Quantitative Prevalence, Phenotypic and Genotypic Characteristics ofBacillus cereusIsolated from Retail Infant Foods in China

Abstract

Bacillus cereus is an important foodborne pathogen, which can cause severe food poisoning. The aim of this study was (i) to evaluate the quantitative prevalence of B. cereus in retail prepackaged infant formula and ready-to-eat rice flour in China and (ii) to gain the basic information on pheno- and genotypic characteristics of B. cereus isolates. We found that 40 out of the 587 samples were positive for B. cereus. B. cereus in 3.5% of infant formula samples and 1.0% of rice flour samples outnumbered 100 Colony-Forming Units (CFU)/g. B. cereus level even attained 10-10 CFU/g in four infant formula samples and one rice flour sample. Furthermore, we identified the distribution patterns of toxin genes in B. cereus isolates. The results showed that 97.5% of B. cereus isolates harbored at least one enterotoxin gene. Antibiotic susceptibility tests revealed that all isolated B. cereus strains were resistant to penicillin and 50% of them were multidrug resistant. Thirteen new sequence types (STs) and four new alleles were identified via multilocus sequence typing. Clonal Complex (CC) ST-205 and CC ST-142 were predominant clonal complexes. Interestingly, we revealed the special relationship between STs of B. cereus isolates and the geographical distributions of infant food manufacturers for the first time. The data implied that B. cereus of different STs might have a distinct ecological niche in China. In view of relatively high contamination level of enterotoxin- producing B. cereus in a proportion of infant foods, especially in those suitable for the ≤6-month-old infant group, appropriate safety criteria and hygienic control measures for infant foods should be drafted in China to prevent B. cereus infection.

A Study on Prevalence and Characterization of Bacillus cereus in Ready-to-Eat Foods in China

“…In this study, we used MLST to analyze the genetic polymorphisms of B. cereus strains isolated from RTE foods ( Supplementary Table S4). Apart from six CCs, most isolates were assigned as singletons; ST-205 and ST-142 were the predominant CCs, consistent with previous reports (Zhang et al, 2017). Moreover, 28 strains were assigned to ST26, including 18 strains that were found to contain the cesB gene.…”

“…MLST is a nucleotide sequence-based approach for the unambiguous characterization of isolates that has been broadly used for epidemiological typing and risk analyses of many pathogenic bacteria, such as S. aureus (Wu et al, 2018), L. monocytogenes (Wu et al, 2016), Cronobacter spp. (Xu et al, 2015), Salmonella (Matheson et al, 2010), and B. cereus (Cardazzo et al, 2008;Yang et al, 2017;Zhang et al, 2017;Yu et al, 2019). In this study, we used MLST to analyze the genetic polymorphisms of B. cereus strains isolated from RTE foods ( Supplementary Table S4).…”

Assessment and molecular characterization of Bacillus cereus isolated from edible fungi in China

“…3; Additional file 4: Table S4). Regarding the phylogenetic relationship, all isolates were grouped into ten clusters with the cutoff value of 43% similarity (Additional file 5: Figure S1) and the cluster numbers were defined depended on the [32,33]. Unlike our previous studies which showed another important foodborne pathogen, Listeria monocytogenes, to be highly associated with F. velutipes [34,35]; here, B. cereus was frequently detected in L. edodes.…”

Prevalence and genetic diversity of the strains of Bacillus cereus groups in food for infants and young children in Mxico

“…In this study, five fruit samples and seven meat samples exceed this amount; an important feature in this regulation, is not included the amount of CFU/g or the presence of B. cereus as an important microbiological indicator, even when the population to which these products are directed, could be a risk group. In this study, B. cereus was isolated in all varieties with a frequency of 9.2%; in studies carried out in China, the prevalence ranges from 1 to 6% (Li et al, 2014;Zhang et al, 2017), while in Iran it is 42% (Rahimi et al, 2013), considering that the main difference is the type of variety analyzed, in these three studies the base was rice and in the present study, it was rice-based foods, fruits and vegetables were included.…”

“…Meanwhile, in countries like Norway, Finland, and Hungary, B. cereus has been held accountable for gastrointestinal diseases (diarrhea syndrome) in contrast with countries like China, Japan, and Belgium, where it is linked to the emetic syndrome (Granum and Lund, 1997;Logan, 2012). The existence of B. cereus as a contaminant of food for babies has been reported in China (Li et al, 2014;Zhang et al, 2017) and Iran (Rahimi et al, 2013), and currently, in Mexico there are no data about this microorganism. In Mexico, until March 2018, over 600 food poisoning cases and more than 90,000 gastrointestinal diseases have been reported without identifying the causal agent (Dirección General de Epidemiología, 2018).…”