Abstract:

Objective To investigate the carrying status， the virulence and drug resistance characteristics of Clostridium perfringens（Cp） in different populations. Methods Totally，699 fresh fecal samples were collected from the Second Affiliated Hospital of Zhejiang University School of Medicine short-term（stay time≤7 d） hospitalized patients and long-term（stay time>7 d） hospitalized patients. The Cp isolates were isolated by anaerobic culture and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry（MALDI-TOF MS）. The E test was used to determine the drug susceptibility in vitro. Cp virulence genes（cpa，cpb，iap，cpb2 and cpe） were determined by polymerase chain reaction（PCR），and carbapenem-resistant organism（CRO） in fecal samples were screened by screening plate method. Carbapenases（KPC，NDM，VIM，IMP，OXA） were determined in the Cp isolates. Results Totally，220 isolates of Cp were isolated from 699 fecal samples. The isolation rate of Cp isolates in short-term hospitalized patients was the highest（69.9%，65/93），followed by that in healthy subjects（39.0%，130/333），and that was the lowest in long-term hospitalized patients（12.8%，35/273）. The determination rate of cpa gene was the highest among all Cp isolates（100.0%，220/220）. The determination rates of cpb and cpb2 were higher in short-term hospitalized patients（52.5%，71.2%），cpe gene was only determined in long-term hospitalized patients（1.8%，4/222），and iap gene was only determined in 1 healthy subject and 3 short-term hospitalized patients. The etx gene was not determined in any population. One linezolid-resistant multi-drug resistant isolate was isolated from fecal samples from long-term hospitalized patients. The co-carrying rate of Cp and CRO in long-term hospitalized patients was 25.7% [95% confidence interval（CI） 13.1%-43.6%]. Conclusions Cp isolation rate and virulence gene carrying rate are high in short-term hospitalized patients. The isolation rate of Cp is lower in long-term hospitalized patients，but the co-carrying rate of Cp and CRO is high. The heavy use of antibiotics affects the colonization of Cp in the intestinal tract of the population，and the epidemiological monitoring of Cp in the intestinal tract should be paid attention to.

Key words: Clostridium perfringens, Epidemic characteristic, Virulence gene, Drug-resistant phenotype