The Relation Between the Emergence of Fluoroquinolone Resistance and Fluoroquinolone Exposure in New Cases of Active Pulmonary Tuberculosis.

OBJECTIVE This study aimed to determine the ratio of fluoroquinolone (FQ) exposure before the diagnosis of patients with a new case of active pulmonary tuberculosis (TB) and to investigate the correlation of this treatment with the emergence of FQ-resistant strains. MATERIAL AND METHODS In this retrospective comparative case series study, a total of 132 patients, who had been diagnosed with adult, culture-positive, active pulmonary TB were reviewed. The FQ group had 30 patients who had had ≥1 time and ≥7 days of FQ exposure within 1 year before the diagnoses. The control group included an equal number of patients with TB with similar demographic characteristics (non-FQ group). Ofloxacin (OFX) and moxifloxacin (MFX) resistance were examined at 2 different concentrations (2 and 4 mg/L for OFX; 0.25 and 0.5 mg/L for MFX). RESULTS Of the 132 patients, 30 (22%) had 7 days or longer of FQ monotherapy within 1 year of initiation of anti-TB treatment. FQ resistance was detected in 2 (3.3%) patients. In the FQ group, MFX resistance at 0.25 mg/L concentration was observed in 1 patient, whereas another patient had OFX and MFX resistance at 4 mg/L and 0.5 mg/L concentrations, respectively. In the non-FQ group, no FQ resistance was detected in any of the patients. No statistically significant difference in terms of development of FQ resistance was found between the ratios of FQ and non-FQ groups (p=0.492). Although there was no statistically significant difference, 2 patients, in whom resistance was detected, had FQ exposure before their diagnosis. CONCLUSION The FQ exposure ratio before the diagnosis is high (22%) in this cohort that includes patients with new active pulmonary TB, and the presence of patients with FQ resistance (even if only a few) should be a noteworthy and cautionary result in terms of FQ exposure and resistance development.