Spigaglia Patrizia, Drigo Ilenia, Barbanti Fabrizio, Mastrantonio Paola, Bano Luca, Bacchin Cosetta, Puiatti Cinzia, Tonon Elena, Berto Giacomo, Agnoletti Fabrizio
Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
Special Bacteriology Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Treviso, Italy.
Anaerobe. 2015 Feb;31:42-6. doi: 10.1016/j.anaerobe.2014.10.003. Epub 2014 Oct 12.
Recent studies suggest animals, in particular farm and companion animals, as possible reservoir for Clostridium difficile human pathogenic strains. The aim of this study was to give a first characterization of C. difficile isolates from Italian swine and dogs. In total, 10 different PCR-ribotypes were identified among porcine strains and six among canine strains. The predominant type found among porcine strains was 078 (50%), whereas the most frequently detected among canine strains was the non-toxinogenic 010 (64%). Considering the CLSI breakpoints, 60% of porcine isolates was resistant to ERY, 35% to MXF, 15% to CLI, 5% to RIF, and none to MTZ or VAN. Among dogs, 51% of strains was resistant to CLI, 46% to ERY, 21% to MTZ and 5% to MXF or RIF, and none to VAN. Five porcine strains (10%) and 9 canine isolates (41%) were MDR. Interestingly, 8 MDR canine strains were highly resistant to MTZ, with MICs ≥32 mg/L. Considering the EUCAST cut-off for MTZ (MIC >2 mg/L), 13 canine isolates and one porcine strain were found with reduced susceptibility to MTZ (MICs ranging from 3 to ≥256 mg/L). Swine and canine strains showing resistance or reduced susceptibility to MTZ belonged to PCR-ribotype 010 and 078. These PCR-ribotypes have been associated to reduced susceptibility to MTZ also in human, suggesting a potential risk for the emergence of C. difficile strains resistant to the current first-line antibiotic for CDI treatment. The agar incorporation method (AIM) was confirmed as the best method to detect C. difficile strains with this phenotype also after strains manipulations. The results obtained add further evidences about the possible role of animals as source of MDR C. difficile strains and reservoir of antibiotic resistance determinants.
近期研究表明，动物，尤其是农场动物和伴侣动物，可能是艰难梭菌人类致病菌株的储存宿主。本研究的目的是对来自意大利猪和犬的艰难梭菌分离株进行首次特征描述。总共在猪源菌株中鉴定出10种不同的PCR核糖体分型，在犬源菌株中鉴定出6种。猪源菌株中占主导地位的类型是078型（50%），而犬源菌株中最常检测到的是无毒力的010型（64%）。根据CLSI标准，60%的猪源分离株对ERY耐药，35%对MXF耐药，15%对CLI耐药，5%对RIF耐药，对MTZ或VAN均无耐药。在犬中，51%的菌株对CLI耐药，46%对ERY耐药，21%对MTZ耐药，5%对MXF或RIF耐药，对VAN均无耐药。5株猪源菌株（10%）和9株犬源分离株（41%）为多重耐药。有趣的是，8株多重耐药犬源菌株对MTZ高度耐药，MIC≥32 mg/L。根据欧盟CAST对MTZ的临界值（MIC>2 mg/L），发现13株犬源分离株和1株猪源菌株对MTZ敏感性降低（MIC范围为3至≥256 mg/L）。对MTZ耐药或敏感性降低的猪源和犬源菌株属于PCR核糖体分型010和078。这些PCR核糖体分型在人类中也与对MTZ敏感性降低有关，这表明出现对当前用于CDI治疗的一线抗生素耐药的艰难梭菌菌株存在潜在风险。琼脂掺入法（AIM）被确认为即使在菌株处理后检测具有此表型的艰难梭菌菌株的最佳方法。所获得的结果进一步证明了动物作为多重耐药艰难梭菌菌株来源和抗生素耐药决定因素储存宿主的可能作用。
