Mycobacterium abscessus. “Pleased to Meet You, Hope You Guess My Name...”

Abstract

Mycobacterium abscessus is a formidable and difficult-to-treat mycobacterial pathogen with multiple drug-resistance mechanisms. The most important of these mechanisms is the presence of an inducible erythromycin methylase (erm) gene, because it confers macrolide resistance. It has recently been found that "M. abscessus" can be split into three species or subspecies based on gene sequence analysis other than the 16S rRNA gene and the presence or absence of a functional erm(41) gene. Several names have been applied to these three organisms, including M. abscessus or M. abscessus subsp. abscessus, Mycobacterium massiliense or M. abscessus subsp. massiliense, and Mycobacterium bolletii or M. abscessus subsp. bolletii. No universally accepted or recognized species or subspecies designations have emerged, and no names have been universally adopted for these organisms. This uncertainty has led to inconsistencies in the medical literature and understandable confusion by clinicians about the appropriate labels for "M. abscessus" isolates. We discuss the complexities involved in mycobacterial species/subspecies identification and taxonomy and suggest possible ways to improve the present state of uncertainty surrounding the labels for "M. abscessus" clinical isolates. We also suggest necessary changes in mycobacterial laboratory processing and reporting procedures for mycobacterial isolates.

Pulmonary Disease Due to Nontuberculous Mycobacteria

“…42 Because Mam usually has a truncated erm gene, rendering previously untreated Mam susceptible to clarithromycin, whereas Maa and M abscessus subspecies bolletii contain the complete gene and are usually ( . 80%) resistant to macrolides, identifi cation to the subspecies level and Ն 14 days incubation with erythromycin to determine likely susceptibility of these rapidly growing mycobacteria is essential.…”

“…80%) resistant to macrolides, identifi cation to the subspecies level and Ն 14 days incubation with erythromycin to determine likely susceptibility of these rapidly growing mycobacteria is essential. [42][43][44] Rapid Detection: A TaqMan real-time polymerase chain reaction (PCR) assay detecting the 16S to 23S ribosomal RNA internal transcribed spacer region of MAC directly from respiratory specimens was developed. When used in combination with real-time PCR testing for MTBC, the assay could guide management and reduce medical costs.…”

“…55 As noted previously, differing response to macrolide-based regimens among subspecies of M abscessus relates to the presence or absence of a truncated erm gene. [42][43][44] Th is raises the question of whether diff erent macrolides equally aff ect erm induction. An in vitro study by Choi and colleagues 44 Bedaquiline, a diarylquinolone the US Food and Drug Administration approved for TB, shows promise for treating refractory PNTM.…”

A rare case ofMycobacterium abscessussubspeciesabscessusprosthetic valve endocarditis and the clinical importance of inducibleerm(41) gene testing

“…The methylation causes a conformational change that prevents macrolides from binding which explains the mechanism of resistance 7. Each subspecies of M abscessus has their own unique erm (41) gene sequence which can be identified via molecular targeting 5 . M abscessus subsp.…”

“You Can’t Always Get What You Want…” The Mycobacterium abscessus Issue. Name versus Function

“…436-439) regarding Mycobacterium abscessus taxonomy illustrates the classic lag between scientific discovery and clinical practice (1). The molecular microbiology laboratory is commonplace in research settings and is contributing significantly both to the exploding dendrograms of mycobacterial taxonomy and to real advances in understanding virulence and treatment response that may be virtually unrecognizable if functionally dissimilar organisms are lumped together.…”