In the Netherlands, the prevalence of methicillin resistance among Staphylococcus aureus isolates has been kept to less than 1% by using active screening programs and isolation. At the University Medical Center Utrecht (UMCU), an active screening program for methicillin-resistant S. aureus (MRSA) in the surgical intensive care unit (ICU) was implemented in 1986. Between 1992 and 2001, only 6 patients with MRSA were admitted to the surgical ICU. However, 4 of these 6 strains were able to spread to 23 other patients and 15 healthcare workers (HCWs). We were surprised by the epidemic behavior of these strains and wondered whether this was exceptional for S. aureus or whether methicillin-susceptible S. aureus (MSSA) was also spreading in the ICU.

A 2-month, prospective, observational study to investigate the incidence and spread of MSSA in the surgical ICU of UMCU and historical data collected during a 10-year period regarding MRSA.

A 10-bed surgical ICU in a 1,042-bed teaching hospital.

Weekly swabs revealed the presence of MSSA in 11 (24%) of 45 patients and 16 (22%) of 72 HCWs. Of all 4,105 patient–HCW contacts, there were only 21 episodes in which both the patient and the HCW were found to carry MSSA. With the use of pulsed-field gel electrophoresis, no identical strains could be identified.

In our surgical ICU, MRSA seems to spread more easily than MSSA, probably because of selection under antibiotic pressure or a still unknown intrinsic factor within MRSA.

The role of rectal carriage of Staphylococcus aureus as a risk factor for nosocomial S. aureus infections in critically ill patients has not been fully discerned.

Nasal and rectal swabs for S. aureus were obtained on admission and weekly thereafter until discharge or death from 204 consecutive patients admitted to the surgical intensive care unit and liver transplant unit.

Overall, 49.5% (101 of 204) of the patients never harbored S. aureus, 21.6% (44 of 204) were nasal carriers only, 3.4% (7 of 204) were rectal carriers only, and 25.5% (52 of 204) were both nasal and rectal carriers. Infections due to S. aureus developed in 15.7% (32 of 204) of the patients; these included 3% (3 of 101) of the non-carriers, 18.2% (8 of 44) of the nasal carriers only, 0% (0 of 7) of the rectal carriers only, and 40.4% (21 of 52) of the patients who were both nasal and rectal carriers (P = .001). Patients with both rectal and nasal carriage were significantly more likely to develop S. aureus infection than were those with nasal carriage only (odds ratio, 3.9; 95% confidence interval, 1.18 to 7.85; P = .025). By pulsed-field gel electrophoresis, the infecting rectal and nasal isolates were clonally identical in 82% (14 of 17) of the patients with S. aureus infections.

Rectal carriage represents an underappreciated reservoir for S. aureus in patients in the intensive care unit and liver transplant recipients. Rectal plus nasal carriage may portend a greater risk for S. aureus infections in these patients than currently realized.

To determine whether patients who were colonized or infected with methicillin-resistant Staphylococcus aureus (MRSA) persistently carried the same strain and to identify the extent of strain variation within a population of patients.

Molecular typing by pulsed-field gel electrophoresis (PFGE) of stored MRSA isolates.

A Veterans Administration Medical Center with 288 hospital, 45 intermediate-care, and 75 extended-care beds.

Between January 1991 and March 1993, 91 patients had MRSA identified in routine cultures. One hundred isolates from 57 patients (63%) were available for typing.

Before 1988, only occasional MRSA isolates were identified. By 1993, 50% of S. aureus isolates from unique patients were resistant to methicillin. PFGE identified 7 MRSA strains, 3 of which were identified in specimens from 1 patient each. The most common strains were SD4 (20 patients), SD1 (12 patients), SD2 (12 patients), and SD5a (5 patients). Twenty patients had 2 or more isolates obtained at least 1 week apart (mean, 30.7 weeks; range, 1 to 102 weeks). Of these patients, 12 were colonized or infected with only one strain (mean time observed, 25.1 weeks; range, 1 to 82 weeks). Eight patients had at least 2 different strains (mean time observed, 39 weeks; range, 2 to 102 weeks).

Numerous MRSA strains circulated in tiiis endemic setting; 40% of patients observed over time were colonized or infected witii more than one strain. Molecular typing was an essential tool for evaluating the epidemiology of MRSA in this setting.

To evaluate the usefulness of an assay using two polymerase chain reaction-based genotyping methods in the practical surveillance of methicillin-resistant Staphylococcus aureus (MRSA).

Nosocomial infection and colonization were surveyed monthly in a university hospital in Japan for 20 months. Genotyping with mec-HVR is based on the size of the mec-associated hypervariable region amplified by polymerase chain reaction. Toxin genotyping uses a multiplex polymerase chain reaction method to amplify eight staphylococcal toxin genes.

