Characterization of Enterotoxigenic Bacillus cereus sensu lato and Staphylococcus aureus Isolates and Associated Enterotoxin Production Dynamics in Milk or Meat-Based Broth

Abstract

Bacillus cereus sensu lato species, as well as Staphylococcus aureus, are important pathogenic bacteria which can cause foodborne illness through the production of enterotoxins. This study characterised enterotoxin genes of these species and examined growth and enterotoxin production dynamics of isolates when grown in milk or meat-based broth. All B. cereus s. l. isolates harboured nheA, hblA and entFM toxin genes, with lower prevalence of bceT and hlyII. When grown at 16 °C, toxin production by individual B. cereus s. l. isolates varied depending on the food matrix; toxin was detected at cell densities below 5 log10(CFU/mL). At 16 °C no staphylococcal enterotoxin C (SEC) production was detected by S. aureus isolates, although low levels of SED production was noted. At 30 °C all S. aureus isolates produced detectable enterotoxin in the simulated meat matrix, whereas SEC production was significantly reduced in milk. Relative to B. cereus s. l. toxin production, S. aureus typically required reaching higher cell numbers to produce detectable levels of enterotoxin. Phylogenetic analysis of the sec and sel genes suggested population evolution which correlated with animal host adaptation, with subgroups of bovine isolates or caprine/ovine isolates noted, which were distinct from human isolates. Taken together, this study highlights the marked differences in the production of enterotoxins both associated with different growth matrices themselves, but also in the behaviour of individual strains when exposed to different food matrices.

Keeping up with the Bacillus cereus group: taxonomy through the genomics era and beyond

“…Multiple toxins likely contribute to the "diarrheal" 2018 ;Sastalla et al 2013;Senesi and Ghelardi 2010). Expression of these toxins is a complex process that involves the interplay of numerous transcriptional, post-transcriptional, and post-translational regulatory mechanisms that are affected by a plethora of environmental factors (Ceuppens et al 2012;Drewnowska et al 2020;Jessberger et al 2015;Miller et al 2018;Sastalla et al 2013;Senesi and Ghelardi 2010;Stenfors Arnesen, Fagerlund, and Granum 2008;Walker-York-Moore, Moore, and Fox 2017). Consequently, the mere presence and absence of genes encoding these toxins cannot be used to predict whether an isolate is likely to cause "diarrheal" toxicoinfection (Miller et al 2018), especially in the absence of animal studies.…”

Processing of Donor Human Milk: Update and Recommendations From the European Milk Bank Association (EMBA)

“…Bacillus is a bacteria genus that is frequently found in DHM, and it represents a special concern for HMBs, as these bacteria are capable of producing heat-resistant toxins and forming spores that are resistant to pasteurization (46, 47). In the HMB of Palma de Mallorca, about 10% of the milk is generally discarded due to the presence of Bacillus sp .…”

Antibacterial Activity of Terpenes and Terpenoids Present in Essential Oils

“…In the medical area, the search for new compounds becomes more and more urgent, as the emergence of resistant pathogens compromises therapy and raises the mortality rate. Staphylococcus aureus, Salmonella spp., Escherichia coli and Bacillus cereus are important example of bacteria that affect the quality and safety of food [10,11].…”

“…B. cereus is recognized for serious cases of food poisoning, it is also involved in cases of pneumonia, bacteremia and meningitis in immunocompromised patients [16,17,18]. In addition, due to its ability to form spores and structure resistant to high temperatures, it presents a significant risk to food safety, as it survives food processing techniques, such as pasteurization [11].…”