Characterization of a Bacillus cereus strain associated with a large feed-related outbreak of severe infection in pigs

Abstract

Aims: Bacillus cereus is often responsible for foodborne diseases and both local and systemic infections in humans. Cases of infection in other mammals are rather rare.In this study, we report a B. cereus feed-related outbreak that caused the death of 6234 pigs in Italy. Methods and Results:Massive doses of a Gram-positive, spore-forming bacterium were recovered from the animal feed, faeces of survived pigs and intestinal content of dead ones. The B. cereus MM1 strain was identified by MALDI-TOF MS and typified by RAPD-PCR. The isolate was tested for the production of PC-PLC, proteases, hemolysins and biofilm, for motility, as well as for the presence of genes encoding tissue-degrading enzymes and toxins. Antimicrobial resistance and pathogenicity in Galleria mellonella larvae were also investigated. Our results show that the isolated B. cereus strain is swimming-proficient, produces PC-PLC, proteases, hemolysins, biofilm and carries many virulence genes. The strain shows high pathogenicity in G. mellonella larvae. Conclusions:The isolated B. cereus strain demonstrates an aggressive profile of pathogenicity and virulence, being able to produce a wide range of determinants potentially hazardous to pigs' health. Significance and Impact of Study:This study highlights the proficiency of B. cereus to behave as a devastating pathogen in swine if ingested at high doses and underlines that more stringent quality controls are needed for livestock feeds and supplements.

Prevalence, Virulence Potential, and Growth in Cheese of Bacillus cereus Strains Isolated from Fresh and Short-Ripened Cheeses Sold on the Italian Market

“…MALDI-TOF MS identification was performed as previously reported [ 14 , 15 ]. Briefly, well-isolated colonies (up to five for each positive sample) were spotted on the MALDI plates and covered with 1 µL of ethanol, 1 µL of formic acid, 1 µL of acetonitrile for lysis, and were overlayed with 1 µL of saturated α-cyano-4-hydroxycinnamic acid (HCCA) matrix solution, accordingly to manufacturer specifications.…”

“…Spectra were imported into the integrated MALDI Biotyper software (version 3.1, Bruker, Billerica, MA, USA) and analyzed by standard pattern matching with a default setting. A score of ≥2.00 indicated identification at the species level; a score ranging from 1.99 to 1.70 indicated identification at the genus level; whereas any score < 1.70 meant no significant similarity of the obtained spectrum with any database entry [ 15 ]. Each isolate was tested in triplicate.…”

“…For the detection of B. cereus toxin-encoding genes (Smase, sph ; enterotoxin Bcet, bcet ; enterotoxin FM, entFM ; phosphatidylinositol-specific phospholipase; PI-PLC, plcA ; cytotoxin K, cytK ; NHEA, nheA ; NHEB, nheB ; and NHEC, nheC ), PCR reactions were performed on bacterial genomic DNA. For each gene, primer pairs and amplification conditions were set as previously described [ 15 ].…”

Epizootological data of cattle infection caused by bacillus cereus on a dairy farm of the Kemerovo region

“…For example, cases of sporadic necrotizing placentitis caused by B. cereus in cows have been described, resulting in abortion and death of the mother due to the production of necrotizing toxins [7,8]. Also, cases of mastitis and inflammatory diseases of the pelvic organs in cows and goats caused by B.cereus are described [9,10].…”

Pathological changes of highly pathogenic Bacillus cereus on Pelodiscus sinensis

“…2019 ), pigs (Calvigioni et al. 2022 ), Half-smooth Tongue-sole (Wang et al. 2018 ), and Chinese Softshell Turtle (Cheng et al.…”