Molecular characterization of Corynebacterium pseudotuberculosis, C. silvaticum, and C. auriscanis by ERIC-PCR / Caracterização molecular de Corynebacterium pseudotuberculosis, C. silvaticum e C. auriscanis pelo ERIC-PCR

The aims of the present study were (i) to genotype Corynebacterium pseudotuberculosis, C. silvaticum, and C. auriscanis strains using enterobacterial repetitive intergenic consensus (ERIC-PCR), and (ii) to analyze the epidemiological relationships among isolates according to biovar (Equi and Ovis), species, host, and geographical origin of the C. pseudotuberculosis strains. Sixty-eight C. pseudotuberculosis, nine C. silvaticum, and one C. auriscanis, C. pseudotuberculosis ATCC® 19410™ strain and the attenuated C. pseudotuberculosis 1002 vaccinal strain were fingerprinted by ERIC 1+2-PCR. Field strains were isolated from various hosts (cattle, buffaloes, sheep, goats, horses, dogs, and pigs) in six countries (Mexico, Portugal, Brazil, Equatorial Guinea, Egypt, and Israel). High genetic diversity was found among the studied Corynebacterium spp. isolates, clustering in 24 genotypes with a Hunter & Gaston diversity index (HGDI) of 0.937. The minimal spanning tree of Corynebacterium spp. revealed three clonal complexes, each associated with one bacterial species. Twenty-two genotypes were observed among C. pseudotuberculosis isolates, with an HGDI of 0.934. Three major clonal complexes were formed at the minimal spanning tree, grouped around the geographic origin of C. pseudotuberculosis isolates. These results reinforce the high typeability, epidemiological concordance, and discriminatory power of ERIC-PCR as a consistent genotyping method for C. pseudotuberculosis, which could be useful as an epidemiological tool to control caseous lymphadenitis. Moreover, our results also indicate the potential of ERIC 1+2-PCR for the genotyping of other species of Corynebacterium other than C. pseudotuberculosis.

Os objetivos do presente estudo foram (i) genotipar amostras de Corynebacterium pseudotuberculosis, C. silvaticum e C. auriscanis usando Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR), bem como (ii) analisar as relações epidemiológicas entre os isolados de acordo com biovar (Equi e Ovis), espécie, hospedeiro e origem geográfica das amostras de C. pseudotuberculosis. Sessenta e oito isolados de C. pseudotuberculosis, nove C. silvaticum, um C. auriscanis, C. pseudotuberculosis ATCC® 19410 ™ e a amostra vacinal atenuada C. pseudotuberculosis 1002 foram tipificadas por ERIC 1 + 2-PCR. As amostras de campo foram isoladas de diferentes hospedeiros (bovinos, búfalos, ovinos, caprinos, equinos, cães e suínos) em seis países (México, Portugal, Brasil, Guiné Equatorial, Egito e Israel). Uma alta diversidade genética foi observada entre os isolados de Corynebacterium spp., agrupados em vinte e quatro genótipos com um índice de diversidade Hunter & Gaston (HGDI) de 0,937. A análise da minimal spanning tree (MST) de Corynebacterium spp. revelou três complexos clonais, cada um associado a uma espécie bacteriana. Vinte e dois genótipos foram observados entre isolados de C. pseudotuberculosis, com um HGDI de 0,934. Na análise da MST, três grandes complexos clonais foram formados, agrupando-se em torno da origem geográfica dos isolados de C. pseudotuberculosis. Esses resultados reforçam a alta tipabilidade, concordância epidemiológica e poder discriminatório do ERIC-PCR como método consistente de genotipagem para C. pseudotuberculosis, podendo ser útil como ferramenta epidemiológica no controle da linfadenite caseosa. Além disso, os resultados também indicam o grande potencial de ERIC 1 + 2-PCR para genotipagem de espécies do gênero Corynebacterium além de C. pseudotuberculosis.

Molecular epidemiology of Corynebacterium pseudotuberculosis isolated from horses in California.

Corynebacterium pseudotuberculosis biovar Equi is an important pathogen of horses. It is increasing in frequency in the United States, and is responsible for various clinical forms of infection, including external abscesses, internal abscesses of the abdominal or thoracic cavities, and ulcerative lymphangitis. The host/pathogen factors dictating the form or severity of infection are currently unknown. Our recent investigations have shown that genotyping C. pseudotuberculosis isolates using enterobacterial repetitive intergenic consensus (ERIC)-PCR is useful for understanding the evolutionary genetics of the species as well for molecular epidemiology studies. The aims of the present study were to assess (i) the genetic diversity of C. pseudotuberculosis strains isolated from horses in California, United States and (ii) the epidemiologic relationships among isolates. One hundred and seven C. pseudotuberculosis biovar Equi isolates from ninety-five horses, and two C. pseudotuberculosis biovar Ovis strains, C. pseudotuberculosis ATCC 19410T type strain and C. pseudotuberculosis 1002 vaccine strain, were fingerprinted using the ERIC 1+2-PCR. C. pseudotuberculosis isolated from horses showed a high genetic diversity, clustering in twenty-seven genotypes with a diversity index of 0.91. Minimal spanning tree showed four major clonal complexes with a pattern of temporal clustering. Strains isolated from the same horse showed identical ERIC 1+2-PCR genotype, with the exception of two strains isolated from the same animal that showed distinct genotypes, suggesting a co-infection. We found no strong genetic signals related to clinical form (including internal versus external infections). However, temporal clustering of genotypes was observed.