Antimicrobials concealing Salmonella debate reignited

By Joseph James Whitworth contact

- Last updated on GMT

USDA-FSIS said it was 'confident' that testing results yield accurate outcomes
USDA-FSIS said it was 'confident' that testing results yield accurate outcomes

Related tags: Microbiology

Antimicrobial chemicals used as processing aids may lead to false-negative results in pathogen testing, according to a study.

Researchers said antimicrobials are used to reduce pathogenic bacteria on processed poultry carcasses.

However, carryover of active sanitizer to a carcass rinse solution intended for recovery of viable pathogenic bacteria may cause false-negative results by remaining in high enough quantities on chicken carcasses to contaminate testing samples.

“These findings potentially indicate that the currently utilized protocol for the recovery of Salmonella bacteria from postchill sanitizer interventions may lead to false-negative results due to sanitizer carryover into the carcass rinsate,”​ they said in the Journal of Food Protection​.

Common antimicrobial interventions when processing chickens include paracetic acid (PAA), chlorinated water, cetylpyridinium chloride (CPC), acidified sodium chlorite (ASC), organic acid rinses, bromine and others, according to the National Chicken Council (NCC).

FSIS data integrity question

Thomas Gremillion, director of food policy at Consumer Federation of America (CFA), said the research calls into question the FSIS data on Salmonella contamination in chicken.

“FSIS has reported significant reductions in positive test samples every year for the last several years, but this study suggests those numbers might reflect flaws in the testing procedures rather than actual gains towards protecting consumers.”

An estimated 1.2 million illnesses are thought to be caused every year by Salmonella, with 375,000 attributed to FSIS-regulated products in Fiscal Year (FY) 2015.  

The study documented the potential carryover effect of five sanitizing chemicals used as poultry processing aids for broilers in a postchill dip.

To test for Salmonella, a technician pulls a poultry carcass from the “chiller” at the end of the slaughter line, said CFA.

The technician puts the carcass into a sample bag containing a buffered peptone solution, and then removes the carcass and sends the solution to the lab for testing.

When USDA established this, companies applied chemical interventions like chlorine earlier in the slaughter process. However, they are now applying antimicrobial agents later in the process, including post-chill antimicrobial dips and sprays.

USDA-FSIS ‘confident’ in results

A USDA-FSIS spokeswoman told FoodQualityNews that it is confident that testing results yield accurate outcomes.

“The report cites a study that did not evaluate the same practices our in-plant personnel utilize. Data shows we are making progress when it comes to confronting Salmonella and protecting American consumers. FSIS is taking additional steps to ensure data quality and integrity of our pathogen tests.”

She said over the past several years FSIS has placed tighter food safety standards on the poultry industry and data show that public health is benefitting.

“In the most recent Center for Disease Control and Prevention (CDC) FoodNet Annual report, the incidence of Salmonella Typhimurium illnesses from all foods had declined 15% (compared to 2012-2014).

“FSIS is encouraged by these findings and will continue to make science based improvements to further ensure the safety of America's poultry supply.”

Wenonah Hauter of Food and Water Watch, said over the last three years, it has asked FSIS officials what the agency is doing to address carryover of these antimicrobials into testing samples.

“They have told us that they are working to develop a new neutralizing agent, but in the meantime, how are we supposed to interpret these test results? FSIS should modify its testing procedures now to avoid false negatives.”

Related topics: Food Safety & Quality

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