Eight hundred nine MRSA isolates were classified into 49 genotypes. We observed differing prevalences of genotypes for different hospital wards, and could rapidly demonstrate the similarity of genotype for outbreak isolates. The incidence of genotype D: SEC/TSST1 was significantly higher in isolates causing nosocomial infections (49.5%; 48 of 97) than in nasal isolates (31.4%; 54 of 172) (P = .004), suggesting that this genotype may represent the nosocomial strains.

The combined use of these two genotyping methods resulted in improved discriminatory ability and should be further investigated.

To determine the prevalence of and the risk factors for methicillin-resistant Staphylococcus aureus (MRSA) carriage in nursing home residents in the Rhine-Neckar region of southern Germany.

Point-prevalence survey.

Forty-seven nursing homes in the region.

All residents of the approached nursing homes who agreed to participate.

After informed consent was obtained, all participants had their nares swabbed, some personal data collected, or both. All swabs were examined for growth of MRSA All S. aureus isolates underwent oxacillin susceptibility testing and polymerase chain reaction for demonstration of the meek gene. All MRSA isolates were typed using pulsed-field gel electrophoresis after digestion with SmaI.

Swabs from 3,236 nursing home residents yielded 36 MRSA strains, contributing to a prevalence rate of 1.1%. Significant risk factors for MRSA carriage in the multivariate analysis were the presence of wounds or urinary catheters, limited mobility, admission to a hospital during the preceding 3 months, or stay in a medium-size nursing home. One predominant MRSA strain could be detected in 30 of the 36 MRSA carriers.

The prevalence of MRSA in German nursing homes is still low. These residents seemed to acquire their MRSA in the hospital and transfer it to their nursing home. Apart from well-known risk factors for the acquisition of MRSA we identified the size of the nursing home as an independent risk factor. This might be due to an increased use of antimicrobials in nursing homes of a certain size.

Following an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infection in our acute rehabilitation unit in 1987, all patients except in-house transfers (because of their low prevalence of MRSA colonization) underwent MRSA screening cultures on admission.

To better characterize the current profile of patients with positive MRSA screening cultures at the time of admission to our acute rehabilitation unit, and to determine the relative yield of nares, perianal, and wound screening cultures in this population.

Prospective chart review with ongoing active surveillance for infections associated with the acute rehabilitation unit.

The rate of MRSA isolation from one or more body sites increased significantly from 5% (1987–1988) to 12% (1999–2000) (P = .0009) for newly admitted patients and from 0% to 7% (P < .0001) for in-house transfers. A negative nares culture was highly predictive (98%) of a negative perianal culture. Prior history of MRSA infection or colonization and transfer from outside sources were independently associated with positive MRSA screening cultures.

The rate of MRSA isolation from screening cultures of newly admitted patients, including in-house transfers, has increased significantly during the past decade in our acute rehabilitation unit. When paired with nares cultures, perianal cultures were of limited value in this patient population.

To assess the ability of hospital air handling systems to filter Aspergillus, other fungi, and particles following the implosion of an adjacent building; to measure the quantity and persistence of airborne fungi and particles at varying distances during a building implosion; and to determine whether manipulating air systems based on the movement of the dust cloud would be an effective strategy for managing the impact of the implosion.

Air sampling study.

A 976-bed teaching hospital in Baltimore, Maryland.

Single-stage impactors and particle counters were placed at outdoor sites 100, 200, and 400 m from the implosion and in five locations in the hospital: two oncology floors, the human immunodeficiency virus unit, the cardiac surgical intensive care unit, and the ophthalmology unit. Air handling systems would operate normally unless the cloud approached the hospital.

Wind carried the bulk of the cloud away from the hospital. Aspergillus counts rose more than tenfold at outdoor locations up to 200 m from the implosion, but did not increase at 400 m. Total fungal counts rose more than sixfold at 100 and 200 m and twofold at 400 m. Similar to Aspergillus, particle counts rose several-fold following the implosion at 100 and 200 m, but did not rise at 400 m. No increases in any fungi or particles were measured at indoor locations.

Reacting to the movement of the cloud was effective, because normal operation of the hospital air handling systems was able to accommodate the modest increase in Aspergillus, other fungi, and particles generated by the implosion. Aspergillus measurements were paralleled by particle counts.

To describe and investigate the cause of an outbreak of 10 cases of nosocomial invasive infection with Aspergillus flavus in a hematologic oncology patient care unit.

A retrospective cohort study.

The hematologic oncology unit of a comprehensive cancer center.

Ninety-one patients admitted to the hematologic oncology service between January 1 and December 31,1992, for 4 or more consecutive days were included in the study.

