This is a report of 4 cases, considered as caused by exogenous reinfection. They were all females, over 48 years old, and had never been treated or treated only for a few days. Bacilli isolated initiallyfrom these patients were sensitive to 8-10 drugs, but when relapse occurred bacillis became resistanteven to the drugs which had never been used before.
In the 1st case, the change in drug resistance pattern took place between 3rd and 6th month fromthe start of chemotherapy, when the bacilli were still scarcely positive. In the other 3 cases, relapsewas found 1-21 months after the completion of their chemotherapy.
The infection source of drug resistant bacilli was not clear for the 1st and 2nd cases. It was suspected, however, that the 3rd case was probably infected from the 2nd case, and the 4th case from the3rd case, because their drug resistant pattern was quite similar, and the relapse of each case occurredapproximately the same period after they shared the same room.
The prognosis of these cases were as follows: Case 1 had finally a favourable result with cavityclosure and bacilli conversion in spite of all the ineffective chemotherapy after relapse. Case 2 is stillalive, 2 years and 10 months after relapse, though her general condition is quite poor, discharginglarge amount of bacilli with extensive bilateral lung lesions. In cases 3 and 4, their initial 6 monthschemotherapy was very effective but relapse had occurred. All the drugs were ineffective and diedwithin 12 and 4 months, respectively.
Case 3 had been treated by predonin for scleroderma over 2 years before the onset of pulmonarytuberculosis. This predonin therapy was continued until her death and in her clinical course a goodresponse to the 1st chemotherapy was seen until the occurrence of relapse. In her case, it is suspectedthat she had some immune depression, but no special investigations about this purpose were done.Only the number of lymphocyte was found to be slightly decreased. According to the findings at autopsy, almost all the lesions were exsudative in their character, necrotic with numerous acid fast bacilliand no tendency of granulom formation. These findings might be a proof of the presence of immune depression.
Primary and secondary complex could not be found anywhere, although intensive and exhaustiveinvestigations including X-ray photography of the sliced lung were done. In the sinusoid of the hilarlymphnode, agromelation of histiocyte which showed the tendency of necrosis with quite a few acidfast bacilli was found, however, no caseous change or granulom formation was visible there. Thisfinding could not be the direct proof of the exogenous reinfection.
Onset of pulmonary tuberculcsis caused by exogenous reinfection is thought to be very rare inJapan, except in such special cases as laboratory workers dealing with tubercle bacilli or the immunedepressed patients under haemodialysis, steroid treatment or complicated with some kind of diseases.Old patients could be included in this category, however, the more detailed essential conditions causingthe exogenous reinfection are not yet fully clarified.
