Potentially pathogenic bacteria and antimicrobial resistance in bioaerosols from cage-housed and floor-housed poultry operations.

BACKGROUND: Antibiotics are used in animal confinement buildings, such as cage-housed (CH) and floor-housed (FH) poultry operations, to lower the likeliness of disease transmission. In FH facilities, antibiotics may also be used at sub-therapeutic levels for growth promotion. Low levels of antibiotic create a selective pressure toward antimicrobial resistance (AMR) in chicken fecal bacteria. OBJECTIVE: The objective of this study was to compare bacteria and AMR genes in bioaerosols from CH and FH poultry facilities. METHODS: Bioaerosols were collected from 15 CH and 15 FH poultry operations, using stationary area samplers as well as personal sampling devices. Bacteria concentrations were determined by genus- or species-specific quantitative polymerase chain reaction (PCR) and AMR genes were detected using endpoint PCR. RESULTS: Enterococcus spp., Escherichia coli, and Staphylococcus spp. were significantly higher in bioaerosols of FH poultry operations than CH bioaerosols (P < 0.001) while Clostridium perfringens was significantly higher in area bioaerosols of CH operations than FH area bioaerosols (P < 0.05). Campylobacter spp. were detected only in bioaerosols of FH facilities. Zinc bacitracin resistance gene, bcrR, erythromycin resistance gene, ermA, and tetracycline resistance gene, tetA/C, were more prevalent in bioaerosols of FH facilities than CH bioaerosols (P < 0.01, P < 0.01, and P < 0.05, respectively). CONCLUSIONS: Most bacteria are more concentrated and most AMR genes are more prevalent in bioaerosols of FH poultry operations, where growth-promoting antibiotics may be used.

Antimicrobial Resistance in the Environment: Towards Elucidating the Roles of Bioaerosols in Transmission and Detection of Antibacterial Resistance Genes.

Antimicrobial resistance (AMR) is continuing to grow across the world. Though often thought of as a mostly public health issue, AMR is also a major agricultural and environmental problem. As such, many researchers refer to it as the preeminent One Health issue. Aerial transport of antimicrobial-resistant bacteria via bioaerosols is still poorly understood. Recent work has highlighted the presence of antibiotic resistance genes in bioaerosols. Emissions of AMR bacteria and genes have been detected from various sources, including wastewater treatment plants, hospitals, and agricultural practices; however, their impacts on the broader environment are poorly understood. Contextualizing the roles of bioaerosols in the dissemination of AMR necessitates a multidisciplinary approach. Environmental factors, industrial and medical practices, as well as ecological principles influence the aerial dissemination of resistant bacteria. This article introduces an ongoing project assessing the presence and fate of AMR in bioaerosols across Canada. Its various sub-studies include the assessment of the emissions of antibiotic resistance genes from many agricultural practices, their long-distance transport, new integrative methods of assessment, and the creation of dissemination models over short and long distances. Results from sub-studies are beginning to be published. Consequently, this paper explains the background behind the development of the various sub-studies and highlight their shared aspects.

Endotoxin and dust at respirable and nonrespirable particle sizes are not consistent between cage- and floor-housed poultry operations.

BACKGROUND: Individuals engaged in work in intensive animal houses experience some of the highest rates of occupationally related respiratory symptoms. Organic dust and in particular endotoxin has been most closely associated with respiratory symptoms and lung function changes in workers. It has previously been shown that for intensive poultry operations, type of poultry housing [cage-housed (CH) versus floor-housed (FH)] can influence the levels of environmental contaminants. The goal of the study was to determine the differences in endotoxin and dust levels at different size fractions between CH and FH poultry operations. METHODS: Fifteen CH and 15 FH poultry operations were sampled for stationary measurements (area) of dust and associated endotoxin. Fractioned samples were collected utilizing Marple cascade impactors. Gravimetric and endotoxin analysis were conducted on each of the filters. RESULTS: When assessed by individual Marple stage, there was significantly greater airborne endotoxin concentration (endotoxin units per cubic meter) in the size fraction >9.8 µm for the FH operations whereas at the size fraction 1.6-3.5 µm, the CH operations had significantly greater airborne endotoxin concentration than the FH operations. Endotoxin concentration in the dust mass (endotoxin units per milligram) was significantly greater in the CH operations as compared to the FH operations for all size fractions >1.6 µm. As such, endotoxin in the respirable fraction accounted for 24% of the total endotoxin in the CH operations whereas it accounted for only 11% in the FH operations. There was significantly more dust in all size fractions in the FH operations as compared to the CH poultry operations. CONCLUSIONS: There is more endotoxin in the presence of significantly lower dust levels in the respirable particle size fractions in CH poultry operations as compared to the FH poultry operations. This difference in respirable endotoxin may be important in relation to the differential respiratory response experienced by CH and FH poultry operation workers.

