Genotyping and preemptive isolation to control an outbreak of vancomycin-resistant Enterococcus faecium.

BACKGROUND: Control of vancomycin-resistant Enterococcus faecium (VRE) in European hospitals is hampered because of widespread asymptomatic carriage of VRE by healthy Europeans. In 2000, our hospital (The University Medical Center Utrecht, Utrecht, The Netherlands) was confronted with a large outbreak of VRE. INTERVENTION: On the basis of genotyping (by pulsed-field gel electrophoresis), epidemic and nonepidemic VRE strains were distinguished, and infection-control measures were exclusively targeted toward epidemic VRE. The outbreak was retrospectively divided into 3 periods of different infection-control measures. Compliance with use of alcohol-based hand rubs was enforced during all periods. Period I involved active surveillance, isolation of carriers, and cohorting (duration, 4 months); preemptive isolation of high-risk patients for VRE colonization was added in period II (7 months); and cohorting and preemptive isolation were abandoned in period III (18 months). METHODS: When the outbreak was identified, 27 patients in 6 wards were colonized; 93% were colonized with an epidemic VRE strain. Detection rates of nonepidemic VRE were 3.5%, 3.0%, and 2.9% among 683, 810, and 977 screened patients in periods I, II, and III, respectively, comparable to a prevalence of 2% (95% confidence interval [CI], 1%-3.5%) among 600 nonhospitalized persons. The relative risks of detecting epidemic VRE in periods II and III, compared with period I, were 0.67 (95% CI, 0.41-1.10) for period II and 0.02 (95% CI, 0.002-0.6) for period III. Infection-control measures were withheld for patients colonized with nonepidemic VRE (76 [54%] of 140 patients with a test result positive for VRE). Use of alcohol-based hand rubs increased by 31%-275% in outbreak wards. CONCLUSION: Genotyping-targeted infection control, isolation of VRE carriers, enhancement of hand-hygiene compliance, and preemptive isolation successfully controlled nosocomial spread of epidemic VRE infection.

Acquisition and duration of vancomycin-resistant enterococcal carriage in relation to strain type.

In May 2000, the first outbreak of vancomycin-resistant Enterococcus faecium (VREF) was detected in the University Medical Center Utrecht in the nephrology ward. The question arose why some VREF strains spread among hospitalized patients, whereas other strains do not. Thirty patients who were found to be colonized with VREF between May and November 2000 were included in the study. Molecular typing confirmed that 19 of them carried an identical epidemic strain which harbored the esp gene while 11 were colonized by nonepidemic strains that were all esp negative. Acquisition of the outbreak strain was significantly associated with diabetes mellitus, renal transplantation, and extensive use of antibiotics, especially cephalosporins, in the 2-month period before the first isolation of VREF. To establish the duration of colonization, prospective surveillance of VREF carriage for a 6-month period starting from the first isolation of VREF was realized for 20 patients. After 6 months, VREF was still recovered from 60% of carriers of the outbreak strain versus 20% of carriers of nonepidemic strains (P < 0.01). However, antibiotic use during the follow-up period was significantly higher by carriers of the outbreak strain than by carriers of nonepidemic strains. The fact that the outbreak strain was recovered for a longer period of time than nonepidemic strains may facilitate dissemination of the strain. The results support a careful restrictive antibiotic policy for wards at risk for spread of VREF and implementation of isolation precautions for patients who are colonized with esp-positive outbreak strains.

Adjuvant Quil A improves protection in mice and enhances opsonic capacity of antisera induced by pneumococcal polysaccharide conjugate vaccines.

The adjuvant effect of Quil A on the primary antibody response of mice to pneumococcal capsular polysaccharide conjugates was examined. Quil A increased the anti-capsular polysaccharide antibody titres, the protection against Streptococcus pneumoniae, and the opsonic capacity of the antibodies as measured in a newly developed in vitro phagocytosis assay, using the mouse macrophage cell line J774.