Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
Department of Health, Animal Science and Food Safety, University of Milan, Milan, Italy.
J Appl Microbiol. 2022 Aug;133(2):1078-1088. doi: 10.1111/jam.15636. Epub 2022 May 31.
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.
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.
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.
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.
蜡状芽孢杆菌通常是导致食源性疾病和人类局部及全身感染的原因。在其他哺乳动物中感染的情况较为罕见。本研究报告了一起与饲料有关的蜡状芽孢杆菌感染事件，该事件导致意大利 6234 头猪死亡。
从动物饲料、幸存猪的粪便和死亡猪的肠道内容物中大量回收了一种革兰氏阳性、产芽孢的细菌。通过 MALDI-TOF MS 鉴定了蜡状芽孢杆菌 MM1 株，并通过 RAPD-PCR 对其进行了分型。对分离株进行了 PC-PLC、蛋白酶、溶血素和生物膜的产生、运动性以及编码组织降解酶和毒素的基因存在情况的检测。还研究了蜡状芽孢杆菌在金龟子幼虫中的耐药性和致病性。我们的结果表明，分离的蜡状芽孢杆菌株是游泳能手，能够产生 PC-PLC、蛋白酶、溶血素、生物膜，并携带许多毒力基因。该菌株对金龟子幼虫具有高致病性。
分离的蜡状芽孢杆菌株表现出强烈的致病性和毒力特征，能够产生广泛的潜在危害猪健康的决定因素。
本研究强调了如果摄入高剂量的蜡状芽孢杆菌，它有能力在猪群中表现为一种破坏性的病原体，这表明需要对牲畜饲料和补充剂进行更严格的质量控制。
