Expanding the mycobacterial diversity of metalworking fluids (MWFs): evidence showing MWF colonization by Mycobacterium abscessus

Abstract

Nontuberculous mycobacteria (NTM) have been associated with hypersensitivity pneumonitis in machinists. Only two species of NTM, namely Mycobacterium immunogenum and Mycobacterium chelonae, have been reported thus far to have the ability to colonize contaminated metalworking fluids (MWFs). Here, we report, for the first time, the presence and characterization (phenotypic and genotypic) of a third species, Mycobacterium abscessus, colonizing these harsh alkaline machining fluids. Two Mycobacterium morphotypes, smooth (S) and rough (R), were isolated (two isolates each) from an in-use industrial MWFs. Biocide susceptibility analysis using triclosan as a model yielded the same minimal inhibitory concentration for the two morphotypes. PCR-restriction analysis-based speciation of the morphotypes confirmed their identity as M. abscessus. Genotyping based on partial DNA sequences corresponding to the variable regions of the hsp65 gene and 16S-23S rRNA operon internal transcribed spacer region and randomly amplified polymorphic DNA-PCR analysis showed that both morphotypes belong to a single genotype. In addition, we isolated and confirmed two novel mycobacterial genotypes, one each of M. immunogenum and M. chelonae from additional in-use MWF screening. Taken together, this study expands the known mycobacterial species- and strain-diversity colonizing MWF. Furthermore, the study emphasizes the need for including M. abscessus species in the existing mycobacterial screening of contaminated MWF.

Microorganisms in metalworking fluids: Current issues in research and management

“…More than 90 species of these microorganisms are currently known, of which about one-third are opportunists that may cause infection in humans [19]. Among these species, M. immunogenum, M. chelonae, M. abscessus and M. diernhoferi have already been isolated from MWFs [20,21]. Mycobacteria are the etiologic representatives of the following genera: Fusarium, Exophiala, Trichoderma, and Penicillium were isolated [13].…”

Early immunopathological events in acute model of mycobacterial hypersensitivity pneumonitis in mice

“…M. immunogenum, M. chelonae, M. abscessus originally isolated from field in-use or used MWFs from geographically diverse automotive industrial plants (Khan et al 2005;Kapoor & Yadav 2012) were used in these studies. A total of 12 strains/genotypes belonging to these three species, including six M. immunogenum genotypes (MI 700506, MJY3, MJY4, MJY10, MJY13, and MJY14), four M. chelonae genotypes (MJY1, MJY2, MJY6, and MJY8), and two M. abscessus strains/morphotypes, rough (MJY23) and smooth (MJY25), were included.…”

“…Furthermore, existing mouse challenge studies on MWF-associated HP have been restricted to the use of one particular causative bacterial species and have not reported species/strain-dependent variation in immunogenicity and severity of the disease (Gordon et al 2006;Thorne et al 2006). Largescale screening of field-collected MWF samples by our laboratory has revealed prevalence of different species (M. immunogenum, M. chelonae, M. abscessus) of the MCA group and several unique genotypes/variants of each of these member species (Khan et al 2005;Kapoor & Yadav 2012) in these fluids. However, the relative immunogenicity and HP-inducing potential of individual mycobacterial genotypes/variants is unclear.…”

Biological and chemical hazards in water-mix metalworking fluids and mists

“…Multiple genotypes of mycobacteria have been identified in MWF since the introduction of water-mix MWF (Kapoor and Yadav, 2012;Falkinham et al, 2003). Following this, within the literature MWF associated mycobacteria have been implicated in the development of OHP.…”

“…In addition, they can also be found in, distilled and un-supplemented water, hot tubs, swimming pools, soil and aerosols (Veillette et al, 2008;Kapoor and Yadav, 2012).…”