Immunologic mechanisms in the adaptation of swine farm workers to their work environment.

Swine building exposure causes inflammatory reactions that appear to be attenuated with prolonged periods of contact. The mechanisms behind this adaptation to a dusty and endotoxin-rich environment are poorly understood. Our aim was to compare levels of selected inflammatory mediators in swine farm workers at times with differences in exposure. Participants had blood sampling done before and after each of three work shifts-two in winter and one in summer. Before one of the winter visits they had avoided pulmonary exposure to the swine buildings by wearing respiratory protection for 4 d. The other visits were done after non-protected periods of work. Protein and mRNA concentrations were measured in blood. Mixed models were used for the statistics. During summer higher concentrations of mRNA to IL-8, lymphocyte function-associated antigen 1 and bactericidal/permeability-increasing protein (BPI) were observed. BPI mRNA increased only over the work shift after the unprotected winter period (P = 0.039). BPI decreased from elevated levels across the shift after use of respiratory protection (P = 0.003), but was unchanged during the other two visits. The findings suggest possible roles for these proteins in adaptation to the swine building environment after repeated exposures.

Work-related health effects in swine building workers after respiratory protection use.

OBJECTIVE: To compare inflammation and lung function in swine workers after periods with and without respiratory protection during work. METHODS: Twenty-three workers were examined before and after two nonprotected work shifts. One shift was preceded by a period with diminished exposure by use of respirators. The other shift was preceded by an unprotected period of work. RESULTS: Endotoxin concentrations were similarly high (24,636 and 28,775 endotoxin units/m(3)). A 3.1% cross-shift decline in forced vital capacity occurred after the period with respiratory protection (P = 0.01). Blood leukocytes increased more (P = 0.01) and bactericidal/permeability-increasing protein was reduced (P = 0.015) only after the period with respiratory protection. Plasma interleukin-6 increased (P < 0.0001) during both visits. CONCLUSION: Respiratory protection resulted in cross-shift inflammatory and respiratory reactions at return to unprotected work.

Human pathogens and tetracycline-resistant bacteria in bioaerosols of swine confinement buildings and in nasal flora of hog producers.

Swine confinement buildings in eastern Canada are enclosed and equipped with modern production systems to manage waste. Bioaerosols of these swine confinement buildings could be contaminated by human pathogens and antimicrobial resistant bacteria which could colonize exposed workers. We therefore wanted to analyze bioaerosols of swine confinement buildings and nasal flora of Canadian hog producers to evaluate possible colonization with human pathogens and tetracycline-resistant bacteria. Culturable and non-culturable human pathogens and tet genes were investigated in the bioaerosols of 18 barns. The nasal passages of 35 hog producers were sampled and total DNA was extracted from the calcium-alginate swabs to detect, by PCR, Campylobacter, C. perfringens, Enterococcus, E. coli, Y. enterocolitica, tetA/tetC, tetG and ribosomal protection protein genes. Airborne culturable C. perfringens, Enterococcus, E. coli, and Y. enterocolitica were present in the bioaerosols of 16, 17, 11 and 6 of the 18 facilities. Aerosolized total (culturable/non culturable) Campylobacter, C. perfringens, Enterococcus, E. coli and Y. enterocolitica were detected in 10, 6, 15, 18 and 2 barns, respectively. Tet genes were found in isolates of culturable human pathogens. TetA/tetC, tetG and ribosomal protection protein genes were detected in the bioaerosols of all 18 studied buildings. Campylobacter, C. perfringens, Enterococcus, E. coli, and Y. enterocolitica were found respectively in 4, 9, 17, 14 and one nasal flora of workers. One and 10 workers were positive for tetA/tetC and tetG genes, respectively. In swine confinement buildings, hog producers are exposed to aerosolized human pathogens and tetracycline-resistant bacteria that can contaminate the nasal flora.

Biological activities of respirable dust from Eastern Canadian peat moss factories.

