Time to Sputum Culture Conversion and Treatment Outcomes among Patients with Isoniazid-Resistant Tuberculosis in Atlanta, Georgia

Marcos C. Schechter, Destani Bizune, Michelle Kagei, Mamuka Machaidze, David P. Holland, Alawode Oladele, Yun F. Wang, Paulina A. Rebolledo, Susan M. Ray, Russell R. Kempker

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Background Although isoniazid-resistant tuberculosis is more common than multidrug-resistant tuberculosis, it has been much less studied. We examined the impact of isoniazid resistance and treatment regimen, including use of a fluoroquinolone, on clinical outcomes. Methods A retrospective cohort study among patients with sputum culture-positive tuberculosis was performed. Early fluoroquinolone (FQ) use was defined as receiving ≥5 doses during the first month of treatment. The primary outcome was time to sputum culture conversion (tSCC). A multivariate proportional hazards model was used to determine the association of isoniazid resistance with tSCC. Results Among 236 patients with pulmonary tuberculosis, 59 (25%) had isoniazid resistance. The median tSCC was similar for isoniazid-resistant and -susceptible cases (35 vs 29 days; P =.39), and isoniazid resistance was not associated with tSCC in multivariate analysis (adjusted hazard ratio = 0.83; 95% confidence interval [CI],.59-1.17). Early FQ use was higher in isoniazid-resistant than -susceptible cases (20% vs 10%; P =.05); however, it was not significantly associated with tSCC in univariate analysis (hazard ratio = 1.48; 95% CI,.95-2.28). Patients with isoniazid-resistant tuberculosis were treated with regimens containing rifampin, pyrazinamide, and ethambutol + a FQ for a median of 9.7 months. Overall, 191 (83%) patients were cured. There was no difference in initial treatment outcomes; however, all cases of acquired-drug resistance (n = 1) and recurrence (n = 3) occurred among patients with isoniazid-resistant tuberculosis. Conclusions There was no significant association with isoniazid resistance and tSCC or initial treatment outcomes. Although patients with isoniazid-resistant tuberculosis had a high cure rate, the cases of recurrence and acquired drug resistance are concerning and highlight the need for longer-term follow-up studies.

Original languageEnglish (US)
Pages (from-to)1762-1771
Number of pages10
JournalClinical Infectious Diseases
Issue number11
StatePublished - Dec 1 2017
Externally publishedYes


  • fluoroquinolones
  • isoniazid resistance
  • time to sputum culture conversion
  • tuberculosis

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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