Prevalence of Cronobacter spp. in a powdered infant formula processing environment.

From November 2005 to August 2006, microbiological analyses were performed in a processing plant for powdered infant formula (PIF) to estimate the occurrence and dissemination of Cronobacter spp. and the contamination levels of Enterobacteriaceae in the processing environment. In total 867 samples were collected from the dry processing environment including powders from vacuum cleaners and filtering (sieving) machines, fluids from the drains and swabs from contact surfaces. In total 35 samples in 14 out of 35 tested locations were positive for Cronobacter spp. Positive samples were found in environmental powders (94.3%) and two fluids (5.7%). The Cronobacter spp. prevalence was highest in powders from vacuum cleaners with 28.0% positive samples on a single location. While powders from the sensitive agglomeration section or production (sieving) had contamination rates of 10.7% or below 3.4%, respectively. In addition vacuum powder samples from the filling and can filling line were positive with 5.3 and 8.0%, respectively. High levels (>500 cfu/g) of Enterobacteriaceae were found in seven locations out of 21 tested powder locations. This fact emphasizes the importance of monitoring of the processing environment to implement effective measures to improve the safety and hygiene in PIF, a very sensitive product.

Bacillus cereus in infant foods and dried milk products.

Dried milk products and infant food are known to be frequently contaminated with Bacillus cereus. Sources of the organism and its behaviour in the product and in the equipment during processing are discussed. With regard to the incidence of B. cereus in infant food, 261 samples distributed in 17 countries were collected and examined for its B. cereus content. Fifty-four percent of the samples were contaminated with B. cereus reaching levels from 0.3 to 600/g. Counts higher than 10/g were found in only 27 samples (10%). Most of the positive samples (44%) contained 0.3 to 10 B. cereus/g. Four samples (1.5%) were contaminated with more than 100 organisms/g reaching a maximum level of 600 B. cereus/g. When classified into different types of products about 50% of the infant formulae based on milk, the follow-on formulae and the weaning foods were contaminated with B. cereus as well as 69% of those based on soy protein and 92% of the special dietetic foods. Compared to our earlier studies from 1982/83, the percentage of contaminated samples from Germany increased from 31% to 70% in the case of infant formulae, from 28% to 55% in the case of follow-on formulae, and from 40% to 100% in the case of special dietetic food. The percentage of weaning food contaminated with B. cereus remained nearly unchanged. It should be stressed, however, that the numbers of B. cereus were almost the same in both studies with the highest count in 1982/83 being 460 and in 1992 600/g. Samples naturally contaminated with counts of about 100 B. cereus/g were reconstituted and incubated at a room temperature of 27 degrees C. Levels of 10(5) B. cereus/g were reached after 7-9 h. Toxigenicity of B. cereus in dried milk products and infant food as well as food poisoning outbreaks attributed to B. cereus are discussed.