INTRODUCTION: Development of drug resistance is one of the most important barriers in achieving global control of tuberculosis (TB). Continuous surveillance, such as observation of susceptibility and resistance patterns to anti-TB drugs, together with nationwide programs aimed at TB case identification, treatment and control, physician and patient education, is a valuable tool in the goal towards reducing TB prevalence and mortality.
OBJECTIVE: It is the aim of this study to determine the prevalence rate and resistance pattern of  first line anti-tuberculosis drugs in a tertiary hospital in Manila, Philippines
MATERIALS AND METHODS: Records of specimens submitted for Mycobacterium tuberculosis (MTB) culture and sensitivity, using BACTEC TM MGIT TM 960 SIRE Kit and PZA Kit, at the Section of Clinical Pathology, University of Santo Tomas Hospital, were reviewed. Isolates cultured for MTB were subjected to sensitivity studies to rifampicin (R),isoniazid (H), ethambutol (E), pyrazinamide (Z) and streptomycin (S).
RESULTS: A total of 546 specimens were cultured for MTB and sent for sensitivity studies. Majority of the specimens were from pulmonary sources (77%). Overall resistance rate was 52.38% (n=286). One-drug resistance was 23.26% (n= 127; highest with R followed by H); two-drug resistance was 15.38% (n=84; highest with H-R); three-drug resistance was 8.61% (n=47; highest with H-R-E and H-R-S); four-drug resistance was 4.58% (n=25; highest with H-R-E-S) and five-drug resistance (H-R-E-S-Z) rate was 0.55% (n=3). 
CONCLUSION: The University of Santo Tomas Hospital, as a referral facility, is encountering an increasing number of drug-resistant tuberculosis from 2003 to 2013.

Human ; Male ; Female ; Aged ; Middle Aged ; Adult ; Ethambutol ; Mycobacterium Tuberculosis ; Isoniazid, Pyrazinamide, Rifampin Drug Combination ; Pyrazinamide ; Isoniazid ; Rifampin ; Streptomycin ; Pathology, Clinical ; Tuberculosis