with extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are
associated with increased morbidity, mortality, and healthcare costs. In the
past decade, there has been a significant increase in the prevalence of
Enterobacteriaceae that produce CTX-M-type ESBLs. The objective of this study
was to evaluate risk factors for infection or colonization with CTX-M-positive Escherichia coli.
case-control study was conducted within a university health system from January
2007 to December 2008. All patients with clinical cultures with E. coli demonstrating resistance to
extended-spectrum cephalosporins were included. The presence of the blaCTX-M gene was detected by
polymerase chain reaction. Case patients were designated as those with cultures
positive for CTX-M-positive E. coli,
and control patients as those with non-CTX-M-producing E. coli. Multivariable logistic regression analyses were performed
to evaluate risk factors for CTX-M-positive isolates.
A total of 146 unique patients with clinical cultures with E. coli resistant to extended-spectrum cephalosporins were
identified during the two year study period. Of these, 83 (56.8%) patients
had cultures with CTX-M-positive E. coli.
majority of isolates (62.6%) belonged to CTX-M group I. On multivariable
analyses, there was a significant association between infection or colonization
with CTX-M-type beta-lactamase-positive E.
coli and receipt of piperacillin-tazobactam in the 30 days prior to the
culture date (odds ratio [OR], 7.36; 95% confidence interval [CI], 1.61-33.8; P=0.01) and a urinary culture source
(OR, 0.36; 95% CI, 0.17-0.77; P=0.008).
Resistance to fluoroquinolones was significantly higher in isolates from cases
as opposed to controls (90.4% and 50.8%, respectively; P<0.001).
Non-urinary sources of clinical cultures and recent use of piperacillin-tazobactam
conferred an increased risk of colonization or infection with CTX-M-positive E. coli as opposed to other ESBL types.
Future studies will need to focus on outcomes associated with infections due to
CTX-M-positive E. coli, as well as
infection control strategies to limit the spread of these increasingly common
Jennifer Han, MD1, Kei Kasahara, MD2, Paul H. Edelstein, MD3, Warren Bilker, PhD4,5, Ebbing Lautenbach, MD, MPH, MScE1,4,5 and the CDC Prevention Epicenter Program, (1)Division of Infectious Diseases, Dept. of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, (2)Nara Medical University, Kashihara, Japan, (3)Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, (4)Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA, (5)Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, PA
None P. H. Edelstein,
None W. Bilker,
None E. Lautenbach,
Merck: Grant Investigator, Research grant
AstraZeneca: Grant Investigator, Research grant
3M: Grant Investigator, Research grant
Cubist: Grant Investigator, Research grant