A retrospective investigation was made to compare the occupational risk of tuberculosis in personnel assisting human immunodeficiency virus (HIV)-infected and uninfected subjects with active tuberculosis.

We retrospectively reviewed 6 years of hospital activity in 3 units where HIV-infected patients with tuberculosis are hospitalized and in 2 units where non-HIV-infected tuberculosis patients are hospitalized. The risk of occupational tuberculosis in healthcare workers who assisted HIV-infected and non-HIV-infected patients with tuberculosis was investigated.

The risk of occupational tuberculosis in healthcare workers was studied by considering the numbers of potential source cases (hospitalized patients with tuberculosis) in the two conditions investigated (HIV-positive and HIV-negative). Both potential source cases and cases of tuberculosis in healthcare workers had to be microbiologically proven in order to be considered..

Seven cases of tuberculosis occurred in persons who cared for 85 HIV-infected subjects with tuberculosis, while only 2 cases occurred in staff members who took care of 1,079 HIV-negative tuberculosis patients over the same period (relative risk=44.4; 95% confidence interval = 8.5-438).

Tuberculosis seems no longer to be a neglectable risk in healthcare workers assisting patients with HIV infection. Further study is urgently needed to see whether such unexpectedly high dissemination of tuberculosis also is demonstrable in the community.

To determine the prevalence of aspergillosis in lymphoma patients housed in a protective environment while undergoing a bone marrow transplant or peripheral stem cell transplant and its relation to lymphoma type, type of transplant, period of neutropenia, method of diagnosis, species of Aspergillus, and the use of empiric amphotericin B.

Clinical, autopsy, and microbiology records were reviewed retrospectively to determine the presence or absence of invasive aspergillosis. All positive specimens underwent further review to determine parameters outlined above.

The review took place at the University of Nebraska Medical Center with lymphoma patients housed in the oncology/hematology special care unit, which consists of 30 single-patient rooms under positive pressure with high-efficiency particulate air filtration.

4 17 lymphoma patients admitted to the oncology/hematology special care unit who underwent 427 courses of high-dose chemotherapy with or without total body irradiation followed by a stem cell rescue.

Twenty-two cases (5.2%) of nosocomial invasive aspergillosis (14 caused by Aspergillus flavus, 2 by Aspergillus terreus, 2 by Aspergillus fumigatus, and 4 by characteristic histology) were diagnosed. The prevalence of disease according to transplant was 8.7% for allogeneic bone marrow transplant (2/23 treatments), 5.6% for autologous peripheral stem cell transplant (9/161), and 4.5% for autologous bone marrow transplant (11/243). Fifteen patients were presumptively diagnosed prior to death (68.2%) most commonly by histologic examination of skin biopsies. All 22 patients received amphotericin B therapy, 17 prior to aspergillosis diagnosis, and 7 (31.8%) survived. No patient with disseminated disease survived.

Even when housing lymphoma patients undergoing myeloablative therapy in a protective environment containing high-efficiency particulate air filtration, there was a risk of developing aspergillosis. These data also showed that antemortem diagnosis with aggressive amphotericin B therapy was most effective in the management of infected lymphoma patients when engraftment occurred and the disease did not become disseminated.

To determine the number and efficacy of respiratory isolation facilities in St. Louis hospitals and to assess the mechanisms in place for evaluating function of hospital ventilation systems.

A prospective multi-hospital surveillance study using direct observation and a standardized questionnaire.

Seven hospitals (including university-affiliated large teaching, private community, private teaching, and private nonteaching adult hospitals, and one pediatric teaching hospital) in St. Louis, Missouri.

Actual direction of airflow in rooms designated for respiratory isolation was measured using smokesticks. Hospital demographic information, respiratory isolation policies, and frequency of ventilation tests were provided by infection control personnel.

One hundred twenty-one (3.4%) of 3,574 hospital rooms were designed to have negative pressure ventilation suitable for respiratory isolation. The percentage of isolation rooms in each institution ranged from 0.4% (92 of 486) to 93% (39 of 42). Only three (43%) of seven hospitals had intensive care respiratory isolation rooms, and none had isolation rooms in the emergency department. No hospital had tested routinely the efficacy of the negative pressure ventilation, and two (28%) of seven had tested airflow for the first time in the past year.

We tested 115 (95%) of 121 isolation rooms. With the doors closed, 52 (45%) of 115 designated negative pressure rooms actually had positive airflow to the corridor. The number of negative pressure rooms and the presence or absence of anterooms did not predict correct direction of airflow. There was a significant difference among hospitals in the percentage of designated isolation rooms that had truly negative pressure (P<0.0001). Hospital age, size, and type corre-latedwith correct direction of airflow (R<.0001).

In the hospitals studied, only a small number of rooms were designated for respiratory isolation, and the performance of these was not tested routinely. High-risk areas including intensive care units and emergency rooms were not equipped to provide respiratory isolation. The direction of airflow in respiratory isolation rooms was not always correct and should be evaluated frequently. (Infect Control Hosp Epidemiol 1993;14:623-628.)

To investigate a cluster of mupirocin-resistant Staphylococcus aureus on a dermatology ward.

