The prevalence of vancomycin-resistant enterococci (VRE) has increased markedly during the past decade. Few data exist regarding the epidemiology of resistance of VRE to chloramphenicol, one of the few therapeutic options.

Survey and case-control study.

A 725-bed, tertiary-care academie medical center and a 344-bed urban community hospital.

Hospitalized patients with blood cultures demonstrating VRE.

We examined the trends in the prevalence of chloramphenicol resistance in VRE blood isolates at our institution from 1991 through 2002 and conducted a case-control study to identify risk factors for chloramphenicol resistance among these isolates.

From 1991 through 2002, the annual prevalence of chloramphenicol-resistant VRE increased from 0% to 12% (P < .001, chi-square test for trend). Twenty-two case-patients with chloramphenicol-resistant VRE bloodstream isolates were compared with 79 randomly selected control-patients with chloramphenicol-susceptible VRE. Independent risk factors for chloramphenicol-resistant VRE were prior chloramphenicol use (odds ratio [OR], 10.9; 95% confidence interval [CI95], 1.72-68.91; P = .01) and prior fluoroquinolone use (OR, 4.74; CI95, 1.15-19.42; P = .03). Chloramphenicol-resistant VRE isolates were more likely to be susceptible to beta-lactams and resistant to tetracycline than were chloramphenicol-susceptible VRE isolates.

Significant increases in the prevalence of chloramphenicol-resistant VRE may limit the future utility of chloramphenicol in the treatment of VRE infections, and close monitoring of susceptibility trends should continue. The association between fluoroquinolone use and chloramphenicol-resistant VRE, reflecting possible co-selection of resistance, suggests that recent dramatic increases in fluoroquinolone use may have broader implications than previously recognized.

Mycobacterium simiae is found primarily in the southwestern United States, Israel, and Cuba, with tap water as its suspected reservoir. Our institution saw an increase in M. simiae isolates in 2001. An investigation into possible contaminated water sources was undertaken.

Environmental cultures were performed from water taps in the microbiology laboratory, patient rooms, points in the flow of water to the hospital, and patients' homes. Patient and environmental M. simiae were compared by PFGE.

Military treatment facility in San Antonio, Texas.

All patients with cultures positive for M. simiae between January 2001 and April 2002. Medical records were reviewed.

M. simiae was recovered from water samples from the hospital, patients' home showers, and a well supplying the hospital. A single PFGE clone was predominant among water isolates (9 of 10) and available patient isolates (14 of 19). There was an association between exposure to hospital water and pulmonary samples positive for the clonal M. simiae strain (P = .0018). Only 3 of 22 culture-positive patients met criteria for M. simiae pulmonary disease. Of them, two had indistinguishable M. simiae strains from tap water to which they were routinely exposed.

This represents an outbreak of M. simiae colonization with one nosocomial infection. It is only the second time that M. simiae has been recovered from hospital tap water and its first presentation in municipal water. This study raises issues about the need and feasibility of eliminating or avoiding exposure to M. simiae from tap water.

To evaluate the emergence of resistance of Pseudomonas aeruginosa and Acinetobacter species to imipenem, ciprofloxacin, or both after the use of these drugs and to compare resistant with susceptible isolates by molecular typing.

Cohort study.

Burn intensive care unit (ICU) with 4 beds in a tertiary-care university hospital.

During 16 months, surveillance cultures were performed for all patients admitted to the ICU. Demographic information was obtained for each patient. Molecular typing was done by pulsed-field gel electrophoresis using restriction enzymes for 71 isolates of P. aeruginosa and Acinetobacter species.

Thirty-four patients were admitted and 22 were colonized by susceptible P. aeruginosa or Acinetobacter species before they used the antimicrobials. Nine (41%) of these patients had a resistant isolate after antimicrobial use: 5 had used imipenem alone, 1 had used ciprofloxacin, and 3 had used both drugs. The interval between isolation of the susceptible and resistant isolates ranged from 4 to 25 days, but was 10 or more days for 6 patients. Molecular typing revealed that susceptible and resistant isolates from each patient were different and that although there were no predominant clones among susceptible isolates, there was a predominant clone among resistant isolates of P. aeruginosa and of Acinetobacter.

