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1.1 This practice covers the detection and enumeration of viable and culturable rapidly growing Mycobacteria (RGM), or non-tuberculosis Mycobacteria (NTM) in aqueous metalworking fluids (MWF) in the presence of high non-mycobacterial background population using standard microbiological culture methods.

1.2 The detection limit is one colony forming unit (CFU)/mL metalworking fluid.

1.3 This practice involves culture of organisms classified as Level 2 pathogens, and should be undertaken by a trained microbiologist in an appropriately equipped facility. The microbiologist should also be capable of distinguishing the diverse colonies of Mycobacteria from other microorganism colonies on a Petri dish and capable of confirming Mycobacteria by acid fast staining method

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

5.1 This practice allows for the recovery and enumeration of viable and culturable, non-tuberculosis, rapidly growing Mycobacteria (M.immunogenum, M.chelonae, M. absessus, M. fortuitum , and M.smegmatis) in the presence of high gram negative background populations in metalworking fluid field samples. During the past decade it has become increasingly apparent that non-tuberculous Mycobacteria are common members of the indigenous MWF bacterial population. This population is predominantly comprised of gram negative bacteria and fungi. Mycobacterial contamination of metalworking fluids has been putatively associated with hypersensitivity pneumonitis (HP) amongst metal grinding machinists. The detection and enumeration of these organisms will aid in better understanding of occupational health related problems and a better assessment of antimicrobial pesticide efficacy.

5.2 The measurement of viable and culturable mycobacterial densities combined with the total mycobacterial counts (including viable culturable (VC), viable-non culturable (VNC) and non viable (NV) counts) is usually the first step in establishing any possible relationship between Mycobacteria and occupational health concerns (for example, HP).

5.3 The practice can be employed in survey studies to characterize the viable-culturable mycobacterial population densities of metal working fluid field samples.

5.4 This practice is also applicable for establishing the mycobacterial resistance of metalworking fluid formulations by determining mycobacterium survival by means of plate count technique.

5.5 This practice can also be used to evaluate the relative efficacy of microbicides against Mycobacteria in metalworking fluids.