Factors influencing the microbial composition of metalworking fluids and potential implications for machine operator's lung

Differential Immunogenicity and Lung Disease-Inducing Potential of Mycobacterium immunogenum Genotypes and Impact of Co-Exposure with Pseudomonas: Optimizing a Mouse Model of Chronic Hypersensitivity Pneumonitis

Mycobacterium immunogenum (MI) colonizing metalworking fluids (MWFs) has been associated with chronic hypersensitivity pneumonitis (HP) in machinists. However, it is etiologically unclear why only certain mycobacteria-contaminated fluids induce this interstitial lung disease. We hypothesized that this may be due to differential immunogenicity and the HP-inducing potential of MI strains/genotypes as well as the confounding effect of co-inhaled endotoxin-producers. To test this hypothesis, we optimized a chronic HP mouse model in terms of MI antigen dose, timepoint of sacrifice, and form of antigen (cell lysates vs. live cells) and compared six different field-isolated MI strains. Overall, MJY10 was identified as the most immunogenic and MJY4 (or MJY13) as the least immunogenic genotype based on lung pathoimmunological changes as well as Th1 cellular response (IFN-γ release). Infection with MI live cells induced a more severe phenotype than MI cell lysate. Co-exposure with Pseudomonas fluorescens caused a greater degree of lung innate immune response and granuloma formation but a diminished adaptive (Th1) immune response (IFN-γ) in the lung and spleen. In summary, this study led to the first demonstration of differential immunogenicity and the disease-inducing potential of field strains of MI and an interfering effect of the co-contaminating Pseudomonas. The improved chronic MI-HP mouse model and the identified polar pair of MI strains will facilitate future diagnostic and therapeutic research on this poorly understood environmental lung disease.

Microbial Community Establishment, Succession, and Temporal Dynamics in an Industrial Semi-Synthetic Metalworking Fluid Operation: A 50-Week Real-Time Tracking

Microorganisms colonizing modern water-based metalworking fluids (MWFs) have been implicated in various occupational respiratory health hazards to machinists. An understanding of the exposure risks from specific microbial groups/genera/species (pathogenic or allergenic) and their endotoxins and the need for strategies for effective, timely fluid management warrant real-time extended tracking of the establishment of microbial diversity and the prevailing fluid-related factors. In the current study, the microbial community composition, succession, and dynamics of a freshly recharged industrial semi-synthetic MWF operation was tracked in real-time over a period of 50 weeks, using a combination of microbiological and molecular approaches. Substantial initial bacterial count (both viable and non-viable) even in the freshly recharged MWF pointed to the inefficiency of the dumping, cleaning, and recharge (DCR) process. Subsequent temporal analysis using optimized targeted genus/group-specific qPCR confirmed the presence of Pseudomonads, Enterics, Legionellae, Mycobacteria (M. immunogenum), Actinomycetes, and Fungi. In contrast, selective culturing using commercial culture media yielded non-specific isolates and collectively revealed Gram-negative (13 genera representing 19 isolates) and Gram-positive (2 genera representing 6 isolates) bacteria and fungi but not mycobacteria. Citrobacter sp. and Bacillus cereus represented the most frequent Gram-negative and Gram-positive isolates, respectively, across different media and Nectria haematococca isolation as the first evidence of this fungal pathogen colonizing semi-synthetic MWF. Unbiased PCR-DGGE analysis revealed a more diverse whole community composition revealing 22 bacterial phylotypes and their succession. Surges in the endotoxin level coincided with the spikes in Gram-negative bacterial population and biocide additions. Taken together, the results showed that semi-synthetic MWF is conducive for the growth of a highly diverse microbial community including potential bacterial and fungal pathogens, the current DCR practices are inefficient in combating microbial reestablishment, and the practice of periodic biocide additions facilitates the build-up of endotoxins and non-viable bacterial population.

