To investigate and control a biphasic outbreak of Serratia marcescens in a neonatal intensive care unit (NICU).

Epidemiological and laboratory investigation of the outbreak.

The NICU of the 1,470-bed teaching hospital of the University “Federico II,” Naples, Italy.

The outbreak involved 56 cases of colonization by S marcescens over a 15-month period, with two epidemic peaks of 6 and 3 months, respectively. Fourteen (25%) of the 56 colonized infants developed clinical infections, 50% of which were major (sepsis, meningitis, or pneumonia).

Epidemiological and microbiological investigations, analysis of macrorestriction pattern of genomic DNA through pulsed-field gel electrophoresis (PFGE) of clinical and environmental isolates, and institution of infection control measures.

Analysis of macrorestriction patterns of genomic DNA by PFGE demonstrated that the vast majority of S marcescens isolates, including three environmental strains isolated from two handwashing disinfectants and the hands of a nurse, were of the same clonal type. The successful control of the outbreak was achieved through cohorting of noncolonized infants, isolation of S marcescens-infected and -colonized infants, and an intense educational program that emphasized the need for adherence to glove use and handwashing policies. The NICU remained open to new admissions.

Outbreaks caused by S marcescens are very difficult to eradicate. An infection control program that includes molecular typing of microorganisms and the proper dissemination among staff members of the typing results is likely to be very effective in reducing NICU-acquired infections and in controlling outbreaks caused by S marcescens, as well as other multiresistant bacteria.

To study the presence of bacterial factors in clinical isolates of Acinetobacter species in order to identify markers of epidemic potential.

Case-control study.

Forty-six isolates of Acinetobacter species, including 23 epidemic and 23 sporadic strains from different outbreaks in nine European countries, were compared for the presence of the following factors: hemagglutination, presence of capsules and fimbriae, binding to salivary mucins, resistance to drying, and antibiogram typing. Genotyping of all strains was performed by amplified fragment-length polymorphism (AFLP).

All outbreak strains except two (91%) were identified as Acinetobacter baumannii. Binding to salivary mucins and resistance to antibiotics were significantly associated with epidemic behavior. Antibiogram typing showed clustering of predominantly A baumannii strains within one group, and these strains were significantly more resistant to antibiotics than sporadic strains. AFLP genotyping revealed a great heterogeneity among the different European Acinetobacter strains. Cluster analysis of AFLP fingerprints showed several small clusters of different A baumannii outbreak strains. AFLP genotyping could not identify a common epidemic marker within the strains studied.

Antibiogram typing can be used in routine clinical laboratories as a screening method to recognize potentially epidemic A baumannii strains. Several other factors were found, both in different outbreaks as well as in sporadic Acinetobacter isolates. These characteristics were unable to predict epidemic behavior and therefore cannot be used as discriminative epidemic markers. AFLP genotyping demonstrated no common clonal origin of European epidemic A baumannii strains. This indicates that any clinical A baumannii isolate with resistance to multiple antibiotics can be a potential nosocomial outbreak strain.

To determine whether alcohol hand disinfection is an effective alternative to traditional agents for the pre-surgical scrub.

A prospective clinical trial of a 70% isopropanol pre-surgical hand disinfectant.

The operating room suites at two hospital sites in British Columbia.

Cases were selected to evaluate both short and longer procedures. The hand disinfectant was compared to agents in current use as surgical scrubs (4% chlorhexidine and 7.5% povidone-iodine). Surgical technique and glove use were not modified. Pre- and postoperative fingertip impression and “glove-juice” cultures were used to determine microbial burden, and hands were evaluated for skin integrity.

There was no statistical difference between the microbial hand counts following use of the alcohol-based product or the current agents, for cases less than 2 hours' duration. Comparison of longer surgical cases revealed significantly better pre- and postoperative culture results with the alcohol hand rinse, but analysis of matched pairs showed no significant difference in microbial counts. The alcohol hand rinse was equivalent to the operative scrub in terms of skin integrity and user acceptability.

An alcohol hand rinse was equivalently effective in reducing microbial hand counts as the traditional pre-surgical scrub, both immediately after hand disinfection and at the end of the surgical procedure.

To compare costs for evaluation and treatment of a healthcare worker (HCW) experiencing an occupational exposure, using a rapid human immunodeficiency virus (HIV) test versus a standard enzyme-linked immunosorbent assay (ELISA) HIV test.

Retrospective chart review of all HCWs presenting to the emergency department (ED) for care of an occupational exposure over a 13-month period.

