The Centers for Disease Control and Prevention has issued new criteria for conversion of the tuberculin skin test; in persons over 35 years of age, an increase in induration of at least 15 mm is considered indicative of new tuberculous infection. We reviewed our experience in a tuberculosis control program in a long-term care facility to assess the applicability of the new criteria to our patient population.

Retrospective review of seven years of tuberculosis control records and outbreak investigation.

Long-term care Veterans Affairs hospital.

All patients in the facility between 1985 and June 1992 who received routine admission and annual tuberculin skin testing or who were evaluated for possible exposure to active tuberculosis. A total of 2,342 skin tests were performed.

Mean increase in skin test diameter in patients with at least two prior negative tests and known exposure to active tuberculosis was 13.9 ± 4.7 mm. Frequency distribution histograms of skin test sizes of initial tuberculin testing in the entire population indicated 10 mm induration as a reasonable criterion for initial positivity.

In our long-term care population, an increase in skin test induration of 10 mm may indicate new tuberculous infection. Criteria for skin test conversion derived from ambulatory populations in other geographic areas may not apply in all situations. Prevalence of infection with Mycobacterium tuberculosis and prevalence of skin test reactivity due to nontuberculous mycobacteria are likely to influence the predictive value of criteria for tuberculin conversion in a given population.

To study the ability of a medical waste disposal process using chlorine dioxide to inactivate human immunodeficiency virus type 1 (HIV 1).

Stock HIV-1 (HTLV-IIIB strain) was treated with chlorine dioxide under the following settings: cell culture medium alone, culture medium with 25% blood, culture medium with medical supplies treated by the Condor machine (Winfield Environmental Corp., Escondido, CA). MT-2 cells in 96-well tissue culture plates were inoculated with serial tenfold dilutions of treated and untreated HIV-1. Cytopathic effect was read on day five, and the TCID50 (50% tissue culture infectious dose) was calculated.

Treatment of HIV-1 with chlorine dioxide in culture medium alone resulted in a 5.25 log10 reduction in TCID50. Treatment of HIV-1 with chlorine dioxide in the presence of 25% blood caused a 6.25 log10 reduction in HIV-1 infectivity Treatment of HIV-1 with chlorine dioxide in the presence of medical supplies treated in the Condor machine resulted in a 4.75 log10 reduction in HIV infectivity.

Chlorine dioxide inactivated HIV-1 in vitro. Chlorine dioxide inactivated HIV-1 in the presence of blood and in the presence of medical supplies under conditions that simulated the conditions existing in the Condor machine.

To report experience with brucellosis among expatriate hospital employees in an area of the world where brucellosis is endemic.

Review of cases from the viewpoints of direct supervisor and treating physician, including epidemiologic interviews and clinical follow-up.

Tertiary care hospital center in a developing country that increased from 125 beds to 450 beds during the period studied.

Employees with clinical findings suggesting brucellosis and in whom a positive blood culture or significantly elevated serologic test confirmed the diagnosis.

Nine hospital employees from nonendemic areas developed brucellosis. Five were from England and four from North America. Seven were bacteriology technologists, one was a nurse, and one was an obstetrician. Each had an acute febrile illness with malaise, arthralgia, or headache. Brucella titers were ≥ 1:1,280. Five were bacteremic with positive Brucella cultures. All responded to anti-Brucella therapy. Three patients had relapses, but there were no complications.

Among Saudi patients, brucellosis is generally attributable to drinking infected milk or contacting infected animals. On the other hand, among expatriate hospital employees, the infection is likely due to processing Brucella cultures or dealing with infected body fluids. In 1988, the laboratory began stricter infection control measures. Since then, there has been only one case of brucellosis among the hospital employees.

To discuss the close affinity between the continuous quality improvement (CQI) concept of monitoring a process for the introduction of special causes and epidemic surveillance.

A case study of a CQI tool for infection control epidemic surveillance.

A 668-bed acute care hospital with 5 intensive care units supporting heart, liver transplant, and trauma teams. The infection control department consists of 2.5 full-time employee nurse epidemiologists and a medical director who is an infectious disease specialist.

The outbreak investigation illustrates principles of CQI and their relationship to epidemic surveillance through the use of applied statistical methods.

The expanding role of hospital epidemiology is enhanced by applying CQI concepts to improving health care. The application of epidemiologic tools and principles to the problems of nosocomial infections is strongly connected to the CQI concept of using dependable data to improve processes.

To determine the cause of meningitis associated with Cryptococcus neoformans in two patients with recent ventricular-peritoneal (VP) shunt placement.

A retrospective review of materials, records, and concurrent cases of VP shunt procedures. Isolates of C neoformans from each patient were submitted for analysis by colony morphology, biochemical testing, and karyotyping by pulsed-field electrophoresis.

Two 400-bed community hospitals.

Two immunocompetent patients presented with symptoms of progressive hydrocephalus in August 1991. Each received a VP shunt on the same day by the same surgeon using materials from a common vendor and hospital.

Both patients presented within six to eight weeks with symptoms of fever, headache, rash, and cultures of cerebrospinal fluid (CSF) that yielded C neoformans. Each patient recovered after therapy with amphotericin B and flucytosine followed by several months of fluconazole, although one required replacement of the VP shunt for cure. Review of each patient's history and CSF characteristics at the time of shunt placement suggested re-activation of a pre-existing infection. Isolates of C neoformans from each patient were submitted for analysis by colony morphology, biochemical testing, and karyotyping by pulsed-field electrophoresis. Each isolate was found to be unique by chromosomal karyotyping.

Our data and previous reports suggest that cryptococcal VP shunt infections appear to be a complication of shunts placed in previously infected persons rather than noso-transmission of cryptococcus during placement.

To evaluate measures intended to reduce Legionella infections in patients undergoing bone marrow transplantation (BMT).

Ongoing clinical and microbiological surveillance for Legionella colonization or infection was undertaken. All neutropenic patients with pulmonary infiltrates and fever unresponsive to broad-spectrum antibiotics were tested for Legionella organisms.

A 505-bed medical-surgical hospital with a designated BMT unit.

Two hundred twenty-five patients underwent BMT; 201 were treated on a new BMT unit. The incidence of Legionella infections was compared to that seen in an estimated 150 neutropenic patients treated on other units.

A combined approach to decontamination of a hospital water supply was assessed. This included heating, particulate filtration, ultraviolet sterilization, and monthly pulse hyperchlorination of water supplied to the BMT unit. The incidence of Legionella infections was assessed on the BMT unit and compared with the frequency elsewhere in the hospital.

There were only three cases of Legionella pneumonia among 201 patients undergoing transplantation on a new BMT unit. In contrast, 33 cases of Legionella infections were detected from approximately 150 patients treated on general medical floors.

A multifaceted approach to decontamination of a hospital water system led to a marked reduction in Legionella infections.