The numbers game: sample-size determination.

Sample-size determination is a crucial component of study design. Estimates of sample size are influenced by the amount of change that must occur between study groups and the degree of risk that the investigator is willing to accept in evaluating the null hypothesis. A complete understanding of the impact of sample size on the interpretation of study data is therefore a prerequisite for quality, innovative, valid research.

Job analysis 1992: infection control practitioner.

The Certification Board of Infection Control directed its Research Subcommittee to compose a Job Analysis Committee in 1991. This 9-member Job Analysis Committee, in collaboration with Applied Measurement Professionals, Inc., conducted a job analysis of ICPs during 1992. The reassessment of the previous Certification Board of Infection Control task analysis, formation of a job-analysis survey tool, and the actual job-analysis process and its results are described in this article. The previous and newly revised test specification outlines are compared. The national Certification Examination for Infection Control for November 1993 will reflect the efforts of this endeavor.

A cluster of four cases of Mycobacterium haemophilum infection.

Four cases of infection with Mycobacterium haemophilum occurred at a single hospital in a seven-month period. Only 22 cases have been reported since 1976. All four patients were immunocompromised; two had AIDS and two were the first known recipients of allogeneic bone marrow transplants (BMT) to develop the infection. One BMT recipient died of Mycobacterium haemophilum pneumonia. The organism requires hemin or ferric ammonium citrate and incubation of media at 30 degrees C for optimum growth. Clinicians and microbiologists should consider infection with Mycobacterium haemophilum, particularly when specimens are from immunocompromised patients with unexplained illness and/or when acid-fast bacilli are seen on smear.