Non-Tubercle Mycobacteria and Other Contaminants in Metalworking Fluids from Small Turneries

Non-Tuberculous Mycobacteria (NTM) have frequently been isolated from metalworking fluids (MWFs) used in large machining industries. This paper concerns the microbial detection, particularly NTM in MWFs employed in small metalworking shops. A total of 21 samples were collected from different turneries and were tested for several microbiological parameters. A total microbial count above 106 CFU ml-1 was observed in 66.6% (14/21) of samples and none of the samples had the count <102 CFU ml-1. The dominant contaminants were Gram-negative bacteria with 90.5% (19/21) of samples revealing the presence of Pseudomonas aeruginosa. Sulfate Reducing Bacteria (SRB) were detected in 52.4% (11/21) of samples, whereas NTM were recovered from 14.3% (3/21) of samples only. Two species of NTM were identified by biochemical reactions as Mycobacterium chelonae and Mycobacterium abscessus. It was concluded that MWFs used in small turneries are usually contaminated with Gram-negative bacteria and SRB but NTM are not common contaminants of these fluids.