Retrospective evaluation of natural course in mild cases of Mycobacterium avium complex pulmonary disease

Abstract

Background There is no proven management for mild cases of Mycobacterium avium complex (MAC) pulmonary disease, who do not immediately receive treatment and are managed with observation alone, because its long term-natural course, factors predictive of deterioration, and the effect of treating the disease remain unclear. Thus, we sought to investigate the natural course of mild cases of MAC pulmonary disease. Methods We conducted a multicenter retrospective study. Sixty-five patients with mild MAC pulmonary disease in whom treatment was withheld for at least 6 months after diagnosis were retrospectively recruited after a review of 747 medical records. Longitudinal changes in clinical features were evaluated by using a mixed effects model. Results Mean follow-up was 6.9 ± 5.7 years. During the follow-up period, 15 patients (23%) required treatment and 50 (77%) were managed with observation alone. At diagnosis, 65 patients had nodular bronchiectatic disease without fibrocavitary lesions. Among clinical features, mean body mass index (BMI), forced expiratory volume in 1 second as percent of forced vital capacity (%FEV 1 ), nodular lung lesions, and bronchiectasis worsened significantly in the observation group during follow-up. In the treatment group, BMI, and %FEV 1 were stable, but bronchiectasis significantly worsened. At diagnosis, the polyclonal MAC infection rate in the treatment group was higher than that in the observation group. Other microbiological factors, such as insertion sequences, did not differ significantly between the groups. Conclusions Mild MAC pulmonary disease progresses slowly but substantially without treatment. Treatment prevents the deterioration of the disease but not the progression of bronchiectasis. Polyclonal MAC infection is a predictor of disease progression.

Recent advances in nontuberculous mycobacterial lung infections

“…The natural history of nodular-bronchiectatic MAC lung disease is less certain, with studies suggesting that almost one-quarter of patients will have radiologic deterioration 26 and almost one-half require treatment initiation 27 over 2–5 years of follow-up. A recent retrospective study assessed patients with nodular-bronchiectatic MAC lung disease who were not treated with antibiotics for at least 6 months after diagnosis 28 . Over a mean follow-up period of 6.9 years, 23% of participants were started on treatment.…”

Methods for Detecting Mycobacterial Mixed Strain Infections–A Systematic Review

“…Our review showed that MSIs involving NTM have not been investigated to the same extent as compared to those caused by M. tuberculosis ( Table 2 ). Amongst the 121 mycobacterial studies identified, 26 (21.5%) examined NTM, of which 17 (14.0%) and eight (6.6%) found MSIs in humans and animals, respectively, whereas one report identified MSIs in both human (Arbeit et al, 1993 ; Slutsky et al, 1994 ; Von Reyn et al, 1995 ; Devallois and Rastogi, 1997 ; Picardeau et al, 1997 ; Wallace et al, 1998 ; Legrand et al, 2000a , b ; Oliveira et al, 2000 ; Saad et al, 2000 ; Dvorska et al, 2002 ; Panunto et al, 2003 ; Ohkusu et al, 2004 ; De Sequeira et al, 2005 ; Fujita et al, 2014 ; García-Pedrazuela et al, 2015 ; Kimizuka et al, 2019 ) and animal (Dvorska et al, 2007 ; Shitaye et al, 2008 ; Furphy et al, 2012 ; Gerritsmann et al, 2014 ; Johansen et al, 2014 ; Gioffré et al, 2015 ; Podder et al, 2015 ; Davidson et al, 2016 ; Pfeiffer et al, 2017 ) populations simultaneously (Pate et al, 2008 ). Many early studies used pulsed field gel electrophoresis (PFGE) to identify MSIs in 14.3–100% of patients infected with MAC bacteria (Arbeit et al, 1993 ; Slutsky et al, 1994 ; Von Reyn et al, 1995 ; Wallace et al, 1998 ; Ohkusu et al, 2004 ).…”

“…Kimizuka et al ( 2019 ) have also used a variety of VNTR loci, including 16 M. avium tandem repeats (MATR) and 5 Higashi Nagoya tandem repeats (HNTR) to identify M. avium MSIs in samples from nine patients (13.8%) out of 65 examined. Another study examined samples from 120 patients with pulmonary MAC infections (94 M. avium and 26 M. intracellulare ) (Fujita et al, 2014 ).…”

Prognosis of nontuberculous mycobacterial pulmonary disease according to the method of microbiologic diagnosis

“…Interestingly, in terms of radiographic aggravation, the non-sputum NTM-PD group clearly had worse prognosis than that of the sputum NTM-PD group; however, the prognosis was similar to that the sputum NTM isolation group. The decision to initiate treatment for suspected NTM-PD often depends on the guidelines [16]. Considering this, the high proportion of patients who initiated treatment in the non-sputum NTM-PD group may not indicate a more advanced disease compared to that in the sputum NTM isolation group.…”