Resistance was not due to the acquisition of resistance mechanisms by a previously susceptible strain, but rather to cross-transmission. Although various measures involving antimicrobial use have received great attention, it would seem that practices to prevent cross-transmission are more important in controlling resistance.

To determine the net benefit and costs associated with gown use in preventing transmission of van-comycin-resistant Enterococcus (VRE).

A cost-benefit analysis measuring the net benefit of gowns was performed. Benefits, defined as averted costs from reduced VRE colonization and infection, were estimated using a matched cohort study. Data sources included a step-down cost allocation system, hospital informatics, and microbiology databases.

The medical intensive care unit (MICU) at Barnes-Jewish Hospital, St. Louis, Missouri.

Patients admitted to the MICU for more than 24 hours from July 1, 1997, to December 31, 1999.

Alternating periods when all healthcare workers and visitors were required to wear gowns and gloves versus gloves alone on entry to the rooms of patients colonized or infected with VRE.

On base-case analysis, 58 VRE cases were averted with gown use during 18 months. The annual net benefit of the gown policy was $419,346 and the cost per case averted of VRE was $1,897. The analysis was most sensitive to the level of VRE transmission.

Infection control policies (eg, gown use) initially increase the cost of health services delivery. However, such policies can be cost saving by averting nosocomial infections and the associated costs of treatment. The cost savings to the hospital plus the benefits to patients and their families of avoiding nosocomial infections make effective infection control policies a good investment.

To describe the epidemiology of healthcare-associated infections (HAIs) among neonates.

Prospective surveillance of HAIs was conducted during 2 years. Infections beginning within 48 hours of birth were defined as HAIs of maternal origin. Death occurring during an active episode of HAI was considered related to HAI.

Seven neonatal units located in three Brazilian cities.

All admitted neonates were included and observed until discharge.

Twenty-two percent of 4,878 neonates had at least one HAI. The overall incidence density was 24.9 per 1,000 patient-days, and 28.1% of all HAIs were maternally acquired. HAI rates ranged from 12.3% in the group with a birth weight (BW) of more than 2,500 g to 51.9% in the group with a BW of 1,000 g or less. The main HAIs were bloodstream infection (BSI) and pneumonia. Coagulase-negative staphylococci, Enterobacter species, Staphylococcus aureus, and Klebsiella pneumoniae were the main pathogens. Forty percent of all deaths were related to HAI. Central venous catheter (CVC)-associated BSIs per 1,000 CVC-days ranged from 17.3 (BW, 1,501 to 2,500 g; device utilization [DU], 0.11) to 34.9 (BW, ≤ 1,000 g; DU, 34.92). Ventilator-associated pneumonia per 1,000 ventilator-days ranged from 7.0 (BW, ≤ 1,000 g; DU, 0.34) to 9.2 (BW, 1,001 to 1,500 g; DU, 0.14).

The high proportion of HAIs of maternal origin highlights perinatal care issues in Brazil and the need to improve the diagnosis of neonatal HAIs. The very low BW group and device-associated infections should be priorities for prevention strategies in this population.

To evaluate the acceptance and usefulness of a hospital-based tabletop bioterrorism exercise.

A descriptive study of responses to a smallpox scenario delivered as a tabletop exercise in three modules.

A large, multi-institutional urban health System.

Healthcare workers representing 16 hospital departments.

Thirty-nine (78%) of 50 invited employees from 4 hospitals participated. Key responses highlighted the importance of pre-event planning in intra-departmental communication, identification of resources for the dependents of health-care workers, clarification of the chain of command within the hospital, establishment of a link to key governmental agencies, and advanced identification of negative pressure rooms for cohorting large numbers of patients. Almost one-fourth of the participants described their hospital departaient as poorly prepared for a bioterrorism event of moderate size. At the conclusion of the tabletop, 79% of the participants stated that the exercise had increased their knowledge of preplanning activities. Seventy-nine percent of all participants, 94% of physicians and nurses, and 95% of participants from non-university hospitals ranked the exercise as extremely or very useful. The exercise was completed in 3% hours and its total direct cost (excluding lost time from work) was $225 (U.S.).