Hypersensitivity pneumonitis due to metal working fluids: detection of specific IgG antibodies to microbial antigens

Occupational exposure to microbially contaminated metal working fluids (MWF) can cause hypersensitivity pneumonitis (HP). An important step in the diagnosis of HP is to identify the triggering antigen by detection of corresponding specific IgG antibodies (sIgG). As commercial sIgG tests are currently not available, protein antigens were prepared from MWF-workplace samples and from MWF-typical bacterial isolates. In 57% of suspected HP-cases (n= 30) elevated sIgG concentrations were measured to at least one MWF-relevant antigen, of which Mycobacterium immunogenum was most prominent (88%), followed by Pseudomonas oleovorans and Pseudomonas spec (82% each), MWF-antigen mix and Pseudomonas alcaliphila (65% each). Elevated sIgG concentrations to other microorganisms were measured to Micropolyspora faeni (82%) and Aureobasidium pullulans (77%). Correlation of sIgG values of all tested microbial antigens showed a significant relationship of MWF-antigen mixture to Pseudomonas antigens, but a low correlation to moulds. These newly prepared MWF-antigens are useful tools for the diagnosis of patients with suspected MWF-HP and are available for further investigations.

Machine operator's lung outbreak due to Eikenella corrodens

BACKGROUND

Outbreaks of hypersensitivity pneumonitis (HP) are not uncommon in workplaces where metalworking fluids (MWFs) are used. The recirculation of MWFs leads to microbiological contamination, which is responsible for outbreaks. Most outbreak reports come from USA and the UK; however, no similar reports have been published from Central Europe.

AIMS

To describe an outbreak of MWF-associated HP in workers from a compressor assembly manufacturing facility in Slovak Republic and to identify the potential antigens responsible for the outbreak.

METHODS

We investigated the history of worker's symptoms, physical examinations, lung function tests, radiographic scans and lung biopsies. The MWF samples were analysed for different strains of bacteria and fungi. Antigen extracts were produced from the microorganisms isolated from MWFs, and positive precipitin reactions were evaluated.

RESULTS

MWF-associated HP was diagnosed in 21 men and 6 women. All workers had work-related dyspnoea and cough with abnormal pulmonary diffusing capacity. Twenty-four cases had evidence of interstitial lung disease. Four cases were classified as having fibrotic HP. Nineteen microbial isolates (12 bacteria and 7 fungi) were cultured from the MWFs. Twenty-five cases had a positive response to at least one isolate. Eikenella corrodens and Bacillus subtilis were the most frequently reacting antigens (in 15 and 12 workers, respectively).

CONCLUSIONS

Despite decreasing reports of MWF-associated HP outbreaks over the past several decades, we describe one of the largest outbreaks in Europe. While the bacterium E. corrodens was found in the MWF samples, its relationship to the disease should be further investigated.

Recovery and Characterization Studies of Post-Production Alloy Waste from the Automotive Industry

Superalloys provide high corrosion resistance and are widely used as high-performance materials in aerospace, automotive, chemical, and other industries. Herein, the investigation into the characteristics and properties of alloy waste; Inconel 625, Inconel 718, and Titanium Grade 5, from the automotive industry, was introduced as a result of a recovery in various processes. For this reason, the following procedures were carried as follows; the washing process to remove oil from the swarf was evaluated using several commercial agents and for the process of thermal disposal of processing fluids, a temperature of 900 °C was used in a muffle furnace without air access. The presented studies show that the commercially available series of washing agents did not modify the composition of the surface. However, the high temperatures during the calcination of oil residues are affecting the elemental composition of the alloys. According to the results of the analyses, it is not possible to remove 100% of the oil residues from alloy waste using washing agents based on light organic fractions; however, the effectiveness of this method reaches 99%. In this report, accurate SEM-EDS analyses show changes that occur on the surface after machining and removal of processing fluids. The NMR and GC/MS investigations indicate contaminants as a mixture of aliphatic and cycloaliphatic hydrocarbons with carbon numbers from C8–C30.