A 404-bed university-based level 1 trauma center with an annual ED census of approximately 35,000.

All HCWs experiencing an occupational exposure treated in the ED using a rapid HPV protocol were included in the analysis.

A calculation of selected costs of the initial evaluation and treatment of patients whose evaluation included a rapid HIV test on the source patient were performed. A similar calculation was then made for these patients, had the standard ELISA test been used. Evaluated costs included laboratory tests, postexposure prophylactic medications, and estimated lost work time. Other costs were constant and were not included in the evaluation.

Total evaluated cost using the rapid HIV test as part of the evaluation and treatment protocol was $465.80 for 17 patients. Had the ELISA test been used instead of the rapid test, the total evaluated cost for the 17 patients would have been $5,965.81.

When used as part of the evaluation and treatment of the HCW with an occupational exposure, the rapid HIV test results in substantial cost savings over the ELISA test.

To estimate the extent of, and evaluate risk factors for, elevated carboxyhemoglobin levels among patients undergoing general anesthesia and to identify the source of carbon monoxide.

Matched case-control study to measure carboxyhemoglobin levels.

Large academic medical center.

45 surgical patients who underwent general anesthesia.

Case-patients were more likely than controls to undergo surgery on Monday or Tuesday (10/15 vs 7/30; matched odds ratio [mOR], 7.7; 95% confidence interval [CI95], 1.8-34; P=.01), in one particular room (7/15 vs 4/30; mOR, 8.5; CI95, 1.5-48; P=.03) or in a room that was idle for ≥24 hours (11/15 vs 1/30; mOR, 95.5; CI95, 8.0-1,138; P≤.001). In a multivariate model, only rooms, and hence the anesthesia equipment, that were idle for ≥24 hours were independently associated with elevated intraoperative carboxyhemoglobin levels (OR, 22.4; CI95, 1.5-338; P=.025). Moreover, peak carboxyhemoglobin levels were correlated with the length of time that the room was idle (r=0.7; CI95, 0.3-0.9). Carbon monoxide was detected in the anesthesia machine outflow during one case-procedure. No contamination of anesthesia gas supplies or CO2 absorbents was found.

Carbon monoxide may accumulate in anesthesia circuits left idle for ≥24 hours as a result of a chemical interaction between CO2-absorbent granules and anesthetic gases. Patients administered anesthesia through such circuits may be at increased risk for elevated carboxyhemoglobin levels during surgery or the early postoperative period.

To study vancomycin-resistant enterococci (VRE) gastrointestinal colonization prevalence in high-risk hospitalized patients and to assess the cost and utility of this laboratory-based surveillance.

Large university teaching hospital.

Quarterly prevalence culture survey of 50 stool specimens submitted for Clostridium difficile toxin A assay from October 1996 through June 1999 (n=526). Screening culture survey of all C difficile-positive stool specimens from July 1998 through June 1999 (n=140).

Specimens for analysis were collected from patients who were admitted to the hospital and who had C difficile toxin A testing ordered. Patient samples were excluded from analysis if they were obtained from patients not hospitalized at UCLA Medical Center, if the C difficile toxin assay result was indeterminate, or if the patient was known to have previous VRE colonization or infection.

During quarterly surveillance, VRE was detected in 19.8%, C difficile toxin A in 9.5%, and both VRE and C difficile toxin A in 3.2% of stool specimens submitted for C difficile toxin assay. Patients whose stool specimens were positive for C difficile toxin A were significantly more likely than those whose specimens were negative to have VRE detected (odds ratio, 2.3; 95% confidence interval, 1.2-4.5). Based on these findings, in July 1998, we began routine screening of all C difficile-positive stool specimens for VRE. From July 1998 through June 1999, 58 (41.4%) of 140 patients with C difficile-positive specimens had VRE newly detected in the stool. The combined cost of the two laboratory-based surveillance strategies was approximately $62 per VRE-positive patient identified and $5,800 per year.

Quarterly surveillance of stool submitted for C difficile assay combined with screening all C difficile-positive stools is a cost-effective and efficient strategy for detecting VRE stool colonization among high-risk hospitalized patients. Such a laboratory-based surveillance should be included as part of a comprehensive program to limit nosocomial VRE transmission.

To determine the costs and savings of a 15-component infection control program that reduced transmission of vancomycin-resistant enterococci (VRE) in an endemic setting.

Evaluation of costs and savings, using historical control data.

Adult oncology unit of a 650-bed hospital.

