Colonization with broad-spectrum cephalosporin-resistant Gram-negative bacilli in intensive care units during a nonoutbreak period: Prevalence, risk factors, and rate of infection
Emc. D'Agata et al., Colonization with broad-spectrum cephalosporin-resistant Gram-negative bacilli in intensive care units during a nonoutbreak period: Prevalence, risk factors, and rate of infection, CRIT CARE M, 27(6), 1999, pp. 1090-1095
Objective: To define the epidemiology of broad-spectrum cephalosporin-resis
tant Gram-negative bacilli in intensive care units (ICUs) during a nonoutbr
eak period, including the prevalence, the risk factors for colonization, th
e frequency of acquisition, and the rate of infection.
Design: Prospective cohort study,
Setting: Tertiary care hospital.
Patients: Consecutive patients admitted to two surgical ICUs.
Main Outcome Measurements: Serial patient surveillance cultures screened fo
r ceftazidime (CAZ) resistance, antibiotic and hospital exposure, and infec
tions.
Results: Of the 333 patients enrolled, 60 (18%) were colonized with CAZ-res
istant Gram-negative bacilli (CAZ-RGN) at admission. Clinical cultures dete
cted CAZ-RGN in only 5% (3/60) of these patients. By using logistic regress
ion, CAZ-RGN colonization was associated with duration of exposure to cefaz
olin (odds ratio, 10.3; p less than or equal to .006) and to broad-spectrum
cephalosporins/penicillins (odds ratio, 2; p less than or equal to .03), A
cute Physiology and Chronic Health Evaluation III(TM) score (Odds ratio, 1.
2; p less than or equal to .008), and previous hospitalization (odds ratio,
3.1; p less than or equal to .006). Of the 100 patients who remained in th
e surgical ICU for greater than or equal to 3 days, 26% acquired a CAZ-RGN.
Of the 14 infections caused by CAZ-RGN, 11 (79%) were attributable to the
same species present in surveillance cultures at admission to the surgical
ICU.
Conclusions: Colonization with CAZ-RGN was common and was usually not recog
nized by clinical cultures. Most patients colonized or infected with CAZ-RG
N had positive surveillance cultures at the time of admission to the surgic
al ICU, suggesting that acquisition frequently occurred in other wards and
institutions, Patients exposed to first-generation cephalosporins, as well
as broad-spectrum cephalosporins/penicillins, were at high risk of coloniza
tion with CAZ-RGN. Empirical treatment of nosocomial Gram-negative infectio
ns with broad-spectrum cephalosporins, especially in the critically ill pat
ient, should be reconsidered.