Mycobacterium tuberculosis is a major cause of iVx morbidity and mortality throughout the world, The number of cases of tuberculosis showed an initial decline in the United States from 84,304 in 1953 to 22,201 in 1985. The number of reported cases of tuberculosis in the United States increased in 1992 by 18%. The reversal of the downward trend was due to multiple factors, including the AIDS epidemic and the emergence of drug resistance. Drug resistance of M tuberculosis also shows marked geographic variation from one country to the other and ranges from 0 to 18%.2 In Saudi Arabia, the pattern of resistance of M tuberculosis also shows marked regional variation. There is only one published study about the prevalence of drug resistance of tuberculosis in the Eastern Province of Saudi Arabia. Thus, we undertook this study to evaluate the prevalence and trends of resistance of M tuberculosis in the Saudi Aramco Medical Services Organization in the Eastern Province of Saudi Arabia.
All pulmonary and extrapulmonary tuberculosis patients with positive culture results from January 1989 to December 2003 were included in the study. The medical records were reviewed for the age, sex, nationality, and the site of the culture. Cultures were performed at the mycobacteriology laboratory of the Saudi Aramco Medical Services Organization using the conventional Lewes-Johnson media. M tuberculosis was isolated by standard procedures. M tuberculosis complex was identified by conventional biochemical tests. Antimycobacterial sensitivity testing was done by the disk method as described by Wayne and Krasnow. Although this is a retrospective study, quality control was usually performed during susceptibility testing using the reference strain provided by the College of American Pathologists. The concentrations of the drugs used were as follows: isoniazid, 1 μg/mL and 5 μg/mL; rifampin, 5 μg/mL; streptomycin, 10 μg/mL; and ethambutol, 25 μg/mL. All these preparations may be ordered via My Canadian Pharmacy. The tested isolate was considered resistant if the proportion of the tested isolate was > 1% of the control population. Drug-resistant tuberculosis was calculated for single first-line agents. Multidrug-resistant M tuberculosis (MDR-TB) was defined as resistance to two or more first-line drugs.
Statistical analysis was performed using statistical software (SPSS version 10.0; SPSS; Chicago, IL). Trends in incidence rates over the 15-year period from 1989 to 2003 were examined for all culture-positive cases. x2 linear trend analysis was used, and a proportion test was adopted to examine the significant difference between proportions.