Genetic diversity of Actinobacillus pleuropneumoniae (App) strains in intensive swine farms in Chile

Abstract

Actinobacillus pleuropneumoniae (App) is the etiologic agent of porcine contagious pleuropneumonia, an important bacterial disease in intensive pig production. In the world were described 15 App serotypes, in Chile serotypes 1 and 5 have been reported. The serotyping technique is slow, expensive and difficult; currently, a molecular tool named PCR is available to "serotyping" by Apx toxins genotyping, which is quick, non-expensive and easy. 60 Appstrains were evaluated, isolated from 9 intensive swine farms distributed in Chile. These isolates were obtained from lungs of pigs with lesions of porcine contagious pleuropneumonia. All the strains were isolated during the years 2007, 2008 and 2009, by means of conventional bacteriology and confirmed by API. A multiplex PCR for Apx toxin genes was performed to differentiate the App serotypes. The results showed genotypes detected only for serotypes 4, 6 and 7, first described in Chile. The most frequently isolated was serotype 7. Also, there was no predominant serotype in the different geographical zones, except in the regions of O'Higgins and Biobío where it was most frequently isolated serotype 7. The present study is the first approach in order to know the distribution of App serotypes in Chile. Studies including greater numbers of farms and isolates per farm are necessary to know the real diversity of App serotypes and genotypes in Chilean swine production farms.