To compare resource use by diagnostic outcome among hospital admissions during which tuberculosis (TB) was suspected.

Retrospective study based on chart review and microbiology laboratory data.

The department of medicine in a municipal hospital serving central Brooklyn, New York.

We identified all adult admissions in 1993 during which TB was suspected. We assigned each admission to one of four mutually exclusive groups defined by the results of microbiological tests (acid-fast bacilli [AFB] smear and culture): culture-positive and smear-positive (C + S +); culture-positive and smear-negative (C + S−); culture-negative and smear-positive (C−S+); or culture-negative and smear-negative (C−S−). Each admission was divided into two separate periods to which the utilization of medical resources was assigned: the diagnostic and the postdiagnostic periods, which were separated by the date of receipt of the first definitive culture report.

Data on 519 admissions (93 C+S+; 57 C+S−; 30 C−S+; and 339 C−S−) were analyzed. Although C+S+ were more likely than other groups to have an admitting diagnosis of TB, approximately one quarter of the admissions without TB (C−S+, C−S−) were admitted with the principal diagnosis of TB. For the four groups, C+S+, C+S−, C−S+, and C−S−, the respective rates of TB isolation and anti-TB treatment, and median lengths of isolation were 98%, 87%, and 34 days; 74%, 74%, and 7 days; 83%, 83%, and 15 days; and 44%, 29%, and 0 days. During the diagnostic period, the rate and length of isolation were similar in the AFB-smear—positive groups (C+S+ and C−S+). We estimated that admissions without culture-proven TB (C−S+ and C−S−) accounted for 3,174 (36%) of the 8,712 days of TB isolation expended and for 65% of the 16,671 days of anti-TB treatment. The vast majority of this resource consumption (2,737 [86%] of 3,174 days of isolation) occurred during the diagnostic period before a definitive culture result was known.

Our results suggest that prolonged diagnostic uncertainty and misclassification of cases due to false-positive and false-negative smears are associated with substantial medical-resource consumption. New diagnostic modalities that reduce the period of diagnostic uncertainty could reduce the utilization of resources later found to be unnecessary

To evaluate the relative efficacy of personal respiratory protection as the concentrations of infectious aerosols increase or as room ventilation rates decrease.

We modified the Wells-Riley mathematical model of airborne transmission of disease by adding a variable for respirator leakage. We modeled three categories of infectiousness using various room ventilation rates and classes of respirators over a 10-hour exposure period.

The risk of infection decreases exponentially with increasing room ventilation or with increasing personal respiratory protection. The relative efficacy of personal respiratory protection decreases as room ventilation rates increase or as the concentrations of infectious aerosols decrease.

These modeling data suggest that the risk of occupational tuberculosis probably can be lowered considerably by using relatively simple respirators combined with modest room ventilation rates for the infectious aerosols likely to be present in isolation rooms of newly diagnosed patients. However, more sophisticated respirators may be needed to achieve a comparable risk reduction for exposures to more highly concentrated aerosols, such as may be generated during cough-inducing procedures or autopsies involving infectious patients. There is probably minimal benefit to the use of respirators in well-ventilated isolation rooms with patients receiving appropriate therapy

To develop a method to evaluate directional airflow patterns, air dilution, and air mixing in facilities where tuberculosis patients are seen.

A tuberculosis patient isolation room was evaluated by analyzing pressure differential between the room and the corridor and by using theatrical fog to visualize room air movement and impact of dilution and exchange, as well as air capture and displacement. Tracer gas was compared to fog results and used to calculate air exchange rates.

A small research hospital.

By adding theatrical fog to the patient room at several locations, we quickly learned that most of the air entering the room through the transom and around the door to the corridor was exhausted through the three exhaust vents. Little air appeared to move toward the exhaust fan.

For comparison and to confirm the room air exchange rate, tracer gas was distributed and sampled. The kinetics of decay were very similar whether the tracer gas and room air were mixed during sampling or not.

The fog procedure allowed good visual confirmation of air mixing and airflow patterns and provided quantitative data for evaluating the efficacy of air capture and displacement or dilution and exchange

To investigate differences in second-, third-, and fourth-year medical students' knowledge of bloodborne pathogen exposure risks, as well as their attitudes toward, and intentions to comply with, Universal Precautions (UP).

Cross-sectional survey.

Surveys about students' knowledge, attitudes, and intentions to comply with UP were completed by 111 second-year (preclinical), 80 third-year, and 60 fourth-year medical students at Washington University School of Medicine in the spring of 1996.