Hypersensitivity pneumonitis in a cystic fibrosis patient

Hypersensitivity pneumonitis (HP) is a chronic inflammatory lung disease caused by repeated inhalation of antigenic substances. We present a case of metalworking fluids (MWFs)-HP sensitized to Pseudomonas oleovorans in a cystic fibrosis patient. This case illustrates that HP diagnosis remains challenging, especially in patients with another pulmonary disease, and that serodiagnosis contributes to identifying the precise microorganism involved. It also demonstrates that P. oleovorans is an important secondary aetiological agent in MWF-HP, less known than Mycobacterium immunogenum.

Review of the British Thoracic Society Winter Meeting 2018, 5-7 December 2018, London, UK

INTRODUCTION

The Winter Meeting of the British Thoracic Society (BTS) is a platform for the latest clinical and scientific research in respiratory medicine. This review summarises some key symposia and presentations from the BTS Winter Meeting 2018.

METHODS

Key symposia and research presentations from the BTS Winter Meeting 2018 were attended and reviewed by the authors.

RESULTS

The seminal messages from the latest clinical and scientific research covering a range of respiratory diseases, including asthma, interstitial lung disease, infection, cystic fibrosis, pulmonary vascular disease, pleural disease and occupational lung disease were summarised in this review.

DISCUSSION

The BTS Winter Meeting 2018 brought the very best of respiratory research to an audience of scientists, physicians, nurses and allied health professionals. The Winter Meeting continues to be a highlight of the UK respiratory research calendar, and we look forward to the next meeting in December 2019.

Hypersensitivity pneumonitis: A new strategy for serodiagnosis and environmental surveys

We propose a strategy for serodiagnosis of hypersensitivity pneumonitis (HP): 1) question patients about their private or occupational activity, or visit him on site; 2) select panels of six somatic specific antigens appropriate for each type of exposure; 3) and use ELISA to test concomitantly two recombinant antigens highly specific to Farmer's lung, Metalworking-fluid HP, and for Bird fancier's lung. The serodiagnosis provides an immunological argument that may complete radiological, functional lung exploration and clinical features; 4) If the serodiagnosis is negative but the suspicion of HP is strong, a microbial analysis of the patient's specific exposure is conducted; 5) "A la carte" antigens are produced from the microorganisms isolated in the patient's environment sample and tested; 6) Finally, the patient may be asked to undergo a specific inhalation challenge with the offending antigens in a safety cabin, or to avoid his usual environment for a few days.

Flow cytometry, a powerful novel tool to rapidly assess bacterial viability in metal working fluids: Proof-of-principle

Metalworking fluids (MWF) are water- or oil-based liquids to cool and lubricate tools, work pieces and machines, inhibit corrosion and remove swarf. One of the major problems in the MWF industry is bacterial growth as bacterial enzymes can cause MWF degradation. In addition, bacteria can form biofilms which hamper the functioning of machines. Last but not least, some bacterial by-products are toxic (e.g. endotoxins) and present potential health risks for metalworking machine operators via the formation of aerosols. Therefore, a novel fast yet accurate analytical method to evaluate and predict the antibacterial capacity of MWF would be an important asset. As such a tool is currently lacking, the present study aimed to develop a protocol based on flow cytometry (FCM) to assess the antibacterial potential of newly developed MWF independent of bacterial growth. Results of this novel method were compared to a biochallenge test currently used in MWF industry and also to traditional plate counts. Our results represent a proof-of-principle that FCM can reliably predict the antibacterial capacity of MWF already within one day of incubation with Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Proteus mirabilis, being substantially faster than the current growth-based methods.

Metal worker's lung: spatial association with Mycobacterium avium

BACKGROUND

Outbreaks 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.

OBJECTIVES

After 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.

METHODS

Custom-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 RESULTS

MWF 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.

CONCLUSIONS

We 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.