Bacteria, moulds, endotoxin and quartz from respirable dust of agricultural and industrial buildings are typically incriminated for the respiratory health decline of exposed workers despite that dust being an undefined mixture and quantification methods of aerosolized bacteria, moulds or endotoxin not being standardized yet. We developed an in vitro alveolar epithelial cell system in which biological activities of peat moss factories' dust might be correlated to bacteria, mould, endotoxin and quartz concentrations of the analyzed samples. Following exposure, interleukin-8 protein secretion, necrosis and apoptosis of the exposed A549 cells were monitored respectively with ELISA on cell supernatants, trypan blue exclusion and DNA fragmentation detection by flow cytometry. Respirable dust was collected with liquid impingers and respirable quartz with 10mm Dorr-Oliver cyclones. We quantified mesophilic bacteria, mesophilic moulds and endotoxins from liquid impinger samples. No correlation was observed between biological activities of dust and bacteria, mould, endotoxin or quartz concentrations under our experimental conditions. Our speculation is that simple measurements, such as dust concentrations, may not be adequate indicators of the human respiratory health hazard for a given environment.

Geological setting and age of Australopithecus sediba from southern Africa.

We describe the geological, geochronological, geomorphological, and faunal context of the Malapa site and the fossils of Australopithecus sediba. The hominins occur with a macrofauna assemblage that existed in Africa between 2.36 and 1.50 million years ago (Ma). The fossils are encased in water-laid, clastic sediments that were deposited along the lower parts of what is now a deeply eroded cave system, immediately above a flowstone layer with a U-Pb date of 2.026 +/- 0.021 Ma. The flowstone has a reversed paleomagnetic signature and the overlying hominin-bearing sediments are of normal polarity, indicating deposition during the 1.95- to 1.78-Ma Olduvai Subchron. The two hominin specimens were buried together in a single debris flow that lithified soon after deposition in a phreatic environment inaccessible to scavengers.

Metalworking fluid-related aerosols in machining plants.

Respiratory problems are observed in machinists using soluble metalworking fluid (MWF). Evidences suggest that these problems could be related to the aerosolized microorganisms and their byproducts from MWF. To establish MWF aerosol exposure thresholds and to better understand their effect on human health, these aerosols must be fully characterized. This article evaluates airborne microorganisms and aerosols from soluble MWF in the working environment. Air quality parameters (endotoxin levels, culturable airborne microorganisms, fluid mist, inhalable dust and air exchange rates) were evaluated at 44 sites, in 25 shops in Quebec, Canada. Microorganism concentrations were also measured in MWF. Culturable airborne bacteria concentrations were low, ranging from 1.2 x 10(1) to 1.5 x 10(3) CFU (colony forming units) m(-3), even for metalworking fluid highly contaminated by bacteria (up to 2.4 x 10(9) CFU mL(-1)). Inhalable dust varied between < 0.1 to 2.6 mg m(-3), while air exchange rates were mostly below the standard (4 h(-1)) for this type of workplace, between 0.6 to 14.2 h(-1). Only nine of 44 sites respected the suggested minimum value for air exchange rates. Fluid mist ranged from 0.02 to 0.89 mg m(-3), which is below the threshold limit value (TLV) (ACGIH) of 5 mg m(-3). Airborne endotoxin concentrations ranged from undetectable to 183 EU m(-3) (endotoxin units), showing no correlation with airborne microorganisms or inhalable dust. Most workstations respected the suggested minimum values for fluid mist and showed low concentrations of airborne endotoxin, culturable microorganisms and inhalable dust despite fluid contamination, even when air exchange rates were below the recommendations. Airborne Pseudomonas pseudoalcaligenes was recovered from many sites at significant concentrations. Health-associated risks following exposure to this microorganism should be further investigated.

Impact of production systems on swine confinement buildings bioaerosols.

Hog production has been substantially intensified in Eastern Canada. Hogs are now fattened in swine confinement buildings with controlled ventilation systems and high animal densities. Newly designed buildings are equipped with conventional manure handling and management systems, shallow or deep litter systems, or source separation systems to manage the large volumes of waste. However, the impacts of those alternative production systems on bioaerosol concentrations within the barns have never been evaluated. Bioaerosols were characterized in 18 modern swine confinement buildings, and the differences in bioaerosol composition in the three different production systems were evaluated. Total dust, endotoxins, culturable actinomycetes, fungi, and bacteria were collected with various apparatuses. The total DNA of the air samples was extracted, and quantitative polymerase chain reaction (PCR) was used to assess the total number of bacterial genomes, as a total (culturable and nonculturable) bacterial assessment. The measured total dust and endotoxin concentrations were not statistically different in the three studied production systems. In buildings with sawdust beds, actinomycetes and molds were found in higher concentrations than in the conventional barns. Aspergillus, Cladosporium, Penicillium, and Scopulariopsis species were identified in all the studied swine confinement buildings. A. flavus, A. terreus, and A. versicolor were abundantly present in the facilities with sawdust beds. Thermotolerant A. fumigatus and Mucor were usually found in all the buildings. The culturable bacteria concentrations were higher in the barns with litters than in the conventional buildings, while real-time PCR revealed nonstatistically different concentrations of total bacteria in all the studied swine confinement buildings. In terms of workers' respiratory health, barns equipped with a solid/liquid separation system may offer better air quality than conventional buildings or barns with sawdust beds. The impact of ventilation rates, air distribution, or building design still has to be explored.

