Background: The prevalence of fluoroquinolone resistance in Escherichia coli has markedly increased in recent years. Efflux pump overexpression is an important mechanism of fluoroquinolone resistance in E. coli and has been associated with high rates of resistance to other antimicrobial classes. The objective of this study was to determine risk factors for efflux overexpression among patients with fluoroquinolone-resistant E. coli (FQREC) gastrointestinal tract colonization.
Methods: This 3-year case-control study was conducted in the University of Pennsylvania Health System. Three annual fecal surveillance surveys were performed hospital-wide, with all patients colonized with FQREC (levofloxacin minimum inhibitory concentration ³8 mcg/mL) eligible for inclusion. Cases and controls were defined on the basis of overexpression of the AcrAB drug efflux pump, as measured indirectly by the organic solvent tolerance (OST) assay. Case patients were designated as those OST-positive, and control patients as those OST-negative. A multivariable logistic regression model was developed to identify risk factors for OST-positivity in patients with FQREC gastrointestinal tract colonization.
P. Tolomeo, None
X. Mao, None
W. Bilker, None
E. Lautenbach, AstraZeneca: Grant Investigator, Research grant
Cubist: Grant Investigator, Research grant
3M: Grant Investigator, Research grant
Merck: Grant Investigator, Research grant
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