Measurement of dust‐borneMRSAin pig farms using different approaches

Abstract

Aims To obtain knowledge about (i) how to sample airborne methicillin‐resistant Staphylococcus aureus (MRSA) and dust in the pig farm environment including effects of sampler on (a) measured exposure, (b) MRSA survival and (c) spatial and temporal variation in exposure, and (ii) the association between exposure to MRSA, dust and optical density OD. Methods and Results Airborne dust was sampled on five pig farms using five active and one passive samplers. Staphylococcus aureus and MRSA (as a subset of S. aureus) were quantified using selective agar media and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The Andersen sampler, electrostatic dust collectors (EDC), and Gesamtstaubprobenahme (GSP) and Institute of Occupational Medicine samplers with polycarbonate or Teflon filters were applicable for sampling airborne MRSA. The half‐life of MRSA was not reduced by active sampling. A significant correlation was found between dust and S. aureus exposure within, but not between, farm section and farms. A significant spatial and temporal variation in dust and MRSA exposure was found within a stable. The dust sampling rate and the concentration of MRSA in the sampled dust decreased after 5 days of sampling. Conclusion Sampling using the GSP can be performed for 1 h without affecting the following half‐life of MRSA. Sampling for MRSA using the EDC should not exceed 3 days due to overloading and the die‐off of MRSA. The measurement of OD may be used as a proxy measure for dust exposure. To obtain knowledge about potential exposure, samples should be taken repeatedly and in different areas within a stable section. Significance and Impact of the Study Sampling method, sampling time and number of samples taken, but not force of airflow on the filter, influence the measured potential exposure to MRSA and dust.

Potential Respiratory Deposition and Species Composition of Airborne Culturable, Viable, and Non-Viable Fungi during Occupancy in a Pig Farm

“…In this study, the concentration of airborne fungi was lower than what has been previous found in pig farms in Poland by a factor of 10 [33] and lower than what was found in Korea by a factor of 2 [34]. Additionally, the concentration of airborne dust was noted to be 1.16 ± 0.18 mg dust/m 3 , which was lower than what was found in another Danish pig farm in the winter of 2015 (average of 1.99 mg dust/m 3 ) [35], and considerably lower in what has been found in older studies (e.g., a geometric mean 4.01 ± 1.73 mg dust/m 3 ) [36]. This could be attributed to the fact that the present study was conducted in a newly built pig farm, which has updated ventilation equipment to reduce the amount of airborne dust.…”

Airborne Staphylococcus aureus in different environments—a review

“…According to the literature (Agersø et al 2013; Madsen et al 2019), the correct option from the variety of methods of air sampling for microbiological analysis requires the huge knowledge and long experience in the field study. Many different factors can influence the result, such as the concentration of airborne microorganisms (closely related with the type of environment), relative humidity (RH), temperature, species composition, and their ability to survive under unfavourable conditions.…”

“…Madsen et al (2019) conducted the study which can be a basis for the description of relevant differences in results (understood as the concentration of airborne MRSA) between six methods of sampling of airborne MRSA (five active and one passive) on five pig farms. Identification of bacteria was carried out on selective agar media using the MALDI-TOF MS method.…”

Livestock-associated MRSA survival on house flies (Musca domestica) and stable flies (Stomoxys calcitrans) after removal from a Danish pig farm

“…It is possible that the experimental setup, where we used a 1mm 2 plastic mesh insect net to construct the cages, had an effect on the observed difference between the two groups for each room. It is also possible that LA-MRSA dust 49 accumulated on the cages or that caged cultivated house flies were able to touch LA-MRSA positive wild free-roaming flies through the mesh, increasing the LA-MRSA prevalence amongst the caged cultivated house flies. It is however unlikely that a significant proportion of the observed LA-MRSA prevalence amongst the caged cultivated flies can be attributed to direct contact with wild free-roaming flies.…”