Seasonal variations in work-related health effects in swine farm workers.

The aim of the project was to investigate whether there were diminished health effects in swine farm workers during summer compared with winter, as seasonal differences in concentrations of bioaerosols have been reported. Twenty-four workers were visited once during each season. Before and after a work shift, they underwent lung function testing and blood sampling. During work, they wore personal air sampling equipment. The mean endotoxin exposure of the workers was highest during winter (25,690 vs. 6,553 EU/m(3); p = 0.004). Although exposures to endotoxin and CO(2) varied between the seasons, no differences in lung function were found between them. White blood cell concentration increased over the work shift from 5.74-6.82 in winter (p < 0.0001) and from 5.80-6.38 in summer (p = 0.014). These increases differed between the two seasons (p = 0.032). Plasma tumour necrosis factor concentrations fell over the work shift only during winter (1.34-1.24 pg/ml (p = 0.03) (p = 0.014 for the difference between seasons). Plasma interleukin-6 increased over the work shift independently of season (p = 0.0006). The study supported our hypothesis of adverse effects on lung function and immune system, but less so during summer than during winter among Quebec swine farm workers.

Measurement of airborne bacteria and endotoxin generated during dental cleaning.

Dynamic dental instruments generate abundant aerosols in the work environment. Dental unit waterlines (DUWL) support a large microbial population and can be a significant source of bioaerosols generated during dental treatments. This study was conducted to characterize bioaerosol generation during dental treatments performed in standardized conditions. Culture-based method (R2A, and blood agar with and without O2) and fluorescence microscopy were used. Dental cleaning procedures were performed in an isolated treatment room with controlled ventilation rate. Andersen microbial samplers were used to collect culturable bioaerosols generated before (baseline), during, and after 2 hr of dental treatments. Inhalable dust samplers were used to measure total bioaerosols content in dental hygienist's and patients' breathing zones. AGI-30 were used for the collection of the endotoxin. The use of fluorescence microscopy in combination with culture demonstrated that dental staff and patients were exposed to up to 1.86 E+05 bacteria/m(3) generated during treatments. Fortunately, bioaerosols returned to baseline within 2 hr after the dental procedures. The small diameter of the aerosols generated (< 1 microm) suggests that the risk of contact between the aerosolized bacteria and the respiratory system of exposed individuals is likely to occur.

Aerosolization of mycobacteria and legionellae during dental treatment: low exposure despite dental unit contamination.

Dental unit waterlines (DUWL) support growth of a dense microbial population that includes pathogens and hypersensitivity-inducing bacteria, such as Legionella spp. and non-tuberculous mycobacteria (NTM). Dynamic dental instruments connected to DUWL generate aerosols in the work environment, which could allow waterborne pathogens to be aerosolized. The use of the real-time quantitative polymerase chain reaction (qPCR) provides a more accurate estimation of exposure levels compared with the traditional culture approach. Bioaerosol sampling was performed 13 times in an isolated dental treatment room according to a standardized protocol that included four dental prophylaxis treatments. Inhalable dust samples were taken at the breathing zone of both the hygienist and patient and outside the treatment room (control). Total bacteria as well as Legionella spp. and NTM were quantified by qPCR in bioaerosol and DUWL water samples. Dental staff and patients are exposed to bacteria generated during dental treatments (up to 4.3 E + 05 bacteria per m(3) of air). Because DUWL water studied was weakly contaminated by Legionella spp. and NTM, their aerosolization during dental treatment was not significant. As a result, infectious and sensitization risks associated with legionellae and NTM should be minimal.

Identification of mycobacteria in peat moss processing plants: application of molecular biology approaches.

Peat moss processing plant workers are exposed to high concentrations of bioaerosols. Although mycobacteria have been cultured from peat moss, no study has examined the workers' exposure to mycobacterial bioaerosols. We evaluated the presence of mycobacteria in air samples from peat moss processing plants using molecular biology approaches (cloning-sequencing and polymerase chain reaction (PCR)) and the workers exposure using immunoglobulin G (IgG) complexes to mycobacteria. In addition, species detected in air samples and in peat moss were compared. Two peat moss processing plants were chosen among 14 previously studied. A total of 49 clones were sequenced. Real-time PCR was also performed on the same air samples to evaluate the airborne concentration of mycobacteria and estimate exposure levels. Several Mycobacterium species were present in the air samples (M. malmoense, M. smegmatis, M. graceum, M. bohemicum, and M. interjectum). Mycobacterium avium was recovered by culture in peat moss but not in the air using the molecular approach. Total airborne Mycobacterium concentration was estimated at 8.2 x 10(8)/m3. Workers had IgG against the mycobacterial mix and M. avium, suggesting significant exposure. The findings from air samples, supported by IgG measurements, demonstrate that peat moss processing plant workers are exposed to mycobacteria in addition to other biological agents.

Bioaerosols in peat moss processing plants.

Peat moss is organic matter colonized by large numbers of microorganisms. Storage prior to its processing may result in massive microbial growth. These biological contaminants can become airborne during processing. Our goals were (a) to evaluate concentrations of bioaerosols (inhalable dust, molds, bacteria) in peat moss processing plants that used dust removing systems, and (b) to evaluate the presence of these microorganisms in peat moss. Fourteen plants from Eastern Canada were visited; 3 plants operated all year (all-year mixing plants), and 11 plants functioned only during summer months (seasonal). Air samples were taken throughout the day at different work sites using IOM cassettes for inhalable dust and All-Glass Impinger-30 samplers and Andersen six-stage impactors for microorganisms. Samples of nonprocessed and bagged peat moss (solid material) were also taken and analyzed. A total of 25 work sites for air sampling and 33 solid material samples were analyzed. Air samples contained up to 441.7 mg/m3 of inhalable dust and up to 1.0 x 10(8) CFU/m3 mesophilic molds and 3.3 x 10(5) CFU/m3 bacteria. Seasonal plants were more contaminated with molds and dust than all-year mixing plants. Sieving sites were the most highly contaminated work sites. Airborne dust concentration was significantly correlated with molds and bacteria. Up to 3.8 x 10(7) CFU/g (dry weight) and 4.8 x 10(7) CFU/g (dry weight) molds and bacteria, respectively, were found in the solid material samples. Airborne contaminants did not correlate with solid material content. Despite the use of dust removing systems, peat moss processing plants contain very large amounts of microbially contaminated bioaerosols that do not correlate with the quality of the processed peat. Efficiency of dust removing systems could influence the contamination levels.

Sensitization to airborne molds and its health effects in peat moss processing plant workers.

The goal of this study was to evaluate the incidence of sensitization to the major molds found in peat dust in workers exposed to stored peat moss and the health impact of this sensitization. Air samples from each plant were obtained to measure the levels of airborne molds, bacteria, and dust. There were 189 workers from 14 peat moss processing plants (3 all-year mixing plants and 11 seasonal plants) recruited for the study. The subjects completed a symptoms questionnaire, underwent spirometric measurements and skin-prick tests, and gave venous blood samples. Blood samples from 43 nonexposed control subjects were also taken. A similar percentage of smokers from both plant types was observed. Twenty-eight percent of the workers tested had a positive serum reaction to at least one of the tested molds. The percentage of positive workers varied from plant to plant, going from none in 4 plants to 14 out of 21 for 1 plant. This variability was not correlated with the airborne levels of molds. FEV tended to be lower in the workers with positive antibodies compared with seronegative workers. IgG positive frequency was higher for those workers employed in the all-year plants, and workers from those plants had lower FEV/FVC than seasonal plant workers. Seasonal plants were more contaminated with molds than all-year mixing plants, suggesting that the duration of exposure may trigger more sensitization than the level of exposure. We conclude that there is a high incidence of mold sensitization in peat moss factory workers and that this sensitization may have a negative respiratory health impact.

Hypersensitivity pneumonitis in a hardwood processing plant related to heavy mold exposure.

Two workers employed in a hardwood floor plant presented symptoms suggestive of hypersensitivity pneumonitis (HP). At that plant, kiln-dried wood often shows moldy growth and is subsequently brought inside for processing. This study evaluated the environment in attempt to identify the causative antigen and verify whether other workers of this and similar plants had or were at risk of developing HP. Dust from dust-removing systems and molds on the surface of wood planks were collected and air samples taken from a sister plant. Blood samples, spirometry, and symptoms' questionnaires were obtained from 11 co-workers. Dense Paecilomyces growth was observed on the surface of the dried processed wood in the index plant. This fungal genus was not detected in the sister plant. An additional worker had symptoms suggestive of HP, and his bronchoalveolar lavage revealed a lymphocytic alveolitis. The 3 confirmed cases of HP and the other 10 workers had positive specific IgG antibodies to Paecilomyces. We report 3 cases of HP out of 13 workers and a 100% sensitization to molds in workers of a hardwood processing plant. This rate is much higher than what is commonly seen in other environments associated with HP. The drying process is suspected of being responsible for the massive Paecilomyces contamination likely responsible for the HP.

Flow cytometry analysis of germinating Bacillus spores, using membrane potential dye.

Germination of Bacillus anthracis spores is necessary for the transcription of plasmidic genes essential to the infection. Assessing germination potential is crucial to predict the risk associated with pathogenic Bacillus exposure. The aim of this study was to set up a viability assay based on membrane potential in order to predict the earliest germination event of spores. B. cereus and two strains of B. subtilis were used. The spores were isolated with a sodium bromide gradient. Approximately 10(7) spores were incubated at 37 degrees C in tryptic soy broth (TSB). Aliquots were harvested at predetermined times and stained with 3,3'-dihexyloxacarbocyanine iodide [DiOC(6)(3)] or with bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC(4)(3)]. Fluorescence characteristics were obtained using flow cytometry. The earliest detectable activation of membrane potential occurred after 15 min of incubation in TSB using DiOC(6)(3). Using DiBAC(4)(3), the earliest detectable signal was after 4 h of incubation. Control experiments using carbonyl cyanide m-chlorophenylhydrazone (CCCP)-treated spores did not show any change in the fluorescence intensity over time. Since no membrane potential and no germination were detected in CCCP-treated spores, the activation of membrane potential seems to be associated with germination. DiOC(6)(3) can be used as an early membrane potential indicator for spores. DiBAC(4)(3), by contrast, is not a early membrane potential marker.

Saccharopolyspora rectivirgula from Quebec dairy barns: application of simplified criteria for the identification of an agent responsible for farmer's lung disease.

Saccharopolyspora rectivirgula (Micropolyspora faeni) is one of the major agents responsible for farmer's lung disease, a form of hypersensitivity pneumonitis. It is frequently isolated from the air of contaminated barns. The identification of this actinomycete is difficult because most of its phenotypic characteristics are variable and classical tests are not easy to perform on actinomycetes. Fatty acid analysis is very useful for the identification of these strains, but is not available except in some research or reference laboratories. Morphological (microscopic and macroscopic observations), physiological and biochemical tests (growth properties; macromolecules degraded; citrate utilisation and acid production from carbohydrates; resistance to antibiotics, lysozyme and heat), cell wall and fatty acid analyses and IgG analyses with serum from patients with farmer's lung were performed on 12 environmental isolates presumed to be S. rectivirgula and two control strains of S. rectivirgula. From this, a simple and rapid scheme for the identification of this actinomycete is proposed: optimal growth temperature (55 degrees C); colony appearance based on morphology (filamentous) and colour (beige to orange-brown); microscopic morphology (chains of spores on both aerial and substrate mycelium); growth on NaCl 10%; cell-wall analysis (type IV); and the verification of antibody response with serum from a patient with farmer's lung. This last criterion is important to confirm the immunogenicity of the strains identified as S. rectivirgula. This scheme provides an accurate and efficient way of identifying S. rectivirgula strains and evaluating exposure to this bacterium. The study shows the limited value and the lack of reproducibility of some classical biochemical tests.