Detection of microbial antigens in metal working fluids

In recent years there have been several reports of hypersensitivity pneumonitis (HP) or an HP-like illness occurring among machinists working with water-based metal working fluids (MWF). Microbial contamination of the MWF is common and microbial agents have been suspected to be causal agents for the HP-like illness, but no specific etiologic agent has been identified to date. In particular, gram negative bacteria and biocide resistant mycobacterial species may colonize the MWF, and may stimulate an inflammatory response if inhaled. Because direct culture techniques provide data only about viable organisms present at the time the sample was collected, we have been evaluating techniques to detect microbial substances (antigens) that may be present and persist in the MWF. We have found that the endotoxin of gram negative bacteria can be detected in MWF using the limulus amoebocyte lysate (LAL) assay, and may be present in high concentrations. In addition, MWF samples have been analyzed by Western Blot techniques using polyclonal antibodies to mycobacteria to demonstrate the presence of mycobacterial antigens in these samples. The use of non-culture-based techniques for the assessment of microbial contamination of MWF may help to determine the role of microorganisms in the etiology of HP associated with MWF exposure.