Worse, four out of every five Salmonella strains found in the chicken were resistant to antibiotics, a result of indiscriminate use of the medicines by poultry producers.

The ready-to-cook (RTC) chicken that you pick from supermarkets is more likely to be contaminated with the dangerous food pathogen Salmonella, if not frozen, a study by the Food Technology Division, Bhabha Atomic Research Centre (BARC), reveals.

Worse, four out of every five Salmonella strains found in the chicken were resistant to antibiotics, a result of indiscriminate use of the medicines by poultry producers.

A five-member team which studied 87 samples of poultry picked up from supermarkets and department stores in Mumbai, found Salmonella in more than 50% of the 48 chilled (kept at temperatures between 8 and 10 °C) samples comprising minimally processed and raw meat – 53% of 34 samples from brand one and 50% of 14 samples from second brand.

Frozen poultry was less likely to be contaminated. While 5% of 19 frozen samples that also contained ingredients such as flour, onion, water, spices and condiments from the fourth brand were contaminated with the bacteria, the 20 frozen samples from the third brand were free of the bacteria. Scientists explained the large variation in the presence of Salmonella to the fact that the pathogen’s growth is inhibited in frozen condition (0 to -20 °C) compared to temperatures above freezing.

Salmonella – considered as one of the most dangerous food-borne pathogen – causes food poisoning with diarrhoea, stomach cramps, vomiting, nausea, and fever. Salmonella is found commonly in the environment and can spread during food processing or food handling, via the unwashed hands of infected food handlers.

The study also found that 81.4% of Salmonella bacteria strains were resistant to 9 of the 15 antibiotics belonging to different classes that were tested for multiple antibiotic resistance. Additionally, 69.9% of the strains were detected with class 1 integron – a genetic mechanism that is known to confer multi-drug resistance to microorganisms against various antibiotics used to control various diseases.

The most common Salmonella species was Salmonella Typhimurium – as high as 75% in the samples, followed by S. Enteritidis (23%) and S. Weltevreden (1.7%).?The brands of the chicken samples were not named in the study.

The researchers did not comment on the study. Dr Sumanth Gandra, resident scholar at US-based Center for Disease Dynamics, Economics & Policy (CDDEP) New Delhi’s office, who was not involved in the present study, said that while the BARC team did not investigate the source of bacterial contamination, whether from the poultry farms or during the processing of meat, the first aim and focus should be to have rigorous processes to prevent these bacteria from getting into chickens at the poultry farms, good handling and processing practices by the industry and stringent surveillance by authorities. “We don’t know what practices are being followed in India, and have to question it,” said Gandra.

A member from the Poultry Federation of India said, “We are not careless, and take utmost care while handling and managing chicken at the farms since we know its for human consumption. Chicken could also get contaminated with salmonella while processing or storing it. As for using antibiotics, we work with national and international laboratories, and some antibiotics are not used for humans.”

Indiscriminate antibiotic use in poultry farms is giving rise to resistant bacteria

The BARC team found Salmonella isolates from brand 1 and brand 2 were resistant to 9 different antibiotics; whereas, Salmonella isolates of brand 4 were resistant to 4 antibiotics.

Growing antibiotic resistance among humans is a concern. “We know certain type antibiotics are used in chicken; to what extent they are used is unknown. But the kind of of resistance seen in the BARC paper is consistent with antibiotics used in poultry farms,” said Dr Gandra. “Some antibiotics that are resistant to salmonella are used to treat humans but also used in poultry farms. But there are other antibiotics that can treat patients infected with salmonella,” said Gandra.

Minimally processed and fresh RTC samples such as mixed boneless, soup pieces, mixed boneless, precut, drumstick and leg cut, and also processed and frozen RTC samples (sausages, kheema, cutlet, nuggets, tandoori chicken nuggets, tandoori chicken tikka, chicken samosa, salami slices, sheekh kebab, burger patty, lollipops, and spring roll) were contaminated with S. Typhimurium and S. Enteritidis.

Better surveillance of the retail meat market can reduce Salmonella contamination

With consumption of RTC poultry and other food products increasing in India, researchers said the study findings are significant because unlike fresh poultry the prevalence of Salmonella in RTC poultry products has not been studied.

Dr Gandra of the Center for Disease Dynamics, Economics & Policy (CDDEP) New Delhi’s office, said that unlike BARC study which showed that 50% chilled RTC poultry samples were contaminated with salmonella, that figure stood at 9% in 2014 in the US where surveillance is done on retail meat. “Salmonella is only generally seen in poultry, but these strains are known to cause food borne infections in humans, and need to keep them to a minimum as possible in meat. These strains are typically present in chicken, and can be expected to be seen in retail meat,” said Dr Gandra.

Researchers said antimicrobial resistance is currently among the leading concerns in global public health as it can result in an increasing number of clinical failures in bacterial-mediated diseases. Last month, a study led by CDDEP – largest of its kind in India –found high levels of antibiotic-resistant pathogens in chickens raised for both meat and eggs on farms in Punjab as a result of using antibiotics to prevent infection or as growth promoters.

Cooking is the best way to kill pathogens

Previous studies have found S. Typhimurium and S. Enteritidis to be the most frequently reported strains or serovars related to human foodborne illnesses and poultry industry in India. Additionally, S. Typhimurium is among the most commonly detected serovars from animals that are used for food and retail meat in the US. Recent studies have also reported S. Weltevreden as the emerging cause of gastroenteritis in tropical regions.

The most effective way to eliminate Salmonella is to cook RTC food thoroughly and eat fresh. “Though most of the food in India is cooked, the pathogen very often can cross-contaminate the kitchen platform, cooking and serving utensils,” said the team adding good manufacturing practices were not followed by concerned poultry processors, which led to a high prevalence of Salmonella, a zero-tolerance bacterium.