Preclinical students knew more than clinical students about the efficacy of hepatitis B vaccine, use of antiretroviral therapy after occupational exposure to human immunodeficiency virus, and nonvaccinated healthcare workers' risk of infection from needlestick injuries (P<.001). Students' perceived risk of occupational exposure to bloodborne pathogens and attitudes toward hepatitis B vaccine did not differ, but preclinical students agreed more strongly that they should double glove for all invasive procedures with sharps (P<.001). Clinical students agreed more strongly with reporting only high-risk needlestick injuries (P = .057) and with rationalizations against using UP (P = .008). Preclinical students more frequently reported contemplating or preparing to comply with double gloving, wearing protective eyewear, reporting all exposures, and safely disposing of sharps, whereas students with clinical experience were more likely to report compliance. Clinical students also were more likely to report having “no plans” to practice the first three of these precautions (P<.001).

Differences in knowledge, attitudes, and intentions to comply with UP between students with and without clinical experience may have important implications for the timing and content of interventions designed to improve compliance with UP.

To determine risk factors for an increase in line-associated bloodstream infections (BSIs) in three pediatric intensive-care units at one hospital that recently had changed brands of needleless access device.

Retrospective case-control studies; review of the units' infection control policies and procedures for accessing and replacing components of needleless access devices.

A community tertiary-care hospital's three pediatric intensive-care units.

Children in one of the three intensive-care units with a central venous catheter in place during January 1, 1995, through May 15, 1996, who developed laboratory-confirmed primary BSI. Children who had central venous catheters in place for >48 hours and who did not develop BSI were chosen randomly as controls.

Eight patients met the case definition; they had 11 episodes of BSI. Multivariate analysis identified duration of catheterization and exposure to the IVAC first-generation needleless device as independent risk factors for BSI. Compared with patients from another pediatric intensive-care unit in which the IVAC device also was used but in which an increased BSI rate did not occur, patients from the unit with an increased BSI rate were more likely to receive intermittent (vs continuous) intravenous therapy through one or more lumens. In both units, the IVAC device valve component was replaced every 6 days, and the endcap used to cover the valve (when connected to an unused lumen) was replaced every 24 hours or after each access. The BSI rate returned to baseline after institution of a policy to replace the entire IVAC device, valve, and endcap every 24 hours.

An increased risk of BSI was associated with use of the IVAC first-generation needleless device when replaced every 6 days. This increased risk may have been more pronounced in one pediatric intensive-care unit, because patients were more likely to receive intermittent intravenous therapy. Intermittent intravenous therapy or central venous catheter flushing practices may be important determinants of BSI risk

To establish the concentration of isopropanol that exerts the same immediate and sustained effects as n-propanol 60% v/v in surgical scrubbing, and to assess the performance of the test method proposed as the European standard in parallel experiments.

Isopropanol at concentrations of 70%, 80%, and 90% v/v was tested in comparison with n-propanol 60%, the proposed reference preparation, in the draft method proposed by the European standard. A Latin square design was used with four balanced blocks of five volunteers each in four experimental runs that were spaced by intervals of 1 week each. Volunteers were allotted randomly to one of the four blocks. Independently, the volunteers' right and left hands also were randomized into two groups for the assessment of either immediate or sustained effects.

Two laboratories supervised by two investigators, one from Vienna, Austria, and one from London, The United Kingdom.

The release of skin flora from the fingertips of clean hands was assessed before and after treatment by immediate sampling from one hand and by sampling of the other, gloved hand after 3 hours. The mean log10 reductions (RF) of bacterial release achieved by rubbing the alcoholic preparations for 3 minutes onto the hands were established.

For both experiments, the immediate effects of isopropanol 70% (RF, 2.0 and 2.1, respectively) were significantly smaller than those of the reference n-propanol 60% (RF, 2.4 and 2.6, respectively). This also was found with the sustained effects (RF, 0.7 and 1.1 vs 1.0 and 1.6, respectively). At 90%, isopropanol equalled the immediate effect of n-propanol 60%, whereas at 80% it proved slightly (although not significantly) less active. There were no significant differences in the results of both investigators. The sustained effects of isopropanol 80% and 90% were both larger than the reference in Vienna but were found smaller by the London investigator; none of the differences were significant. Mean RFs were significantly different between Vienna and London with n-propanol 60% and isopropanol 70%, but not with isopropanol at 80% or 90%.

At 90%, isopropanol is as effective as n-propanol 60%, which was proposed by the European Committee for Standardization as a reference in testing :products for surgical hand disinfection. It could, therefore, serve as an alternative if the proposed agent is undesirable for any reason. In parallel experiments by two investigators, the proposed test method proved well workable; the results were very similar and the conclusions identical