Hypersensitivity Pneumonitis Due to Metalworking Fluid Aerosols

PURPOSE OF REVIEW

This review summarises the clinical knowledge of hypersensitivity pneumonitis in workers exposed to aerosols of metalworking fluid, reviewing published outbreaks and clinical cases.

RECENT FINDINGS

Metalworking fluid exposure has become the commonest recognised cause of occupational hypersensitivity pneumonitis, having been rare before 2000. There are many possible agents in the metalworking fluid which may be the cause of disease including bacteria, mycobacteria, fungae, biocides, emulsifiers, reodorants and dissolved chrome and cobalt. Causes are likely to be different in different outbreaks. Mycobacteria growing in the metalworking fluid have generated immune responses in some workers, but their role in disease causation is not yet established. Many outbreaks have been identified in large workplaces using common sumps. It is not possible to prevent microbial contamination of metalworking fluids in use. Disease prevention should focus on stopping inhalation of aerosols, particularly by re-engineering to remove recirculation.

Fungal peptides from pneumonitis hypersensitivity etiologic agents are able to induce specific cellular immune response

PURPOSE

Hypersensitivity pneumonitis (HP) is an immunoallergic disease due to chronic exposure to high quantities of different microorganisms such as Mycobacterium immunogenum (Mi), a mycobacterium, and Lichtheimia corymbifera (Lc), a filamentous fungus. It has recently been demonstrated that the protein DLDH (dihydrolipoyl dehydrogenase), is common to these microorganisms. This study aimed to investigate the immune potential of overlapping peptide pools covering the MiDLDH and LcDLDH.

EXPERIMENTAL DESIGN

A selection of 34 peptides, from the MiDLDH and LcDLDH, able to interact with Major Histocompatibility Complex (MHC) 1 and MHC 2, was obtained using three different epitope prediction websites. By means of ELISPOT assays, we compared the frequency of Interferon gamma (IFNγ) secreting peripheral blood mononuclear cells (PBMC) after stimulation with overlapping peptide pools. Tests were performed using cells from 35 healthy blood donors.

RESULTS

One peptide pool containing five peptides from MiDLDH and able to interact with MHC 2 induced a marked IFNγ specific immune response (Pool F, p<0.001, Wilcoxon signed-rank test).

CONCLUSION

This study demonstrated that peptides from microorganisms involved in HP were able to induce a high IFNγ specific immune response after stimulation of PBMCs from healthy blood donors which could be useful to develop an effective prevention strategy.

More than 70 Years of Pyrogen Detection: Current State and Future Perspectives

In the quality assurance of medical products, tests for sterility are essential. For parenteral pharmaceuticals, avoiding the presence of pyrogens is crucial. These fever-inducing substances (endotoxins and non-endotoxins) are not eliminated by standard sterilisation processes, and are biologically active once in the bloodstream, causing risks to human health, ranging from mild reactions (e.g. fever) to septic shock and death. Therefore, for injectable formulations, pyrogen testing is mandatory. Over the years, various pyrogen testing methods have been introduced, namely: in the 1940s, the rabbit pyrogen test, which is an in vivo test that measures the fever reaction as an endpoint; in the 1970s, the Limulus Amoebocyte Lysate (LAL) test, which is an in vitro test (with the haemolymph of the horseshoe crab) that specifically detects endotoxin; and in 2010, the Monocyte-Activation Test (MAT), which is a non-animal based in vitro pyrogen test that represents a full replacement of the rabbit test. Due to the ubiquity and biological significance of pyrogens, we are currently further developing the MAT so that it can be used for other applications. More specifically, our focus is on the detection of pyrogenic contamination on medical devices, as well as on the measurement of air quality. In addition, further improvements to permit the use of cryopreserved blood in the MAT, to overcome the limitations in the availability of freshly-drawn blood from human donors, are ongoing.

