Mycobacterium malmesburyense sp. nov., a non-tuberculous species of the genus Mycobacterium revealed by multiple gene sequence characterization

Abstract

Non-tuberculous mycobacteria (NTM) are ubiquitous in the environment, and an increasing number of NTM species have been isolated and characterized from both humans and animals, highlighting the zoonotic potential of these bacteria. Host exposure to NTM may impact on cross-reactive immune responsiveness, which may affect diagnosis of bovine tuberculosis and may also play a role in the variability of the efficacy of Mycobacterium bovis BCG vaccination against tuberculosis. In this study we characterized 10 NTM isolates originating from water, soil, nasal swabs of cattle and African buffalo as well as bovine tissue samples. These isolates were previously identified during an NTM survey and were all found, using 16S rRNA gene sequence analysis to be closely related to Mycobacterium moriokaense. A polyphasic approach that included phenotypic characterization, antibiotic susceptibility profiling, mycolic acid profiling and phylogenetic analysis of four gene loci, 16S rRNA, hsp65, sodA and rpoB, was employed to characterize these isolates. Sequence data analysis of the four gene loci revealed that these isolates belong to a unique species of the genus Mycobacterium. This evidence was further supported by several differences in phenotypic characteristics between the isolates and the closely related species. We propose the name Mycobacterium malmesburyense sp. nov. for this novel species. The type strain is WCM 7299T (=ATCC BAA-2759T=CIP 110822T).

Challenges to the control of Mycobacterium bovis in livestock and wildlife populations in the South African context

“…Other methods of cow management may also negatively impact on disease control. The damp moist conditions found in dairies can allow for the growth of bTB and other Non-Tuberculous Mycobacteria (NTM) which can sensitise the animal and interfere with the skin tests [ 35 , 36 ]. From personal experience the use of molasses wheels to increase energy consumption and prevent ketosis in the dry cow camp, led to a resurgence of bTB in a chronically infected dairy herd.…”

“…A novel NTM, Mycobacterium malmesburyense was cultured from various places in South Africa from water, nasal and pharyngeal swabs, as well as bovine lymph nodes [ 11 ]. Skin reactions on the dairy farm in the Malmesbury district where this species was identified are extremely difficult to interpret – the non-specific skin reactions may or may not be due to this species [ 35 , 36 ].…”

Mycolicibacterium baixiangningiae sp. nov. and Mycolicibacterium mengxianglii sp. nov., two new rapidly growing mycobacterial species

“…Based on phylogenomics and comparative genomic evidence, Gupta et al [4] in 2018 suggested reclassifying the genus Mycobacterium into five genera, Mycobacterium, Mycolicibacterium, Mycolicibacter, Mycolicibacillus and Mycobacteroides to accommodate the following five distinct clades, 'Tuberculosis-Simiae' , 'Fortuitum-Vaccae' , 'Terrae' , 'Triviale' and 'Abscessus-Chelonae' , respectively. Different from the genus Mycobacterium with Mycobacterium tuberculosis and all other major human pathogens as its members, the genus Mycolicibacterium contains 87 validly published species, primarily NTM species potentially pathogenic for human [5], isolated from environmental samples [4] (contaminated soils [5][6][7][8], sediment [9], water [10,11], plant [12]), clinical specimens (cerebrospinal fluid [13], pulmonary tissue [14]) and animal samples (blood of cattle [15], nasal swab [16]). All members in the genus Mycolicibacterium are relatively rapidly growing (forming colonies in or even less than 7 days), with Mycolicibacterium fortuitum as the type strain [4].…”

Formal description of Mycobacterium neglectum sp. nov. and Mycobacterium palauense sp. nov., rapidly growing actinobacteria

“…The genus Mycobacterium (Lehmann and Neumann 1896), the sole representative of the family Mycobacteriaceae (Chester 1897) can be distinguished from all of the other genera classified in the order Corynebacteriales by using a selection of genotypic and phenotypic methods (Goodfellow and Jones 2012). The genus encompasses pathogenic and nontuberculous mycobacteria (Magee and Ward 2012;Forbes 2017;Gcebe et al 2017) which can be assigned to two groups based on growth rates. Slowly growing strains require 7 or more days of incubation at optimal temperature to produce visible colonies from highly diluted inocula whereas those of rapidly growing strains are evident in fewer than 7 days under comparable conditions (Wayne and Kubica 1986).…”