Patients with leukemia, lymphoma, and solid tumors, excluding bone marrow transplant recipients.

Costs and savings with estimated ranges were calculated. Excess length of stay (LOS) associated with VRE bloodstream infection (BSI) was determined by matching VRE BSI patients with VRE-negative patients by oncology diagnosis. Differences in LOS between the matched groups were evaluated using a mixed-effect analysis of variance linear-regression model.

The cost of enhanced infection control strategies for 1 year was $116,515. VRE BSI was associated with an increased LOS of 13.7 days. The savings associated with fewer VRE BSI ($123,081), fewer patients with VRE colonization ($2,755), and reductions in antimicrobial use ($179,997) totaled $305,833. Estimated ranges of costs and savings for enhanced infection control strategies were $97,939 to $148,883 for costs and $271,531 to $421,461 for savings.

The net savings due to enhanced infection control strategies for 1 year was $189,318. Estimates suggest that these strategies would be cost-beneficial for hospital units where the number of patients with VRE BSI is at least see to nine patients per year or if the savings from fewer VRE BSI patients in combination with decreased antimicrobial use equalled $100,000 to $150,000 per year.

To analyze the rate of occupational exposure to blood and body fluids from all sources and specifically from human immunodeficiency virus (HIV)-infected sources among hospital workers, by job category and work area.

Multicenter prospective study. Occupational exposure data (numerator) and full-time equivalents ([FTEs] denominator) were collected over a 5-year period (1994-1998) and analyzed.

18 Italian urban acute-care hospitals with infectious disease units.

A total of 10,988 percutaneous and 3,361 mucocutaneous exposures were reported. The highest rate of percutaneous exposure per 100 FTEs was observed among general surgery (11%) and general medicine (10.6%) nurses, the lowest among infectious diseases (1.1%) and laboratory (1%) physicians. The highest rates of mucocutaneous exposure were observed among midwives (5.3%) and dialysis nurses (4.7%), the lowest among pathologists (0%). Inadequate sharps disposal and the prevalence of sharps in the working unit influence the risk to housekeepers. The highest combined HIV exposure rates were observed among nurses (7.8%) and physicians (1.9%) working in infectious disease units. The highest rates of high-risk percutaneous exposures per 100 FTE were again observed in nurses regardless of work area, but this risk was higher in medical areas than in surgery (odds ratio, 2.1; 95% confidence interval, 1.9-2.5; P<.0001).

Exposure risk is related to job tasks, as well as to the type and complexity of care provided in different areas, whereas HIV exposure risk mainly relates to the prevalence of HIV-infected patients in a specific area. The number of accident-prone procedures, especially those involving the use of hollow-bore needles, performed by job category influence the rate of exposure with high risk of infection. Job- and area-specific exposure rates permit monitoring of the effectiveness of targeted interventions and control measures over time.

To determine modifiable risk factors for nosocomial Clostridium difficile-associated diarrhea (CDAD).

Case-control study.

300-bed tertiary-care hospital.

Hospital inpatients present during the 3-month study period.

Case-patients identified with nosocomial CDAD over the study period were compared to two sets of control patients: inpatients matched by age, gender, and date of admission; and inpatients matched by duration of hospital stay. Variables including demographic data, comorbid illnesses, antibiotic exposure, and use of gastrointestinal medications were assessed for case- and control-patients. Conditional logistic regression was performed to identify risk factors for nosocomial CDAD.

27 case-patients were identified and were compared to the two sets of controls (1:1 match for each comparison set). For the first set of controls, use of ciprofloxacin (odds ratio [OR], 5.5; 95% confidence interval [CI95], 1.2-24.8; P=.03) was the only variable that remained significant in the multivariable model. For the second set of controls, prior exposure to cephalosporins (OR, 6.7; CL,5, 1.3-33.7; P=.02) and to ciprofloxacin (OR, 9.5; CI95, 1.01-88.4; P=.05) were kept in the final model.

Along with cephalosporins, prior quinolone use predisposed hospitalized patients to nosocomial CDAD. Quinolones should be used judiciously in acute-care hospitals, particularly in those where CDAD is endemic.

To assess the risk of nosocomial infection in transferred patients and to determine whether transfer is only a risk marker or is independently associated with nosocomial infection.

Retrospective analysis.

A 400-bed general hospital in the Paris area.

All the patients hospitalized on the days of the surveys were included.

Epidemiological analysis of data collected in four annual nosocomial infection prevalence surveys conducted between 1993 and 1996.

