OBJECTIVE: To assess the accuracy of nosocomial infections data reported on patients in the intensive-care unit by nine hospitals participating in the National Nosocomial Infections Surveillance (NNIS) System.

DESIGN: A pilot study was done in two phases to review the charts of selected intensive-care–unit patients who had nosocomial infections reported to the NNIS System. The charts of selected high- and low-risk patients in the same cohort who had no infections reported to the NNIS System also were included. In phase I, trained data collectors reviewed a sample of charts for nosocomial infections. Retrospectively detected infections that matched with previously reported infections were deemed to be true infections. In phase II, two Centers for Disease Control and Prevention (CDC) epidemiologists reexamined a sample of charts for which a discrepancy existed. Each sampled infection either was confirmed or disallowed by the epidemiologists. Confirmed infections also were deemed to be true infections. True infections from both phases were used to estimate the accuracy of reported NNIS data by calculating the predictive value positive, sensitivity, and specificity at each major infection site and the “other sites.”

RESULTS: The data collectors examined a total of 1,136 patients' charts in phase I. Among these charts were 611 infections that the study hospitals had reported to the CDC. The data collectors retrospectively matched 474 (78%) of the prospectively identified infections, but also detected 790 infections that were not reported prospectively. Phase II focused on the discrepant infections: the 137 infections that were identified prospectively and reported but not detected retrospectively, and the 790 infections that were detected retrospectively but not reported previously. The CDC epidemiologists examined a sample of 113 of the discrepant reported infections and 369 of the discrepant detected infections, and estimated that 37% of all discrepant reported infections and 43% of all discrepant detected infections were true infections. The predictive value positive for reported bloodstream infections, pneumonia, surgical-site infection, urinary tract infection, and other sites was 87%, 89%, 72%, 92%, and 80%, respectively; the sensitivity was 85%, 68%, 67%, 59%, and 30%, respectively; and the specificity was 98.3%, 97.8%, 97.7%, 98.7%, and 98.6%, respectively.

CONCLUSIONS: When the NNIS hospitals in the study reported a nosocomial infection, the infection most likely was a true infection, and they infrequently reported conditions that were not infections. The hospitals also identified and reported most of the nosocomial infections that occurred in the patients they monitored, but accuracy varied by infection site. Primary bloodstream infection was the most accurately identified and reported site. Measures that will be taken to improve the quality of the infection data reported to the NNIS System include reviewing the criteria for definitions of infections and other data fields, enhancing communication between the CDC and NNIS hospitals, and improving the training of surveillance personnel in NNIS hospitals

OBJECTIVE: To assess the utility of postoperative antibiotic exposure as an indicator of postoperative infection after coronary artery bypass graft surgery.

DESIGN: We determined an optimal antibiotic exposure threshold by creating receiver operating characteristic curves.

SETTING:Tertiary healthcare institution (United States); national sample (Israel).

PATIENTS:5,887 patients undergoing coronary artery bypass graft surgery.

RESULTS: Postoperative antibiotic exposure with at least 9 days between the first and last dates of antibiotic administration, excluding the first postoperative day, had a sensitivity of 95% (261/276) and specificity of 85% (3,944/4,628) for identifying surgical-site infection, using as a gold standard surgical-site infections identified by conventional prospective surveillance or extrapolated from review of a sample of medical records. In contrast, using the same gold standard for surgical-site infections, the sensitivity of routine prospective surveillance alone was only 60%. The predictive value positive of the defined antibiotic exposure was 28% (261/945) for surgical-site infection and 60% (563/945) for any nosocomial infection. In the Israeli cohort, the sensitivity was 87% (74/85) and the specificity was 82% (735/898).

CONCLUSION:Antibiotic exposure of sufficient duration and timing was more sensitive than conventional methods in detecting nosocomial infection and required substantially less effort to collect. Although the predictive value positive for surgical-site infection was only moderate, the majority of individuals identified this way had a nosocomial infection

OBJECTIVES: To determine the stability of sodium hypochlorite (diluted household bleach) when stored for 30 days in various types of containers and to determine the efficacy of low concentrations of free available chlorine to inactivate test bacteria.

DESIGN: Laboratory-based study. Solutions of standard household bleach were prepared using tap water or sterile distilled water at dilutions of 1:100, 1:50, and 1:5. Chlorine concentrations were measured, and then the solutions were placed into five polyethylene containers and left at room temperature (20°C) under various conditions (translucent containers with light exposure and with or without air; brown opaque container without light or air exposure). Samples for chlorine and pH determinations were taken at time 0 and on days 7, 14, 21, 30, and 40. Bactericidal activity of chlorine solutions was assessed using the Association of Official Analytical Chemists Use-Dilution Method. Test bacteria included Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella choleraesuis.

