Toxigenic potential and antimicrobial susceptibility of Bacillus cereus group bacteria isolated from Tunisian foodstuffs

Abstract : Background: Despite the importance of the B. cereus group as major foodborne pathogens that may cause diarrheal and/or emetic syndrome(s), no study in Tunisia has been conducted in order to characterize the pathogenic potential of the B. cereus group. The aim of this study was to assess the sanitary potential risks of 174 B. cereus group strains isolated from different foodstuffs by detecting and profiling virulence genes (hblA, hblB, hblC, hblD, nheA, nheB, nheC, cytK, bceT and ces), testing the isolates cytotoxic activity on Caco-2 cells and antimicrobial susceptibility towards 11 antibiotics. Results: The entertoxin genes detected among B. cereus isolates were, in decreasing order, nheA (98.9%), nheC (97.7%) and nheB (86.8%) versus hblC (54.6%), hblD (54.6%), hblA (29.9%) and hblB (14.9%), respectively encoding for Non-hemolytic enterotoxin (NHE) and Hemolysin BL (HBL). The isolates are multi-toxigenic, harbouring at least one gene of each NHE and HBL complexes associated or not to bceT, cytK-2 and ces genes. Based on the incidence of virulence genes, the strains were separated into 12 toxigenic groups. Isolates positive for cytK (37,9%) harbored the cytK-2 variant. The detection rates of bceT and ces genes were 50.6 and 4%, respectively. When bacteria were incubated in BHI-YE at 30°C for 18 h and for 5 d, 70.7 and 35% of the strains were shown to be cytotoxic to Caco-2 cells, respectively. The cytotoxicity of B. cereus strains depended on the food source of isolation. The presence of virulence factors is not always consistent with cytotoxicity. However, different combinations of enterotoxin genetic determinants are significantly associated to the cytotoxic potential of the bacteria. All strains were fully sensitive to rifampicin, chloramphenicol, ciprofloxacin, and gentamycin. The majority of the isolates were susceptible to streptomycin, kanamycin, erythromycin, vancomycin and tetracycline but showed resistance to ampicillin and novobiocin. Conclusion: Our results contribute data that are primary to facilitate risk assessments in order to prevent food poisoning due to B. cereus group.
Complete list of metadatas

Cited literature [82 references]  Display  Hide  Download

https://hal-agrocampus-ouest.archives-ouvertes.fr/hal-02284093
Contributor : Catherine Cliquet <>
Submitted on : Wednesday, September 11, 2019 - 2:32:10 PM
Last modification on : Thursday, September 12, 2019 - 1:16:19 AM

File

s12866-019-1571-y.pdf
Files produced by the author(s)

Licence


Distributed under a Creative Commons Attribution - NonCommercial - ShareAlike 4.0 International License

Identifiers

Citation

Maroua Gdoura-Ben, Sophie Jan, Florence Baron, Noel Grosset, Antoine Culot, et al.. Toxigenic potential and antimicrobial susceptibility of Bacillus cereus group bacteria isolated from Tunisian foodstuffs. BMC Microbiology, BioMed Central, 2019, 19 (1), ⟨10.1186/s12866-019-1571-y⟩. ⟨hal-02284093⟩

Share

Metrics

Record views

10

Files downloads

12