Age as a Factor Influencing Diversity of Commensal E. coli Microflora in Pigs

Abstract

Commensal, intestinal E. coli microflora plays a role in maintenance of intestinal balance of the host, is responsible for defending against pathogenic E. coli. This study encompasses the analysis of BOX-PCR fingerprinting patterns, phylogenetic grouping and virulence genes prevalence among commensal E. coli isolates derived from healthy pigs. Altogether, 274 unique E. coli isolates were identified, 110 from weaned piglets (Piglets I and Piglets II) and 164 from adult sows (Sows I and Sows II). BOX-PCR analysis distinguished isolates from pigs in different age and indicated that during maturation the changes in E. coli microflora occurred. Phylogenetic grouping revealed significant differences between distribution of four phylogenetic groups among isolates derived from piglets and sows. In phylogenetic structure of isolates from the piglets group B1 prevailed significantly, while among isolates derived from the sows the majority of them were classified into phylogenetic group A. The identification of 17 virulence factors in E. coli isolates derived from healthy pigs was performed. Three of 13 intestinal (escV, ehxA, estII) and four extra-intestinal virulence genes (VGs) (hlyA, fimH, papA, sfaS) were detected in the porcine isolates. The percentage of VGs positive isolates among piglets is higher than among sows, moreover, the VGs occurring in E. coli isolates from piglets revealed greater diversity than that detected among isolates from sows.

Extended Phylogeny and Extraintestinal Virulence Potential of Commensal Escherichia coli from Piglets and Sows

“…The first one consisted of 49 post-weaning piglets (6 weeks and 8 weeks old), and the second comprised 50 sows (5 months and 7 months old). Fresh fecal samples were collected only once, and E. coli was selected as described previously [21]. Briefly, fecal samples were plated on membrane Fecal Coliform (mFC) chromogenic agar (Merck, Darmstadt, Germany) and incubated at 44 • C for 24 h. The blue colonies typical for fecal coliforms were subcultured on the MacConkey's agar (Merck) and incubated at 37 • C for 24 h. The typical lactose fermenting colonies were randomly selected and identified by biochemical tests: Indole production, Methyl red reaction, Voges-Proskauer test, and Citrate utilization (IMVC).…”

“…Briefly, fecal samples were plated on membrane Fecal Coliform (mFC) chromogenic agar (Merck, Darmstadt, Germany) and incubated at 44 • C for 24 h. The blue colonies typical for fecal coliforms were subcultured on the MacConkey's agar (Merck) and incubated at 37 • C for 24 h. The typical lactose fermenting colonies were randomly selected and identified by biochemical tests: Indole production, Methyl red reaction, Voges-Proskauer test, and Citrate utilization (IMVC). This study involved the same set of isolates as in the earlier study [21], namely 274 unique E. coli, from one to four per animal, 110 isolated from post-weaning piglets, and 164 from sows. The DNA extraction was carried out using the thermal cell lysis method, 1.5-3 µL of the boiled bacterial supernatant was used as a template in all the PCR reactions.…”

“…Among strains from piglets, phylogenetic group B1 prevailed significantly, while in sows, E. coli in group A were the most frequent. The strains belonging to phylogroup B2 are the least frequent in both groups [21]. In the literature, there is information concerning the phylogeny of porcine commensal E. coli based on the previous Clermont phylogenetic typing method [22], but there is a lack of analyses using the new, revised Clermont scheme [15].…”

“…The scope of this study was to investigate the extended phylogeny and extraintestinal virulence potential of commensal E. coli isolated from two groups of healthy pigs (post-weaning piglets and sows). We aimed to compare the phylogenetic assignment using the revised (this study) and previous (the earlier data [21]) Clermont phylogenetic typing methods. The purpose was also the identification of the VGs typical for extraintestinal pathogens, their distribution in the phylogenetic structure, and genotypic analysis of two fimbrial operons for type I and P fimbriae among E. coli from piglets and sows.…”

Antimicrobial resistance in Portuguese swine production—2013 and 2014 Laboratory data

“…In contrast, samples from laboratory commonly miss information on animals' region of origin or antimicrobials use on the collected samples. Animals age also influence the commensal flora of pigs (Bok, 2013) and it would be of great interest the antimicrobial resistance evaluation between different groups of ages. The reason to not compare groups of animals with different ages in this study was because age information was available for only 50% of the samples included in our data analysis.…”