“TRANSIENT INFECTION” OF THE LUNG DUE TO <I>MYCOBACTERIUM AVIUM-MYCOBACTERIUM INTRACELLULARE COMPLEX</I>

Previously, Tsukamura observed that there were a number of patients, who showed negative conversion of sputum cultures within three months after the onset of lung disease due to M. avium-M. intracellulare complex (M. avium complex) and showed the closure of cavities within six months. Such cases were named as “transient infection” cases. In the present study, the frequency and the back ground factors of the transient infection cases were investigated.<BR>The disease due to M. avium complex was diagnosed according to the criteria shown in Table1, and types of the disease were classified and defined as shown in Table2. For the diagnosis of transient infection, it is important to make daily sputum examinations at early stage of the disease, as, in these cases, sputum conversion occurs soon after the onset of disease. In the National Chubu Hospital, daily sputum examinations were carried out in all newly hospitalized patients since 1974. The frequency of transient infection cases thus found among patients with the disease due to M. avium complex was ca. 22% (9/41) (Table3).<BR>No patient with dusty occupation was found among the patients with transient infection, whereas such patients* were found at a rate of 24% (7/29) among intermittent and continuous excreters (Table4) (*Three welders, one cloisonne worker, one ceramist (potter), one molding worker, and one artificial teeth factory worker.).<BR>All patients with transient infection showed fresh lesions in their chest X-ray at the onset of disease, and were considered to belong to “primary infection-type”. In contrast, ca. 55% (16/29) of intermittent and continuous excreters showed cavities with sclerotic lesion (Table 5), which were suggested to belong to “secondary infection-type” (infection to tuberculous cavities).<BR>The average age of patients with transient infection was younger than that of intermittent or continuous excreters (Table6).<BR>The frequency of transient infection in three other hospitals, Kinki, Tokyo and Fukuoka, where no intended daily sputum examinations were carried out, was ca. 6% (13/225) (Table7). The X-ray feature, sex, and age of patients in all four hospitals are shown in Tables 8 and 9, and the chemotherapy used for the patients with transient infection is shown in Table 10. Out of 22 patients with transient infection, five (23%) showed negative conversion by a regimen of SM-INH-PAS, which has never been reported as effective for the treatment of the disease due to M. avium complex. Moreover, there is no paper which has reported that the use of antituberculous agents succeeded certainly to produce the negative conversion in this disease. Considering these facts, it is suggested that the phenomenon of transient infection is not due to a success of chemotherapy but due to host superiority in host-parasite-relationship. Such background of transient infection as younger age, presence of fresh lesions, and absence of the history of dusty occupation, supports the above concept. It is considered that transient infection is a type of disease produced by a better balance of the host-parasite-relationship, and that the transient infection occupies the position of intermediate type between asymptomatic infection and established infection, in which persistent excretion of the organism and persistent presence of cavities are seen.