To describe the molecular epidemiology of Legionella pneumophila infections in the University of Iowa Hospitals and Clinics (UIHC).

Molecular epidemiological study using pulsed-field gel electrophoresis (PFGE).

A large university teaching hospital.

All surviving isolates obtained from culture-proven nosocomial L pneumophila infections and all surviving isolates obtained from the University of Iowa Hospital and Clinics' water supply between 1981 and 1993.

Thirty-three isolates from culture-proven nosocomial cases of L pneumophila pneumonia were available for typing. PFGE of genomic DNA from the clinical isolates identified six different strains. However, only strain C (16 cases) and strain D (13 cases) caused more than 1 case. Strain C caused clusters of nosocomial infection in 1981, 1986, and 1993 and also caused 4 sporadic cases. Strain D caused a cluster in 1987 and 1988 plus 4 sporadic cases. Of the six strains causing clinical infections, only strains C and D were identified in water samples. PFGE identified three strains in the water supply, of which strains C and D caused clinical disease and also persisted in the water supply during most of the study period.

Specific strains of L pneumophila can colonize hospital water supplies and cause nosocomial infections over long periods of time.

To investigate an increase in reports of legionnaires' disease by multiple hospitals in San Antonio, Texas, and to study risk factors for nosocomial transmission of legionnaires' disease and determinants for Legionella colonization of hospital hot-water systems.

The 16 largest hospitals in the cities of San Antonio, Temple, and Austin, Texas.

Review of laboratory databases to identify patients with legionnaires' disease in the 3 years prior to the investigation and to determine the number of diagnostic tests for Legionella performed; measurement of hot-water temperature and chlorine concentration and culture of potable water for Legionella. Exact univariate calculations, Poisson regression, and linear regression were used to determine factors associated with water-system colonization and transmission of Legionella.

Twelve cases of nosocomial legionnaires' disease were identified; eight of these occurred in 1996. The rise in cases occurred shortly after physicians started requesting Legionella urinary antigen tests. Hospitals that frequently used Legionella urinary antigen tests tended to detect more cases of legionnaires' disease. Legionella was isolated from the water systems of 11 of 12 hospitals in San Antonio; the 12th had just experienced an outbreak of legionnaires' disease and had implemented control measures. Nosocomial legionellosis cases probably occurred in 5 hospitals. The number of nosocomial legionnaires' disease cases in each hospital correlated better with the proportion of water-system sites that tested positive for Legionella (P=.07) than with the concentration of Legionella bacteria in water samples (P=.23). Hospitals in municipalities where the water treatment plant used monochloramine as a residual disinfectant (n=4) and the hospital that had implemented control measures were Legionella-free. The hot-water systems of all other hospitals (n=11) were colonized with Legionella. These were all supplied with municipal drinking water that contained free chlorine as a residual disinfectant. In these contaminated hospitals, the proportion of sites testing positive was inversely correlated with free residual chlorine concentration (P=.01). In all hospitals, hot-water temperatures were too low to inhibit Legionella growth.

The increase in reporting of nosocomial legionnaires' disease was attributable to increased use of urinary antigen tests; prior cases may have gone unrecognized. Risk of legionnaires' disease in hospital patients was better predicted by the proportion of water-system sites testing positive for Legionella than by the measured concentration of Legionella bacteria. Use of monochloramine by municipalities for residual drinking water disinfection may help prevent legionnaires' disease.

To determine the impact of a multifocused interventional program on sharps injury rates.

Sharps injury data were collected prospectively over a 9-year period (1990-1998). Pre- and postinterventional rates were compared after the implementation of sharps injury prevention interventions, which consisted of administrative, work-practice, and engineering controls (ie, the introduction of an anti-needlestick intravenous catheter and a new sharps disposal system).

Sharps injury data were collected from healthcare workers employed by a mid-sized, acute-care community hospital.

Preinterventional annual sharps injury incidence rates decreased significantly from 82 sharps injuries/1,000 worked full-time-equivalent employees (WFTE) to 24 sharps injuries/1,000 WFTE employees postintervention (P<.0001), representing a 70% decline in incidence rate overall. Over the course of the study, the incidence rate for sharps injuries related to intravenous lines declined by 93%, hollow-bore needlesticks decreased by 75%, and non-hollow-bore injuries decreased by 25%.

The implementation of a multifocused interventional program led to a significant and sustained decrease in the overall rate of sharps injuries in hospital-based healthcare workers.

To compare mortality following isolation of influenza A to mortality following isolation of other respiratory viruses in a nursing home.

The Wisconsin Veterans Home, a 688-bed skilled nursing facility for veterans and their spouses.

All residents with respiratory viral isolates obtained between 1988 and 1999.

Thirty-day mortality was determined following each culture-proven illness.

Thirty-day mortality following isolation of viral respiratory pathogens was 4.7% (15/322) for influenza A 5.4% (7/129) for influenza B; 6.1% (3/49) for parainfluenza type 1; 0% (0/26) for parainfluenza types 2,3, and 4; 0% (0/26) for respiratory syncytial virus (RSV); and 1.6% (1/61) for rhinovirus.

Mortality following isolation of certain other respiratory viruses may be comparable to that following influenza A (although influenza A mortality might be higher without vaccination and antiviral agents). The use of uniform secretion precautions for all viral respiratory illness deserves consideration in nursing homes.

