Clinical characteristics and treatment outcomes of patients with low- and high-concentration isoniazid-monoresistant tuberculosis.
BACKGROUND
Isoniazid (INH) resistance is now the most common type of tuberculosis (TB) infection resistance worldwide. The aim of this study was to evaluate the clinical characteristics and treatment outcomes of patients with low- and high-concentration INH-monoresistant TB.


METHODS
One hundred and thirty-four patients with culture-confirmed INH-monoresistant TB during 2006 January to 2007 December were retrospectively enrolled. INH resistance was classified as either low-concentration or high-concentration resistance according to the critical concentrations of 0.2 µg/mL or 1 µg/mL of INH, respectively. The patients' clinical outcomes, treatment regimens, and treatment duration were analyzed.


RESULTS
The treatment success rates between low- and high-concentration INH-resistant TB were similar (81.8% vs. 86.7%). The treatment regimens and treatment duration were similar between both groups. Only a minor percentage of the patients in both groups received 6-month treatment regimens (low vs. high concentration resistance, 9.1% vs. 13.3%; respectively, p = 0.447) The most common reason for treatment duration longer than 6 months was pyrazinamide given for less than 6 months, followed by a delay in clinical response to treatment. Multivariable analysis showed that prior tuberculosis treatment (Odds ratio, 2.82, 95% C.I., 1.02-7.77, p = 0.045) was the only independent risk factor for unsuccessful treatment outcome.


CONCLUSIONS
Different levels of INH resistance did not affect the treatment outcomes of patients with INH-monoresistant tuberculosis. Prolonged Rifampin-containing regimens may achieve those good outcomes in patients with low- and high-concentration INH-monoresistant TB.
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Tsai-Yu
TY
Wang
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Shu-Min
SM
Lin
Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Shian-Sen
SS
Shie
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Pai-Chien
PC
Chou
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Chien-Da
CD
Huang
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Fu-Tsai
FT
Chung
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Chih-His
CH
Kuo
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Po-Jui
PJ
Chang
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taipei, Taiwan.
Han-Pin
HP
Kuo
D000995:Antitubercular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D007538:Isoniazid / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D017211:Treatment Failure; D016896:Treatment Outcome; D014376:Tuberculosis / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality
D000995:Antitubercular Agents; D007538:Isoniazid