Lung function and farm size predict healthy worker effect in swine farmers.

BACKGROUND: Swine farmers are exposed to a number of airborne contaminants associated with respiratory ill health. OBJECTIVES: To examine the factors associated with healthy worker effect in the swine industry from a longitudinal follow-up of farmers at 4 years and 13 years. DESIGN: A prospective study of swine farmers and nonexposed rural residents was conducted using similar questionnaires and same spirometer at each time point. RESULTS: In the original observations in 1990/1991, we studied 302 swine farmers and 261 nonfarming control subjects. Four years later in 1994/1995, 217 swine farmers and 171 nonfarming control subjects of the original group participated again. In 2003/2004, 163 swine farmers and 118 control subjects were retested. Of the 163 swine farmers, 52 remained active swine farmers and 111 were no longer swine farming, thus providing the opportunity to evaluate work continuity in the industry. Among farmers studied in 2003/2004, mean values for percentage of predicted FEV(1)/FVC ratio and forced expiratory flow between 25% and 75% of FVC were lower in those who had quit swine farming compared to those still swine farming and nonfarming control subjects. The herd size in the barn at baseline in 1990/1991 and at interim follow-up in 1994/1995 was a significant predictor of quitting swine farming. In addition, percentage of predicted FEV(1)/FVC at the interim observation was a significant predictor of quitting swine farming. CONCLUSIONS: There is a significant healthy worker effect among swine farmers. The continuation of work in the facilities may be predicted by herd size and interim lung function.

Updated systematic review: associations between proximity to animal feeding operations and health of individuals in nearby communities.

OBJECTIVE: The objective of this review was to update a systematic review of associations between living near an animal feeding operation (AFO) and human health. METHODS: The MEDLINE® and MEDLINE® In-Process, Centre for Agricultural Biosciences Abstracts, and Science Citation Index databases were searched. Reference lists of included articles were hand-searched. Eligible studies reported exposure to an AFO and an individual-level human health outcome. Two reviewers performed study selection and data extraction. RESULTS: The search returned 3702 citations. Sixteen articles consisting of 10 study populations were included in the analysis. The health outcomes were lower and upper respiratory tracts, MRSA, other infectious disease, neurological, psychological, dermatological, otologic, ocular, gastrointestinal, stress and mood, and other non-infectious health outcomes. Most studies were observational and used prevalence measures of outcome. An association between Q fever risk and proximity to goat production was reported. Other associations were unclear. Risk of bias was serious or critical for most exposure-outcome associations. Multiplicity (i.e., a large number of potentially correlated outcomes and exposures assessed on the same study subjects) was common in the evidence base. CONCLUSIONS: Few studies reported an association between surrogate clinical outcomes and AFO proximity for respiratory tract-related outcomes. There were no consistent dose-response relationships between surrogate clinical outcome and AFO proximity. A new finding was that Q fever in goats is likely associated with an increased Q fever risk in community members. The review results for the non-respiratory health outcomes were inconclusive because only a small number of studies were available or the between-study results were inconsistent. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42014010521.

Authors' response to comments from Nachman KE et al.

Authors' response to comments letter to the editor from Nachman KE et al.

Tumor necrosis factor alpha and pulmonary function in Saskatchewan grain handlers.

