animal products such as eggs and milk during slaughter and processing.

“They can also enter the environment when animals shed the bacteria or their resistance genes through manure and waste,” DVS said.

Once inside the human body, these bacteria or their resistance genes can persist in the gut and make it harder for human to treat infections.

In 2024, E. coli isolates from pigs recorded resistance of 97% to ampicillin, 97% to tetracycline, and 91% to chloramphenicol, while those from broiler chickens showed similar high resistance — 93% to ampicillin and 91% to tetracycline.

Salmonella isolates also showed persistent resistance.

Pigs recorded 92% resistance to ampicillin and 84% to tetracycline, while broiler chicken were at 84% and 82% respectively.

Take a look at the tables below for the resistance rates of Salmonella spp. and E. coli isolated from livestock against various antibiotics.

Resistance to quinolones has also been detected, with E. coli from broilers showing 58% resistance to enrofloxacin in 2024.

Quinolones is another class of drugs vital for human medicine, to treat serious bacterial infection in human including respiratory and urinary tract infection.

The department said it is actively monitoring the antimicrobial resistance in food-producing animals through the Malaysian Action Plan on Antimicrobial Resistance (MyAP-AMR).

Through the surveillance programme, DVS found no significant difference in resistance rates across the country.

“This indicates the issue is consistent nationwide and our surveillance efforts will continue to track changes over time to ensure early detection of any emerging concerns,” DVS said.

In 2024 alone, DVS isolated 276 Salmonella spp. and 1,104 E. coli samples from farms, slaughterhouses and processing plants.

The surveillance forms part of Malaysia’s commitment to the global One Health framework, which recognises that human, animal and environmental health are closely interconnected.

To reduce unnecessary use of antibiotics in animals, DVS has rolled out a series of policies and bans over the past decade.

Among them are the Feed Act 2009, which regulates the import, sale and use of animal feed containing antimicrobials, and the ban on the use of WHO-designated CIAs as growth promoters or for preventive use, which started in year 2012.

The department also promotes good farm management practices through the Malaysian Good Agricultural Practices (MyGAP) and the Veterinary Health Mark (VHM) certification schemes for livestock farms, which emphasise hygiene, biosecurity, and disease prevention instead of antibiotic dependence.

“We encourage farmers to adopt vaccination, regular disease monitoring and strong biosecurity measures to reduce the risk of antimicrobial resistance at the farm level,” DVS said.