Recent data conflict on the clinical efficacy of later-generation
fluoroquinolones, such as
moxifloxacin or
levofloxacin, for the treatment of
multidrug-resistant tuberculosis (MDR-TB) that is resistant to
ofloxacin but susceptible to
moxifloxacin. The purpose of the present study was to evaluate whether later-generation
fluoroquinolones can improve treatment outcomes in patients with
ofloxacin-resistant,
moxifloxacin-susceptible MDR-TB. A retrospective cohort study was performed on 208 patients with
moxifloxacin-susceptible MDR-TB who were treated between 2006 and 2011. Later-generation
fluoroquinolones were used for all patients. Overall, 171 patients (82%) had
ofloxacin-susceptible,
moxifloxacin-susceptible MDR-TB (
ofloxacin-susceptible group), and 37 (18%) had
ofloxacin-resistant,
moxifloxacin-susceptible MDR-TB (
ofloxacin-resistant group). Compared to the
ofloxacin-susceptible group, the
ofloxacin-resistant group was more likely to have a history of MDR-TB treatment (P < 0.001) and cavitary lesions on chest radiography (P < 0.001). In addition, the
ofloxacin-resistant group was more likely than the
ofloxacin-susceptible group to have resistance to the drugs
pyrazinamide (P = 0.003),
streptomycin (P = 0.015),
prothionamide (P < 0.001), and
para-aminosalicylic acid (P < 0.001). Favorable outcomes were more frequently achieved for the
ofloxacin-susceptible group than for the
ofloxacin-resistant group (91% [156/171] versus 57% [21/37], respectively [P < 0.001]). In multivariable regression logistic analysis, the
ofloxacin-susceptible group was about 5.36 (95% confidence interval, 1.55 to 18.53) times more likely than the
ofloxacin-resistant group (P < 0.001) to have favorable outcomes. Despite in vitro
moxifloxacin susceptibility, the frequency of favorable treatment outcomes for
ofloxacin-resistant MDR-TB was significantly lower than that for
ofloxacin-susceptible MDR-TB, even when later-generation
fluoroquinolones were used, indicating that more-aggressive
therapies may be needed for
ofloxacin-resistant MDR-TB.