Classificação filogenética e caracterização patotípica de isolados de Escherichia coli patogênicos e comensais de suínos da região Sul do Brasil

Abstract

The aim of the study was to evaluate the presence of different virulence factors in intestinal and extra-intestinal Escherichia coli swine isolates from Southern Brazil by multiplex PCR (mPCR) and classify them in A, B1, B2 and D phylogenetic groups based on three pathogenicity markers: chuA, yjaA and a DNA anonymous fragment designated TSPE4.C2. Were analyzed 152 samples from different origins: urine (70), feces (35), small intestine (35) and tissues (12). The mPCR was carried out to pathotypification of the isolates and a PCR with the pathogenicity markers, to classify in phylogenetic groups. Seventy seven (51%) isolates when tested by mPCR were positive to at least one of the virulence factors, while the phylogenetic characterization of the isolates showed 21 (14%) isolates in A, 65 (42%) in B1, 19 (13%) in B2 and 47 (31%) in D group. Fourteen (20%) urine isolates were characterized as UPEC; nine (12.8%) presented UPEC and ETEC factors simultaneously and four (5.8%) were classified as ETEC. In the phylogenetic classification, the groups of major occurrence were D (45.8%) and B1 (32.8%). Of the analyzed feces samples, 25 (71.4%) demonstrated virulence factors characteristic of pathotype ETEC. Phylogeneticaly, the group of higher incidence was B1 with 21 (60%) samples, followed by B2 with six (17.2%), group A with five (14.2%) and group D with three (8.6%) isolates. For the small intestine samples, 20 (57.2%) were characterized as ETEC. By the phylogeny, 23 (65.6%) isolates were classified in groups A or B1, among them 51.4% belonged to B1 and six (17.2%) were located in equal percentage in groups B2 and D. Six tissue isolates (50%) were qualified as ETEC. In regards to the phylogenetic classification, six (50%) samples were located in group D, followed by A and B1, with three (50%) samples in each group. For the tested isolates, the phylogenetic analysis demonstrated to be efficient, and it may be included in laboratorial routine for epidemiologic studies of the intestinal and extra intestinal swine samples, allowing the differentiation of pathogenic and non-pathogenic isolates, as well as helping in the strains selection for the vaccine production.