RESULTS: Chlorine concentrations at 30 days varied from the 40% to 50% range for 1:50 or 1:100 dilutions stored in containers other than closed brown containers to 83% to 85% for the 1:5 dilution stored in closed but non-opaque containers to 97% to 100% for 1:50 or 1:5 solutions stored in closed brown containers. The lowest concentration of sodium hypochlorite solution that reliably inactivated all the test organisms was 100 ppm.

CONCLUSIONS:These data suggest that chlorine solutions do not need to be prepared fresh daily, as is recommended currently, and the lowest concentration of chlorine that reliably inactivates S aureus, S choleraesuis, and P aeruginosa is 100 ppm

OBJECTIVE: To determine if Staphylococcus aureus colonization of the anterior nares was a risk factor for S aureus infection in patients with cirrhosis and to determine the predictors of S aureus infection in colonized patients.

DESIGN: Prospective cohort study.

PATIENTS:84 consecutive patients with cirrhosis admitted to the liver transplant unit of a university-affiliated Veterans' Affairs Medical Center.

RESULTS: Overall, 39 (46%) of the 84 patients were nasal carriers of S aureus, of which 24 (29%) were methicillin-resistant Staphylococcus aureus (MRSA) and 15 (18%) were methicillin-sensitive Staphylococcus aureus (MSSA). Only MRSA, but never MSSA, carriage was acquired in the hospital; all 15 of the MSSA versus 14 (58%) of the 24 MRSA carriers were nasal carriers on first (admission) culture (P=.001). Of the 10 (42%) of 24 MRSA carriers who were not colonized on admission, 3 became MRSA carriers within 1 month, and 7 acquired MRSA carriage more than a month later. Higher Child-Pugh score was independently associated with MRSA carriage (odds ratio [OR], 1.54; 95% confidence interval [CI95], 1.1-2.3). S aureus nasal carriers (9 [23%] of 39) were significantly more likely to develop S aureus infections than noncarriers (2 [4%] of 45; P=.02). Central venous catheter use was associated independently with S aureus infections in the carriers (OR, 4.1; CI95, 2.8-6.1). Mortality was significantly higher in carriers who developed S aureus infections as compared to those who did not (57% vs 13%; P=.022); S aureus infection was an independent predictor of mortality in the carriers (OR, 8.7; CI95, 1.2-63.8).

CONCLUSIONS:Colonization of the anterior nares was a significant predictor of S aureus infection in patients with cirrhosis

OBJECTIVE: To contain a nosocomial outbreak of vancomycin-resistant Enterococcus (VRE).

DESIGN: Intervention study, with comparison of incidence rates before and after intervention to assess whether changes in incidence followed the intervention and were greater than expected based on trends observed before the intervention.

SETTING: A 343-bed acute-care hospital serving a predominantly elderly population referred from nursing homes, as well as patients admitted from the community.

METHODS: Interventions strategies were tested on three high-risk nursing stations. These included enhanced environmental sanitation; intensive staff retraining in Universal Precautions, body substance isolation, and proper use of gloves; and the use of tympanic thermometers to avoid possible rectal or oral VRE transmission during temperature taking.

RESULTS: Nosocomial VRE infections were reduced by 48% 9 months after switching to tympanic thermometers; incidence of Clostridium difficile infections also was reduced. As a result, tympanic thermometers were introduced facilitywide; additional observation for 20 months showed a risk reduction of 60% for VRE and 40% for C difficile.

CONCLUSION:Cross-transmission of VRE and C difficile during temperature taking may result in bowel colonization, placing the patient at increased risk for infection. This risk may be reduced by the use of tympanic thermometers

OBJECTIVE: In spite of yearly recalls, influenza immunization rates of healthcare workers (HCWs) remained low (10%) at the University Hospitals of Geneva. This study was conducted to identify HCWs' reasons for rejection of immunization, to design specific intervention methods based on these reasons, and to evaluate the impact of such interventions.

METHODS:Three departments with high-risk patients (geriatrics, obstetrics, and pediatrics) were selected as main targets. Questionnaires were distributed in these units. Based on HCWs' perceptions, different intervention methods were designed and used either in these departments only (educational conferences, on-site availability of a vaccination nurse) or in the whole institution (posters, personal letters). Immunization rates were collected throughout the institution.

