Molecular Characterization ofEscherichia coliIsolated from Chickens with Colibacillosis in Senegal

Abstract

Avian pathogenic Escherichia coli (APEC), a subset of extraintestinal pathogenic E. coli (ExPEC), are the etiologic agent of avian colibacillosis, one of the main causes of economic losses in the poultry industry. The aim of this study was to characterize E. coli isolated from diseased chickens in Senegal to elucidate their virulence potential and antimicrobial resistance (AMR). A total of 58 isolates, each from a separate farm, were characterized for AMR, virulence, and AMR genes, phylogroup, serogroup, biofilm formation, and pulsed-field gel electrophoresis, and for two isolates, whole-genome sequencing (WGS). Fifty isolates (86.2%) were multidrug resistant. Many AMR genes were detected, including variants of bla encoding resistance to third-generation cephalosporins (five isolates [8.6%]). Most fluoroquinolone-nonsusceptible isolates (21/26) were carriers of mutations in gyrA (Ser83Leu, Asp87Asn, and/or Asp87Tyr) and/or parC (Ser80Ile) genes. Forty-nine (84.5%) isolates exhibited at least one of the virulence markers of APEC, among which 23 (39.7%) were defined as potential virulent APEC. In addition, 10 isolates, of which 9 were defined as APEC, carried virulence profiles corresponding to ExPEC. Seven isolates, of which six were classified as ExPEC, belonged to phylo-serogroup F-O25, and following WGS of two of these isolates, were found to belong to the serotype O25:H1 and to the sequence type ST624. Some isolates classified as ExPEC, including F-O25, were found to strongly produce biofilm, suggesting their capability to persist for long time in the environment. F-O25-isolates, although found in different widely separated farms, formed a single cluster that included clones, suggesting that these isolates may have originated from a common source. Taken together, these results suggest that some E. coli involved in chicken colibacillosis in Senegal may pose a human health risk.

Prevalence, risk factors, and characterization of multidrug resistant and extended spectrum β‐lactamase/AmpC β‐lactamase producing Escherichia coli in healthy horses in France in 2015

“…When isolates were nonsusceptible (intermediate or resistant) to third‐generation cephalosporins, we looked for 5 β‐lactamase resistance genes ( bla SHV , bla TEM , bla CMY‐2 , bla OXA , bla CTX‐M ) by PCR multiplex. We used the primer sequences described previoulsy . The ESBL/AmpC resistance genes were detected by PCR performed on DNA extracted by heat lysis, as previously described .…”

Prevalence of antimicrobial resistance and potential pathogenicity, and possible spread of third generation cephalosporin resistance, in Escherichia coli isolated from healthy chicken farms in the region of Dakar, Senegal

“…coli collection, was examined by PCR [22] for detection of ExPEC-associated virulence genes iucD , tsh , cnf and papC permitting a rapid and inexpensive initial screen for a wide spectrum of possible ExPEC strains [23] including APEC considered to have zoonotic potential [6]. When the pool of five colonies was positive, each isolate was individually tested for the four ExPEC-associated virulence genes, and then one isolate per sample was randomly selected for each virulence profile and examined by PCR for additional virulence genes associated with ExPEC or APEC [21].…”

“…coli and potential ExPEC isolates were examined for 14 genes encoding for resistance against streptomycin ( aadA1 ), tetracycline ( tetA , tetB and tetC ), trimethoprim-sulfamethoxazole ( dfrA1 , dfrA5 and dfrA7 ), fluoroquinolones ( qnrB ) and β-lactams ( bla TEM , bla SHV , bla OXA-1 , bla CTX-M and bla CMY-2 ). In the potential ESBL/AmpC collection, 50 isolates nonsusceptible to at least one cephalosporin and originating from 15 farms, were randomly selected among 75 3GC-nonsusceptible isolates found in this study and tested for the presence of beta-lactamase genes, as previously described [21].…”

“…All isolates from the indicator E . coli and potential ExPEC collections tested above for AMR genes were also examined for the presence of human ExPEC and APEC virulence genes and other virulence-associated genes that may be used to further discriminate APEC isolates as previously described [21]. In addition, some isolates from the potential ESBL/AmpC collection, carrying ESBL/AmpC genes, were tested for the same virulence genes.…”

“…In addition, we recently found that multiresistant E . coli isolated from chickens with colibacillosis in Senegal carried ExPEC-associated virulence genes and some isolates were carriers of bla CTX-M-1 or bla CTX-M-8 [21].…”