Biomedical subjects

V J Fraser

Publications and source records attributed to V J Fraser.

64 records · Page 4Linked to original sources

PubMed1993

A prospective randomized trial comparing manual and automated endoscope disinfection methods.

OBJECTIVE: To compare the efficacy of endoscope disinfection using automated and manual systems. DESIGN: Prospective randomized trial. SETTING: A 1,000-bed tertiary care referral center. METHODS: All endoscopes underwent a three-stage decontamination process including brushing and cleaning with water and detergent, manual or automated disinfection with 2% glutaraldehyde, and 70% alcohol rinse with forced air drying. Cultures were obtained from endoscopes from both groups before and after alcohol rinse and then after overnight storage. RESULTS: Cultures from 8/30 (27%) automated and 11/30 (37%) manually disinfected (P = 0.58) endoscopes grew gram-negative bacteria and/or nontuberculous mycobacteria before the alcohol rinse. After alcohol rinse, 3 (10%) of 30 automated and 8 (27%) of 30 manually disinfected endoscopes remained contaminated (P = 0.28). Manually disinfected endoscopes were contaminated more frequently with coliform bacteria, whereas endoscopes undergoing automated disinfection were more frequently contaminated with nontuberculous mycobacteria, but the differences were not statistically significant. After alcohol rinse and forced air drying, there was no difference in contamination rates between freshly disinfected endoscopes and those stored overnight (7/30 (23%) versus 4/30 (13%), P = 0.50). Colonoscopes and duodenoscopes were contaminated more often than gastroscopes (P = 0.00001). CONCLUSION: The persistent endoscope contamination after manual and automated disinfection indicates the importance of developing more reliable and effective disinfection methods.

Automation↗

PubMed1993

An expert system for culture-based infection control surveillance.

Hospital-acquired infections represent a significant cause of prolonged inpatient days and additional hospital charges. We describe an expert system, called GERMWATCHER, which applies the Centers for Disease Control's National Nosocomial Infection Surveillance culture-based criteria for detecting nosocomial infections. GERMWATCHER has been deployed at Barnes Hospital, a large tertiary-care teaching hospital, since February 1993. We describe the Barnes Hospital infection control environment, the expert system design, and a predeployment performance evaluation. We then compare our system to other efforts in computer-based infection control.

Cells, Cultured↗

PubMed1992

Blastomycosis in patients with the acquired immunodeficiency syndrome.

OBJECTIVE: To describe the clinical, demographic, radiographic, diagnostic, and therapeutic aspects of blastomycosis in patients with the acquired immunodeficiency syndrome (AIDS). DESIGN: A retrospective survey. SETTING: Ten university medical centers and community hospitals, six in geographic areas endemic for Blastomyces dermatitidis, and four outside the endemic area. PATIENTS: We identified 15 patients with blastomycosis and positive serologic test results for human immunodeficiency virus (HIV). MEASUREMENTS: A diagnosis of blastomycosis was based on a positive culture (14 patients) or typical histopathologic features (one patient) for B. dermatitidis in clinical specimens. RESULTS: Twelve of 15 patients had a previous or concomitant AIDS-defining illness at the time of diagnosis of blastomycosis, and only one patient had a CD4 lymphocyte count of greater than 200 cells/mm3. Two patterns of disease emerged: localized pulmonary involvement (seven patients), and disseminated or extrapulmonary blastomycosis (eight patients). Central nervous system involvement was common (40%). Six patients died within 21 days of presentation with blastomycosis, including four patients with disseminated and two with fulminant pulmonary disease. Among the nine patients who survived longer than 1 month, all received amphotericin B as initial antifungal therapy, and most received subsequent therapy with ketoconazole. Only two of these nine patients died with evidence of progressive blastomycosis. CONCLUSIONS: Blastomycosis is a late and frequently fatal infectious complication in a few patients with AIDS. In these patients, overwhelming disseminated disease including involvement of the central nervous system is common, and it is associated with a high early mortality. Initial therapy with amphotericin B is appropriate in patients with AIDS and presumptive blastomycosis.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Candidemia in a tertiary care hospital: epidemiology, risk factors, and predictors of mortality.

