Implementation of a quantitative real-time PCR assay for the detection of Mycobacterium immunogenum in metalworking fluids

Quantification of members of the Mycobacterium chelonae-abscessus complex in lesions of the endangered houston toad (Anaxyrus houstonensis)

Illumina-based 16S rRNA V3 amplicon sequencing of total DNA obtained from soft tissue lesions (joint granulomas) of the endangered Houston toad (Anaxyrus houstonensis) demonstrated that many reads represented members of the actinobacterial Mycobacterium chelonae-abscessus complex. In order to quantify members of this complex in those lesions, we designed three complex-specific primer set/probe combinations (sets I, II and III) targeting variable regions on the 23S rRNA gene for SybrGreen- and Taqman-based quantitative polymerase chain reaction (qPCR). Both SybrGreen- and Taqman-based analyses specifically detected members of the M. chelonae-abscessus complex in lesion samples, with numbers between 10⁴ and 10⁷ cells per 100-mg sample. Values within individual samples were generally comparable between SybrGreen- and Taqman-based detection methods and between all primer set/probe combinations, except for SybrGreen-based analyses of a few samples analyzed with primer set I that used a less specific forward primer. The development of highly specific detection and quantification methods for members of the M. chelonae-abscessus complex in lesion samples can enable group specific tracking of these organisms, particularly in captive or stewardship settings where source and transmission monitoring are valuable tools to husbandry and species conservation.

Circulating purification of cutting fluid: an overview

Cutting fluid has cooling and lubricating properties and is an important part of the field of metal machining. Owing to harmful additives, base oils with poor biodegradability, defects in processing methods, and unreasonable emissions of waste cutting fluids, cutting fluids have serious pollution problems, which pose challenges to global carbon emissions laws and regulations. However, the current research on cutting fluid and its circulating purification technique lacks systematic review papers to provide scientific technical guidance for actual production. In this study, the key scientific issues in the research achievements of eco-friendly cutting fluid and waste fluid treatment are clarified. First, the preparation and mechanism of organic additives are summarized, and the influence of the physical and chemical properties of vegetable base oils on lubricating properties is analyzed. Then, the process characteristics of cutting fluid reduction supply methods are systematically evaluated. Second, the treatment of oil mist and miscellaneous oil, the removal mechanism and approach of microorganisms, and the design principles of integrated recycling equipment are outlined. The conclusion is concluded that the synergistic effect of organic additives, biodegradable vegetable base oils and recycling purification effectively reduces the environmental pollution of cutting fluids. Finally, in view of the limitations of the cutting fluid and its circulating purification technique, the prospects of amino acid additive development, self-adapting jet parameter supply system, matching mechanism between processing conditions and cutting fluid are put forward, which provides the basis and support for the engineering application and development of cutting fluid and its circulating purification.

Management of a Mycobacterium immunogenum infection of a peritoneal dialysis catheter site

Mycobacterium immunogenum is a member of the rapidly growing non-tuberculous mycobacteria and is a relatively new species identified within this group. An 81-year-old immune-competent male was diagnosed with M. immunogenum infection of his peritoneal dialysis catheter exit site and surrounding soft tissue. To our knowledge, this is the first reported case of M. immunogenum infection of a peritoneal catheter. Treatment included catheter removal, local surgical debridement, and combination antimicrobial therapy. Herein, we review literature describing antibiotic management of M. immunogenum, an organism for which optimal therapy is not defined.

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.

Management of hypersensivity pneumonitis

Hypersensitivity pneumonitis (HP) is an interstitial lung disease due to a combined type III and IV reaction with a granulomatous inflammation, caused by cytotoxic delayed hypersensitivity lymphocytes, in a Th1/Th17 milieu, chaperoned by a deficient suppressor function of T regulatory cells. Skewing toward a Th2 phenotype is reported for chronic HP. Phenotypic expression and severity depends on environmental and/or host genetic and immune co-factors. The wide spectrum of causative antigens is continuously up-dated with new sources of airborne organic particles and drug-induced HP. The diagnosis requires a detailed history, measurement of environmental exposure, pulmonary function tests, imaging, detection of serum specific antibodies, broncho-alveolar lavage, antigen-induced lymphocyte proliferation, environmental or laboratory-controlled inhalation challenge and lung biopsy. Complete antigen avoidance is the best therapeutic measure, although very difficult to achieve in some cases. Systemic steroids are of value for subacute and chronic forms of HP, but do not influence long term outcome. Manipulation of the immune response in HP holds future promise.