Objective: To determine the prevalence and risk factors on second-line drug resistance in patients with multidrug resistant tuberculosis (MDR-TB) in Shanghai, China.
Methods: All pulmonary TB patients with sputum culture positivity detected in Shanghai during January to December, 2009, were enrolled. All of the pretreatment sputum-positive cultures samples were tested for routine specimen identification and routine drug susceptibility testing for first-line drugs (Isoniazid, Rifampin, Ethambutol and Streptomycin). Drug susceptibility testing on second-line anti-TB drugs (Ofloxacin, Amikacin, Kanamycin, Capreomycin, P-aminosalicylic acid and Prothionamide) was routinely performed on isolates of Mycobacterium (M.) TB with MDR. Logistic regression analysis was conducted to determine the risk factors regarding second-line drug resistance.
Results: A total of 1867 patients infected with M. TB isolates were diagnosed at the TB hospitals/clinics in Shanghai during the study period, of whom 112 (6.0%) were MDR-TB, in which 58 cases (51.8%) showed resistant to at least one of the second-line drugs tested and 10 cases belonged to extensively drug-resistant. In the multivariate analyses, MDR-TB patients who were aged 45 - 59 years (aOR = 4.76, P = 0.001), with sputum smear positivity (aOR = 6.51, P = 0.026) were significantly more likely to show resistance to second-line drugs.
Conclusion: The prevalence of second-line drug resistance among MDR-TB patients was high in Shanghai. MDR-TB patients who were under age of 45 - 59 years and with sputum smear positivity would represent important common risk factors for the resistance to second-line drugs.