Most hospitals in the United States do not perform active surveillance cultures and, thus, rely on clinical microbiological cultures (CMCs) to identify patients colonized with methicillin-resistant Staphylococcus aureus (MRSA). We sought to determine what proportion of patients who are colonized with MRSA at admission are identified by CMCs during hospitalization.

From February 1998 through November 2002, patients found to be colonized with MRSA at admission by use of active surveillance cultures were identified. The proportion of colonized patients who had a CMC that was positive for MRSA, the number of CMCs performed and their type (ie, according to the anatomical site from which specimens were obtained for culture), and the number and type of CMCs that were positive for MRSA were calculated.

Four hundred thirty-seven patients were found to be colonized with MRSA at admission, and 98 of 1,238 CMCs (7.9%; 95% confidence interval, 6.5%-9.6%) performed for 66 of these patients (15%; 95% confidence interval, 11.9%-18.8%) were positive for MRSA. The number of nonisolated days that would have occurred by relying on CMCs to identify MRSA-colonized patients was 3,247 (mean, 7.4 days per patient). Among the anatomical sites from which specimens were obtained for CMC, wounds demonstrated the highest sensitivity (30.2%) for identifying MRSA-colonized patients.

CMCs failed to identify 85% of MRSA-colonized patients, because, in part, CMCs identified only a small proportion of colonized patients. Because many studies have shown a decrease in the transmission of MRSA from colonized patients for whom contact precautions, rather than standard precautions, are used, the findings of this study suggest that failure to identify colonized patients and to use contact precautions may be an important reason for the increasing rate of nosocomial MRSA infection in hospitals in the United States.

To assess the effects of interventions to prevent transmission of influenza and to increase employee compliance with influenza vaccination.

The change in the proportion of hospitalized patients with laboratory-confirmed nosocomial influenza was observed over time and assessed using chi-square for trend analysis. The association between nosocomial influenza in patients and healthcare worker (HCW) compliance with vaccine was assessed by logistic regression.

A 600-bed, tertiary-care academic hospital.

After an outbreak of influenza A at this hospital in 1988, a mobile cart program was instituted with increased efforts to motivate employees to be vaccinated and furloughed when ill as well as new measures to prevent nosocomial spread.

HCW vaccination rates increased from 4% in 1987–1988 to 67% in 1999–2000 (P < .0001). Proportions of nosocomially acquired influenza cases among employees or patients both declined significantly (P < .0001). Logistic regression analysis revealed a significant inverse association between HCW compliance with vaccination and the rate of nosocomial influenza among patients (P < .001).

A mobile cart vaccination program and an increased emphasis on HCWs to receive the vaccine were associated with a significant increase in vaccine acceptance and a significant decrease in the rate of nosocomial influenza among patients.

Oral vancomycin therapy has been a risk factor for turning culture positive for vancomycin-resistant Enterococcus (VRE). VRE colonization status was reviewed for all patients who received oral vancomycin and underwent prospective cultures.

Data were extracted from the medical records of all patients receiving oral vancomycin between August 1995 and February 2001 regarding history, hospital course, and perirectal VRE cultures. Hospital policy required contact isolation for patients receiving oral vancomycin until colonization with VRE was excluded.

Twenty-six courses of oral vancomycin were given to 22 patients. VRE colonization status after completion of therapy was evaluated for 23 courses in 20 (91%) of these patients. None of these patients became VRE culture positive during a median follow-up of 18 days (range, 9 to 39 days), with a median duration of treatment of 10 days (range, 3 to 58 days), and with a median total dose of 6,500 mg (range, 1,250 to 29,000 mg). All patients received other antibiotics within 30 days prior to therapy with oral vancomycin, during therapy with oral vancomycin, or both; 95% had received anti-anaerobic therapy and 35% had received parenteral vancomycin.

Even when other risk factors were present, no patient receiving oral vancomycin at our facility subsequently became culture positive for VRE. This suggests that oral vancomycin therapy or other antibiotic use, including anti-anaerobic therapy, may not be a significant independent risk factor for turning culture positive for VRE among patients not previously exposed to the microbe.

Because patients with vancomycin-resistant Enterococcus bacteremia (VREB) usually have a higher severity of illness, it has been unclear whether VREB is worse than vancomycin-susceptible Enterococcus bacteremia (VSEB).

Data on morbidity and case fatality rates and costs were pooled from studies comparing VREB and VSEB, identified by Medline (January 1986 to April 2002) and meeting abstracts. Heterogeneity across studies was assessed with contingency table chi-square. Multivariate analyses (MVAs) controlling for other predictors were evaluated.

Thirteen studies compared case-fatality rates of VREB and VSEB. VREB case fatality was significantly higher (48.9% vs 19%; RR, 2.57; CI95, 2.27 to 2.91; attributable mortality = 30%). Five studies compared VREB with VSEB when bacteremia was the direct cause of death; VREB case fatality was significantly higher (39.1% vs 21.8%; RR, 1.79; CI95, 1.28 to 2.5; attributable mortality = 17%). Four MVAs found significant increases in case-fatality rates (OR 2.10 to 4.0), 3 showed trends toward increase (OR, 1.74 to 3.34 with wide confidence intervals), and 3 with low statistical power found no difference. VREB recurred in 16.9% versus 3.7% with VSEB (P < .0001). Three studies reported significant increases in LOS, costs, or both with VREB.

