Molecular epidemiological characteristics of Mycobacterium abscessus complex in non-cystic fibrosis patients in Japan and Taiwan

Mycobacterium abscessus complex (MABC) is an emerging non-tuberculous mycobacterium (NTM). Specific MABC clones are reportedly spreading globally in cystic fibrosis (CF) patients, however, associated genomic epidemiology studies are lacking in East Asia. Analysis of whole-genome sequencing data for MABC isolates from 220 pre-treatment, non-CF patients in Japan and Taiwan revealed that 112/220, 105/220, and 3/220 were M. abscessus subsp. abscessus (ABS), M. abscessus subsp. massiliense (MAS), and M. abscessus subsp. bolletii (BOL), respectively. No significant differences in subspecies composition were noted based on location. Moreover, >50% of ABS and >70% of MAS were related to four predominant clones in the region. Known mutations conferring acquired macrolide resistance were rare (1.4%) and not enriched in the predominant clones. Conversely, the macrolide-susceptible erm(41) T28C mutation was significantly enriched in one predominant ABS clone. The most predominant ABS clone was genetically related to the dominant circulating clone (DCC). Hence, we have clarified the relationship between the predominant clones in Japan and Taiwan, and those reported in the international CF patient community. Our results provide insights regarding the genetic characteristics of globally dominant and area-specific strains isolated from patients with or without CF, as well as differences between globally spread and regionally-specific strains.

Decontamination Strategies Used for AFB Culture Significantly Reduce the Viability of Mycobacterium abscessus Complex in Sputum Samples from Patients with Cystic Fibrosis

Nontuberculous mycobacteria are important respiratory pathogens in patients with cystic fibrosis (CF). For diagnosis, international guidelines recommend culture of sputum that has been decontaminated via chemical treatment. Fifty-six sputum samples from 32 patients known to be previously colonized or infected with NTM were subdivided, and the aliquots were subjected to six different decontamination strategies, followed by quantitative culture for NTM. Thirty sputum samples contained Mycobacterium abscessus complex (MABSC) and 11 contained Mycobacterium avium complex (MAC). Decontamination strategies included treatment with N-acetyl L-cysteine with 2% sodium hydroxide (NALC-NaOH), 4% NaOH, 1% chlorhexidine, 0.5 N sulfuric acid, 5% oxalic acid, double decontamination with NALC-NaOH, followed by 5% oxalic acid, and saline (0.85%) as a control. The samples were also cultured directly with no treatment. Treatment with NALC-NaOH resulted in an average reduction in colony count of 87% for MABSC when compared with direct culture. NaOH at 4% caused a 98.3% average reduction in colony count. All treatments that included NaOH resulted in colony counts that were statistically lower than those obtained from direct culture or the saline-treated control (p < 0.05). Standard treatments using sulfuric or oxalic acids were less deleterious, but still resulted in an average reduction in colony count of at least 30%. The viability of MAC was much less affected by most decontamination treatments. In conclusion, the viability of MABSC was severely compromised by standard decontamination regimens. This supports recent evidence showing that optimal recovery of MABSC is achieved by culture on an appropriate selective agar without decontamination of sputum samples.

Minimum-inhibitory-concentration of iclaprim and lefamulin against Mycobacterium abscessus complex

Infections with rapid-growing-mycobacteria (RGM) are often difficult to treat.…

Early disseminated Mycobacterium Abscessus Complex Infection in an Infant with Coexisting Cystic Fibrosis and Progressive Familial Intrahepatic Cholestasis

Mycobacterium abscessus complex (MABSC) is a rapidly growing mycobacterium and may rarely cause disseminated infections in immunocompromised patients. In patients with Cystic Fibrosis (CF), it peaks between the ages of 11 and 15 years. We present a 5 months old infant with coexisting CF and Progressive Familial Intrahepatic Cholestasis (PFIC) who had pulmonary and cutaneous dissemination of MABSC infection. The management of this disseminated infection in an infant with two coexisting chronic diseases was challenging which resulted in a rapid deterioration of lung disease and the progression of PFIC to liver cirrhosis with a fatal outcome. Keywords: Cystic Fibrosis; Atypical Mycobacterium; Mycobacterium abscessus complex; Progressive Familial Intrahepatic Cholestasis