Tabletop exercises are a feasible, well-accepted modality for hospital bioterrorism preparedness training. Hospital employees, including physicians and nurses, rank this method as highly useful for guiding preplanning activities. Infection control staff and hospital epidemiologists should play a lead role in hospital preparedness activities. Further assessment of the optimal duration, type, and frequency of tabletop exercises is needed.

To identify the source of an epidemic of Burkholderia cepacia bloodstream infections during 7 years (411 episodes in 361 patients).

Outbreak investigation.

A 250-bed university hospital in Beirut, Lebanon.

Matched case-control and retrospective cohort studies, and microbiological surveillance and polymerase chain reaction–restriction fragment length ascertainment were employed. Special media and filtration techniques were used to isolate organisms from water and diluted alcohol solutions.

In a group of 50 randomly selected case-matched patients from 1999, the positive blood cultures were concomitant with fever in 98%, intravenous phlebitis in 44%, and recurrent bacteremia in 20%. Fever disappeared approximately 6 hours after intravenous catheter removal. Polymerase chain reaction–restriction fragment length polymorphism revealed strain homogeneity in patient, water, and alcohol isolates. Contaminated tap water had been used to dilute alcohol for skin antisepsis and for decontamination of the caps of heparin vials. Only sporadic cases directly attributable to breach of protocol were reported after single-use alcohol swabs were substituted.

This is potentially the largest single-source nosocomial bloodstream infection outbreak ever reported, and the first report of an alcohol skin antiseptic contaminated by tap water as a source for nosocomial bacteremia.

Rates of annual influenza vaccination of healthcare workers (HCWs) remained low in our university hospital. This study was conducted to evaluate the impact of a mobile cart influenza vaccination program on HCW vaccination.

From 2000 to 2002, the employee health service continued its annual influenza vaccination program and the mobile cart program was implemented throughout the institution. This program offered influenza vaccination to all employees directly on the units. Each employee completed a questionnaire. Vaccination rates were analyzed using the Mantel–Haenszel test.

The program proposed vaccination to 50% to 56% of the employees. Among the nonvaccinated employees, 52% to 53% agreed to be vaccinated. The compliance with vaccination varied from 61% to 77% among physicians and medical students and from 38% to 55% among nurses and other employees. Vaccination of the chief or associate professor of the unit was associated with a higher vaccination rate of the medical staff (P < .01). Altogether, the vaccination program led to an increase in influenza vaccination among employees from 6% in 1998 and 7% in 1999 before the mobile cart program to 32% in 2000, 35% in 2001, and 32% in 2002 (P < .001).

The mobile cart program was associated with a significantly increased vaccination acceptance. Our study was able to identify HCW groups for which the mobile cart was effective and highlight the role of the unit head in its success.

To evaluate the prevalence and risk factors of nasal Staphylococcus aureus (SA) in the community.

Cross-sectional study.

Wake Forest University, Winston-Salem, North Carolina.

Four hundred fifty students were screened for nasal SA carriage during the fall of 2000, 2001, and 2002.

Students were screened by nose swabs. A self-administered questionnaire collected information on demographics and medical history. Antibiotic testing and PFGE were performed on isolates. Risk factors were determined by logistic regression analysis.

