Infection-control measures reduce transmission of vancomycin-resistant enterococci in an endemic setting.

BACKGROUND: Vancomycin-resistant enterococci (VRE) are nosocomial pathogens in many U. S. hospitals. OBJECTIVE: To determine whether enhanced infection-control strategies reduce transmission of VRE in an endemic setting. DESIGN: Prospective cohort study. SETTING: Adult oncology inpatient unit. PATIENTS: 259 patients evaluated during use of enhanced infection-control strategies and 184 patients evaluated during use of standard infection-control practices. INTERVENTIONS: Patient surveillance cultures were taken, patients were assigned to geographic cohorts, nurses were assigned to patient cohorts, gowns and gloves were worn on room entry, compliance with infection-control procedures was monitored, patients were educated about VRE transmission, patients taking antimicrobial agents were evaluated by an infectious disease specialist, and environmental surveillance was performed. MEASUREMENTS: VRE infection rates, VRE colonization rates, and changes in antimicrobial use. RESULTS: During use of enhanced infection-control strategies, incidence of VRE bloodstream infections decreased significantly (0.45 patients per 1000 patient-days compared with 2.1 patients per 1000 patient-days; relative rate ratio, 0.22 [95% CI, 0.05 to 0.92]; P = 0.04), as did VRE colonization (10.3 patients per 1000 patient-days compared with 20.7 patients per 1000 patient-days; relative rate ratio, 0.5 [CI, 0.33 to 0.75]; P < 0.001). Use of all antimicrobial agents except clindamycin and amikacin was significantly reduced. CONCLUSION: Enhanced infection-control strategies reduced VRE transmission in an oncology unit in which VRE were endemic.

Epidemiology and control of vancomycin-resistant enterococci in a regional neonatal intensive care unit.

BACKGROUND: After the occurrence of two cases of bloodstream infection with vancomycin-resistant enterococci (VRE) in our regional neonatal intensive care unit, we studied the epidemiology of VRE and applied extensive infection control measures to the unit to control VRE transmission. METHODS: Infection control measures applied to the unit included weekly surveillance for VRE colonization; education; cohorting of VRE-positive, VRE-negative and VRE-exposed babies with separate personnel and equipment for each group; use of gowns and gloves on room entry; and hand washing before and after each patient contact. Risk factors for VRE colonization were determined with a stepwise logistic regression model. RESULTS: Thirty-three (40.2%) babies became colonized with VRE. The VRE colonization rate was reduced from 67% to 7% after implementation of infection control measures. Prolonged antimicrobial treatment and low birth weight were significantly associated with an increased risk of VRE colonization. CONCLUSION: VRE can spread rapidly among newborns in a regional neonatal intensive care unit. Strict infection control measures can reduce the rate of VRE colonization among neonates.

Evaluation of commercial vancomycin agar screen plates for detection of vancomycin-resistant enterococci.

Brain heart infusion-6-micrograms/ml vancomycin agar plates obtained from five commercial sources (B-D Microbiology Systems, Carr-Scarborough Microbiologicals, MicroBio Products, PML Microbiologicals, and REMEL) were evaluated with 714 enterococci for detection of vancomycin resistance. All 465 (100%) vancomycin-resistant enterococci (MIC > or = 32 micrograms/ml) were detected by each manufacturer's agar screen plate, and each manufacturer's agar screen plate detected at least 99% of the 177 vancomycin-susceptible enterococci (MIC < or = 4 micrograms/ml). Detection of the 72 vancomycin-intermediate enterococci (MIC = 6 to 16 micrograms/ml) ranged from 94% for B-D Microbiology Systems to 99% for PML Microbiologicals.

Selective isolation of vancomycin-resistant enterococci.

