Impact of anti-tuberculosis legislation in Libya on the prevalence of primary and acquired resistance to the three main drugs at a majortuberculosis centre.

The effect of legislative actions taken in 1973 on the prevalence of primary and acquired drug resistance was studied from the records on the Regional Tuberculosis and Chest Diseases Centre in Benghazi during the period June 1971 to August 1976. There were available for analysis 771 culture-positive cases of newly diagnosed pulmonary tuberculosis in Libyan nationals, and 789 cases of both Libyan nationals and others with positive cultures during treatment. The legislative actions included screening of all foreign and local workers for tuberculosis before employment or in the course of employement for those already employed and strict control of the use of antituberculosis drugs, which were not made available to private practitioners, private pharmacies, general dispensaries and general hospitals. The proportion of newly diagnosed cases with resistance to one or more of the 3 drugs streptomycin, isoniazid, PAS (resistance to PAS was negligible, occurring in only 0.7% of the whole series) during the first 3 months of the survey was 16.6%. During the first 9 3-month periods there was a small decrease of 0.15% per quarter. However, after adoption of the antituberculosis measures in mid-1973 the rate of decline accelerated to 0.61% per quarter, a 4-fold increase over the earlier rates (P less than 0.001 for comparison of rates). If the rate of decline observed in the first 9 quarters had continued unchanged the expected proportion resistant at the end of the period would have been 13.5%, compared with the observed proportion of 8.6%. The proportion of patients under treatment from whom resistant cultures were isolated was 33.3% in the first quarter. It remained at about this level until the 14th quarter, approximately a year after the legislation came into force, when the proportion began to decline. By the end of the period it was only 14.7%.