An outbreak of mupirocin-resistant S aureus was noted on the dermatology ward during a prospective epidemiologic study of methicillin-resistant S aureus (MRSA) and borderline methicillin-susceptible S aureus (BMSSA). Pulsed-field gel electrophoresis (PFGE) of whole-cell DNA digested with Sma I was used as a marker of strain identity.

An 850-bed university hospital with a 12-bed inpatient dermatology ward. Most patients have severe, exfoliating dermatologic disorders.

MRSA or BMSSA were isolated from 13 patients on the dermatology ward over a 14-month period. Eleven of these isolates (84.6%) were mupirocin-resistant. Nine isolates were present on admission (81.8%); 8 of these patients had been hospitalized on the same ward within the last two months. Nasal and hand cultures from 36 personnel were negative for mupirocin-resistant MRSA or BMSSA. Extensive environmental culturing revealed that a blood pressure cuff and the patients' communal shower were positive for mupirocin-resistant BMSSA. PFGE of all mupirocin-resistant isolates demonstrated that the nine patients and both environmental sources had identical DNA typing patterns.

Changing of blood pressure cuffs between patients and more stringent cleaning of communal areas was initiated. Repeat environmental cultures were negative.

S aureus is not usually associated with an environmental reservoir; however, these patients all had severe desquamation, which may have prolonged environmental contamination.

To determine the ability of a commercially available biological indicator (BI), used to monitor steam and ethylene oxide sterilization, to biologically monitor a liquid sterilization process consisting of a sterile processor, a proprietary peracetic acid sterilant, and a sterile rinse system.

Analysis of spore survival in BIs tested in STERIS SYSTEM 1™ liquid chemical sterilization processor and in vitro.

STERIS Corp. research laboratory.

In vitro tests were performed in the STERIS SYSTEM 1 Processor using 12-minute and 6-minute sterilant exposure cycles. D values (time to inactivate one log of spores), spore washoff and outgrowth time, and inhibitory effects of the sterilant were determined.

Sterilization of the spore-inoculated filter paper strips in the BIs was ascertained in both processor testing and in vitro tests using conditions identical to those in the processor. The extensive washing and dilution during the processor cycle resulted in only 0.2% and 1.8% removal of the spores from Bacillus stearother-mophilus and Bacillus subtilis inoculated spore strips, respectively.

Carryover of the diluted sterilant to the culture medium did not inhibit the outgrowth of the spores, and D values could be obtained. B Stearothermophilus was two to three times more resistant to the sterilant than B subtilis. However, either spore meets the performance specifications applicable to BIs for monitoring sterilization processes.

The data demonstrate that the commercial Bis evaluated are reproducible and verifiable indicators of the liquid chemical sterilization process. The same kind of performance specifications for producing BIs used to monitor steam or ethylene oxide systems also apply to the evaluated liquid chemical sterilization system.

To investigate the possibility of interhospital spread of multiresistant Staphylococcus aureus in Sao Paulo, Brazil.

We evaluated 13 nosocomial S aureus strains selected because of resistance to oxacillin and ciprofloxacin.

The strains were collected between March 1991 and September 1991 from four hospitals in Sao Paulo. Two were teaching hospitals, and two were private hospitals.

Each strain was isolated from a different patient. All patients were hospitalized when the strains were isolated.

The strains were typed by restriction endonuclease analyses of plasmid DNA (REAP) using EcoRI, HindIII, RsaI, and Alu1 and by extended antibiogram profile (34 drugs).

All strains had identical plasmid and antibiogram profile. They demonstrated the same plasmid pattern as previously described in one of the hospitals studied.

Our results suggest the dissemination of a unique oxacillin- and quinolone-resistant strain of S aureus in several hospitals of Sao Paulo, Brazil.

To describe the distribution of nosocomial infections among surgical patients by site of infection for different types of operations, and to show how the risk of certain adverse outcomes associated with nosocomial infection varied by site, type of operation, and exposure to specific medical devices.

Surveillance of surgical patients during January 1986-June 1992 using standard definitions and protocols for both comprehensive (all sites, all operations) and targeted (all sites, selected operations) infection detection.

Acute care US hospitals participating in the National Nosocomial Infection Surveillance (NNIS) System: 42,509 patients with 52,388 infections from 95 hospitals using comprehensive surveillance protocols and an additional 5,659 patients with 6,963 infections from 11 more hospitals using a targeted protocol.

Surgical site infection was the most common nosocomial infection site (37%) when data were reported by hospitals using the comprehensive protocols. When infections reported from both types of protocols were stratified by type of operation, other sites were most frequent following certain operations (e.g., urinary tract infection after joint prosthesis surgery [52%]). Among the infected surgical patients who died, the probability that an infection was related to the patient's death varied significantly with the site of infection, from 22% for urinary tract infection to 89% for organ/space surgical site infection, but was independent of the type of operation performed. The probability of developing a secondary bloodstream infection also varied significantly with the primary site of infection, from 3.1% for incisional surgical site infection to 9.5% for organ/space surgical site infection (p<.001). For all infections except pneumonia, the risk of developing a secondary bloodstream infection also varied significantly with the type of operation performed (p<.00l) and was generally highest for cardiac surgery and lowest for abdominal hysterectomy. Surgical patients who developed ventilator-associated pneumonia were more than twice as likely to develop a secondary bloodstream infection as nonventilated pneumonia patients (8.1% versus 3.3%, p<.001).

