PURPOSE: Sputum microscopy and culture for acid fast bacilli (AFB) remains the first diagnostic test for pulmonary tuberculosis (TB). However sputum smear is only 50% sensitive for diagnosing active pulmonary disease. Current guidelines recommend initiation of TB therapy pending AFB culture and further diagnostic work-up when there is high clinical suspicion. In hospitals with a low prevalence of disease, clinicians may have difficulty identifying appropriate patients in whom to begin therapy. We evaluated the management of smear negative TB at our hospital, a suburban hospital in the New York metropolitan area with a low prevalence of TB.
METHODS: We retrospectively reviewed all subjects with a specimen sent for AFB culture. Subjects >10 years of age with proven active pulmonary TB, as defined by positive culture of sputum, bronchoscopy or lung tissue, who had sputum samples submitted for AFB testing were identified. Charts were reviewed for age, sex, nationality, duration of symptoms or hemoptysis, PPD status, result of AFB smears and culture, and the day treatment was started.
RESULTS: Over 5 year period in our hospital, only 214 (4%) of 5211 samples sent for AFB culture grew TB. Charts from 21 subjects with pulmonary TB were reviewed. Mean age was 41.6±25.5 years; 76% were male; 93% were foreign born; 71% were PPD positive. Of the 39% who were smear positive, all were begun on anti-TB therapy. Of the 61% who were smear negative, 7 were treated pending cultures, 4 were discharged or expired without anti-TB treatment, and 2 were treated after >1 week of hospitalization when culture results returned.
CONCLUSION: Nearly 50% of the smear negative pulmonary TB patients were not treated prior to culture results despite significant risk factors of TB. Clinicians working at institutions with a low TB prevalence should maintain a high level of suspicion of active pulmonary disease, especially in high-risk groups.
CLINICAL IMPLICATIONS: Treatment of TB in suspected cases should be started pending workup despite negative AFB smears.
DISCLOSURE: Sean Dhar, None.