RESULTS: 797 completed questionnaires from 1,092 HCWs (73%) were returned. Major reasons for immunization rejection were confidence that their bodies' self-defense mechanisms would ward off infection (32%), perception of low exposure risk (23%), and doubts concerning vaccine efficacy (19%). The use of intervention methods designed to address these factors increased influenza immunization rates in the three targeted departments from 13% (95% confidence interval [CI95], 11.4-15.6) in 1995 and 1996 to 37% (CI95, 34.5-40.3) in the following season (P<.001). In all other departments, immunization rates rose from 9% (CI95, 8.5-10.3) to 23%% (CI95, 21.6-24.1; P<.001). Nurses were, and remained, more reluctant to be immunized compared to other HCWs.

CONCLUSIONS:Influenza immunization rates can be increased significantly by specific interventions based on local concerns of HCWs, among which educational conferences and the on-site availability of a vaccination nurse appeared important

Candida lusitaniae is an increasingly important nosocomial bloodstream pathogen. Epidemiological investigation and molecular typing techniques identified three neonates infected with identical strains of C lusitaniae that were distinguished readily from epidemiologically unrelated strains from other locations in the hospital. The results of this study provide evidence for nosocomial transmission of C lusitaniae in a neonatal intensive-care unit and suggest that these infants are at increased risk for infection with this agent

A 10-fold increase in patients with Mycobacterium tuberculosis-positive specimens in one hospital laboratory prompted an investigation. Clinical and epidemiological data, along with M tuberculosis DNA fingerprinting results, indicated that laboratory contamination led to nine falsepositive M tuberculosis cultures. Pseudo-infection should be considered in patients with unusual tuberculosis presentations, negative acid-fast bacilli smears, and only one positive culture with a low colony count

OBJECTIVE: In June 1996, a resolution was introduced to the House of Delegates of the American Medical Association (AMA) asking the AMA to advocate that healthcare workers be given the informed option of receiving the varicella vaccine. The AMA Council on Scientific Affairs studied this issue and presented this report to the House of Delegates in June 1997.

METHODS:Information for the report was derived from published literature and from personal communications with medical and public health experts and the vaccine manufacturer.

FINDINGS: Nosocomial outbreaks of varicella-zoster virus (VZV) can result in serious morbidity and mortality. Sero-logical testing of healthcare workers and immunization of nonimmune individuals is recommended by infection control and infectious disease experts to prevent nosocomial transmission of VZV. While current data indicate that the vaccine is safe and poses minimal risks to both adults and children, ongoing research should address various concerns about the long-term safety, efficacy, and epidemiological impact of more widespread use of the vaccine.

CONCLUSION:Unless contraindicated, all susceptible healthcare workers should receive the varicella vaccine. Whereas individuals with a definite history of VZV infection can be considered immune, those with a negative or uncertain history should undergo serological testing and, if seronegative, should be immunized

The following article, “Microbiological Hazards Related to Xenotransplantation of Porcine Organs in Man” inaugurates this section of the Journal, which will focus on the interface between the world of emerging infectious diseases and the delivery of healthcare. Emerging infectious diseases, that is, diseases of infectious origin whose incidence in humans has increased within the past 2 decades or threatens to increase in the near future, are of great importance to hospital epidemiologists and infection control practitioners. Many of the diseases in this category, eg, Clostridium difficile colitis, infections caused by methicillin-resistant Staphylococcus aureus or van-comycin-resistant enterococci, and legionellosis, are well-recognized causes of nosocomial infections. Others, such as hepatitis C virus, human immunodeficiency virus, and Ebola virus, are potential threats to healthcare workers in certain occupational settings. Still others, group B streptococcal infections in neonates, for example, may be prevented by implementation of strategies that infection control programs can promote.

Pigs are emerging as the most likely providers of genetically engineered organs and cells for the purpose of clinical xenotransplantation. Introduction of clinical trials has been delayed primarily by uncertainties regarding the risk of swine pathogen transmission that could harm the recipient. The concern that xenotransplantation carries the potential for a new epidemic has been highlighted by recent experiences with both bovine spongiform encephalopathy and human immunodeficiency diseases.

As clinical trials have been postponed and xenotransplantation teams are working actively to gather data for an estimation of the risk, this review provides the reader with a state-of-the-art estimation of the microbiological hazards related to xenotransplantation of porcine organs to man. Particular emphasis is put on viral and retroviral hazards. Both current diagnostic tools and those under development are described, along with breeding strategies to provide donor animals that would not put the recipient or the general population at risk

Infection control in the long-term–care facility has expanded substantially since “Topics in Long-Term Care” debuted in this journal in 1989. This section has been on hiatus, but now, after a 4-year lag, resumes its exploration of these topics.

In the first article, endemic and epidemic infections in long-term care are discussed and compared to nosocomial infections in the hospital. The basic elements of an infection control program in this setting, as well as the recent advances in the field, are reviewed