INTRODUCTION
Farm animals are colonized by a co-evolved specific bacterial community. In particular, the nostril (anterior nare) is an important niche for bacterial colonization by both opportunistic pathogens and commensal. A study performed in France (Armand-Lefevre et al., 2005) was the first to show that a particular clonal complex of methicillin-resistant Staphylococus aureus (MRSA), namely CC398, was able to colonize healthy pig farmers and pigs. A subsequent worrying report indicated that 40% of pigs from Holland carried MRSA CC398 ... The aim of this project was to assess the airborne concentrations of zoonotic MRSA and MSSA in pig farms by using a traditional culture-dependent method and by using molecular quantification of DNA to estimate the proportion of airborne Staphylococcus sp. Influence of environmental factors such as season, size, and type of pig farms has been studied. Other important classical airborne contamination indicators (fungi and endotoxins) were measured to allow comparison with other studies.
Potential Public Health Consequences of Exposure Assessment for Staphylococcus aureus
Abstract(s): Commentary on the Paper by Masclaux et al.
The study of Masclaux et al., in this issue of the Annals of Occupational Hygiene, describes measurement of Staphylococcus bacteria in pig farms using classical viable measurement techniques and molecular techniques. Molecular techniques find application in hygiene field studies more often and create new opportunities. Common dust sampling approaches can be used in combination with molecular techniques and high numbers of samples can be processed creating opportunities for hygiene control and for exposure assessment in the context of epidemiological surveys. Hygienists should be aware of the advantages and disadvantages of the use of these techniques. Aspects of microbial sampling are briefly reviewed.
THE PUBLIC HEALTH CONTEXT: MRSA ON LIVESTOCK FARMS
MRSA was rarely isolated from animals before 2000, and if isolated from animals, MRSA strains were generally assumed to be of human origin, especially when found in companion animals. The emergence of livestock-associated MRSA (LA-MRSA) changed this picture dramatically. The initial case was a 6-month-old girl. She was admitted in 2004 to a hospital in the Netherlands for major surgery. She appeared colonized with MRSA during preoperative screening (Voss et al., 2005). The strain had been observed a few years earlier in France, in a study among pig farmers and their animals (Armand-Lefevre et al., 2005). Further sampling and genotyping showed that her parents carried the same MRSA strain as did the pigs on the farm. Neighbouring pig farmers and their animals were also carriers. The strain is referred to as LA-MRSA, or MRSA ST398 (Sequence Type 398), and pigs or other animals are probably the natural host. MRSA ST398 probably originated in humans and jumped to animals where it acquired resistance genes possibly as a result of selective pressure due to antibiotics use in livestock production (Price et al., 2012). Use of antimicrobials for treatment of animals, often at the herd level, probably contributed to the evolution of ST398 as well as presence of coagulase-negative staphylococci, which probably carried the resistance genes, which have been transferred to MRSA and led to the evolution of ST398....
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