Of the 1,326 patients included in the four surveys, 70 (5.3%) had been transferred from another hospital and 199 (15.0%) from another ward of our hospital. Transferred patients more frequently had known risk factors of nosocomial infection: age >65 years (P<10-5), a length of hospital stay >7 days on the day of the survey (P<10-6), at least one invasive procedure (34.2% vs 27.2%; P<.05), a recent surgical intervention (P<.05), and an immunosuppression (P<.01). The prevalence rate of infected patients was 6.7% (95% confidence interval, 5.3-8.1). The risk of being infected on a given day was more than 4 times higher in transferred patients (P<10-6); however, the risk was similar between patients transferred from another hospital (20.0%) and patients transferred within the hospital (17.1%). The multivariate analysis performed by logistic regression showed that intrahospi-tal transfer, a length of hospital stay >7 days, and having had at least one invasive procedure were independent risk factors of infection.

According to this study, patient transfer is both a risk marker (associated with several known risk factors) and independently associated with nosocomial infection. The origin of a transferred patient is readily known at admission. It would be useful to adopt specific measures for such patients, particularly if they have other risk factors of nosocomial infection, both to protect them and to prevent transmission of the infection to other hospitalized patients.

To determine the frequency and the epidemiological characteristics of biological-exposure incidents occurring among healthcare personnel.

Prospective surveillance study.

Participating Spanish primary-care and specialty centers from January 1994 to December 1997.

70 centers in 1994, 87 in 1995, 97 in 1996, and 104 in 1997.

Absolute and relative frequencies were calculated for several variables (position held, area of care, type of injuring object, activity, etc) and for the different categories of each variable.

There were 20,235 registered incidents. Annual incidence rates were as follows: 1994, 51 per 1,000; 1995, 58 per 1,000; 1996, 54 per 1,000; and 1997, 59 per 1,000. Mean age of accident victims was as follows: 1994, 35.68 (standard deviation [SD], 16.26); 1995, 33.6 (SD, 11.9); 1996, 38.2 (SD, 17.27); and 1997, 36.7 (SD, 16.33) years. Of the 20,235 incidents, 15,860 (80.7%) occurred to women; 50% (9,833) accidents were among nursing staff. The type of incident most frequently reported was percutaneous injury (81.1%). The highest frequency of accidents was seen in medical and surgical areas (28% and 25.6%, respectively). Blood and blood products were the most commonly involved material (87.6%). Administration of intramuscular or intravenous medication was the activity associated with the highest accident rate (20.3%). The most frequent immediate action in response was rinsing and disinfecting (65.6%).

The incident registry was highly stable in terms of incidence rates over the observation period and served to highlight the large number of incidents recorded each year. The potential implications of die results are the need to explore reasons for increased exposures in certain areas, with the aim of focusing prevention efforts, and, similarly, to establish the factors associated with diminished incidence rates to model successful measures.

To identify factors predictive of length of stay (LOS) and the level of functional improvement achieved among patients admitted to an acute rehabilitation unit for the first time, with special reference to the role of nosocomial infection.

A 40-bed acute rehabilitation unit within a 300-bed, tertiary-care, public, university-affiliated hospital.

All patients admitted to the unit between January 1997 and July 1998.

Prospective cohort study in which demographic and clinical data, including occurrence of nosocomial infection, were collected during the entire unit admission of each patient. Multivariate linear regression analysis was used to identify factors predictive of unit LOS or improvement in functional status as measured by the change in the Functional Independence Measure (FIM) score between admission and discharge (ΔFIM).

There were 423 admissions to the rehabilitation unit during the study period, of which 91 (21.5%) had spinal cord injury (SCI) as a principal diagnosis. One hundred seven nosocomial infections occurred during 84 (19.9%) of the 423 admissions. The most common infections were urinary tract (31.8% of all infections), surgical-site (18.5%), and Clostridium difficile diarrhea (15%). Only one patient died of infection. After controlling for severity of illness on admission, functional status on admission, age, and other clinical factors, the significant positive predictors of unit LOS were as follows: SCI (P<.001), pressure ulcer (.002), and nosocomial infection (<.001). Significant negative predictors of ΔFIM were age (P<.001), FIM score on admission (<.001), prior hospital LOS (.002), and nosocomial infection (.007).

Several variables were identified as contributing to a longer LOS or to a smaller improvement in functional status among patients admitted for the first time to an acute rehabilitation unit Of these variables, only nosocomial infection has the potential for modification. Studies of new approaches to prevent infections among patients undergoing acute rehabilitation should be pursued.

