Isolation and Characterization of Potentially Pathogenic Antimicrobial-Resistant Escherichia coli Strains from Chicken and Pig Farms in Spain

Abstract

To ascertain whether on animal farms there reside extended-spectrum ␤-lactamase (ESBL) and plasmidic class C ␤-lactamase-producing Escherichia coli isolates potentially pathogenic for humans, phylogenetic analyses, pulsed-field gel electrophoresis (PFGE) typing, serotyping, and virulence genotyping were performed for 86 isolates from poultry (57 isolates) and pig (29 isolates) farms. E. coli isolates from poultry farms carried genes encoding enzymes of the CTX-M-9 group as well as CMY-2, whereas those from pig farms mainly carried genes encoding CTX-M-1 enzymes. Poultry and pig isolates differed significantly in their phylogenetic group assignments, with phylogroup A predominating in pig isolates and phylogroup D predominating in avian isolates. Among the 86 farm isolates, 23 (26.7%) carried two or more virulence genes typical of extraintestinal pathogenic E. coli (ExPEC). Of these, 20 were isolated from poultry farms and only 3 from pig farms. Ten of the 23 isolates belonged to the classic human ExPEC serotypes O2:H6, O2:HNM, O2:H7, O15:H1, and O25:H4. Despite the high diversity of serotypes and pulsotypes detected among the 86 farm isolates, 13 PFGE clusters were identified. Four of these clusters contained isolates with two or more virulence genes, and two clusters exhibited the classic human ExPEC serotypes O2:HNM (ST10) and O2:H6 (ST115). Although O2:HNM and O2:H6 isolates of human and animal origins differed with respect to their virulence genes and PFGE pulsotypes, the O2:HNM isolates from pigs showed the same sequence type (ST10) as those from humans. The single avian O15:H1 isolate was compared with human clinical isolates of this serotype. Although all were found to belong to phylogroup D and shared the same virulence gene profile, they differed in their sequence types (ST362-avian and ST393-human) and PFGE pulsotypes. Noteworthy was the detection, for the first time, in poultry farms of the clonal groups O25b:H4-ST131-B2, producing CTX-M-9, and O25a-ST648-D, producing CTX-M-32. The virulence genes and PFGE profiles of these two groups were very similar to those of clinical human isolates. While further studies are required to determine the true zoonotic potential of these clonal groups, our results emphasize the zoonotic risk posed especially by poultry farms, but also by pig farms, as reservoirs of ESBL-and CMY-2-encoding E. coli.

Antibiotic Resistance Profile in Relation to Phylogenetic Background in Escherichia coli Isolated From Fecal Samples of Healthy Ostrich

“…The phylogenetic group B1 is usually in relation to commensal bacteria (7). Cortes et al (15) reported that phylo-group B1 was predominant group among isolates from poultry farms. Farm poultry E. coli isolates were compared with wild birds, by a higher ratio of A and B1 strains and a lower ratio of B2 and D strains.…”

A Survey of Antimicrobial Agents Usage in Poultry Farms and Antibiotic Resistance in Escherichia Coli and Staphylococci Isolates from the Poultry in Ile-Ife, Nigeria

“…Morphological characteristics of the colonies were noted for characterization. Further characterization of isolates involved biochemical tests such as catalase tests, indole production and sugar fermentations [10,13].…”

Technical specifications on harmonised epidemiological indicators for biological hazards to be covered by meat inspection of poultry

“…From these hosts, the species more commonly identified have been Ecoli and non-typhoidal salmonellae. Among E. coli, the clonal lineages phylogroup B2 (E. coli O25:H4-ST131) and phylogroup D (E. coli O25a-ST648 and E. coli ST69 and ST393) are being increasingly detected among both humans and animals (Cortes et al, 2010;Vincent et al, 2010;Mora et al, 2011). The most common Salmonella serovars producing ESBLs are S. Typhimurium, Newport and Heidelberg, but such enzymes have also been detected in an expanding number of other serovars (Gonzalez-Sanz et al, 2009).…”

“…ESBL-/AmpC-producing organisms have been detected in a variety of food-producing animals, mainly poultry and cattle (but also swine, horse, rabbit, ostrich, wild boars), and food of animal origin Vo et al, 2007;Carattoli, 2008;Poeta et al, 2009;Rodriguez et al, 2009;Carneiro et al, 2010;Cortes et al, 2010;Dierikx et al, 2010;Escudero et al, 2010;Hunter et al, 2010) in many European countries. From these hosts, the species more commonly identified have been Ecoli and non-typhoidal salmonellae.…”