Demographic information, risk factors, therapy, and outcome for all patients who had candidemia at Barnes Hospital, St. Louis, between 1 September 1988 and 1 September 1989 were retrospectively reviewed. One hundred six candidemic patients were identified, representing 0.5% of all medical and surgical discharges and 0.33% of total patient discharges. These percentages represent a 20-fold increase in the incidence of candidemia at our hospital in comparison with that during 1976-1979. Candida albicans was the most frequently isolated species (63%), followed by Candida tropicalis (17%), Candida glabrata (13%), Candida parapsilosis (6.5%), and Candida krusei (0.9%). Overall mortality was 57%, and 14 (23%) of 60 deaths occurred within 48 hours of the detection of candidemia. Mortality was associated with higher APACHE II scores (25 for nonsurvivors vs. 16 for survivors; P = .0001), the presence of a rapidly fatal underlying illness (P = .0009), and sustained positivity of blood cultures (P = .02). In cases of sustained candidemia, the isolation of non-albicans Candida species also correlated with increased mortality (8 of 8 vs. 10 of 21; P = .005). Thirty candidemic patients (28%) did not receive any antifungal therapy, and 19 (63%) of these untreated patients died. Eleven untreated patients (37%) survived without sequelae. There has been a marked increase in the incidence of candidemia in our institution that is associated with a high overall mortality. Candidemia lasting less than 24 hours was associated with a lower mortality than was that of longer duration. Severity of illness and duration of candidemia should be used as stratifying factors in prospective studies to determine optimum therapy.

Adolescent↗

PubMed1992

Contamination of flexible fiberoptic bronchoscopes with Mycobacterium chelonae linked to an automated bronchoscope disinfection machine.

Between December 5, 1989, and September 25, 1990, Mycobacterium chelonae was isolated from endoscopic or bronchial washings in 14 patients on a single clinical service. A phenotypically unique strain of M. chelonae subspecies abscessus that was highly resistant to cefoxitin (MIC greater than 256 micrograms/ml) and different from 13 control isolates of M. chelonae recovered elsewhere in the hospital was identified in all these patients and the rinse water from the bronchoscope disinfecting machine. None of the outbreak patients had evidence of invasive M. chelonae disease. Aggressive infection control measures on the disinfecting machine, including use of sterile water in the wash and rinse cycles, increasing the 2% alkaline glutaraldehyde exposure time, frequent replacement of the glutaraldehyde, and disinfection of the machine, failed to eradicate the M. chelonae, presumably because of the presence of a biofilm inside the machine. Rinsing the scopes with 70% alcohol after automated disinfection eliminated the outbreak strain. This study demonstrates that automated bronchoscope disinfecting machines may become heavily contaminated with mycobacteria that resist usual disinfection, resulting in a source of bronchoscope contamination.

Bronchoscopes↗

PubMed1991

Two cases of blastomycosis from a common source: use of DNA restriction analysis to identify strains.

Two friends, one with AIDS, developed severe pulmonary blastomycosis but differed markedly in clinical course. The human immunodeficiency virus-negative patient responded completely to ketoconazole; the patient with AIDS died of progressive disseminated infection despite treatment with fluconazole and amphotericin B. Epidemiologic investigation suggested a common source of infection, but serologic evaluation and environmental cultures were unrevealing. EcoRI digestion of the Blastomyces dermatitidis isolates showed identical restriction fragment patterns that differed from patterns obtained from other clinical isolates. Analysis using a Histoplasma capsulatum ribosomal DNA probe that cross-hybridizes with B. dermatitidis showed that the isolates from the two patients were identical and different from others. Thus, the patients were probably infected with the same strain, possibly from a common source. These data indicate the critical role of cellular immunity in patients with blastomycosis, show that there are multiple genotypes of B. dermatitidis, and suggest that DNA restriction analysis is a useful epidemiologic tool.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Disclosure of HIV status to medical providers: differences by gender, "race," and immune function.

OBJECTIVE: The authors used data from a larger study to explore differences by gender, self-reported racial identification, and immune function in disclosure of HIV-positive serostatus to medical providers (dentists, family doctors, and emergency room [ER] and obstetrics-gynecology [ob/gyn] providers). METHOD: The authors analyzed interview responses from a convenience sample of African American and white men and women receiving HIV medical care at urban hospitals and clinics in St. Louis. Missouri. RESULTS: Of 179 respondents using at least one of three types of providers, 124 (69%) disclosed their HIV status to all applicable types of providers, 39 (22%) disclosed to only one or two types of providers, and 16 (9%) did not disclose to any of these types of providers. "Race" and CD4 count, but not gender, were independently associated with disclosure to dentists, family doctors, and ER providers in multivariate logistic regression analyses. CONCLUSIONS: Differences in disclosure rates, especially among patients who may be asymptomatic, suggest a need for public health education of both medical providers and patients with HIV.