Most studies have had inadequate sample size, inadequate adjustment for other predictors of adverse outcomes, or both, but available data suggest that VREB is associated with higher recurrence, mortality, and excess costs than VSEB including multiple studies adjusting for severity of illness.

CDC has estimated that 23% of Legionella infections are nosocomial. When a new hospital was being constructed and a substantial increase in transplantation was anticipated, an ultraviolet light apparatus was installed in the water main of the new building because 27% of water samples from taps in the old hospital contained Legionella. This study reports the rate of nosocomial Legionella infection and water contamination since opening the new hospital.

Charts of all patients with positive Legionella cultures, direct immunofluorescent antibody (DFA), or urine antigen between April 1989 and November 2001 were reviewed. Frequencies of DFAs and urine antigens were obtained from the laboratory.

None of the 930 cultures of hospital water have been positive since moving into the new building. Fifty-three (0.02%) of 219,521 patients had a positive Legionella test; 41 had pneumonia (40 community acquired). One definite L. pneumophila pneumonia confirmed by culture and DFA in August 1994 was nosocomial (0.0005%) by dates. This patient was transferred after prolonged hospitalization in another country, was transplanted 11 days after admission, and developed symptoms 5 days after liver transplant. However, tap water from the patient's room did not grow Legionella. Seventeen (2.5%) of 670 urine antigens were positive for Legionella (none nosocomial). Thirty-three (1.2%) of 2,671 DFAs were positive, including 7 patients (21%) without evidence of pneumonia and 6 (18%) who had an alternative diagnosis.

Ultraviolet light usage was associated with negative water cultures and lack of clearly documented nosocomial Legionella infection for 13 years at this hospital.

To determine the frequency with which methicillin-resistant Staphylococcus aureus (MRSA) is spread from colonized or infected patients to their household and community contacts.

Retrospective cohort study.

University hospital.

Household and community contacts of MRSA-colonized or -infected patients for whom MRSA screening cultures were performed.

MRSA was isolated from 25 (14.5%) of 172 individuals. Among the contacts of index patients who had at least one MRSA-colonized contact, those with close contact to the index patient were 7.5 times more likely to be colonized (53% vs 7%; 95% confidence interval, 1.1 to 50.3; P = .002). An analysis of antimicrobial susceptibility and DNA fingerprint patterns suggested person-to-person spread.

MRSA colonization occurs frequently among household and community contacts of patients with nosocomially acquired MRSA, suggesting that transmission of nosocomially acquired MRSA outside of the healthcare setting may be a substantial source of MRSA colonization and infection in the community.

Infection control programs were created three decades ago to control antibiotic-resistant healthcare-associated infections, but there has been little evidence of control in most facilities. After long, steady increases of MRSA and VRE infections in NNIS System hospitals, the Society for Healthcare Epidemiology of America (SHEA) Board of Directors made reducing antibiotic-resistant infections a strategic SHEA goal in January 2000. After 2 more years without improvement, a SHEA task force was appointed to draft this evidence-based guideline on preventing nosocomial transmission of such pathogens, focusing on the two considered most out of control: MRSA and VRE.

Medline searches were conducted spanning 1966 to 2002. Pertinent abstracts of unpublished studies providing sufficient data were included.

Frequent antibiotic therapy in healthcare settings provides a selective advantage for resistant flora, but patients with MRSA or VRE usually acquire it via spread. The CDC has long-recommended contact precautions for patients colonized or infected with such pathogens. Most facilities have required this as policy, but have not actively identified colonized patients with surveillance cultures, leaving most colonized patients undetected and unisolated. Many studies have shown control of endemic and/or epidemic MRSA and VRE infections using surveillance cultures and contact precautions, demonstrating consistency of evidence, high strength of association, reversibility, a dose gradient, and specificity for control with this approach. Adjunctive control measures are also discussed.

Active surveillance cultures are essential to identify the reservoir for spread of MRSA and VRE infections and make control possible using the CDC's long-recommended contact precautions.

Several hospitals opting not to use active surveillance cultures to identify carriers of vancomycin-resistant Enterococcus (VRE) have reported that adoption of other parts of the Centers for Disease Control and Prevention guideline for controlling VRE has had little to no impact. Because use of surveillance cultures and contact isolation controlled a large outbreak at this hospital, their costs were estimated for comparison with the excess costs of VRE bacteremias occurring at a higher rate at a hospital not employing these measures.

Two university hospitals.

Inpatients deemed high risk for VRE acquisition at this hospital underwent weekly perirectal surveillance cultures. Estimated costs of cultures and resulting isolation during a 2-year period were compared with the estimated excess costs of more frequent VRE bacteremias at another hospital of similar size and complexity not using surveillance cultures to control spread throughout the hospital.

Of 54,052 patients admitted, 10,400 had perirectal swabs taken. Cultures and isolation cost an estimated $253,099. VRE culture positivity was limited to 193 (0.38%) and VRE bacteremia to 1 (0.002%) as compared with 29 bacteremias at the comparison hospital. The estimated attributable cost of VRE bacteremia at the comparison hospital of $761,320 exceeded the cost of the control program at this hospital by threefold.

The excess costs of VRE bacteremia may justify the costs of preventive measures. The costs of VRE infections at other body sites, of deaths from untreatable infections, and of dissemination of genes for vancomycin resistance also help to justify the costs of implementing an effective control program.