Metal worker’s lung: spatial association with Mycobacterium avium

Abstract

BackgroundOutbreaks of hypersensitivity pneumonitis (HP) are not uncommon in workplaces where metal working fluid (MWF) is used to facilitate metal turning. Inhalation of microbe-contaminated MWF has been assumed to be the cause, but previous investigations have failed to establish a spatial relationship between a contaminated source and an outbreak.ObjectivesAfter an outbreak of five cases of HP in a UK factory, we carried out blinded, molecular-based microbiological investigation of MWF samples in order to identify potential links between specific microbial taxa and machines in the outbreak zone.MethodsCustom-quantitative PCR assays, microscopy and phylogenetic analyses were performed on blinded MWF samples to quantify microbial burden and identify potential aetiological agents of HP in metal workers.Measurements and main resultsMWF from machines fed by a central sump, but not those with an isolated supply, was contaminated by mycobacteria. The factory sump and a single linked machine at the centre of the outbreak zone, known to be the workstation of the index cases, had very high levels of detectable organisms. Phylogenetic placement of mycobacterial taxonomic marker genes generated from these samples indicated that the contaminating organisms were closely related to Mycobacterium avium.ConclusionsWe describe, for the first time, a close spatial relationship between the abundance of a mycobacterium-like organism, most probably M. avium, and a localised outbreak of MWF-associated HP. The further development of sequence-based analytic techniques should assist in the prevention of this important occupational disease.

Identifying causation in hypersensitivity pneumonitis: a British perspective

“…This is entirely in keeping with data from the UK reporting scheme for occupational HP between 1996 and 2015, where exposure to MWF (35% of cases) and farming (17% of cases) were the most common causes 27. The reporting data demonstrated that over this time period, ‘Metalworking fluid HP’ has become the most commonly reported cause of occupational HP in the UK, a change in epidemiology that merits further research 28…”

Characteristics of hypersensitivity pneumonitis diagnosed by interstitial and occupational lung disease multi-disciplinary team consensus

“…Barber et al [11] revealed that MWF has replaced farmers' lung as the commonest cause of occupational HP from the UK SWORD surveillance scheme for work-related respiratory disease; there is co-linearity with our cases, as these would also have been reported to SWORD. MWF-related HP is often precipitated by pooling and re-circulation of used MWF via common sumps, the exact cause usually remaining elusive; mycobacterial species have been implicated in some outbreaks [17,18] although evidence for cause and effect is lacking. Regulations in the UK [19] require employers, who undertake processes that use MWF and expose their workforce by inhalation, ingestion or skin contact, to put prevention-or control measures in place.…”

Exposure to heavy metals alters the surface topology of alveolar macrophages and induces respiratory dysfunction among Indian metal arc-welders

“…Our approach of identifying the irregularities of the lung specimen through ultramicroscopy provides unique evidence of the adverse effects of heavy metals on lung cells (Sporn and Roggli, 2016). A recent report described an outbreak of metalworking fluid (MWF)-associated hypersensitivity pneumonitis caused by mycobacterium-like organisms among some metal workers (James et al, 2018). Although workers working with MWF are in a different category than those which we studied, such findings also can be explained in the context of an altered spectrum of immune cells in the lungs due to occupational exposure, such as that we found in our study on welders.…”