For surgical patients with nosocomial infection, the distribution of nosocomial infections by site varies by type of operation, the frequency with which nosocomial infections contribute to patient mortality varies by site of infection but not by type of operation, and the risk of developing a secondary bloodstream infection varies by type of primary infection and, except for pneumonia, by type of operation.

Antimicrobials are a major part of hospital pharmacy budgets and must be considered in resource planning and spending projections. Logically, trends in antimicrobial usage should be linked to trends in resistant pathogens.

To examine long-term trends in antimicrobial use over a 15-year period (1978 to 1992) and contrast them with changes in pathogens causing nosocomial bacteremia.

A 900-bed, tertiary care teaching hospital.

Pharmacy records were reviewed to identify parenteral antimicrobial agents administered to adult inpatients. Results were expressed in average daily adult doses per 1,000 patient days.

Chloramphenicol use decreased, while use of penicillin G, antistaphylococcal penicillins, first-generation cephalosporins, and aminoglycosides remained relatively stable. In contrast, there was a sharp increase in the use of second- and third-generation cephalosporins (7-fold and 6.5-fold increase, respectively), vancomycin (161 -fold increase), metronidazole (32-fold increase) and amphotericin B (35-fold increase). The proportion of nosocomial bacteremias due to methicillin-resistant gram-positive bacteria rose, but gentamicin resistance in gram-negatives remained at low levels. During the past 14 years, the percentage of patients receiving at least one parenteral antimicrobial rose from 23% to 44%. Among patients receiving antimicrobials, the average number of different agents used per patient increased from 1.8 to 2.1

If newer agents were available, use of older agents usually declined. If newer alternatives were not available, use of older agents rose sharply. The increased use of antimicrobials in adults was related to the expanded proportion of patients receiving these agents.

To report the contamination of ventilator equipment with Bacillus cereus and to outline the measures taken to trace the source of the organism.

A prospective survey of all intensive care unit patients who were culture-positive for B cereus and obtaining of environmental cultures of the cleaning and assembly area of the respiratory services division between October 1991 and September 1992.

Ventilated patients from a 16-bed medical and surgical intensive care unit (ICU) in a 1,000-bed adult tertiary care hospital.

From October 1991 to April 1992, B cereus colonized the ventilator circuitry of patients in the ICU. One of two washer/decontaminators in the cleaning and assembly area of the respiratory services division was found to yield the microorganism consistently from the water intake port. The design of the machine precluded easy decontamination of the port with 2% gluteraldehyde and a second outbreak occurred. Following the second outbreak, aqueous chlorhexidine in a final concentration of 0.05% was added to the first of two pasteurization cycles in an attempt to achieve sporicidal activity. This ended the outbreak. Sixty-two patients became colonized with the organism including two with nonfatal Bacillus sepsis and one death due to pneumonia associated with the organism.

This experience emphasizes the importance of obtaining cultures of machine parts to identify the source of contamination and thereby direct control measures. Use of chlor-hexidine gluconate at high temperatures effectively eradicated B cereus from ventilator circuitry in a practical and cost-effective manner.

The development of a new method for achieving respiratory isolation in hospitals, clinics, and residential facilities, in response to the increasing risk of transmission of tuberculosis and the limitations of the currently available isolation systems.

Ultraviolet (UV) light and ultra-low-penetration air filtration were combined with a ventilation unit and adapted for use in modular isolation rooms or for conversion of existing rooms.

The ventilation-filtration unit efficiently cleared bacterial aerosols and particles >0.2 μm from the air, maintained required negative pressures and airflows, and provided directional airflow within rooms.

To determine the proportion of Los Angeles County (LAC) hospitals offering obstetrical services that have postpartum and postabortion rubella vaccination policies.

A survey was sent to the infection control practitioners (ICPs) of all operational acute care hospitals (N = 133) in LAC in 1992. A reminder and second survey was mailed to ICPs who did not respond to the first mailing.

Of 75 hospitals with obstetrical departments, 56 (75%) responded. Thirty-four (61%) of the 56 respondent hospitals had postpartum rubella vaccination policies. Of the 34 hospitals with policies, 30 (88%) accepted only a written record of rubella seropositivity as proof of immunity, 30 (88%) screened women with unknown immunity status before hospital discharge, and 32 (94%) vaccinated susceptible women before hospital discharge. Of the 32 hospitals that performed induced abortions, only two (6%) provided screening and vaccination services for these women.

Only 61% of hospitals in LAC offering obstetrical services had postpartum rubella vaccination policies while only minimal screening and vaccination occurred in association with abortion services. Widespread implementation of postabortion screening and vaccination, and more stringent compliance with Advisory Committee on Immunization Practices recommendations for postpartum screening and vaccination in hospitals offering obstetrical services would reduce the number of rubella-susceptible women who have been missed by other prevention strategies.