Primary tuberculosis in children. 1. Incidence of primary drug-resistant disease in 332 children observed between the years 1961 and 1964 at the Kings County Medical Center of Brooklyn.

Resistant strains of Mycobacterium tuberculosis were recovered from cultures of gastric washings of children who had received no prior drug therapy and in whom demonstrable tuberculous disease was present. The incidence of primary strains resistant to streptomycin and PAS was of a low order (3 per cent) and comparable to that reported in adults. Combined-drug resistance was found in only 2 out of 101 strains. The incidence of primary isoniazid drug resistance, when analyzed by the United States Public Health Service criterion, was 16.3 per cent as compared to 6.3 per cent by the Veterans Administration criteria for resistance. Reasons are given for suggesting that the Veterans Administration criteria for isoniazid drug resistance may be more suitable than those of the United States Public Health Service for analysis of primary drug-resistant strains isolated from gastric washings in children. With the use of similar criteria for drug resistance the incidence of 6.3 per cent reported here for isoniazid was greater than that of 2.6 per cent for adults reported in New York City in 1961, the most suitable population group for comparison. The lower incidence of primary resistant disease in the adult group may be in part a reflection of disease due to endogenous reinfection by sensitive organisms acquired during childhood before the use of isoniazid. Since the factor of endogenous reinfection is eliminated in the present study the incidence of primary resistant disease reported here probably represents transmission of infection by individuals in the community whose organisms had become resistant during treatment. Another factor contributing to the higher incidence of resistant infection in the present group may be that the patients in the present study were drawn from a limited geographic area and one of high risk for tuberculosis. Since the incidence of primary drug-resistant disease represents, in a measure, the level of tuberculosis control in a given community, continuing studies are necessary to determine its rate of increase or decrease. Such studies are now in progress.