Of 450 volunteers, 131 (29%) were SA carriers. Antibiotic resistance was high for azithromycin (26%) and low for ciprofloxacin (1%), tetracycline (5%), mupirocin (1%), and methicillin (2%). PFGE patterns were not associated with carriage. Age, male gender, white race, medical student, allergen injection therapy, chronic sinusitis, rheumatoid arthritis, hospitalization for 6 months or less, and use of antibiotics were associated with carrier status by univariate analysis. Stepwise multivariate logistic regression led to a best fitting model with older age (OR, 1.04; CI95, 1.005-1.079), male gender (OR, 1.50; CI95, 0.982-2.296), and chronic sinusitis (OR, 2.71; CI95, 0.897-8.195) as risk factors. Antibiotic use (< 4 weeks) (OR, 0.41; CI95, 0.152-1.095) and allergen injection therapy (OR 0.41; CI95, 0.133-1.238) were protective. Analyses of carriers revealed candidate factors for persistent carriage to be nasal SA colonization rate and male gender. Factors for azithromycin resistance were non-medical students and antibiotic use in the past 6 months.

Older male volunteers suffering from chronic sinusitis and not taking antibiotics were at higher risk for carrying SA.

To evaluate cost-effective screening and treatment strategies for healthcare workers (HCWs) at risk for tuberculosis exposure.

A Markov model was developed to track three hypothetical cohorts of HCWs at low, moderate, and high risk for tuberculosis exposure. For those found to be tuberculin reactors at entry, the choice was for isoniazid treatment or no treatment. For those without tuberculin reactivity, the choice of screening intervals was 6 months, 1 year, 2 years, or 5 years. Outcomes measured were tuberculosis cases, death, life expectancy, and cost. Assumptions were derived from published data and analyses.

Treatment of initial reactors with isoniazid in all three risk groups was associated with a net savings of $14,800 to $15,700 for each tuberculosis case prevented. For those without evidence of infection at entry, the most cost-effective screening interval was 1 year for high-risk groups, 2 years for moderate-risk groups, and 5 years for low-risk groups, with a net savings $0.20 to $26 per HCW per year. Screening at a more frequent interval was still cost-effective.

For HCWs found to be tuberculin reactors, treatment of their latent infection is to their benefit and is associated with a net cost-savings. Regular tuberculin screening of HCWs can be cost-effective or result in a net cost-savings. Each institution could use its own skin test surveillance data to create an optimum screening program for its employees. However, for most HCWs, a 1-year screening interval would be a cost-effective and safe choice.

To assess the influence of prophylactic selective bowel decontamination (SBD) on the spectrum of microbes causing bloodstream infection (BSI).

The microbes causing BSI in neutropenic patients of a hematologic ward (HW) and a bone marrow transplantation unit (BMTU), respectively, were compared by retrospective analysis of blood culture results from January 1996 to June 2003.

A 30-bed HW (no SBD) and a BMTU including a 7-bed normal care ward and an 8-bed intensive care unit (SBD used) of a 2,200-bed university teaching hospital.

The overall incidences of bacteremia in the HW and the BMTU were similar (72.6 vs 70.6 episodes per 1,000 admissions; P = .8). Two hundred twenty episodes of BSI were recorded in 164 neutropenic patients of the HW and 153 episodes in 127 neutropenic patients of the BMTU. Enterobacteriaceae (OR, 3.14; CI95, 1.67–5.97; P = .0002) and Streptococcus species (OR, 2.04; CI95, 1.14–3.70; P = .015) were observed more frequently in HW patients and coagulase-negative staphylococci more frequently in BMTU patients (OR, 0.15; CI95, 0.09–0.26; P< .00001). No statistically significant differences were found for gram-negative nonfermentative bacilli (P = .53), Staphylococcus aureus (P = .21), Enterococcus species (P = .48), anaerobic bacteria (P = .1), or fungi (P = .50).

SBD did not lead to a significant reduction in the incidence of bacteremia, but significant changes in microbes recovered from blood cultures were observed. SBD should be considered when empiric antimicrobial therapy is prescribed for suspected BSI.

To determine the susceptibilities of Candida species isolated from Taiwan to amphotericin B and fluconazole.

Prospective surveillance study.

Each hospital was asked to submit up to 10 C. albicans and 40 non-albicans Candida species during the collection period, from April 15 to June 15, 1999. One isolate was accepted from each episode of infection. The broth microdilution method was used to determine susceptibilities to amphotericin B and fluconazole.

