Resumo O presente estudo descreve a presença de Bacillus cereus em alimentos contaminados de origem animal e prontos para consumo humano, com destaque para seus fatores de contribuição de virulência por meio da detecção de seus genes de virulência, além da identificação de seu sequenciamento. Trezentas e sessenta amostras de alimentos categorizados como produtos cárneos (228) e produtos lácteos (132) foram examinadas para isolamento de B. cereus, e todos esses isolados foram confirmados por testes bioquímicos. Dezoito cepas obtidas de diferentes amostras de alimentos foram examinadas para a presença de uma série de genes de virulência (genes nheA, cytK, entFM, bceT e hblC) usando o método de PCR uniplex. Além disso, as cepas de B. cereus foram avaliadas para o sequenciamento dos genes descritos. De forma geral, 24,44% (88/360) das amostras de alimentos classificados como produtos cárneos (11,11%; 40/360) e produtos lácteos (13,33%; 48/360) transportavam B. cereus, de acordo com as propriedades culturais e bioquímicas, com média geométrica de 1,5 × 10 7 ± 0,15 CFU/g ou mL. Os resultados revelaram que todos os nossos isolados tinham um ou mais genes de virulência (enterotoxina). Em nossa pesquisa, os genes mais predominantes foram nheA (100%), seguidos de cytK (61,11%), entFM (33,33%), bceT (11,11%) e hblC (5,56%). O método molecular detectou que, no geral, 5 cepas (27,78%) apresentavam apenas 1 gene (nheA) e 7 cepas (38,88%) continham 2 genes que foram classificados como 5 cepas (27,78%) (nheA e cytK), 2 cepas (11,11%) possuíam (nheA e entFM). Além disso, 5 cepas (27,78%) continham 3 genes classificados como 3 cepas (16,67%) hospedados (nheA, cytK e entFM), 1 cepa (5,56%) tinha (nheA, cytK e hblC) e 1 cepa (5,56%) teve (nheA, cytK e bceT). Apenas 1 cepa (5,56%) carregava 4 genes de virulência testados (nheA, cytK, entFM e bceT). As sequências de nucleotídeos (genes bceT, cytK, entFM, hblC e nheA) de cepas de B. cereus foram depositadas no GenBank sob o número de acesso (MW911824, MW911825, MW911826, MW911827 e MW911828), respectivamente. Nosso estudo foi estabelecido para indicar a virulência de B. cereus em carnes e produtos lácteos prontos para consumo humano como resultado de ações higiênicas deficientes. Portanto, deve ser estabelecido um plano com boas medidas de higiene para evitar sérios problemas de saúde humana por causa da ingestão de tais produtos.
Abstract The current study describes the presence of Bacillus cereus (B. cereus) in contaminated foods of animal source and ready for human consumption with highlighting on their virulence contributing factors by detection of its virulence genes in addition to identification of their sequencing. Three hundred sixty food samples categorized as (228) meat products and (132) milk products were examined for B. cereus isolation and all of these isolates were confirmed by biochemical tests. Eighteen strains obtained from different food samples were examined for the attendance of a number of virulence genes (nheA, cytK, entFM, bceT and hblC genes) using uniplex PCR method. Furthermore, the B. cereus strains were valued for the sequencing of described genes. Generally 24.44% (88/360) food samples classified as 11.11% (40/360) meat products and 13.33% (48/360) milk products carried B. cereus according to cultural and biochemical properties, with geometric mean (1.5×107±0.15 CFU/g or mL) . The highest counts (above 105 CFU/g or mL) were originated from milk products (with geometric mean 2.2×107±0.22 CFU/g or mL) more than meat products (with geometric mean 1×107±0.19 CFU/g or mL). The results revealed that all of our isolates had one or more virulence (enterotoxin) genes. In our research, the most predominant genes were nheA (100%), followed by cytK (61.11%), entFM (33.33%), bceT (11.11%) then hblC (5.56%). Molecular method detected that overall, 5 strains (27.78%) harbored only 1 gene (nheA), 7 strains (38.88%) harbored 2 genes which classified as 5 strains (27.78%) (nheA and cytK), 2 strains (11.11%) have (nheA and entFM). Moreover, 5 strains (27.78%) have 3 genes classified as 3 strains (16.67%) harbored (nheA, cytK and entFM), 1 strain (5.56%) had (nheA, cytK and hblC), and 1 strain (5.56%) had (nheA, cytK and bceT). Only 1 strain (5.56%) carried 4 tested virulence genes (nheA, cytK, entFM and bceT) genes. The most prevalent gene in meat and dairy foods was nheA (100%). The nucleotide sequences of (bceT, cytK, entFM, hblC and nheA genes) of B. cereus strains were deposited in GenBank under accession no. (MW911824, MW911825, MW911826, MW911827 and MW911828), respectively. Our study was established to indicate the presence of virulent B. cereus in meat and milk products ready for human consumption as a result of deficient hygienic actions. So, a plain for good hygienic measures should be modified to avoid causing serious health problems to human due to ingestion of such products.