High proportion of multi-drug resistant Mycobacterium tuberculosis in Saudi Arabia.

289 patients with TB, presented to a single tertiary care unit in Saudi Arabia between 1989 and 1994. The isolate from each patient was tested for in vitro susceptibility to rifampicin, isoniazid, ethambutol, pyrazinamide and streptomycin. 25 patients (8.7%) had isolates resistant to at least 1 anti-tuberculous drug. Single drug resistance (SDR)-mainly isoniazid-occurred in 14, and resistance to at least 2 drugs (multi-drug resistance-MDR) in 11, of which 8 were due to both isoniazid and rifampicin. Previous drug treatment occurred significantly more often in patients with MDR (8/11), than SDR (1/14) (p = 0.0021). A literature review of another 5571 patients from Saudi Arabia with TB revealed an incidence of resistance of M. tuberculosis isolates to at least 1 anti-tuberculous drug tested, of between 5.9% and 44%. The overall percentage of patients with resistant tuberculosis (including our own patients) was 14.9%. Resistance to streptomycin (8.9%), isoniazid (6.6%), and rifampicin (6.1%) were the commonest reported. There were as many patients with MDR as there were SDR. A history of previous anti-tuberculous treatment was found in over 40%. The high rate of anti-tuberculous resistance in Saudi Arabia may be due to poor supervision of anti-TB treatment, the embryonic healthcare system, over-the-counter antibiotic availability, treatment of endemic diseases such as brucella with rifampicin etc., a large migrant work force, and possibly increased toxicity of anti-tuberculous drugs secondary to the high incidence of chronic liver disease in the country.