Ten (18%) of 55 patients admitted from July to December 1992 were diagnosed as having invasive aspergillosis compared with 0 (0%) of 36 patients admitted from January to June 1992 to the same patient care units. Patient characteristics, mortality rate, autopsy rate, and admitting location did not change significantly during the course of the year to result in a sudden increase in the number of aspergillosis cases. The source of the outbreak was the high counts of Aspergillus conidia determined from air sampling in the non–bone marrow transplant wing during the outbreak. After high-efficiency particulate air (HEPA) filters were installed as an infection control measure, there were only two additional cases of nosocomial aspergillosis in the 2 years following the outbreak.

This outbreak occurred among hematologic oncology patients with prolonged granulocytopenia housed in an environment with neither HEPA filters nor laminar air flow units. Our data demonstrate that in the setting of an outbreak of aspergillosis, HEPA filters are protective for highly immunocompromised patients with hematologic malignancies and are effective at controlling outbreaks due to air contamination with Aspergillus conidia.

To investigate the epidemiology and environmental sources of Fusarium infections in patients with cancer.

Retrospective case-control study conducted following surveillance environmental cultures and DNA analysis of isolated organisms.

A tertiary-care, university cancer center.

In 1996 and 1997, environmental cultures were performed on air samples and water systems. A retrospective chart review was performed for 70 patients with cancer identified with fusariosis between 1987 and 1997. Patients with fusariosis were compared with 49 uninfected control patients who occupied hospital rooms with positive environmental cultures for Fusarium. With the use of random amplification of polymorphic DNA organisms isolated from infected patients were compared with environmental organisms.

Most of the patients with Fusarium (40, 57%) were infected on or within 3 days of admission, indicating community rather than nosocomial acquisition. Patients were comparable in terms of underlying immunocompromised status to 49 uninfected control patients. However, the duration from admission to infection in the patients with fusariosis tended to be shorter than the duration from admission to discharge in the exposed control patients (P = .06). Water cultured from the hospital tanks and from sinks and water fountains was negative for Fusarium. With the use of polymerase chain reaction, environmental isolates did not match clinical ones. Quantitative air sampling showed that the quantitative outdoor Fusarium levels were eightfold higher than the indoor levels. During the rainy summer season, outdoor air concentrations of Fusarium were at their highest, coinciding with the peak incidence of fusariosis at our center.

The most likely source of fusariosis was the external environment rather than nosocomial sources, such as water.

To describe an outbreak of infections with permanent cuffed hemodialysis catheters recognized through ongoing surveillance and related to a specific malfunctioning permanent catheter.

The outbreak was suspected from the results of prospective infection surveillance and confirmed by a retrospective cohort study using medical records for patients receiving dialysis between April 1,1999, and March 31, 2000.

Integrated network of six outpatient hemodialysis facilities in southern Idaho and eastern Oregon.

Outpatients receiving long-term hemodialysis.

During the 18 months prior to the outbreak, the overall infection rate was 4.1 infections per 1,000 dialysis sessions with a catheter rate of 8.9 per 1,000 dialysis sessions. During the 7 months of the outbreak, the overall rate increased to 5.8 per 1,000 dialysis sessions, whereas the catheter rate increased to 18.1 per 1,000 dialysis sessions. Reports of malfunctioning “Brand A” catheters prompted discontinuation of their placement. A manufacturer recall occurred in April 2000. During the 14 months after the outbreak, the overall infection rate decreased to 3.3 per 1,000 dialysis sessions and the catheter rate to 10.8 per 1,000 dialysis sessions. A 12-month retrospective cohort study recognized 96 patients with an identifiable catheter brand and 48 infections. Of these, 27 (56%) occurred in patients with Brand A catheters. The relative risk for infection when compared with other catheter brands was 1.96 (95% confidence interval, 1.32 to 2.92; P < .001).

Ongoing infection surveillance in hemodialysis facilities can identify specific device-related outbreaks of infections and promote interventions to reduce infectious complications and promote patient safety. Surveillance for vascular access site infections is recommended as a routine activity in hemodialysis facilities.

To evaluate the risk factors associated with breakthrough candidemia in patients with cancer and to compare them with those of de novo candidemia in this patient population. DESIGN: Retrospective case series of 120 episodes of candidemia, 90 de novo and 30 breakthrough candidemias.

University-affiliated, tertiary-care cancer center in Houston, Texas.

All patients with cancer who acquired candidemia between January 1993 and December 1998 were included if they had non-catheter-related candidemia and information about quantitative blood cultures.

Although less frequent, breakthrough candidemia was seen more often in neutropenic patients with leukemia. The intensity of breakthrough candidemia was comparable to that of de novo candidemia. Most (70%) of the breakthrough candidemias were due to Candida glabrata or C. krusei.

In breakthrough candidemia, the same risk factors seen in de novo candidemia were encountered, although more frequently. C. glabrata and C. krusei are the leading causes of breakthrough candidemia in patients with cancer.