Nature of drug resistance and predictors of multidrug-resistant tuberculosis among patients seen at the Philippine General Hospital, Manila, Philippines.

The authors conducted a study at the University of the Philippines Philippine General Hospital in Manila to determine the nature of drug resistance among patients with pulmonary tuberculosis (PTB) and to identify the clinical predictors of drug-resistant tuberculosis (TB). M. tuberculosis isolates from 299 patients were tested for susceptibility to rifampicin isoniazid (INH) ethambutol and streptomycin using the submerged disc proportion method while a pyrazinamide (PZA) susceptibility test was undertaken with standard laboratory powder in 7H10 media. 16.7% of the 299 isolates were fully susceptible to the 5 primary drugs and 54% were resistant to 2 or more drugs. Levels of initial drug resistance among the 249 patients with resistant TB were 39% with ethambutol 17% with INH 10% with PZA 8% with rifampicin and 7% with streptomycin. Patients with acquired drug resistance had higher resistance rates to isoniazid rifampicin and ethambutol. Previous history of anti-tuberculosis treatment was significantly associated with multidrug resistant TB (MDR-TB) with incomplete anti-TB treatment taken for longer than 3 months increasing the probability of MDR-TB.