Only 3 of 632 isolates, one each of C. famata, C. krusei, and C. tropicalis, were resistant to amphotericin B. A total of 53 (8.4%) of 632 clinical yeast isolates, consisting of 4% C. albicans, 8% C. glabrata, 15% C. tropicalis, and 70% C. krusei, were resistant to fluconazole. In contrast, no C. parapsilosis isolate was resistant to fluconazole. Isolates from tertiary-care medical centers had higher rates of resistance to fluconazole than did those from regional and local hospitals (11.4% vs 6.6%). Isolates from different sources showed different levels of susceptibility to fluconazole. All of the isolates with the exception of C. tropicalis and C. krusei isolated from blood were susceptible to fluconazole. A pattern of co-resistance to both amphotericin B and fluconazole was observed.

Non-albicans Candida species had higher rates of resistance to fluconazole than did C. albicans (44 of 395 [11.2%] vs 9 of 237 [3.8%]; P = .002). The increasing rate of fluconazole resistance in C. tropicalis (15%) is important because C. tropicalis is one of the most commonly isolated non-albicans Candida species.

To investigate and control an outbreak of bloodstream infections (BSIs) caused by Serratia marcescens and to identify risk factors for respiratory colonization or infection with S. marcescens.

Epidemiologic investigation, including review of medical and laboratory records, procedural investigations, pulsed-field gel electrophoresis (PFGE) typing of environmental and patient isolates, statistical study, and recommendation of control measures.

All patients admitted to a 380-bed, secondary-care hospital in Osaka Prefecture, Japan, from July 1999 through June 2000 (study period).

Seventy-one patients were colonized or infected with S. marcescens; 3 patients who developed primary BSIs on the same ward within 5 days in June 2000 had isolates with indistinguishable PFGE patterns and indwelling intravenous catheters for more than 5 days. On multivariate analysis, among 36 case-patients with positive sputum specimens and 95 control-patients, being bedridden (odds ratio [OR], 15.91; 95% confidence interval [CI95], 4.17-60.77), receiving mechanical ventilation (OR, 7.86; CI95, 2.27-27.16), being older than 80 years (OR, 3.12; CI95, 1.05-9.27), and receiving oral cleaning care (OR 3.10; CI95, 1-9.58) were significant risk factors. S. marcescens was isolated from the fluid tanks of three nebulizers and a liquid soap dispenser. The hospital did not have written infection control standards, and many infection control practices were found to be inadequate (eg, respiratory equipment was used without disinfection between patients).

Poor hospital hygiene and the lack of standard infection control measures contributed to infections hospital-wide. Recommendations to the hospital included adoption of written infection control policies.

To determine a potential source of MRSA colonization and infection among preterm infants in a neonatal intensive care unit (NICU) using molecular analysis of breast milk samples.

Case report, outbreak investigation.

Preterm triplets were delivered at 26 weeks' gestation via cesarean section when routine active surveillance for MRSA was performed for all infants in a NICU. Surveillance consisted of swabbing the throat, nose, and umbilicus (TNU) weekly. Although infants A and B initially had negative TNU swabs, repeat cultures were positive for MRSA on day of life (DOL) 10 and DOL 18, respectively. Surveillance and clinical cultures for infant C were negative. Infant A developed sepsis, and multiple blood cultures were positive for MRSA beginning on DOL 14. Infant B developed conjunctivitis and a conjunctival exudate culture was positive for MRSA on DOL 70. Both infants were fed breast milk via nasogastric tube. Cultures of breast milk samples for infants A and B dated prior to either infant's first positive surveillance culture were positive for MRSA. All MRSA isolates had identical results on antibiotic susceptibility testing. PFGE demonstrated identical banding patterns for the MRSA isolates from the blood culture of infant A, breast milk for infants A and B, and a surveillance swab from infant B. At no time did the mother develop evidence of mastitis or other local breast infection.

MRSA can be passed from mother to preterm infant through contaminated breast milk, even in the absence of maternal infection. Colonization and clinical disease can result.