Treatment of isoniazid-resistant pulmonary tuberculosis.
BACKGROUND
Although resistance to isoniazid (INH) is the most common form of drug resistance seen among Mycobacterium tuberculosis isolates, there have been few studies on the efficacy and optimal duration of treatment for patients with INH-resistant tuberculosis (TB).


METHODS
We evaluated retrospectively the treatment outcomes of 39 patients who were treated for INH-resistant pulmonary TB. The treatment regimens consisted of a 12-month regimen of rifampin (RIF) and ethambutol (EMB), with pyrazinamide (PZA) given during the first 2 months (2HREZ/10RE) (n = 21), a 9-month regimen of RIF and EMB with PZA during the first 2 months (2HREZ/7RE) (n = 5), and a 6-month regimen of RIF, EMB, and PZA (2HREZ/4REZ) (n = 13). After drug susceptibility testing confirmed the INH-resistance of the isolated M. tuberculosis strains, INH was discontinued for all the patients.


RESULTS
Among the 39 patients, treatment was successfully completed by 36 patients (92%). However, treatment failure occurred, and acquired resistance to other first-line drugs, such as RIF, developed in three patients (8%). Cavitary and bilateral extensive lesions were commonly found in the chest radiographs of the patients who exhibited treatment failure.


CONCLUSIONS
These findings underline the seriousness of concerns regarding treatment failure and the development of multidrug-resistant TB in patients with INH-resistant TB following treatment with recommended regimens.
Kim
Yee Hyung
YH
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. yeehyung0@paran.com
Suh
Gee Young
GY
Chung
Man Pyo
MP
Kim
Hojoong
H
Kwon
O Jung
OJ
Lim
Seong Yong
SY
Lim
Si Young
SY
Koh
Won-Jung
WJ
D000328:Adult; D000368:Aged; D000995:Antitubercular Agents / Q000494:pharmacology*; D004334:Drug Administration Schedule; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination; D004977:Ethambutol / Q000494:pharmacology; D005260:Female; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology*; D008297:Male; D008485:Medical Audit; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D011718:Pyrazinamide / Q000494:pharmacology; D012189:Retrospective Studies; D012293:Rifampin / Q000494:pharmacology; D017211:Treatment Failure; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy*; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy*
D000995:Antitubercular Agents; D011718:Pyrazinamide; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin