Susceptibility of Mycobacterium immunogenum and Pseudomonas fluorescens to Formaldehyde and Non-Formaldehyde Biocides in Semi-Synthetic Metalworking Fluids

Mycobacterium immunogenum, a newly identified member of the Mycobacterium chelonae_M. abscessus complex is considered a potential etiological agent for hypersensitivity pneumonitis (HP) in machine workers exposed to contaminated metalworking fluid (MWF). This study investigated the biocidal efficacy of the frequently applied commercial formaldehyde-releasing (HCHO) biocides Grotan and Bioban CS 1135 and non-HCHO type biocides Kathon 886 MW (isothiazolone) and Preventol CMK 40 (phenolic) toward this emerging mycobacterial species (M. immunogenum) in HP-linked MWFs, alone and in presence of a representative of the Gram-negative bacterial contaminants, Pseudomonas fluorescens, using two semi-synthetic MWF matrices (designated Fluid A and Fluid B). Relative biocide susceptibility analysis indicated M immunogenum to be comparatively more resistant (2–1600 fold) than P. fluorescens to the tested biocides under the varied test conditions. In terms of minimum inhibitory concentration, Kathon was the most effective biocide against M. immunogenum. Fluid factors had a major effect on the biocide susceptibility. Fluid A formulation provided greater protective advantage to the test organisms than Fluid B. Fluid dialysis (Fluid A) led to an increased biocidal efficacy of Grotan, Kathon and Preventol against M. immunogenum further implying the role of native fluid components. Used fluid matrix, in general, increased the resistance of the two test organisms against the biocides, with certain exceptions. M. immunogenum resistance increased in presence of the co-contaminant P. fluorescens. Collectively, the results show a multifactorial nature of the biocide susceptibility of MWF-colonizing mycobacteria and highlight the importance of more rigorous efficacy testing and validation of biocides prior to and during their application in metalworking fluid operations

Evaluation of Three Influenza A and B Real-Time Reverse Transcription-PCR Assays and a New 2009 H1N1 Assay for Detection of Influenza Viruses ▿

The performance characteristics of three real-time influenza A/B virus reverse transcription-PCR (RT-PCR) assays and two real-time 2009 H1N1 RT-PCR assays were evaluated using previously characterized clinical specimens. A total of 150 respiratory specimens from children (30 influenza A/H1 virus-, 30 influenza A/H3 virus-, 30 2009 H1N1-, and 30 influenza B virus-positive specimens and 30 influenza virus-negative specimens) were tested with the CDC influenza A/B PCR (CDC), ProFlu+ multiplex real-time RT-PCR assay (ProFlu+), and MGB Alert Influenza A/B & RSV RUO (MGB) assays. A second set of 157 respiratory specimens (100 2009 H1N1-, 22 seasonal influenza A/H1-, and 15 seasonal influenza A/H3-positive specimens and 20 influenza-negative specimens) were tested with a new laboratory-developed 2009 H1N1 RT-PCR and the CDC 2009 H1N1 assay. The overall sensitivities of the CDC, ProFlu+, and MGB assays for detection of influenza A and B viruses were 100%, 98.3%, and 94%, respectively. The ProFlu+ assay failed to detect one influenza A/H1 virus-positive specimen and yielded one unresolved result with another influenza A/H1 virus-positive specimen. The MGB assay detected 84/87 (96.5%) of influenza A and B viruses and 26/30 (86.6%) of 2009 H1N1 viruses. The new laboratory-developed 2009 H1N1 RT-PCR assay detected 100/100 (100%) 2009 H1N1 virus-positive specimens, while the CDC SW Inf A and SW H1 PCR assays failed to detect one and three low-positive 2009 H1N1-positive specimens, respectively. The CDC influenza A/B virus assay and the newly developed 2009 H1N1 RT-PCR assay with an internal control can be set up in two separate reactions in the same assay for routine clinical testing to detect influenza A and B viruses and to specifically identify the 2009 H1N1 influenza virus

Biocidal Activity of Formaldehyde and Nonformaldehyde Biocides toward Mycobacterium immunogenum and Pseudomonas fluorescens in Pure and Mixed Suspensions in Synthetic Metalworking Fluid and Saline

The microbicidal activity of four different biocides was studied in synthetic metalworking fluid (MWF) against Mycobacterium immunogenum, a suspected causative agent for hypersensitivity pneumonitis, and Pseudomonas fluorescens, a representative for the predominant gram-negative bacterial contaminants of MWF. The results indicated that M. immunogenum is more resistant than P. fluorescens to the tested formaldehyde-releasing biocides (Grotan and Bioban), isothiazolone (Kathon), and phenolic biocide (Preventol). Kathon was effective against mycobacteria at lower concentrations than the other three test biocides in MWF. In general, there was a marked increase in biocidal resistance of both the test organisms when present in MWF matrix compared to saline. Increased resistance of the two test organisms to biocides was observed when they were in a mixed suspension (1:1 ratio). The results indicate the protective effect of the MWF matrix against the action of commonly used biocides on the MWF-colonizing microbial species of occupational health significance, including mycobacteria

Method for Rapid Identification and Differentiation of the Species of the Mycobacterium chelonae Complex Based on 16S-23S rRNA Gene Internal Transcribed Spacer PCR-Restriction Analysis

Members of the Mycobacterium chelonae complex (MCC), including M. immunogenum, M. chelonae, and M. abscessus, have been associated with nosocomial infections and occupational hypersensitivity pneumonitis due to metalworking fluid (MWF) exposures. In order to minimize these health hazards, an effective and rapid assay for detection of MCC species and differentiation of MCC species from other species of rapidly growing mycobacteria (RGM) and from one another is warranted. Here we report such a method, based on the variable 16S-23S rRNA gene internal transcribed spacer (ITS) region. Mycobacterium genus-specific primers derived from highly conserved sequences in the ITS region and the flanking 16S rRNA gene were used. Specificity of the primers was verified using the MCC member species, 11 non-MCC RGM species, 3 slow-growing mycobacterial (SGM) species (two strains each), and 19 field isolates, including 18 MCC isolates (from in-use MWF) and one non-MCC isolate (from reverse osmosis water). The ITS amplicon size of M. immunogenum varied from those of M. chelonae and M. abscessus. Sequencing of the ∼250-bp-long ITS amplicons of the three MCC member species showed differences in 24 to 34 bases, thereby yielding variable deduced restriction maps. ITS PCR-restriction analysis using the in silico-selected restriction enzyme MaeII or HphI differentiated the three MCC members from one another and from other RGM and SGM species without sequencing. The enzyme MaeII discriminated all three member species; however, HphI could only differentiate M. immunogenum from M. chelonae and M. abscessus. Use of an optimized rapid DNA template preparation step based on direct cell lysis in the PCR tube added to the simplicity and adaptability of the developed assay