Researchers have investigated the prevalence of Bacillus cereus in infant formula sold in China.

No legal microbiological criteria for the pathogen in powdered infant formula (PIF) and powdered follow-up formula (PFUF) exists in the country.

From 6,656 samples, 92.47 percent contained less than 10  colony forming units per gram (CFU/g) of Bacillus cereus. However, 501 samples were contaminated in the range of ≥10 CFU/g and 74 had more than 100 CFU/g.

It is generally accepted that low levels of <100 CFU/g may be present in PIF products and should be monitored by the manufacturer, according to Food Standards Australia New Zealand (FSANZ) in 2016.

Samples of imported and domestic product were collected quarterly from urban and rural markets in 31 provincial-level administrative units in China in 2014, according to the study published in the Food Control journal.

All sampling regions provided Bacillus cereus-positive samples, although they ranged from 3.68 percent for South China to 14.53 percent for Northeast China.

There were no statistical differences of contamination levels between PIF and PFUF or in samples from retail, wholesale and online outlets. Positives in samples produced domestically was higher than from imported ones.

Bacillus cereus positive samples differed between sampling areas and in domestic production regions. Positives and samples with >100 CFU/g from Northeast China were much higher than other regions because of more contamination in products made by several local facilities.

Results indicated Bacillus cereus >10 CFU/g in samples produced in summer and autumn, which were 8.80 percent (111/1262) and 9.18 percent (136/1481), respectively, were higher than those in spring and winter.

Statistical analysis showed that powdered formula sampled in winter was significantly higher in Bacillus cereus compared with the other three sampling seasons. The main reason for this may be the time between production and sampling date. After products were packaged, they were stacked in warehouses, then transported to different cities for sale, and only these products were sampled.

Outbreaks and sporadic foodborne disease due to Bacillus cereus have been reported in children. It was detected at 2,500 CFU/g, 600 CFU/g and 160 CFU/g in PIF products implicated in three foodborne outbreaks in China involving infants.

Foodborne disease caused by it were associated with 5 log to 8 log cells/spores per gram of the food vehicle. However, lower numbers (3-4 log per g) have been reported by the European Food Safety Authority (EFSA) in 2005.

Earlier studies  — Li, Pei, Yang, & Li, 2014 — found Bacillus cereus ≥10 and > 100 CFU/g in powdered formula in China retail markets were 14.08 percent (115/817) and 2.2 percent in 2012, respectively.

“This may be the effect of strengthening microbial controls in production facilities after the previous survey results were notified by the manufacturers. This nationwide Bacillus cereus prevalence data in powdered formula could be used as reference for future comparison and trend analysis,” said researchers.

Powdered infant formula is the primary source of nutrition for infants and should be viewed as a high-risk food because of the greater susceptibility of infants and young children to illness compared to adults.

“The purpose of the study was to investigate the prevalence of Bacillus cereus in PIF and PFUF sold in China and to provide data that could be used for risk assessment and management to ensure the safety of these kinds of products. There is a need to conduct further research on Bacillus cereus contamination in powdered formula products in China before microbiological criteria are developed,” added researchers.