Using DNA fingerprinting to detect transmission of Mycobacterium tuberculosis among AIDS patients in two health-care facilities in Puerto Rico

Fourteen cases of tuberculosis (TB) in Puerto Rico, diagnosed from April 1993 to April 1995, had the same DNA fingerprint, documenting disease caused by the same strain of Mycobacterium tuberculosis. The 14 cases were retrospectively investigated for epidemiologic links. Records were reviewed and staffs of the TB program, hospital/clinic, and AIDS residential facilities were interviewed. Half of the AIDS cases were epidemiologically related, providing evidence of TB transmission in an emergency department, an AIDS inpatient ward, and an AIDS residential facility. DNA fingerprinting allowed detection of M tuberculosis transmission, but contact investigators could have documented it sooner. Factors contributing to transmission included delayed diagnosis, prolonged infectiousness, inadequate discharge planning and infection control procedures, and poor communication between health-care facilities. The numbers of AIDS residential facilities are increasing and must understand proper monitoring of TB patients and infection control measures that prevent transmissions.