To compare the efficacy of a new antiseptic catheter containing silver sulfadiazine and chlorhexidine on the external surface and chlorhexidine in the lumens to an antibiotic catheter impregnated with minocycline and rifampin on its external and luminal surfaces.

Experimental trial.

Antimicrobial spectrum of catheters was determined by zones of inhibition. Resistance to luminal colonization was tested in vitro by locking catheter lumens with Staphylococcus epidermidis or Staphylococcus aureus culture after 7 days of perfusion. In vitro development of resistance to the antiseptic or antibiotic combination used in catheters was investigated. In vivo efficacy was tested (rat subcutaneous model) by challenge with sensitive or antibiotic-resistant bacteria.

Antiseptic and antibiotic catheters exhibited broad-spectrum action. However, antibiotic catheters were not effective against Candida species and Pseudomonas aeruginosa. Both catheters prevented luminal colonization. Compared to controls, both test catheters resisted colonization when challenged with S aureus 7 and 14 days' postimplant (P<.05).

Repeated in vitro exposure of S epidermidis culture to the antibiotic and antiseptic combinations led to small increases in the minimum inhibitory concentration (15 times and 2 times, respectively). Unlike the antibiotic catheter, the in vitro and in vivo activity of the antiseptic catheter was unaffected by the resistance profile of the test organism. Antiseptic catheters were more effective than antibiotic catheters in preventing colonization by rifampin-resistant S epidermidis in vivo (P<.05).

Antiseptic and antibiotic catheters exhibit similar efficacy; however, when challenged with a rifampin-resistant strain, the antibiotic catheter appeared to be more susceptible to colonization than the antiseptic device.

To establish a new, rapid, and reliable genotypic fingerprinting technique for methicillin-resistant Staphylococcus aureus (MRSA) typing in routine epidemiological surveillance.

The method is based on polymerase chain reaction (PCR) restriction fragment-length polymorphism (RFLP) following HaeII digestion of simultaneously amplified parts of the protein A gene, the coagulase gene, and the hypervariable region adjacent to mecA. A total of 46 MRSA initial isolates were analyzed, including 14 isolates from five countries; the six German epidemic strains; 16 isolates from the Frankfurt metropolitan area, which were known to be heterogeneous by pulsed-field gel electrophoresis (PFGE); and 10 isolates obtained during three epidemics, all of which displayed an identical genotype.

Restriction analysis by PCR-RFLP permitted discrimination of 10 of 14 international isolates, all six German epidemic strains, and 15 of 16 national isolates. It also confirmed the homogeneous character of the 10 outbreak isolates.

This new and rapid PCR-RFLP typing method is an attractive tool in routine epidemiological surveillance. Its impressive characteristics are ease of performance and interpretation, while at the same time guaranteeing good discriminatory power, reproducibility, and typeability.

To identify risk factors associated with tuberculin reactivity in healthcare workers (HCWs).

Cross-sectional survey of tuberculin reactivity (2 TU of purified protein derivative (PPD) RT23, using the Mantoux two-step test).

Two general hospitals located in a region with a high prevalence of tuberculosis and high bacille Calmette-Guérin (BCG) coverage.

Volunteer sample of HCWs.

605 HCWs were recruited: 71.2% female; mean age, 36.4 (standard deviation [SD], 8.2) years; 48.9% nurses, 10.4% physicians, 26.8% administrative personnel; mean time of employment, 10.9 (SD, 6.7) years. PPD reactivity (≥10 mm) was found in 390 (64.5%). Multivariate analysis revealed an association of tuberculin reactivity with occupational exposure in the hospital: participation in autopsies (odds ratio [OR], 9.3; 95% confidence interval [CI95], 2.1-40.5; P=.003.), more than 1 year of employment (OR, 2.4; CI95, 1.1-5.0; P=.02), work in the emergency or radiology departments (OR, 2.0; CI95,1.03-3.81; P=.04), being physicians or nurses (OR, 1.5; CI95, 1.04-2.11; P=.03), age (OR, 1.04; CI95, 1.02-1.07 per year of age; P<.001), and BCG scar (OR, 2.1; CI95, 1.2-3.4; P=.005).

Although the studied population has a high baseline prevalence of tuberculosis infection and high coverage of BCG vaccination, nosocomial risk factors associated with PPD reactivity were identified as professional risks; strict early preventive measures must be implemented accordingly.