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Community-acquired MRSA and pig-farming

Xander W Huijsdens1*, Beatrix J van Dijke2, Emile Spalburg1, Marga G van Santen-Verheuvel1, Max EOC Heck1, Gerlinde N Pluister1, Andreas Voss34, Wim JB Wannet1 and Albert J de Neeling1

Author Affiliations

1 National Institute for Public Health and the Environment (RIVM), Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, P.O. Box 1, 3720 BA, Bilthoven, The Netherlands

2 St. Jansgasthuis, Department of Medical Microbiology, P.O. Box 29, 6000 AA, Weert, The Netherlands

3 Radboud University Medical Centre, Department of Medical Microbiology, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands

4 Canisius-Wilhelmina Hospital, Department of Medical Microbiology, P.O. Box 9015, 6500 GS, Nijmegen, The Netherlands

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Annals of Clinical Microbiology and Antimicrobials 2006, 5:26  doi:10.1186/1476-0711-5-26

Published: 10 November 2006

Abstract

Background

Sporadic cases of CA-MRSA in persons without risk-factors for MRSA carriage are increasing.

Case presentation

We report a MRSA cluster among family members of a pig-farmer, his co-workers and his pigs. Initially a young mother was seen with mastitis due to MRSA. Six months later her baby daughter was admitted to the hospital with pneumococcal otitis. After staying five days in hospital, the baby was found to be MRSA positive. At that point it was decided to look for a possible source, such as other family members and house-hold animals, including pigs on the farm, since those were reported as a possible source of MRSA earlier.

Swabs were taken from the throat and nares of family members and co-workers. A veterinarian obtained swabs from the nares, throat and perineum of 10 pigs. Swabs were cultured following a national protocol to detect MRSA that included the use of an enrichment broth. Animal and human strains were characterized by PFGE, spa-typing, MLST analysis, SSCmec, AGR typing, and the detection for PVL, LukM, and TSST toxin genes.

Three family members, three co-workers, and 8 of the 10 pigs were MRSA positive. With the exception of the initial case (the mother) all persons were solely colonized, with no signs of clinical infections.

After digestion with SmaI, none of the strains showed any bands using PFGE. All isolates belonged to spa type t108 and ST398.

Conclusion

1. This report clearly shows clonal spread and transmission between humans and pigs in the Netherlands. 2. MLST sequence type 398 might be of international importance as pig-MRSA, since this type was shown earlier to be present in epidemiologically unrelated French pigs and pig-farmers. 3. Research is needed to evaluate whether this is a local problem or a new source of MRSA, that puts the until now successful Search and Destroy policy of the Netherlands at risk.