Antibiotic-resistant bloodstream infections in hospitalized patients: specific risk factors in a high-risk population?

BACKGROUND: The aim of this study was to explore characteristics that are associated with bloodstream infections due to specific multiresistant microorganisms (methicillinresitant Staphylococcus aureus, MRSA; vancomycin-resistant enterococci, VRE; third-generation cephalosporin-resistant Enterobacteriaceae) or Candida spp. in hospitalized patients. PATIENTS AND METHODS: All patients who experienced a bloodstream infection with one of the aforementioned pathogens between September 1999 and October 2001 were included into a statistical analysis of independent risk factors. The possible impact of previous antibiotic and antifungal therapies was evaluated. RESULTS: Of the study population, 22% had two or more episodes with different pathogens. In the 314 patients with a single bloodstream infection MRSA was isolated in 189 patients, VRE in 31, Enterobacteriaceae in 13, and Candida spp. in 80 patients. Crude mortality was high in the study population (overall 40%) and varied between 33% (MRSA bacteremia only) and 58% (VRE bacteremia only). Patients who yielded more than one of the pathogens under surveillance had crude mortalities ranging from 41% to 83% (all four pathogens). In this group of high-risk patients, the following factors were independently associated with the individual pathogen: prior chemotherapy (OR 4.88 CI(95) 1.50-15.87) and bronchoscopy (OR 3.17 CI(95) 1.05-9.52) for VRE patients; burns (OR 4.50 CI(95) 0.90-22.73), presence of a tracheostomy (OR 4.22 CI(95) 1.15-15.38) and acute dialysis (OR 3.62 CI(95) 0.99-13.16) for patients with Enterobacteriaceae; and an underlying malignant disease (OR 1.98 CI95 0.99-3.97), performance of a bowel endoscopy (OR 2.80 CI(95) 1.27-6.13) and presence of a central venous catheter (CVC) (OR 12.34 CI(95) 1.63-90.91) for patients with candidemia. CONCLUSION: Patients with bacteremia due to VRE, Enterobacteriaceae or Candida spp. had more severe risk factors associated with the respective pathogen than patients with MRSA bacteremia.

Preventing nosocomial infections from gastrointestinal endoscopy.

Gastrointestinal procedures have been associated with a wide range of infectious complications, including bacterial endocarditis. Although the rate of bacteremia from the patient's own flora is quite high after some procedures, only a few cases of endocarditis caused by gastrointestinal instrumentation have been reported. Because of the severity of the illness, however, antibiotic prophylaxis has been recommended for patients who are categorized as high risk for some procedures. Bacteremia and other infections, such as colitis, may also originate from a contaminated endoscope. To prevent such an occurrence, high-level disinfection has been recommended for gastrointestinal endoscopes. High-level disinfection includes manual cleaning of the endoscope, flushing of internal channels with a liquid chemical sterilant, and thorough rinsing and drying of internal lumens.

Vancomycin-resistant enterococcal bacteremia: natural history and attributable mortality.

Previous studies have shown that bacteremia due to vancomycin-resistant Enterococcus species (VRE) is associated with mortality of 17%-100%, but comorbid conditions may have confounded the estimates. We designed a historical cohort study to determine the mortality attributable to VRE bacteremia. Twenty-seven patients with VRE bacteremia were identified as cases. Within 7 days of the onset of bacteremia, severe sepsis developed in 12 patients (44%) and septic shock developed in 10 (37%). Case patients were closely matched to control patients without VRE bacteremia (1:1) by time of hospitalization, duration of exposure, underlying disease, age, gender, and surgical procedure. The mortality was 67% among cases and 30% among matched controls (P = 0.1). Thus, the mortality attributable to VRE bacteremia was 37% (95% confidence interval [CI], 10%-64%) and the risk ratio for death was 2.3 [CI, 1.2-4.1). We conclude that VRE bacteremia is associated with high rates of severe sepsis and septic shock. The attributable mortality approaches 40%, and patients who have VRE bacteremia are twice as likely to die than closely matched controls.

Vancomycin-resistant Enterococcus faecium bacteremia: risk factors for infection.

We describe an outbreak of vancomycin-resistant Enterococcus faecium (vanA phenotype) bacteremia on the oncology ward of a tertiary care community hospital. In 10 of the 11 cases the patients had leukemia and were neutropenic (median duration of neutropenia, 21 days) at the time of bacteremia. On average, patients received six antibiotic agents for a total of 61 agent-days prior to development of vancomycin-resistant E. faecium bacteremia. The mortality rate was 73%. Molecular typing of 22 isolates revealed that the majority (83%) represented a common strain, indicating nosocomial spread. When the 11 cases were compared to 22 matched control patients, gastrointestinal colonization with vancomycin-resistant E. faecium (odds ratio [denominator, 0] infinity, P = .005) and the use of antimicrobial agents with significant activity against anaerobes (metronidazole, clindamycin, and imipenem; odds ratio infinity, P = .02) were found to be risk factors for the development of vancomycin-resistant E. faecium bacteremia. Since no proven therapy for such infection exists, there is an urgent need to identify effective measures to prevent and control the development of vancomycin-resistant E. faecium bacteremia.