Isolation and molecular characterization of nalidixic acid-resistant extraintestinal pathogenic Escherichia coli from retail chicken products.
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 >or=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.
Johnson
James R
JR
Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55417, USA. johns007@tc.umn.edu
Murray
Andrew C
AC
Gajewski
Abby
A
Sullivan
Maureen
M
Snippes
Paula
P
Kuskowski
Michael A
MA
Smith
Kirk E
KE
D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002645:Chickens; D016000:Cluster Analysis; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D007422:Intestines / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009268:Nalidixic Acid / Q000494:pharmacology*; D019081:O Antigens / Q000235:genetics; D010641:Phenotype; D010802:Phylogeny; D011201:Poultry Diseases / Q000188:drug therapy / Q000382:microbiology*; D011202:Poultry Products / Q000382:microbiology; D019105:Random Amplified Polymorphic DNA Technique; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
D000890:Anti-Infective Agents; D019081:O Antigens; D037521:Virulence Factors; D009268:Nalidixic Acid