[A case of environmental infection with pulmonary Mycobacterium avium complex disease from a residential bathroom of a patient suggested by variable-number tandem-repeat typing of Mycobacterium avium tandem repeat loci].

A 63-year-old woman was referred to our hospital because of bilateral infiltrations and nodular opacities in her chest radiograph taken in the mass radiography screening in September 2010. The chest computed tomography showed patchy infiltrations with bronchiectasis in the lower lung fields on both sides. She was diagnosed with pulmonary Mycobacterium avium complex (MAC) disease based on the bacteria recovered from the sputum and the bronchoalveolar lavage fluid. To elucidate an environmental MAC source, we investigated her home, and isolated M. avium and M. gordonae from the bathtub and shower tap, respectively, in her residential bathroom. Analysis of the hsp65-PRA variants digested with BamHI and some insertion sequences showed that the clinical strains recovered from sputum and strains from the bathtub were M. avium subsp. hominissuis. A dendrogram of the Mycobacterium avium tandem repeat loci variable-number tandem-repeat (MATR-VNTR) analysis of the MAC strains showed that the bathtub strains formed a polyclonal colonization, and that 1 of the 5 MATR-VNTR patterns was identical to the corresponding pattern of the sputum strain from the patient. In conclusion, we believe that the residential bathroom of the patient was the environmental source of her pulmonary MAC disease, as has been previously reported.

[A study of genetic characteristics of Mycobacterium avium strains from patients with pulmonary M. avium disease in Japan and Korea].

INTRODUCTION: To determine the characteristics of Mycobacterium avium in Japan, we compared the genetic properties of M. avium isolated in different countries. METHODS: A Mycobacterium avium tandem-repeat variable-number tandem-repeat (MATR-VNTR) analysis was performed using South Korean strains (n = 119) and Japanese strains (n = 76). In addition, we compared the frequencies of a new insertion sequence, ISMav6. RESULTS: A phylogenetic analysis identified different clusters between the two countries' strains. The prevalence of ISMav6 was significantly different between them, i.e., 75.0% in Japanese strains and 59.8% in the Korean ones (P < 0.035). The frequency of strains with IS Mav6 in the Shine-Dalgarno (SD) sequence of the cfp29 gene that is involved in the interferon-gamma induction was also different, with stronger significance (Japan: 38.2%, Korea: 12.4%, P < 0.001). DISCUSSION: It is possible that M. avium strains prevalent in Japan and in Korea are genetically distinct. The analyses of the presence of ISMav6, as well as the VNTR patterns of M.avium strains from many different countries would be a promising methodology in elucidating the causes of the recent increase in cases of pulmonary MAC diseases.

[Identification of novel variable number tandem repeat (VNTR) loci in Mycobacterium avium and development of an effective means of VNTR typing].

INTRODUCTION: To make more effective use of variable number tandem repeat (VNTR) typing, we identified novel VNTR loci in Mycobacterium avium and used them for modified M. avium tandem repeat-VNTR (MATR-VNTR) typing. METHOD: Analysis of a DNA sample extracted from a clinical isolate (strain HN135) with the FLX system genome sequencer (Roche Diagnostic System) led to discovery of several novel VNTR loci. The allelic diversity of the novel VNTR loci was evaluated for 71 clinical isolates and compared with the diversity of the MATR-VNTR loci. To improve efficacy of MATR-VNTR typing, we tested typing using 2 sets of loci selected from the newly identified loci and the MATR loci, i.e., one set containing 7 and another 16 loci. Hunter Gaston's discriminatory index (HGDI) was calculated for these sets. RESULTS: Six VNTR loci were newly identified, of which 5 showed a high diversity. The HGDI was 0.980 for the improved new typing using a set of 7 loci, and 0.995 for another set of 16 loci, while it was 0.992 for the conventional MATR-VNTR typing. DISCUSSION: VNTR typing with the set of the 7 loci enabled a rapid analysis, and another set of 16 loci enabled a precise analysis, as compared with conventional MATR-VNTR typing. A method that uses only VNTR loci with relatively high allelic diversity is considered to be a useful tool for VNTR typing of MAC isolates.

Acquired immune-deficiency syndrome with focal onset of Mycobacterium avium infection displaying a histological/genetic pattern of disseminated mycobacteria.

A 66-year-old man with human immunodeficiency virus (HIV) infection was admitted for treatment of Pneumocystis pneumonia. Upon admission, a tumor mass adjacent to the thoracic descending aorta was revealed on computed tomography. Histology revealed an exudative granuloma with histiocytes packed with numerous acid-fast bacilli. Mycobacterium avium was isolated from the tissue. A genetic examination of the isolates demonstrated this strain to be located in the cluster consisting of strains that cause systemic infection. The patient's baseline CD4+ cell count was 9/µL and the HIV-RNA viral load was 43,800 copies/mL. This case suggests the possibility of a localized onset of disseminated M. avium infection.