First report of Wautersiella falsenii genomovar 2 isolated from the respiratory tract of an immunosuppressed man

Wautersiella falsenii is a Gram-negative, non-motile rod, which grows aerobically on common isolation media and is the only acknowledged species among the genus Wautersiella. Two genomovars, namely 1 and 2, phenotypically indistinguishable but genotypically different, are described. To date, few case reports detailing the clinical disease associated with W. falsenii have been reported, all describing localized infection. To our knowledge, this study reports the first isolation of W. falsenii genomovar 2 from a respiratory sample of an immunosuppressed man. Our hypothesis is that the patient was harboring W. falsenii genomovar 2 and both the immunosuppression and the antimicrobial treatments provided a chance for this organism to emerge. The clinical significance of this result is yet to be evaluated. Although infection with W. falsenii remains rare, this bacterium should not be underestimated mainly because of its natural resistance to many available antimicrobials.

External validation of recombinant antigens for serodiagnosis of machine operator's lung

BACKGROUND

Machine operator's lung (MOL) is a hypersensitivity pneumonitis the diagnosis of which is difficult. Our laboratory previously developed an ELISA test using recombinant antigens from Mycobacterium immunogenum isolated in French plant. The objective was to validate the previous ELISA results with ten new suspected cases from Germany.

METHODS

Two serological analyses were performed: ELISA with the six recombinant antigens, and electrosyneresis with crude antigens of M. immunogenum and three other main species isolated from contaminated metalworking fluids.

RESULTS

The two recombinant antigens acyl-CoA dehydrogenase and dihydrolipoyl dehydrogenase, combined together, and electrosyneresis are useful in making the diagnosis regardless of the clinical and radiological data. Finally 9 out of the 10 suspected cases were declared as MOL.

CONCLUSIONS

Despite the geographical distance, the crude and recombinant antigens produced to investigate the clustered French cases also proved to be useful in diagnosing the suspected cases in Germany.

Airway symptoms and biological markers in nasal lavage fluid in subjects exposed to metalworking fluids

BACKGROUNDS

Occurrence of airway irritation among industrial metal workers was investigated. The aims were to study the association between exposures from water-based metal working fluids (MWF) and the health outcome among the personnel, to assess potential effects on the proteome in nasal mucous membranes, and evaluate preventive actions.

METHODS

The prevalence of airway symptoms related to work were examined among 271 metalworkers exposed to MWF and 24 metal workers not exposed to MWF at the same factory. At the same time, air levels of potentially harmful substances (oil mist, morpholine, monoethanolamine, formaldehyde) generated from MWF was measured. Nasal lavage fluid was collected from 13 workers and 15 controls and protein profiles were determined by a proteomic approach.

RESULTS

Airway symptoms were reported in 39% of the workers exposed to MWF although the measured levels of MWF substances in the work place air were low. Highest prevalence was found among workers handling the MWF machines but also those working in the same hall were affected. Improvement of the ventilation to reduce MWF exposure lowered the prevalence of airway problems. Protein profiling showed significantly higher levels of S100-A9 and lower levels of SPLUNC1, cystatin SN, Ig J and β2-microglobulin among workers with airway symptoms.

CONCLUSIONS

This study confirms that upper airway symptoms among metal workers are a common problem and despite low levels of MWF-generated substances, effects on airway immune proteins are found. Further studies to clarify the role of specific MWF components in connection to airway inflammation and the identified biological markers are warranted.

