Is Serious Pulmonary Disease Caused by Nonphotochromogenic ("Atypical") Acid-Fast Mycobacteria Communicable

¹ Battey State Hospital, Rome, Georgia.

It has been shown that 158 patients, about one per cent of 15,180 patients, admitted during the past 10 years had demonstrable pulmonary lesions associated with non-photochromogenic mycobacteria in the sputum.

At one time or another, 81 per cent of them had lived on a farm. The ratio of patients per 100,000 population ranged from 4 to 15 times higher in rural and small town areas than in the large, urban centers. The incidence of the disease was higher in the southern than in the northern part of the state.

There was no history or evidence that the spouses of 151 married or widowed patients had ever had tuberculosis.

Pretreatment susceptibility of these organisms to streptomycin showed that 58 patient strains of 81 examined were susceptible, 23 partially resistant and none resistant. The strains of 80 patients were examined for susceptibility to isoniazid and all of whom were resistant.

Response to streptomycin plus PAS, INH plus PAS, or, to all three drugs given simultaneously, was poor. The sputum of about 70 per cent remained positive after many months and even years of treatment.

Only 68 per cent were positive to OT or PPD. Of 51 tested with PPD-S and PPD-B, 54 per cent were positive to S, and 85 per cent were positive to B.

Among 458 household contacts, 27 per cent were positive to OT or PPD. Among 296 household contacts tested with PPD-S and PPD-B, only 15 per cent were positive to S and only 35 per cent were positive to B.

The percentage of positive reactors to B was twice as high in men as in women. The percentage of reactors of all contacts was only 6 per cent greater than that found among a group of 140 non-contacts.

The incidence of positive reactors to PPD-B has been found to be greater in the Negro, in all groups tested, than in the white race. However, the incidence of disease in the Negro was found to be only 11.7 per cent of that found in the two races combined. Yet, of the 15,180 patients admitted, 41 per cent were Negroes.

If a 6 mm. or greater induration to PPD-B is accepted as being specific, the incidence of infection is high. However, the incidence of known disease is rare.

From the evidence at hand, we conclude that the source of infection may well be environmental, and that the organisms may be avirulent to man except under certain circumstances or predisposing conditions.