Genetic relatedness between Japanese and European isolates of Clostridium difficile originating from piglets and their risk associated with human health.

Masaru Usui,Tetsuo Asai,Kentaro Oka,Motomichi Takahashi,Takashi Inamatsu,Yutaka Tamura,Shigeru Kamiya,Yukie Nanbu

doi:10.3389/fmicb.2014.00513

Abstract

Clostridium difficile colonization in pig intestine has been a public health concern. We analyzed C. difficile prevalence among piglets in Japan to clarify their origin and extent of the associated risk by using molecular and microbiological methods for both swine and human clinical isolates and foreign isolates. C. difficile was isolated from 120 neonatal piglet fecal samples. Toxin gene profile, antimicrobial susceptibilities, PCR ribotype, and multiple-locus variable-number tandem-repeat analysis (MLVA) type of swine isolates were determined and compared with those of human clinical and foreign isolates. One-hundred C. difficile strains were isolated from 69 (57.5%) samples, and 61 isolates (61%) were toxin gene-positive. Some isolates were resistant to antimicrobials, contributing to antibiotic-associated diarrhea by C. difficile. These results suggest that C. difficile, prevalent among Japanese pigs, is a potential risk for antibiotic-associated diarrhea. Furthermore, PCR ribotype 078 (12 isolates), which has been linked to multiple outbreaks worldwide, was the third-most frequently isolated of the 14 PCR ribotypes identified. Moreover, MLVA revealed that all 12 PCR ribotype 078 isolates were genetically related to European PCR ribotype 078 strains found in both humans and pigs. To date, in Japan, many breeding pigs have been imported from European countries. The genetic relatedness of C. difficile isolates of Japanese swine origin to those of European origin suggests that they were introduced into Japan via imported pigs.

Highlights

Clostridium difficile is a gram-positive spore-forming anaerobic bacterium that causes antibiotic-associated diarrhea and pseudomembranous colitis in humans
Some reports have highlighted the high-level relatedness that exists between C. difficile Polymerase chain reaction (PCR) ribotype 078 isolates from both human and swine origins by using highly discriminative typing methods such as multiple-locus variable-number tandemrepeat analysis (MLVA; Debast et al, 2009; Bakker et al, 2010)
We demonstrated the high prevalence of C. difficile in clinically normal piglets (57.5%), despite the previous isolation of only two strains from slaughter pigs (0.8%) in Japan (Asai et al, 2013)

Summary

Introduction

Clostridium difficile is a gram-positive spore-forming anaerobic bacterium that causes antibiotic-associated diarrhea and pseudomembranous colitis in humans. The prevalence of PCR ribotype 078, a strain commonly found in pigs, has increased since 2006 and is currently one of the most common types in European countries (Bauer et al, 2011). Some reports have highlighted the high-level relatedness that exists between C. difficile PCR ribotype 078 isolates from both human and swine origins by using highly discriminative typing methods such as multiple-locus variable-number tandemrepeat analysis (MLVA; Debast et al, 2009; Bakker et al, 2010). PCR ribotype 018 (smz) is the most prevalent isolate detected from human cases of C. difficile infection in Japan (Collins et al, 2013). To evaluate the risk to human health, it is important to determine bacterial properties of swine C. difficile isolates, such as toxigenicity, genotype, and antimicrobial susceptibility, and compare them with those of human isolates

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