OBJECTIVE: The objective of this study was to estimate the contribution of lifestyle (cigarettes) and tumor necrosis factor (TNF) alpha polymorphisms at position 308 of the tumor necrosis factor alpha gene promotor (TNF-308*1/*2) to pulmonary function among grain handlers. METHODS: Employed male grain handlers (157) provided occupational and respiratory symptom information, pulmonary function measurements, and DNA for genotyping. RESULTS: The genotypes of 101 were TNF-308*1/*1, 47 were *1/*2, and nine were *2/*2. Current smokers whose genotype was *2/*2 or *1/*2 had lower values compared with other combinations of genotype and smoking status. Among *1/*1 homozygotes, current smokers had better percent of predicted forced expiratory volume in 1 second (P = 0.04) mean values than nonsmokers and better percent of predicted forced vital capacity than exsmokers (P = 0.017) or nonsmokers (P = 0.008). CONCLUSIONS: These results indicate the complexity of determining which workers will develop acute and chronic adverse pulmonary conditions in response to exposure to grain dust and the toxins in cigarette smoke interacting with their genotype.

Respiratory symptoms and lung function in poultry confinement workers in Western Canada.

OBJECTIVE: To determine whether poultry production methods impact respiratory health, and whether poultry farmers have more respiratory symptoms and lower lung function than comparison control groups. DESIGN: Cross-sectional study. SETTING: Provinces of Saskatchewan, Alberta and Manitoba during the winters of 1997 to 1999. POPULATION: Three hundred three poultry workers, 241 grain farmers and 206 nonfarming control subjects were studied. Poultry workers were further classified according to the poultry housing type in which they worked, ie, workers who worked with poultry raised on the floor (floor-based operations), which included broiler/roaster, broiler/breeder and turkey operations (n=181), and workers who worked with poultry raised in a caged setting (cage-based operations), which included egg operations (n=122). INTERVENTIONS: Subjects completed a respiratory health questionnaire, which included questions on the poultry operation and work habits, and participated in lung function testing. MAIN RESULTS: Overall, this study indicated that poultry workers report greater prevalences of current and chronic respiratory symptoms than control populations, and that the type of production method (cage-based versus floor-based) appears to influence the prevalence of respiratory symptoms and lung function values. Workers from cage-based operations report greater prevalences of current cough and wheeze, as well as lower mean values for forced expiratory volume in the first second (FEV1), forced expiratory flow at 25% to 75% of vital capacity (FEF25-75) and FEV1/FVC than workers from floor-based facilities. Workers from cage-based facilities also reported greater prevalences of current and chronic cough and phlegm, as well as significantly lower FEF25-75 and FEV1/FVC values than nonfarming control subjects. Furthermore, grain farmers had lower FVC and FEV1 values than nonfarmers. CONCLUSIONS: The results suggest that the type of poultry production system (ie, floor- versus cage-based) appears to have an effect on the respiratory response of workers from these facilities. Further studies are required to understand the physiological mechanisms of respiratory dysfunction and the relationships concerning workplace exposure among poultry workers.

The association between proximity to animal-feeding operations and community health: a protocol for updating a systematic review.

BACKGROUND: Livestock and poultry operations that feed large numbers of animals are common. Facility capacity varies, but it is not uncommon for facilities to house 1,000 swine with multiple barns at a single site, feedlots to house 50,000 cattle, and poultry houses to house 250,000 hens. There is primary research that suggests livestock facilities that confine animals indoors for feeding can represent a health hazard for surrounding communities. In this protocol, we describe a review about the association between proximity to animal-feeding operations (AFOs) and the health of individuals in nearby communities. A systematic review of the topic was published by some members of our group in 2010. The purpose of this review is to update that review. METHODS/DESIGN: The populations of interest are people living in communities near livestock production facilities. Outcomes of interest are any health outcome measured in humans such as respiratory disease, gastrointestinal disease, and mental health. Measures of antibiotic resistance in people from the communities compared to measures of resistance found in animals and the environment on animal-feeding operations will also be summarized. The exposure of interest will be exposure to livestock production using a variety of metrics such as distance from facilities, endotoxin levels, and measures of odor. Electronic searches will be conducted using MEDLINE and MEDLINE In-Process (via OvidSP), CAB Abstracts (via Web of Knowledge), and Science Citation Index (via Web of Knowledge). No language or date restriction will be applied. We will access the risk of bias using a pilot version of a tool developed by the Methods Groups of the Cochrane Collaboration for non-randomized interventions.We propose to conduct a meta-analysis for each health metric (e.g., combining all respiratory disease outcomes, combining all gastrointestinal outcomes). A planned subgroup analysis will be based on the domains of the risk of bias. DISCUSSION: This systematic review will provide synthesis of current evidence reporting the association between living near an animal-feeding operation and human health. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42014010521.

