Laboratório de Inspeção de Produtos de Origem Animal, Departamento de Veterinária, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil (ORCID: https://orcid.org/0000-0002-4954-5824 [L.A.N.]); and.
Laboratório de Inspeção e Controle de Qualidade de Alimentos e Água, Universidade Federal do Paraná, R. Pioneiro 2153 Jardim Dallas, Palotina, Paraná 85950-000, Brazil.
J Food Prot. 2020 Mar 1;83(3):485-490. doi: 10.4315/0362-028X.JFP-19-379.
Listeria monocytogenes contamination was assessed in different steps of a pork production chain. Ten lots of pigs were sampled at termination barns, at slaughter (after bleeding, after buckling, after evisceration, and after final washing), at processing (knives, deboning tables, and employees' hands), and of end products (ribs, shoulder, ham, and sausage). All samples (n = 670) were subjected to L. monocytogenes detection, and the obtained isolates (n = 18, identified as Listeria spp.) were characterized by their biochemical characteristics, serogroups, virulence genes, pulsed-field gel electrophoresis profiles, antibiotic resistances (ampicillin, penicillin, gentamicin, and sulfamethoxazole-trimethoprim), and adhesion abilities. The results revealed the low occurrence of Listeria spp. in the evaluated pork production chain. However, four tested sausage samples (40%) were positive for Listeria spp., with L. monocytogenes identified in two (20%) of these samples. Ten isolates were identified as L. monocytogenes (eight from serogroup 1/2a or 3a and two from serogroup 4b, 4d, or 4e): all isolates were also positive for the virulence-related genes hlyA, iap, plcA, actA, inlA, inlB, inlC, and inlJ and susceptible to the tested antibiotics. One sausage sample was contaminated by both serogroups 1/2a or 3a and 4b, 4d, or 4e. Isolates from serogroup 1/2a or 3a obtained during visits 5 and 6 presented distinct genetic profiles by pulsed-field gel electrophoresis, indicating that contamination may come from different sources. The adhesion potential exhibited by Listeria spp. isolates (n = 18) ranged from weak (serogroup 4b, 4d, or 4e) to moderate (L. innocua and L. monocytogenes serogroup 1/2a or 3a). Despite the low occurrence of L. monocytogenes, pathogenic serogroups were detected in sausages, demanding control measures by the industry.
本研究评估了猪肉生产链不同环节李斯特菌的污染情况。在终止栏、屠宰后（放血后、去头蹄后、去内脏后、最后清洗后）、加工过程（刀具、去骨台和员工的手）以及终端产品（肋骨、肩部、火腿和香肠）中，对 10 批猪进行了采样。对所有样本（n=670）进行了李斯特菌检测，获得的分离株（n=18，鉴定为李斯特菌属）通过其生化特征、血清群、毒力基因、脉冲场凝胶电泳图谱、抗生素耐药性（氨苄西林、青霉素、庆大霉素和磺胺甲噁唑-甲氧苄啶）和黏附能力进行了表征。结果表明，在所评估的猪肉生产链中，李斯特菌属的发生率较低。然而，4 个测试的香肠样品（40%）呈李斯特菌属阳性，其中 2 个（20%）样本中鉴定出李斯特菌。10 个分离株被鉴定为李斯特菌（8 个属于血清群 1/2a 或 3a，2 个属于血清群 4b、4d 或 4e）：所有分离株均为 hlyA、iap、plcA、actA、inlA、inlB、inlC 和 inlJ 等毒力相关基因阳性，且对测试抗生素敏感。一个香肠样本同时被血清群 1/2a 或 3a 和 4b、4d 或 4e 污染。在第 5 次和第 6 次访问期间获得的血清群 1/2a 或 3a 分离株通过脉冲场凝胶电泳呈现出不同的遗传图谱，表明污染可能来自不同的来源。李斯特菌分离株的黏附能力（n=18）范围从弱（血清群 4b、4d 或 4e）到中等（L. innocua 和李斯特菌血清群 1/2a 或 3a）。尽管李斯特菌属的发生率较低，但在香肠中检测到了致病性血清群，这需要行业采取控制措施。
