To study the epidemiology of Yersinia enterocolitica infections in hospitalized patients and to determine the frequency of hospital-acquired infection and the modes of transmission within the hospital.

Descriptive study in which the clinical microbiology laboratory reported all positive Yersinia cultures to the infection control department; each case was investigated to determine the source of infection.

A 700-bed university teaching hospital.

All patients who were culture-positive for Y enterocolitica after admission to the University of Cincinnati Hospital during the 4-year period between 1987 and 1990.

Of 18 patients who were diagnosed with Yersinia infections, 8 (44%) were community-acquired. These patients were admitted with gastrointestinal symptoms and had their first positive cultures between days 1 and 5 of their hospitalizations. Five patients (28%) had hospital-acquired infections, having developed diarrhea after admission for unrelated problems, and became culture-positive between days 18 and 66. The remaining 5 patients could not be classified as either community- or hospital-acquired. These patients had gastrointestinal symptoms at the time of admission, but these could have been explained by other diseases. Their first positive stool cultures were not obtained until the second week or later during hospitalization, and 3 of these patients had negative stool cultures prior to a positive culture.

Although Y enterocolitica has not previously been recognized as a common hospital problem, at least 28% of our patients acquired their Yersinia infections in the hospital. In some cases, cross infections, transmitted by healthcare workers, occurred between patients. Four of the 18 infections occurred in patients with acquired immunodeficiency syndrome.

To determine the use of pneumococcal vaccination in a general medicine ambulatory clinic and the effect of a quality assessment monitor on use.

A prospective 8-month (October 1990 through May 1991) survey and 8-month (October 1989 through May 1990) retrospective survey of use of pneumococcal vaccination in the clinic.

A general medicine clinic where patients are seen for their first internal medicine clinic visit at The University of Iowa Hospitals and Clinics, Iowa City, Iowa.

One thousand sixty adult patients who presented to the clinic during the study interval.

The use of the form constituted an intervention.

Use of pneumococcal vaccination was increased more than 5 times over the baseline level following implementation of the quality assessment monitor.

Underuse of pneumococcal vaccination occurred in this general medicine clinic, and the introduction of a quality assessment monitor constituted an intervention that significantly increased the use of pneumococcal vaccination.

To determine the clinical significance and source of fungemia following a cluster of positive blood cultures during a 3-day period.

Chart review was used to determine the clinical significance of positive blood cultures. Microbiologic sampling of the laboratory environment was used to determine potential sources of fungal contamination.

A large, tertiary care, community teaching hospital.

All patients with blood cultures positive for Aspergillusspecies, Penicillium species, or both during the outbreak period.

Thirteen patients, all children, were reported to have positive blood cultures for fungus during a 3-day period in early 1990. None had clinical features consistent with fungemia. Investigation of specimen processing procedures revealed that microbiologic plates were not processed-as per protocol-under the biologic hood but inadvertently were left open to air on the work bench by laboratory technicians. Settling plates left at the workbench, at door entry sites, and at sites of renovation immediately adjacent to the laboratory were positive forAspergillus and/or Penicillium; control plates placed elsewhere were negative. Airflow patterns suggested spread into the microbiologic laboratory through an open door located near the implicated workbench station and a false ceiling above the workbench area.

Our investigation demonstrates that faulty technique in the laboratory coupled with a change in environmental conditions can result in false-positive cultures and an outbreak of pseudofungemia.

TO evaluate the effect of antimicrobial therapy on patients and staff colonized with methicillin-resistant Staphylococcusaureus (MRSA) in a skilled nursing facility and to assess the role of the environment as a potential reservoir for MRSA in the nursing home setting.

As part of a comprehensive program to control an MRSA outbreak in a nursing home, patients and staff colonized with MRSA received 1 of 3 antimicrobial decolonization regimens depending upon the site and extent of colonization. Followup cultures were performed during therapy and on days 2, 7, 14, and 30 following the completion of therapy. Cultures of tbe patients' inanimate environment (pajamas, sheet, and floor) were obtained during and after therapy Antimicrobial susceptibility tests were performed on 54 MRSA isolates obtained before and 44 MRSA isolates recovered after therapy

A 120-bed Veterans Affairs nursing home care unit.

Thirty-six patients and 7 staff nurses colonized with MRSA at 1 or more sites.

Decolonization therapy with rifampin, trimethoprim-sulfamethoxazole, and clindamycin used alone or in various combinations for 5 or 10 days in conjunction with other infection control measures employed to combat the MRSA outbreak.

Twenty (56%) of the 36 NHCU patients were either persistently colonized or became recolonized with MRSA during tbe 30-day followup period. Positive cultures on day 3 during therapy frequently identified patients who subsequently exhibited persistent or recurrent colonization. Before therapy, 92% of MRSA isolates were susceptible to rifampin, whereas only 43% of the isolates obtained after therapy were susceptible. Sixteen (80%) of 20 patients with persistent or recurrent colonization had rifampin-resistant strains of MRSA isolated after therapy Twenty-three (18%) of 125 environmental cultures obtained during and after therapy from patients who exhibited persistent or recurrent colonization were positive for MRSA, in contrast to 9 (8%) of 107 from patients who were successfully decolonized.

The decolonization component of the outbreak control program was judged to be ineffective and potentially hazardous because colonization persisted or recurred in more than half of the patients, and substantial antimicrobial resistance was noted in MRSA strains isolated after therapy Resistance, especially to rifampin, and possibly re-acquisition of MRSA from other human or environmental sources were 2 factors that appeared to impede the decolonization effort.

To determine the cause of clustered bacteremias occurring among chronic hemodialysis patients.

A retrospective investigation of clinical and laboratory records with direct observation of dialysis facilities and technique. Bacterial blood isolates were identified and compared with environmental isolates.

The 1 1-station chronic hemodialysis unit that serves approximately 50 patients in a 450-bed military hospital.

Hemodialysis unit patients with aerobic gram-negative bacillus orEnterococcus casseliflavus blood isolates between April 1988 and February 1990.

The recovery and species identification of the unique isolate, Ecasseliflavus, from 2 index cases of bacteremia in February 1990 helped identify the cluster and demonstrated its protracted course. Dialysis blood tubing was contaminated with ultrafiltrate waste during dialyzer setup.

Bacteremias were controlled by halting the practice of attaching the venous tubing directly to a waste container while priming the membrane, by emphasizing glove changes and handwashing after contact with ultrafiltrate waste and by daily decontamination of ultrafiltrate waste bags.

We recommend that other hemodialysis units institute these interventions.