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Fifty one episodes of bacteremia due to Enterobacter spp. appearing within 7 years among 12 301 admissions in a single cancer institution were studied for risk factors, clinical presentation and outcome. Fifteen episodes were due to Enterobacter aerogenes, 23 due to E. cloacae and 13 due to E. agglomerans. The proportion of bacteremia due to Enterobacter spp. among Gram-negative bacteremias was 10.1% and infection associated mortality was 13.8%. The incidence in 1989-1995 varied from 3.7 to 8.7% and was relatively stable. Most common risk factors were: solid tumors as underlying disease, central venous catheter insertion, prior surgery and prior chemotherapy within 48 h. Neutropenia and urinary catheters were not at high risk in either one of the patients subgroups. Comparing two subgroups of 51 bacteremias, monomicrobial and polymicrobial (when Enterobacter spp. was isolated from blood culture with other microorganism), previous chemotherapy, vascular catheter insertion and prior endoscopy were more frequently associated with polymicrobial Enterobacter spp. bacteremia. There was also differences in infection associated mortality: bacteremias due to Enterobacter spp. only had significantly lower mortality in comparison to polymicrobial Enterobacter spp. bacteremias (3.3 vs. 29.3%; P<0.02). Susceptibility of Enterobacter spp. strains isolated from 51 episodes was stable and showed only two episodes due to quinolone-resistant strains, both in 1992 despite of the use of ofloxacin in prophylaxis of neutropenic patients since 1990 in our institute. Ninety-two to 94% of all strains were susceptible to aminoglycosides, 96-98% to ofloxacin and ciprofloxacin, respectively and 94.9% to meropenem but only 75.5% to ceftazidime.

Two hundred and fourteen episodes of polymicrobial bacteremia in 182 cancer patients in a period of 6 years in a 360-bed National Cancer Institute were analyzed for etiology, risk factors and outcome. Variables were compared with 187 episodes of monomicrobial bacteremias in 147 cancer patients to find statistical significance among risk factors, etiology and outcome. Urinary catheters and breakthrough bacteremia were the only risk factors associated with polymicrobial in comparison to monomicrobial bacteremia (P < 0.05). Concerning etiology, Enterococcus faecalis, Candida spp., Acinetobacter calcoaceticus and Stenotrophomonas maltophilia were more commonly isolated in polymicrobial than in monomicrobial bacteremic episodes. Polymicrobial bacteremia presented more frequently with septic shock (22.9% vs. 9.0%, P < 0.05) and/or organ complications (25.2% vs. 11.8%, P < 0.05). However, mortality due to bacteremia did not significantly differ between polymicrobial and monomicrobial, but when polymicrobial bacteremia with and without coagulase negative staphylococci were compared, mortality in polymicrobial bacteremia without staphylococci was higher (10% vs. 4.7%, P < 0.04).