Objective: To investigate a possible nosocomial outbreak of tuberculosis (TB).
Design: Retrospective cohort study.
Setting: Community hospital.
Methods: We reviewed medical records, hospital infection control measures, and potential locations of nosocomial exposure. We examined the results of acid-fast bacilli (AFB) smears, cultures, and drug susceptibility testing, and performed a DNA fingerprint analysis. We observed laboratory specimen processing procedures and bronchoscope disinfection procedures. We also reviewed bronchoscopy records.
Results: In October 2000, three patients had bronchoscopy specimen cultures that were positive for Mycobacterium tuberculosis. Of the three, only one had clinical signs and symptoms consistent with TB and positive AFB sputum smears. The other two did not have signs and symptoms consistent with TB and had no known exposure to individuals with infectious TB. The three M. tuberculosis isolates had matching DNA fingerprints. No evidence of laboratory cross-contamination was identified. The three culture-positive specimens of M. tuberculosis were collected with the same bronchoscope within 9 days. This bronchoscope was inadequately cleaned and disinfected between patients, and the automated reprocessor used was not approved for use with the hospital bronchoscope.
Conclusions: One of the bronchoscopes at this hospital was contaminated with M. tuberculosis during bronchoscopy of an AFB-smear-positive patient. Subsequent specimen contamination likely occurred because the bronchoscope had been inadequately cleaned and disinfected. Patients who subsequently underwent bronchoscopy were also potentially exposed to M. tuberculosis from this bronchoscope.