Extended tracking of the microbial community structure and dynamics in an industrial synthetic metalworking fluid system

Understanding of the occupational exposure risk scenario and disease etiology associated with industrial metalworking fluids (MWFs) requires knowledge of the development and composition of their microbial diversity in relation to the underlying fluid management factors. In this study, a managed synthetic MWF operation freshly recharged following the dumping, cleaning, and recharge (DCR) process was tracked in real time for microbial community changes over a period of 1.25 years (65 weeks). The recharged fluid developed very high bacterial counts (viable and nonviable) fairly quickly after the DCR process, indicating its inadequacy. Genus-/group-specific real-time qPCR confirmed the prevalence of six potentially pathogenic/immunogenic microbial genera/groups, viz. pseudomonads, enterics, mycobacteria, legionellae, actinomycetes, and fungi. Selective culturing revealed Acinetobacter and Bacillus as the most frequently isolated Gram-negative and Gram-positive genera, respectively, in addition to the presence of fungi and actinomycetes. Endotoxin perturbations (< 1000 to > 100000 EU mL⁻¹) coincided with temporal increases in Gram-negative bacteria and/or periodic biocide additions. PCR-DGGE-sequencing revealed an expanded estimated bacterial richness (up to 23 bands per sample). Of the 16 dominant bacterial phylotypes identified, the majority were detected for the first time in MWF. Interestingly, the study revealed a crucial role for MWF brand, among other fluid factors, in modulating the community structure and dynamics.

Human monocyte-derived dendritic cells exposed to microorganisms involved in hypersensitivity pneumonitis induce a Th1-polarized immune response

Hypersensitivity pneumonitis (HP) is an immunoallergic disease characterized by a prominent interstitial infiltrate composed predominantly of lymphocytes secreting inflammatory cytokines. Dendritic cells (DCs) are known to play a pivotal role in the lymphocytic response. However, their cross talk with microorganisms that cause HP has yet to be elucidated. This study aimed to investigate the initial interactions between human monocyte-derived DCs (MoDCs) and four microorganisms that are different in nature (Saccharopolyspora rectivirgula [actinomycetes], Mycobacterium immunogenum [mycobacteria], and Wallemia sebi and Eurotium amstelodami [filamentous fungi]) and are involved in HP. Our objectives were to determine the cross talk between MoDCs and HP-causative agents and to determine whether the resulting immune response varied according to the microbial extract tested. The phenotypic activation of MoDCs was measured by the increased expression of costimulatory molecules and levels of cytokines in supernatants. The functional activation of MoDCs was measured by the ability of MoDCs to induce lymphocytic proliferation and differentiation in a mixed lymphocytic reaction (MLR). E. amstelodami-exposed (EA) MoDCs expressed higher percentages of costimulatory molecules than did W. sebi-exposed (WS), S. rectivirgula-exposed (SR), or M. immunogenum-exposed (MI) MoDCs (P < 0.05, Wilcoxon signed-rank test). EA-MoDCs, WS-MoDCs, SR-MoDCs, and MI-MoDCs induced CD4(+) T cell proliferation and a Th1-polarized immune response. The present study provides evidence that, although differences were initially observed between MoDCs exposed to filamentous fungi and MoDCs exposed to bacteria, a Th1 response was ultimately promoted by DCs regardless of the microbial extract tested.

Microorganisms in metalworking fluids: current issues in research and management

The microbial contamination of water miscible metalworking fluids (MWFs) is a serious problem in metal industry. A good maintenance of MWF re-circulation systems can extend the lifetime of coolants and ensure the quality of the tools produced. In MWFs, as in the other water-based environments, microorganisms usually live in the form of biofilms, the communities of bacteria and fungi attached to the surface of sumps, metal parts and also to each other. Biofilms exhibit very high resistance to biocides. The effect of biocides that are used as additives to MWFs to control the growth of the bacterial and fungal microbiomes (microorganisms characteristic to the individual coolant system) have become the subject of research only in recent years. There are also only sparse reports on the impact of biocides on microorganisms growing in biofilms in MWF installations. Fast growing mycobacteria are important members of these biofilm communities. Their presence has recently been linked with the occurrence of cases of hypersensitivity pneumonitis, a serious respiratory disorder in the metal industry employees. The new, relatively fast and inexpensive techniques to assess the species diversity within MWF microbiomes and their population size should be developed in order to control the microorganisms' proliferation in MWFs and to diminish the occupational exposure to harmful bioaerosols in metal industry.