Adolescent↗

PubMedDate not supplied

Monitoring expert system performance using continuous user feedback.

OBJECTIVE: To evaluate the applicability of metrics collected during routine use to monitor the performance of a deployed expert system. METHODS: Two extensive formal evaluations of the GermWatcher (Washington University School of Medicine) expert system were performed approximately six months apart. Deficiencies noted during the first evaluation were corrected via a series of interim changes to the expert system rules, even though the expert system was in routine use. As part of their daily work routine, infection control nurses reviewed expert system output and changed the output results with which they disagreed. The rate of nurse disagreement with expert system output was used as an indirect or surrogate metric of expert system performance between formal evaluations. The results of the second evaluation were used to validate the disagreement rate as an indirect performance measure. Based on continued monitoring of user feedback, expert system changes incorporated after the second formal evaluation have resulted in additional improvements in performance. RESULTS: The rate of nurse disagreement with GermWatcher output decreased consistently after each change to the program. The second formal evaluation confirmed a marked improvement in the program's performance, justifying the use of the nurses' disagreement rate as an indirect performance metric. CONCLUSIONS: Metrics collected during the routine use of the GermWatcher expert system can be used to monitor the performance of the expert system. The impact of improvements to the program can be followed using continuous user feedback without requiring extensive formal evaluations after each modification. When possible, the design of an expert system should incorporate measures of system performance that can be collected and monitored during the routine use of the system.

Expert Systems↗

PubMedDate not supplied

Statistical process control methods for expert system performance monitoring.

The literature on the performance evaluation of medical expert system is extensive, yet most of the techniques used in the early stages of system development are inappropriate for deployed expert systems. Because extensive clinical and informatics expertise and resources are required to perform evaluations, efficient yet effective methods of monitoring performance during the long-term maintenance phase of the expert system life cycle must be devised. Statistical process control techniques provide a well-established methodology that can be used to define policies and procedures for continuous, concurrent performance evaluation. Although the field of statistical process control has been developed for monitoring industrial processes, its tools, techniques, and theory are easily transferred to the evaluation of expert systems. Statistical process tools provide convenient visual methods and heuristic guidelines for detecting meaningful changes in expert system performance. The underlying statistical theory provides estimates of the detection capabilities of alternative evaluation strategies. This paper describes a set of statistical process control tools that can be used to monitor the performance of a number of deployed medical expert systems. It describes how p-charts are used in practice to monitor the GermWatcher expert system. The case volume and error rate of GermWatcher are then used to demonstrate how different inspection strategies would perform.

Evaluation Studies as Topic↗

PubMedDate not supplied

Estimating the prevalence of chronic fatigue syndrome and associated symptoms in the community.

Chronic fatigue syndrome is a poorly understood disease characterized by debilitating fatigue and neuromuscular and neuropsychological symptoms. Despite numerous studies on the subject, the epidemiology of the syndrome in the community remains largely unexplored. An estimate of the prevalence in the population is presented, approximating the Centers for Disease Control criteria as well as the prevalence estimates of the fatigue symptom complex that include fatigue, disability, and neuromuscular and neuropsychological symptoms. The study population consisted of a very large, multicenter, stratified, and random sample of a general population health survey known as the Epidemiologic Catchment Area Program. Data used for this study were gathered between 1981 and 1984. The Diagnostic Interview Schedule, a highly structured mental health interview, was used to assess the lifetime prevalence of medical and psychological symptoms. Chronic fatigue was common. A total of 23 percent of the subjects reported having experienced the symptom of persistent fatigue sometime during their lives. Chronic fatigue syndrome, however, as defined by the Centers for Disease Control, appeared to be quite rare in the general population. Only 1 of 13,538 people examined was found to meet a diagnosis of the syndrome with an approximation of the CDC criteria. Fatigue symptom complex was frequently related to medical or psychiatric illness or substance abuse; thus, persons meeting partial criteria of chronic fatigue syndrome were also found to be rare when psychiatric or medical exclusions were applied.

Adult↗