Microbial strain typing is a useful adjunct to clinical epidemiology. Phenotypic typing systems examine expressed characteristics, whereas genotypic systems, including recent PCR-based systems, examine chromosomal or plasmid DNA. Typing systems have evaluated bacteria, fungi, and viruses successfully. The criteria used to assess the utility of each system include typeability, reproducibility, and discriminatory power.

A cluster of bacteremia episodes with Klebsiella pneumoniae was noted in patients in a hematology-oncology ward during a 3-week period. Random amplified polymorphic DNA (RAPD) analysis, a novel technique for generating chromosomal fingerprints from bacterial isolates, was used as an aid to the epidemiological investigation of this cluster. For each of the two patients from whom multiple isolates had been obtained, identical RAPD patterns were observed in the serial isolates, even for a patient where the isolates had different biotypes. Isolates from different patients gave distinct patterns. Random amplified polymorphic DNA was found to be a useful typing technique for this cluster of K pneumonia bacteremias.

Objective: To determine the incidence of aspergillosis in patients with leukemia or bone marrow transplants during a construction-associated outbreak, and the effect of an environmental control program for Aspergillus.

Design: Clinical, microbiological, and pathological records were reviewed retrospectively once the outbreak was appreciated, and prospectively thereafter, to determine the presence or absence of aspergillosis and duration of neutropenia.

Setting: A university tertiary-care center with a single designated hematology-oncology unit.

Patients: From January 1988 to September 1993, there were 141 patients with leukemia or bone marrow transplants identified as being neutropenic during 231 admissions to this specialized unit.

Interventions: Installation of wall-mounted portable high-efficiency particulate air (HEPA)-filter air purifiers, application of copper-8-quinolinolate–formulated paint, replacement of perforated ceiling tiles with nonperforated type, sealing of all windows, replacement of horizontal, dust-accumulating blinds with vinyl, opaque, roller shades, and systematic and regular cleaning of surfaces.

Results: Thirty-six cases of nosocomial aspergillosis were diagnosed during this period. The incidence density (ID) in the preconstruction period was 3.18 per 1,000 days at risk. During construction activity—before the implementation of a control strategy—the ID increased dramatically to 9.88 per 1,000 days at risk. With infection control measures implemented and continued construction work, the ID decreased to 2.91 per 1,000 days at risk, comparable to the preconstruction baseline rate.

Conclusions: An environmental control strategy incorporating widely available technology may have played an important role in controlling this outbreak of construction-associated invasive aspergillosis.

We report an outbreak of Clostridium difficile-associated diarrhea at our medical center following adoption of Universal Precautions. Environmental cultures revealed unexpected contamination of blood pressure cuffs at a rate similar to that for bedside commodes (10% and 11.5%, respectively). An obser vational sur vey revealed that healthcare workers in the patient care areas not infrequently failed to remove their potentially stool-contaminated gloves prior to touching clean surfaces, which might have contributed to contamination of blood pressure cuffs.

Recent research indicates that antiretroviral prophylaxis significantly reduces occupationally related human immunodeficiency virus (HIV) seroconversion. This article outlines principles on which guidelines were based for treating aggressively those healthcare workers (HCWs) exposed to HIV occupationally at the Catholic Medical Center in Jamaica, New York. These recommendations attempt to provide HCWs with the best possible available antiretroviral therapy to treat occupational HIV seroconversion. New options must continue to be explored as new information becomes available.

Intravascular devices are the source of most primary bloodstream infections. Unfortunately, there are few studies that demonstrate how surveillance for catheter-related infection should be done. This article attempts to provide infection control personnel with information necessary to develop such surveillance.

We provide guidance for new practitioners in the vocabulary of modern epidemiology and the application of quantitative methods. Most hospital epidemiology involves surveillance (observational) data that were not part of a planned experiment, so the rubric and logic of controlled experimental studies cannot be applied. Forms of incidence and prevalence often are confused. The names “cohort study” and “case-control study” are unfortunate, as cohort studies rarely involve cohorts and case-control studies allow no active control by the investigator. Either type of study can be prospective or retrospective. Results of studies with discrete outcomes (infected or not, lived or died) often are represented best by a form of the risk ratio with 95% confidence intervals. The potential distorting effects of selection bias, misclassification, and confounding need to be considered.

Exploratory Data Analysis offers a set of graphical and statistical tools to find the full meaning from data sets. The user visualizes, analyzes, and transforms data distributions with these tools. Graphs reveal relationships between variables; the residuals left after fitting data show the adequacy of the model. Without this careful examination and understanding of the data, rote data analysis using standard statistical tests can give misleading results. Exploratory Data Analysis has its own set of pitfalls and must be used with confirmatory statistics and studies. Increasing power and resolution in personal computers enables modern statistical software to make these methods widely accessible. By easily moving between data and their graphic representation, analysis can be comprehensive without being tedious. Exploratory Data Analysis can add an exciting and useful tool to the epidemiologist's repertoire. This article illustrates several tools from an evolving list.

Primary cutaneous aspergillosis is an uncommon entity that may occur in immunosuppressed hosts, usually resulting from contact with contaminated medical devices used in patient care. The infection spreads locally with subsequent skin necrosis due to angioinvasion and thrombosis. We report primary cutaneous aspergillosis following contact with contaminated gauze, and we review the relevant literature.

Dr. Glatt makes some thoughtful observations, and his recommendations are similar in many respects to those developed by the Public Health Service (PHS) with advice from expert consultants. However, the PHS did not recommend that new antiretroviral drugs be used routinely to treat lower-risk exposures, because relatively limited data are available on the safety and tolerability of the newer drugs and because the overwhelming majority of workers with lower-risk exposures will not become infected. (The average risk of human immunodeficiency virus [HIV] transmission is 0.3% after a percutaneous exposure to HIV-infected blood and less than that for a mucous membrane or skin exposure.)

There is increased media attention to healthcare outcome in the current reform atmosphere. Surgical care is a natural target for both print and electronic coverage. Hospital public relations departments often will be the interface with media representatives. Because surgical care outcome interpretation requires thoughtful evaluation of both single-patient and grouped-patient data, as well as knowledge of realistic risk-benefit ratios, it always is prudent to work with your local surgeon when the request for a story comes to the public relations department.

The group A streptococcus may cause pharyngitis, rheumatic fever, streptococcal toxic shock syndrome, and serious skin and soft-tissue infections. More than 50 nosocomial outbreaks have been reported since 1966. For this reason, healthcare facilities should develop policies for the diagnosis and treatment of symptomatic hospital employees, and for the recognition and management of potential outbreaks. The clinical diagnosis of streptococcal pharyngitis is unreliable. Rapid streptococcal tests may be used for initial screening, but a negative rapid test should be confirmed with a properly obtained culture. Penicillin remains the treatment of choice, but new alternatives now include a 5-day course of either azithromycin or cefpodoxime.