33% of animal-use probiotics contain pathogens; spillover to humans documented
A study of animal-use probiotics in China showed that approximately one-third contained “life-threatening” pathogens, and that colonized animals shed pathogens into the environment, facilitating spillover to humans.
“Human-use probiotics have recently been associated with clinical infections and antibiotic resistance transfer, raising public concern over their safety,” researchers wrote. “However, despite their extensive application in aquaculture and animal husbandry, the safety of animal-use probiotics remains poorly described.”
In their study, the researchers evaluated 92 Bacillus-containing animal-use probiotics collected in China between 2016 and 2018 and monitored the spread of pathogens through in-field genomic surveillance at two farms.
According to the study, a total of 123 probiotic Bacillus species isolates were obtained from the 92 brands of probiotics, of which 45 were resistant to antibiotics. The researchers found that 33.7% of probiotic products were contaminated with life-threatening pathogens, including Klebsiella pneumoniae.
Genomic surveillance identified an anthrax toxin-positive Bacillus cereus strain in a probiotic product used as a feed supplement at a chicken farm that was transferred into the groundwater and to a nearby fish farm, according to the study. The researchers retrospectively examined surveillance data from 2015 to 2018 in three provinces and found two B. cereus strains from humans with intestinal anthrax symptoms, confirming the transmission of B. cereus from the farm to humans.
“This study provides the first national safety survey of animal-use probiotics in China and confirms the spillover effects of probiotics from the farms to humans,” the authors concluded. “These results suggest that the large-scale application of pathogen-containing probiotics leads to the transfer of pathogens, with worrisome implications for public health. Good manufacturing practice should be implemented during the production of all probiotics.” – by Caitlyn Stulpin
Disclosures: The authors report no relevant financial disclosures.