Abstract
ObjectiveTo determine the extent of drug resistance in multidrug-resistant tuberculosis (MDR-TB) cases, we conducted a retrospective, population-based analysis using drug susceptibility testing (DST) results of MDR Mycobacterium tuberculosis complex isolates obtained from 2007–2014 in Taiwan.MethodsM. tuberculosis isolates collected from 1,331 MDR-TB cases were included in this survey. Treatment histories, age, sex, chest radiograph and bacteriological results of patients were analyzed. Standard DST was performed to assess resistance to the following drugs: isoniazid (INH), rifampicin (RIF), streptomycin (SM), ethambutol (EMB), amikacin (AM), kanamycin (KM), capreomycin (CAP), ofloxacin (OFX), moxifloxacin (MOX), levofloxacin (LVX), gatifloxacin (GAT), para-aminosalicylate (PAS), ethionamide (EA), and pyrazinamide (PZA). The Cochran-Armitage trend test was used for statistical analysis.ResultsWe observed a significant increasing trend in portion of new MDR-TB cases, from 59.5% to 80.2% (p < 0.0001), and significant decreasing trend of portion in the 15-44-year-old age group (p < 0.05). Of the MDR M. tuberculosis isolates tested, 6.2% were resistant to AM, 8.6% were resistant to KM, 4.6% were resistant to CAP, 19.5% were resistant to OFX, 17.1% were resistant to MOX, 16.0% were resistant to LVX, 5.8% were resistant to GAT, 9.5% were resistant to PAS, 28.5% were resistant to EA and 33.3% were resistant to PZA. Fifty (3.8%) extensively drug-resistant TB cases were identified. No significant differences were found in drug resistance frequencies between new and previously treated MDR cases. However, we observed significant decreases in the rates of AM resistance (p < 0.05), OFX resistance (p < 0.00001), PAS resistance (p < 0.00001), EA resistance (p < 0.05) and PZA resistance (p < 0.05). Moreover, younger age groups had higher rates of resistance to fluoroquinolones.ConclusionA policy implemented in 2007 to restrict the prescription of fluoroquinolones was shown to be effective. Our survey revealed a decreasing trend of resistance to PZA, OFX and AM, which suggests the feasibility of adopting a short-course regimen and demonstrates the effectiveness of our management program for MDR-TB.
Highlights
Tuberculosis (TB) is a major infectious disease worldwide
Of the MDR M. tuberculosis isolates tested, 6.2% were resistant to AM, 8.6% were resistant to KM, 4.6% were resistant to CAP, 19.5% were resistant to OFX, 17.1% were resistant to MOX, 16.0% were resistant to LVX, 5.8% were resistant to GAT, 9.5% were resistant to PAS, 28.5% were resistant to EA and 33.3% were resistant to PZA
Multidrug-resistant TB (MDR-TB), defined as TB caused by Mycobacterium tuberculosis that is resistant to at least isoniazid (INH) and rifampicin (RIF), is an increasing problem in global TB control
Summary
The World Health Organization (WHO) estimated that there are 9.6 million new TB cases and 1.5 million deaths annually [1]. In 2014, there were 11,326 new TB cases and 591 deaths were notified in Taiwan. The TB incidence increased with age and 52.1% of new TB cases were in the age group of 65 years old or over. Multidrug-resistant TB (MDR-TB), defined as TB caused by Mycobacterium tuberculosis that is resistant to at least isoniazid (INH) and rifampicin (RIF), is an increasing problem in global TB control. In 2014, there were an estimated 480,000 cases of MDR-TB, comprising 5% of all incident TB cases (3.3% of new cases and 20.0% of previously treated cases) [1, 4]. In Taiwan, MDR-TB accounted for approximately 1% of annual new TB cases and 6% of retreatment cases [2]
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