Image processing techniques for identifying Mycobacterium tuberculosis in Ziehl-Neelsen stains.

Worldwide, laboratory technicians tediously read sputum smears for tuberculosis (TB) diagnosis. We demonstrate proof of principle of an innovative computational algorithm that successfully recognizes Ziehl-Neelsen (ZN) stained acid-fast bacilli (AFB) in digital images. Automated, multi-stage, color-based Bayesian segmentation identified possible 'TB objects', removed artifacts by shape comparison and color-labeled objects as 'definite', 'possible' or 'non-TB', bypassing photomicrographic calibration. Superimposed AFB clusters, extreme stain variation and low depth of field were challenges. Our novel method facilitates electronic diagnosis of TB, permitting wider application in developing countries where fluorescent microscopy is currently inaccessible and unaffordable. We plan refinement and validation in the future.

Isoniazid preventive therapy, hepatitis C virus infection, and hepatotoxicity among injection drug users infected with Mycobacterium tuberculosis.

Treatment of latent Mycobacterium tuberculosis infection with isoniazid can cause hepatotoxicity, but the risk of isoniazid-associated hepatotoxicity among persons coinfected with hepatitis C virus (HCV) is unknown. We conducted a prospective study among 146 injection drug users with M. tuberculosis infection and normal baseline hepatic transaminase values who were treated with isoniazid. Of 146 participants, 138 (95%) were HCV-seropositive. Thirty-seven participants (25%) were human immunodeficiency virus (HIV)-seropositive. Thirty-two (22%; 95% confidence interval [CI], 16%-30%) of 146 participants developed transaminase value elevations to >3 times the upper limit of normal. Transaminase value elevation was associated with concurrent alcohol use but not with race, age, presence of hepatitis B surface antigen, HIV-1 infection, or current injection drug use. Isoniazid was withdrawn from 11 participants (8%; 95% CI, 4%-13%). Of 8 deaths during follow-up, none were attributed to isoniazid-associated hepatotoxicity. The risk of transaminase value elevation and drug discontinuation for HCV-infected persons receiving isoniazid was within the range reported for populations with lower HCV prevalence.