TY - JOUR
T1 - Virulence characteristics and phylogenetic background of multidrug-resistant and antimicrobial-susceptible clinical isolates of Escherichia coli from across the United States, 2000-2001
AU - Johnson, James R.
AU - Kuskowski, Michael A.
AU - Gajewski, Abby
AU - Sahm, Daniel F.
AU - Karlowsky, James A.
N1 - Funding Information:
Financial support: Office of Research and Development, Medical Research Service, Department of Veterans Affairs; National Research Initiative Competitive Grants Program/US Department of Agriculture (grant 00-35212-9408) (all to J.R.J.).
PY - 2004/11/15
Y1 - 2004/11/15
N2 - Background. Increases in antimicrobial resistance in Escherichia coli have been paralleled by an increasing incidence of E. coli sepsis, suggesting a possible link between resistance and virulence. Methods. All 76 multidrug-resistant (MDR) E. coli isolates (i.e., those resistant to ≥3 antimicrobial agents, including ampicillin, ceftazidime, trimethoprim- sulfamethoxazole, gentamicin, and ciprofloxacin) reported to the Tracking Resistance in the United States Today studies during 2000-2001 and 76 closely matched pansusceptible control isolates were studied. Extended virulence profiles and E. coli phylogenetic group (A, B1, B2, or D) were compared between groups. Results. The MDR isolates, which represented predominantly non-B2 phylogenetic groups (91%), exhibited significantly reduced molecular virulence, compared with the predominantly group B2-derived control isolates (58%). Only 30% of MDR isolates, compared with 61% of control isolates (P<.001), qualified as extraintestinal pathogenic E. coli (ExPEC), and even these isolates exhibited significantly lower virulence scores than did susceptible ExPEC (7.25 vs. 9.0; P = .001). Phylogenetic differences accounted for the apparent virulence differences between MDR and control isolates. Conclusions. These findings argue against a direct link between virulence traits and antimicrobial resistance in E. coli. Instead, they call into question why non-B2 strains are more commonly MDR, with differential exposure to selection pressure (includine in agriculture) as one possible explanation.
AB - Background. Increases in antimicrobial resistance in Escherichia coli have been paralleled by an increasing incidence of E. coli sepsis, suggesting a possible link between resistance and virulence. Methods. All 76 multidrug-resistant (MDR) E. coli isolates (i.e., those resistant to ≥3 antimicrobial agents, including ampicillin, ceftazidime, trimethoprim- sulfamethoxazole, gentamicin, and ciprofloxacin) reported to the Tracking Resistance in the United States Today studies during 2000-2001 and 76 closely matched pansusceptible control isolates were studied. Extended virulence profiles and E. coli phylogenetic group (A, B1, B2, or D) were compared between groups. Results. The MDR isolates, which represented predominantly non-B2 phylogenetic groups (91%), exhibited significantly reduced molecular virulence, compared with the predominantly group B2-derived control isolates (58%). Only 30% of MDR isolates, compared with 61% of control isolates (P<.001), qualified as extraintestinal pathogenic E. coli (ExPEC), and even these isolates exhibited significantly lower virulence scores than did susceptible ExPEC (7.25 vs. 9.0; P = .001). Phylogenetic differences accounted for the apparent virulence differences between MDR and control isolates. Conclusions. These findings argue against a direct link between virulence traits and antimicrobial resistance in E. coli. Instead, they call into question why non-B2 strains are more commonly MDR, with differential exposure to selection pressure (includine in agriculture) as one possible explanation.
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U2 - 10.1086/425018
DO - 10.1086/425018
M3 - Article
C2 - 15499527
AN - SCOPUS:8444242084
SN - 0022-1899
VL - 190
SP - 1739
EP - 1744
JO - Journal of Infectious Diseases
JF - Journal of Infectious Diseases
IS - 10
ER -