To characterize the epidemiological relationships among Stenotrophomonas maltophilia isolates in the neonatology unit of our institution over a 4-month period in which an increased number of isolates was observed.

The neonatology ward in a 2,000-bed university hospital in Madrid, Spain.

A retrospective molecular epidemiological analysis using three different typing methods, arbitrarily primed polymerase chain reaction (PCR), pulsed-field gel electrophoresis, and enterobacterial repetitive intergenic consensus-PCR, was performed with 11 isolates obtained from seven neonates over a 4-month period. Presumed unrelated isolates also were included as controls. A similarity dendrogram was obtained, to analyze the genetic relatedness among the isolates.

All isolates from the neonates, except one, showed a remarkably high homology among their typing patterns for the three methods assayed and clustered in the relatedness dendrogram at 96% similarity. The unrelated strains selected as controls were unclustered. The index case was considered to be a newborn who had an S maltophilia isolate from a culture drawn on the day of admission to the neonatology unit and which was included in the clustered similarity group.

Such a high genetic similarity among the isolates, together with the presence of an index case who had been colonized or infected by S maltophilia before arrival at our institution, constitutes the first evidence of nosocomial cross-transmission of this microorganism.

To assess the virucidal activity of three disinfectants (sodium hypochlorite, a phenolic, and a quaternary ammonium compound) in the presence and absence of blood.

Disinfectants at varying concentrations (hypochlorite: 5,000, 500, or 50 ppm; phenolic: 1:10 or 1:128 dilution; quaternary ammonium compound: 1:10 or 1:128 dilution) were added to either saline or whole blood (final concentration, 80% or 20% blood) and mixed. Test organisms included an attenuated vaccine strain of poliovirus type 1 (prototype for relatively resistant hydrophilic viruses) and herpes simplex virus (HSV) type 1 (prototype for relatively susceptible lipophilic viruses). Virus was added to create a viral-blood suspension. Viral survival was tested at room temperature at the following times: 0, 15 seconds, 30 seconds, 1 minute, 2 minutes, 5 minutes, and 10 minutes. A neutralizer stopped the reaction, and virus was assayed using a plaque technique.

In the absence of blood, complete inactivation of HSV was achieved within 30 seconds with 5,000 (1:10 dilution of bleach) and 500 (1:100 dilution of bleach) ppm chlorine, 1:10 and 1:128 diluted phenolic (use dilution), and 1:10 and 1:128 diluted quaternary ammonium compound (use dilution). In the presence of 80% blood, only 5,000 ppm hypochlorite, 1:10 phenolic, and 1:10 or 1:128 quaternary ammonium compound were effective. In the absence of blood, complete inactivation of polio was achieved within 30 seconds by 5,000 and 500 ppm chlorine and 1:10 quaternary ammonium compound. In the presence of 80% blood, no solution tested was capable of completely inactivating poliovirus within 10 minutes.

Our data suggest that, in the absence of visible blood, environmental surfaces may be disinfected with a diluted hypochlorite solution (1:10 or 1:100), a phenolic, or a quaternary ammonium compound. Based on our studies using HSV, which has similar susceptibilities to disinfectants as human immunodeficiency virus (HIV), phenolics at their use dilution and 1:100 diluted hypochlorite are unlikely to inactivate HIV or hepatitis B virus reliably in the presence of blood. Hypochlorite at a final concentration of 5,000 ppm (1:10 dilution) should be used to decontaminate blood spills, but, even after decontamination, care should be used to avoid sharps injuries.

To describe the epidemiology of vancomycin-resistant enterococci (VRE) in a university hospital in Taipei, Taiwan.

Retrospective review over a 27-month period, from March 1996 to May 1998.

A tertiary-care teaching hospital in Taiwan.

Patients with VRE isolated from any body site.

Patients were identified through hospital microbiology and infection control records. Patient charts were reviewed for clinical and epidemiology data, including age, gender, previous hospital admissions, underlying diseases, types of infection, and recent antibiotic use. VRE isolates were characterized by their typical biochemical reactions, cellular fatty acid profiles, and the presence of van genes. Antibiotypes using the E-test and randomly amplified polymorphic DNA (RAPD) patterns of these isolates were used to determine the clonality.

Twenty-five isolates of VRE recovered from 12 patients were identified. One patient with a perianal abscess had 12 isolates of VRE (4 Enterococcus faecalis, 7 Enterococcus faecium, and 1 Enterococcus casseliflavus) recovered from perianal lesions. Among 3 patients who were hospitalized in the same room, 1 had a community-acquired cellulitis over the left leg caused by E faecalis, and the other 2 patients both had anal colonization with 2 isolates of E faecalis. The other 8 patients had 1 E faecalis isolate each from various clinical specimens. All isolates possessed vanA resistance phenotype and vanA genes. Different antibiotypes and RAPD patterns of the isolates from different patients excluded the possibility of nosocomial spread at the hospital.

Multiple species of VRE (E faecalis, E faecium, and E casseliflavus) and multiple clones of E faecium could colonize or infect hospitalized patients. In addition, clones of VRE can persist long-term in patients' lower gastrointestinal tracts. These results extend our knowledge of the coexistence and the persistence of multiple species and multiple clones of VRE in hospitalized patients.