Dec Marta, Herman-Ostrzyżek Klaudia, Zomer Aldert, Urban-Chmiel Renata
Department of Veterinary Prevention and Avian Diseases, University of Life Sciences in Lublin, 20-612 Lublin, Poland.
Division of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands.
Life (Basel). 2025 Apr 30;15(5):732. doi: 10.3390/life15050732.
is a large family of bacteria from which probiotic strains often originate. Microorganisms used as feed additives in the EU must meet a number of formal criteria, some of which concern antimicrobial susceptibility. In this study, we determined the susceptibility of 19 reference strains and 121 wild-type strains of to aminoglycoside antibiotics using the broth microdilution method based on the ISO 10932:2010/IDF 223:2010 standard. Strains were categorized as resistant or susceptible according to European Food Safety Authority (EFSA) guidelines. Resistance genes were detected by whole genome sequence (WGS) analysis or by PCR. The MICs read after 48 h of incubation showed that 36.8% of reference strains were resistant to kanamycin, 26.3% to streptomycin, and 5.3% to gentamicin, with no aminoglycoside resistance genes detected in any genome. As many as 93.2% of field isolates of , 85% of , and 58.8% of were classified as resistant to kanamycin, with the gene detected only in two isolates. In six of 12 streptomycin-resistant strains, the gene was identified, which usually coexisted with the gene. Three isolates with high neomycin MICs harbored the gene. In strain LMG 9435, characterized by streptomycin MIC value > 1024 µg/mL, a potential resistance-causing mutation in the gene (Lys56 → Arg) was detected. The results of the study indicate that some genera of , in particular and , exhibit natural resistance to aminoglycoside antibiotics, mainly kanamycin. Therefore, there is a need to update the EFSA guidelines on antimicrobial susceptibility testing of so that strains lacking resistance genes and/or chromosomal mutations are not considered to be resistant.
是益生菌菌株的一个主要来源的大细菌家族。在欧盟用作饲料添加剂的微生物必须满足一些正式标准，其中一些涉及抗菌药敏性。在本研究中，我们根据ISO 10932:2010/IDF 223:2010标准，采用肉汤微量稀释法测定了19株参考菌株和121株野生型菌株对氨基糖苷类抗生素的药敏性。根据欧洲食品安全局（EFSA）指南将菌株分类为耐药或敏感。通过全基因组序列（WGS）分析或PCR检测耐药基因。孵育48小时后读取的最低抑菌浓度（MIC）显示，36.8%的参考菌株对卡那霉素耐药，26.3%对链霉素耐药，5.3%对庆大霉素耐药，在任何基因组中均未检测到氨基糖苷类耐药基因。多达93.2%的该菌野外分离株、85%的另一菌以及58.8%的又一菌被分类为对卡那霉素耐药，仅在两株分离株中检测到该基因。在12株链霉素耐药菌株中的6株中，鉴定出该基因，其通常与另一基因共存。三株新霉素MIC值高的分离株携带该基因。在链霉素MIC值>1024µg/mL的该菌菌株LMG 9435中，检测到该基因中的一个潜在耐药性突变（Lys56→Arg）。研究结果表明，该菌的一些属，特别是某两属，对氨基糖苷类抗生素表现出天然耐药性，主要是对卡那霉素。因此，有必要更新EFSA关于该菌抗菌药敏试验的指南，以便不将缺乏耐药基因和/或染色体突变的菌株视为耐药菌株。
