title: Virulence genotype and nematode-killing properties of extra-intestinal Escherichia coli producing CTX-M beta-lactamases.
abstract: This study evaluated the virulence potential of Escherichia coli isolates producing CTX-M beta-lactamases. During a 24-month period, 33 extended-spectrum beta-lactamase (ESBL)-producing E. coli, including 14 CTX-M-producers, were isolated from urinary tract infections at Nîmes University Hospital, France. The prevalence of 14 major virulence factors (VFs) was investigated by PCR and compared with the prevalence in a group of 99 susceptible E. coli isolates. Ten VFs were less prevalent (p <0.05) in the ESBL isolates than the susceptible E. coli, while iutA and traT were more prevalent in ESBL isolates (p <0.05). Moreover, the CTX-M-producing isolates had significantly fewer VFs than TEM-producing isolates. A novel infection model using the nematode Caenorhabditis elegans was developed to assess the virulence properties of extra-intestinal pathogenic E. coli (ExPEC) strains in vivo. C. elegans infection assays, using 14 ESBL-producing E. coli and ten susceptible E. coli isolates, indicated that the ability to kill nematodes correlated with the presence of VFs, and that CTX-M-producing isolates had relatively low virulence in vivo. Overall, the results suggested that hospital-acquired CTX-M-producing E. coli, although adapted for survival in an antibiotic-rich environment such as the hospital milieu, have a relatively low intrinsic virulence potential.
authors.affiliation: Laboratoire Universitaire d'Antibiologie, UFR de Médecine, Nîmes, France.
authors.forename: J-P
authors.initials: JP
authors.lastname: Lavigne
authors.forename: A-B
authors.initials: AB
authors.lastname: Blanc-Potard
authors.forename: G
authors.initials: G
authors.lastname: Bourg
authors.forename: J
authors.initials: J
authors.lastname: Moreau
authors.forename: C
authors.initials: C
authors.lastname: Chanal
authors.forename: N
authors.initials: N
authors.lastname: Bouziges
authors.forename: D
authors.initials: D
authors.lastname: O'callaghan
authors.forename: A
authors.initials: A
authors.lastname: Sotto
mesh_terms: D000368:Aged; D000818:Animals; D017173:Caenorhabditis elegans / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D005838:Genotype; D006801:Humans; D016867:Immunocompromised Host; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D016019:Survival Analysis; D013997:Time Factors; D014556:Urine / Q000382:microbiology; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D037521:Virulence Factors; D001618:beta-Lactamases