Investigation of an outbreak of vancomycin-resistant Enterococcus faecium in a low prevalence university hospital.

BACKGROUND: Until 1995, there were no cases of vancomycin resistant enterococcus (VRE) identified at our university hospital. From May 1995 to August 1996, we investigated a cluster of 10 cases of phenotypic class Van B Enterococcus faecium. METHODS: Patients were matched with controls who were on the same unit for at least 7 days prior to the case developing VRE. Control patients were age and sex matched if possible, and had duration of hospitalization at least as long as the number of days it took the patient to become VRE positive. We analyzed 16 independent risk factors using Epi-info version 6. Environmental cultures were obtained in the MICU where 5 of the patients were located. All 10 patient isolates and environmental isolates were analyzed by pulsed field gel electrophoresis (PFGE). RESULTS: PFGE confirmed the genetic relatedness of all 10 patient isolates and environmental isolates. The VRE-positive group was more likely to be immunosuppressed and to have exposure to 3 physicians. In the MICU, significant, P < 0.05) risk factors for VRE were higher Apache scores, location adjacent to a VRE case, duration of vancomycin and amino-glycoside use, duration of invasive catheter use, and diarrhea. Among the VRE-positive environmental cultures was a blood pressure cuff wash that was used on several patients. CONCLUSION: We hypothesize that a VRE strain was introduced into our hospital environment and was spread by personnel or contaminated equipment. As a consequence of this study, a hospital-wide VRE policy was implemented.

New computer-based tools for empiric antibiotic decision support.

Since 1995 we have been developing a decision-support model, called Q-ID, which uses a series of infectious disease knowledge bases to make recommendations for empirical treatment or to check the appropriateness of current antibiotic therapy. From disease manifestations and risk factors, a differential diagnosis for the patient is generated by a diagnostic medical expert system. The resulting probability of each: disease is multiplied by the expected benefit in improved mortality and morbidity from optimal antibiotic treatment of each disease. To generate empirical treatment recommendations, site-specific data on sensitivity to antibiotics of each organism is used as an estimate of the likelihood of achieving maximum benefit for each disease on the patient's differential. Combining this data with drug and patient specific factors, the model recommends the antibiotic(s) most likely to produce the optimal benefit in this patient with the least risk and expense. In this paper the model is described, excerpts from each of the knowledge bases are presented, and performance of the model in a real case is shown for illustration.

Bacillus licheniformis bacteremia: five cases associated with indwelling central venous catheters.

Bacillus species are being more frequently recognized as pathogens in immunocompromised hosts or in patients with cancer and central venous catheters. Only nine cases of Bacillus licheniformis infection have been reported in the English-language literature since 1966. In a retrospective study we describe six patients and 17 episodes of B. licheniformis bacteremia over a 5-year span. All six patients had either a Hickman or a Broviac catheter in place for more than 3 months. Five of the six patients had multiple clinically significant episodes of bacteremia due to B. licheniformis. The six patients ranged in age from 4 years to 62 years. Two patients had leukemia or lymphoma and three patients had solid tumors, but only one patient was neutropenic. No deaths were related to B. licheniformis bacteremia. B. licheniformis should be considered as a potential pathogen in immunocompromised patients, especially when bacteremia is associated with the presence of long-term central venous catheters. Mortality due to B. licheniformis bacteremia is low, but recurrent bacteremia due to this organism causes significant morbidity and usually necessitates removal of the catheter.