Limiting the emergence of extended-spectrum Beta-lactamase-producing enterobacteriaceae: influence of patient population characteristics on the response to antimicrobial formulary interventions.
BACKGROUND
Effective methods to control the emergence of extended-spectrum beta -lactamase-producing Escherichia coli and Klebsiella species (ESBL-EK) remain unclear. Variations in the patient populations at different hospitals may influence the effect of antimicrobial formulary interventions.


METHODS
To examine variations across hospitals in the response to antimicrobial interventions (ie, restriction of ceftazidime and ceftriaxone) designed to curb the spread of ESBL-EK, we conducted a 5-year quasi-experimental study. This study was conducted at 2 hospitals within the same health system: Hospital A is a 625-bed academic medical center, and Hospital B is a 344-bed urban community hospital. All adult patients with a healthcare-acquired clinical culture of ESBL-EK from July 1, 1997 through December 31, 2002 were included.


RESULTS
After the interventions, the use of ceftriaxone decreased by 86% at Hospital A and by 95% at Hospital B, whereas the use of ceftazidime decreased by 95% at Hospital A and by 97% at Hospital B. The prevalence of ESBL-EK at Hospital A decreased by 45% (P < .001), compared with a 22% decrease at Hospital B (P = .36). The following variables were significantly more common among ESBL-EK-infected patients at Hospital B: residence in a long-term care facility (adjusted odds ratio, 3.77 [95% confidence interval, 1.70-8.37]), advanced age (adjusted odds ratio, 1.04 [95% confidence interval, 1.01-1.06]), and presence of a decubitus ulcer (adjusted odds ratio, 4.13 [95% confidence interval, 1.97-8.65]).


CONCLUSIONS
The effect of antimicrobial formulary interventions intended to curb emergence of ESBL-EK may differ substantially across institutions, perhaps as a result of differences in patient populations. Variability in the epidemiological profiles of ESBL-EK isolates at different hospitals must be considered when designing interventions to respond to these pathogens.
Division of Infectious Diseases, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, 19104-6021, USA.
Adam D
AD
Lipworth
Emily P
EP
Hyle
Neil O
NO
Fishman
Irving
I
Nachamkin
Warren B
WB
Bilker
Ann Marie
AM
Marr
Lori A
LA
Larosa
Nishaminy
N
Kasbekar
Ebbing
E
Lautenbach
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002442:Ceftazidime / Q000627:therapeutic use*; D002443:Ceftriaxone / Q000627:therapeutic use*; D004755:Enterobacteriaceae / Q000378:metabolism* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000209:etiology / Q000517:prevention & control*; D005572:Formularies, Hospital as Topic; D006801:Humans; D007710:Klebsiella Infections / Q000209:etiology / Q000517:prevention & control*; D008875:Middle Aged; D044382:Population Groups; D001618:beta-Lactamases / Q000187:drug effects / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D002443:Ceftriaxone; D002442:Ceftazidime; D001618:beta-Lactamases