Çetin Büşra Sultan, Akpınar Kankaya Didem, Özden Tuncer Banu, Tuncer Yasin
Faculty of Engineering and Natural Sciences, Department of Food Engineering, Süleyman Demirel University, Isparta, Türkiye.
Department of Food Technology, Gelendost Vocational School, Isparta University of Applied Sciences, Isparta, Türkiye.
Folia Microbiol (Praha). 2025 May 28. doi: 10.1007/s12223-025-01275-3.
In this study, the virulence potential-including hemolytic activity, toxin gene content, and antibiotic resistance patterns-of Bacillus cereus sensu lato (B. cereus s.l.) group bacteria isolated from green leafy vegetables (mint, parsley, purslane, dill, cress, arugula, lettuce, and baby spinach) was investigated. A total of 59 presumptive B. cereus s.l. bacteria were isolated from 40 vegetable samples. Fourty-six isolates were confirmed as members of the B. cereus s.l. group by polymerase chain reaction (PCR). Species-specific PCR identified 42 of the 46 isolates as B. cereus sensu stricto (B. cereus) and four as B. mycoides. All isolates showed β-hemolytic activity on Columbia sheep blood agar. Except for B. cereus 472 and B. mycoides 571, all isolates harbored between one and eight toxin genes. The most frequently detected toxin gene was entFM, found in 81.0% (34/42) of B. cereus and 75.0% (3/4) of B. mycoides strains. The hblACD and nheABC gene clusters were identified in only 19.1% (8/42) and 7.1% (3/42) of B. cereus strains, respectively. Similarly, the emetic toxin genes ces (9.5%, 4/42) and CER (4.8%, 2/42) were detected exclusively in B. cereus strains. In total, 31 distinct toxin gene profiles were observed. Linezolid and vancomycin were the most effective antibiotics against both B. cereus and B. mycoides strains. However, B. cereus strains exhibited varying degrees of resistance to all tested antibiotics. All B. mycoides strains were resistant to clindamycin, and 75.0% (3/4) were also resistant to ciprofloxacin, imipenem, levofloxacin, meropenem, and norfloxacin. The multiple antibiotic resistance (MAR) index was greater than 0.20 in 60.9% (28/46) of the B. cereus s.l. isolates, and 52.2% (24/46)-including 21 B. cereus and three B. mycoides isolates-exhibited multidrug resistance (MDR). In conclusion, these findings suggest that B. cereus s.l. group isolates from green leafy vegetables may pose a potential risk to public health.
在本研究中，对从绿叶蔬菜（薄荷、欧芹、马齿苋、莳萝、水芹、芝麻菜、生菜和嫩菠菜）中分离出的蜡样芽孢杆菌复合群（蜡样芽孢杆菌复合群）细菌的毒力潜力，包括溶血活性、毒素基因含量和抗生素抗性模式进行了调查。从40个蔬菜样本中共分离出59株疑似蜡样芽孢杆菌复合群细菌。通过聚合酶链反应（PCR）确认其中46株分离株为蜡样芽孢杆菌复合群成员。种特异性PCR鉴定出46株分离株中的42株为狭义蜡样芽孢杆菌（蜡样芽孢杆菌），4株为蕈状芽孢杆菌。所有分离株在哥伦比亚绵羊血琼脂上均表现出β溶血活性。除蜡样芽孢杆菌472和蕈状芽孢杆菌571外，所有分离株均携带1至8个毒素基因。最常检测到的毒素基因是entFM，在81.0%（34/42）的蜡样芽孢杆菌和75.0%（3/4）的蕈状芽孢杆菌菌株中被发现。hblACD和nheABC基因簇分别仅在19.1%（8/42）和7.1%（3/42）的蜡样芽孢杆菌菌株中被鉴定出。同样，催吐毒素基因ces（9.5%，4/42）和CER（4.8%，2/42）仅在蜡样芽孢杆菌菌株中被检测到。总共观察到31种不同的毒素基因谱。利奈唑胺和万古霉素是对蜡样芽孢杆菌和蕈状芽孢杆菌菌株最有效的抗生素。然而，蜡样芽孢杆菌菌株对所有测试抗生素均表现出不同程度的抗性。所有蕈状芽孢杆菌菌株均对克林霉素耐药，75.0%（3/4）的菌株还对环丙沙星、亚胺培南、左氧氟沙星、美罗培南和诺氟沙星耐药。60.9%（28/46）的蜡样芽孢杆菌复合群分离株的多重抗生素抗性（MAR）指数大于0.20，52.2%（24/46），包括21株蜡样芽孢杆菌和3株蕈状芽孢杆菌分离株，表现出多重耐药性（MDR）。总之，这些发现表明，从绿叶蔬菜中分离出的蜡样芽孢杆菌复合群分离株可能对公众健康构成潜在风险。
