Isolation and Molecular Characterization of Nalidixic Acid-Resistant Extraintestinal Pathogenic Escherichia coli from Retail Chicken Products

Abstract

Fluoroquinolone use in poultry production may select for resistant Escherichia coli that can be transmitted to humans. To define the prevalence and virulence potential of poultry-associated, quinolone-resistant E. coli in the United States, 169 retail chicken products from the Minneapolis-St. Paul area (1999 to 2000) were screened for nalidixic acid (Nal)-resistant E. coli. Sixty-two (37%) products yielded Nal-resistant E. coli. From 55 products that yielded both Nal-resistant and susceptible E. coli, two isolates (one resistant, one susceptible) per sample were further characterized. Twenty-three (21%) of the 110 E. coli isolates (13 resistant, 10 susceptible) satisfied criteria for extraintestinal pathogenic E. coli (ExPEC), i.e., exhibited >2 of pap (P fimbriae), sfa/foc (S/F1C fimbriae), afa/dra (Dr binding adhesins), iutA (aerobactin receptor), and kpsMT II (group 2 capsule synthesis). Compared with other isolates, ExPEC isolates more often derived from virulence-associated E. coli phylogenetic groups B2 or D (74% versus 32%; P < 0.001) and exhibited more ExPEC-associated virulence markers (median, 10.0 versus 4.0; P < 0.001). In contrast, the Nal-resistant and -susceptible populations were indistinguishable according to all characteristics analyzed, including pulsed-field gel electrophoresis profiles. These findings indicate that Nal-resistant E. coli is prevalent in retail poultry products and that a substantial minority of such strains represent potential human pathogens. The similarity of the Nal-resistant and -susceptible populations suggests that they derive from the same source population, presumably the avian fecal flora, with Nal resistance emerging by spontaneous mutation as a result of fluoroquinolone exposure.

Environmental adaptation and vertical dissemination of ESBL‐/pAmpC‐producing Escherichia coli in an integrated broiler production chain in the absence of an antibiotic treatment

“…Even though all analysed isolates showed very high numbers of detectable VAGs, according to the definition of ExPEC strains by Johnson et al . (2003)(≥2 of papA/C , afa/dra , sfa/foc , iutA and kpsMTII ), only the ST‐354 strains and two of three ST‐38 strains (3565, 10026) could be assigned as an ExPEC. Interestingly, ExPEC‐related invasion genes also occurred in ST‐354 and ST‐38 strains, only.…”

Occurrence of virulence-related sequences and phylogenetic analysis of commensal and pathogenic avian Escherichia coli strains (APEC)

“…These studies have suggested that APEC strains and bacterial human pathogens may show similar adaptations for an extra intestinal lifestyle, with APEC being able to cause disease in humans (Johnson et al 2003, Mokady et al 2005, Rodriguez-Siek et al 2005, Stocki et al 2005. In this study, we analyzed the presence of virulence genes related to adhesion and invasion to eukaryotic cells and tissues and the expression of iron uptake systems, which were originally described to be present in human pathogenic Escherichia coli, Yersinia and Shigella, among pathogenic and commensal avian E. coli strains, and associated these findings to the four major phylogenetic groups of E. coli (A, B1, B2, and D) described by Clermont et al (2000).…”

“…The irp-2 gene encodes for a high molecular mass protein involved in the siderophore production and fyuA gene encodes for the yersiniabactin receptor (Lucier et al 1996). These sequences have been found in E. coli pathogenic for humans and poultry in a high percentage (Schubert et al, 1998, Gophna et al 2001, JanBen et al 2001, Johnson et al 2003, Ewers et al 2004). In our study, genes irp-2 and fyuA were found in higher frequency (40% and 35%, respectively) among pathogenic strains than among commensal strains (13% for both genes), with differences statistically significant (P = 0.016 and P = 0.03, respectively) ( Table 2).…”

“…JanBen et al (2001) using PCR to detect virulence-related genes demonstrated that Yersinia spp genes necessary to iron uptake (fyuA and irp-2), pyelonephritis-associated pili (papC) and enteroaggregative heat stable toxin gene (astA) of E. coli genes were frequently found among APEC isolated from internal organs of poultry died from colibacillosis. Johnson et al (2003) recovered strains from chicken retails products that presented virulence profiles, phylogenetic group background, and O antigens resembling those of humans ExPEC isolates. Recently, a subtractive hybridization study performed with a human UTI E. coli and an avian colisepticemia strain demonstrated that both group of strains have common virulence determinants such as the TTSS (Type Three Secretion System) and iron uptake systems but they shared few virulence related sequences (Mokady et al 2005).…”

Clonal study of avian Escherichia coli strains by fliC conserved-DNA-sequence regions analysis

“…In recent years, several works demonstrated the presence of genetic similarities among APEC strains, human Escherichia coli and other Enterobacteriaceae species, which suggested that APEC strains present a zoonotic risk (Stocki et al 2002, Johnson et al 2003, Mokady et al 2005, Rodriguez-Siek et al 2005. The aim of the present study was to verify if there is a genetic similarity, as determined by the DNA sequencing and comparison of the fliC gene among avian pathogenic E. coli and other strains of human bacterial pathogens such as E. coli, Salmonella enterica, Yersinia enterocolitica, and Proteus mirabilis.…”