Antibiotic sensitivity of Mycobacterium tuberculosis isolates; a retrospective study from a Saudi tertiary hospital

This study aims to examine the antibiotic sensitivity of Mycobacterium tuberculosis isolates and its drug resistance. We also evaluated the relationship between demographic characteristics and tuberculosis (TB) drug susceptibilities.

A retrospective study was conducted to analyse the antibiotic sensitivity of M. tuberculosis isolates and its resistance to first-line anti-TB drugs. During the period 2008-2013, the medical records of 191 patients from the TB ward and the Out-Patient Department in an Eastern KSA tertiary hospital were reviewed.

We classified the specimens into two categories: extra-pulmonary and pulmonary TB. Among the extra-pulmonary TB specimens, 36.5% were from body fluids, 29.2% from tissue cultures and 5.2% from body abscesses. In case of pulmonary TB, sputum samples accounted for the highest proportion of the specimens (28.6%), followed by bronchial aspirates and pleural fluid (13.2% and 5.7%, respectively). Clinical isolates from women showed higher resistance to ethambutol compared to those from men. Isoniazid showed the highest resistance pattern among all antibiotics tested (17%). Meanwhile, tissue cultures had higher resistance to Isoniazid antibiotic compared to the other specimens.

Resistance to first-line TB drugs is higher in extra-pulmonary TB isolates than pulmonary isolates. Nearly one-fourth of all M. tuberculosis clinical strains were resistant to the antibiotics tested in mono-resistant or multi-resistant manners. Women had greater resistance to TB drug ethambutol as compared to men. Meanwhile, extra-pulmonary TB specimens, specifically that from tissue cultures, showed greater resistance to Isoniazid than other clinical specimens.