Broth formulations of two media selective for enterococci, Enterococcel, M-Enterococcosel broths were supplemented with 6 micrograms of vancomycin per ml and evaluated for isolation of vancomycin-resistant enterococci (VRE). Each broth was challenged with various concentrations of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and vancomycin-susceptible and vancomycin-resistant enterococci and with 193 perianal specimens obtained from patients at risk in our institution for VRE colonization. Both the Enterococcosel and M-Enterococcus broths with vancomycin detected as few as 1 to 9 CFU of VRE while inhibiting growth of the other organisms tested. Enterococcus faecium organisms (MIC, > 256 micrograms/ml) were recovered from 66 perianal swab cultures in the enterococcosel-vancomycin broth, and VRE were recovered from 62 perianal swab cultures in the M-Enterococcus-vancomycin broth. Enterococcosel-vancomycin broth detected VRE in perianal specimens 48 h earlier than did M-Enterococcus-vancomycin broth. Enterococcosel broth with 6 micrograms of vancomycin per ml can be used for the rapid and selective isolation of VRE from surveillance specimens.

Natural history of colonization with vancomycin-resistant Enterococcus faecium.

OBJECTIVE: To determine the incidence, duration, and genetic diversity of colonization with vancomycin-resistant Enterococcus faecium (VREF). SETTING: Oncology unit of a 650-bed university hospital. METHODS: Surveillance perianal swab cultures were performed on admission and weekly. The molecular relatedness of VREF isolates was determined by pulsed-field gel electrophoresis and by the hybridization pattern of the vanA resistance determinant. RESULTS: During 8 months of surveillance, the VREF colonization rate was 16.6 patients per 1,000 patient-hospital days, which was 10.6 times greater than the VREF infection rate. Eighty-six patients with VREF colonization were identified. Colonization persisted for at least 7 weeks in the majority of patients. Of 36 colonized patients discharged from the hospital and then readmitted, an average of 2 1/2 weeks later, 22 (61%) patients still were colonized with VREF. Of the 14 patients who were VREF-negative at readmission, only three patients remained culture-negative throughout hospitalizations. PFGE demonstrated that colonization with the same VREF isolate may persist for at least 1 year, and patients may be colonized with more than one strain of VREF. CONCLUSION: VREF colonization is at least 10-fold more prevalent than infection among oncology patients. Colonization often persists throughout lengthy hospitalizations and may continue for long periods following hospitalization.

Outbreak of vancomycin-, ampicillin-, and aminoglycoside-resistant Enterococcus faecium bacteremia in an adult oncology unit.

An outbreak of bacteremia caused by Enterococcus faecium with high-level resistance to vancomycin (MIC of > or = 256 micrograms/ml), ampicillin (MIC of > or = 64 micrograms/ml), and gentamicin or streptomycin (MIC of > or = 2,000 micrograms/ml) occurred in an adult oncology unit from June 1991 to May 1992. Active surveillance for the presence of this organism in stool or perianal cultures was begun in September 1991. Between June 1991 and May 1992, seven patients with bacteremia and 22 noninfected carriers of the organism in stool were identified. The vanA gene, tested for by PCR and gene probe, was present in all isolates evaluated. All bacteremic patients also had resistant E. faecium present in a stool or perianal culture; the stool isolates tested were closely related to the respective blood isolates as determined by pulsed-field gel electrophoresis. Antibiotic regimens using high-dose ampicillin and an aminoglycoside were ineffective with four patients. Five patients (71%) had multiple positive blood cultures; four of these patients died. Following a multiple logistic regression analysis, it was found that bacteremic patients received a significantly greater number of total antibiotic days compared with noninfected stool carriers (P = 0.019). The emergence of E. faecium with high-level resistance to vancomycin, ampicillin, and aminoglycosides underscores the importance of performing susceptibility testing on all clinically significant isolates. In the neutropenic adult oncology patient, bacteremia with this organism is of probable gastrointestinal origin, is often persistent, and is refractory to treatment with ampicillin in combination with an aminoglycoside. Prolonged use of antibiotics may predispose patients with gastrointestinal colonization to develop bacteremia.

Bacteremia and urinary tract infection associated with CDC group Vd biovar 2.

A case of urinary tract infection and bacteremia caused by CDC group Vd biovar 2 in a 23-year-old woman with Hodgkin's disease is described. This is the first report of CDC group Vd biovar 2 isolated from a clinical specimen and considered as a pathogen. Detailed antimicrobial susceptibility data are presented.