Size distribution of particulate and associated endotoxin and bacteria in traditional swine barn rooms and rooms sprinkled with oil.

The objective of this pilot study was to investigate if a once-a-day sprinkling of canola oil in a swine confinement facility alters the airborne concentration and distribution of particulate matter and associated compounds (endotoxin and culturable microbes). Particulate was collected using an eight-stage cascade impactor in four identical swine grower/finisher rooms of a swine barn. Particulate (mg/m(3)) and endotoxin (EU/m(3) and EU/mg) distribution was determined. A six-stage viable cascade impactor was used to quantify total bacteria, enteric bacteria, and fungi. Microbes were characterized from subcultures prepared from the 10 most predominant colony types on each stage 3 (aerodynamic size 3.3-4.7µm) of the collection plates. Results indicated that oil sprinkling reduced total dust by 86% and total endotoxin concentration by 82.5%. However, the distribution patterns indicate that reduction is observed predominantly on large dust particles. In addition, the proportion of endotoxin associated with smaller particulate sizes (i.e., particles <4.7 µm) was higher in the oil-sprinkled rooms. Oil sprinkling does not markedly alter distribution of total bacteria, enteric bacteria, or fungi. The most frequently identified species were gram-positive genera. Oil sprinkling in swine confinement grower/finisher rooms can significantly reduce airborne total dust and endotoxin; however, smaller particles and associated endotoxin appear to remain in suspension, suggesting the overall improvement in air quality is uncertain. Further distribution studies and exposure outcome studies would need to be undertaken to determine the impacts of oil sprinkling.

Excess longitudinal decline in lung function in grain farmers.

Workers in intensive agricultural operations are exposed to dust and endotoxin that are associated with respiratory effects. The authors investigated the longitudinal changes in lung function in male grain farmers. In this study, male grain farmers (n = 263) and male nonfarming control subjects (n = 261) studies initially in 1990/91 were followed-up in 1994/95 and 2003/04. After controlling for potential confounders, grain farmers had an excess annual decline of 9.2 ml/year (95% confidence interval [CI]: 2.7, 15.8, p = .006) in forced vital capacity (FVC) in comparison to control. Long-term exposure to grain dust and other substances in lifetime grain farmers results in progressive loss in lung function.

Comparison of endotoxin and particle bounce in Marple cascade samplers with and without impaction grease.

The health of persons engaged in agricultural activities are often related or associated with environmental exposures in their workplace. Accurately measuring, analyzing, and reporting these exposures is paramount to outcomes interpretation. This paper describes issues related to sampling air in poultry barns with a cascade impactor. Specifically, the authors describe how particle bounce can affect measurement outcomes and how the use of impaction grease can impact particle bounce and laboratory analyses such as endotoxin measurements. This project was designed to (1) study the effect of particle bounce in Marple cascade impactors that use polyvinyl chloride (PVC) filters; (2) to determine the effect of impaction grease on endotoxin assays when sampling poultry barn dust. A pilot study was undertaken utilizing six-stage Marple cascade impactors with PVC filters. Distortion of particulate size distributions and the effects of impaction grease on endotoxin analysis in samples of poultry dust distributed into a wind tunnel were studied. Although there was no significant difference in the overall dust concentration between utilizing impaction grease and not, there was a greater than 50% decrease in the mass median aerodynamic diameter (MMAD) values when impaction grease was not utilized. There was no difference in airborne endotoxin concentration or endotoxin MMAD between filters treated with impaction grease and those not treated. The results indicate that particle bounce should be a consideration when sampling poultry barn dust with Marple samplers containing PVC filters with no impaction grease. Careful consideration should be given to the utilization of impaction grease on PVC filters, which will undergo endotoxin analysis, as there is potential for interference, particularly if high or low levels of endotoxin are anticipated.