About a third of their cases have no livestock link
In Denmark, a total of 32 human cases of ST398 infection have been detected since 2003, including 4 cases in 2007.
Case-control study
To identify sources of MRSA ST398 infection, a case-control study was undertaken in the spring of 2007. MRSA ST398 cases were compared with two control groups (1:2:2): one group was selected via the Central National Register, the other included persons with community-acquired MRSA of subtypes other than ST398. The groups were matched with regards to age, sex and geographical distribution. Telephone interviews were used to collect information regarding admission to hospital, other medical contact, clinical data such as skin lesions and sores, chronic diseases, use of antibiotics, travel and exposure to agriculture and animals. In cases where several MRSA ST398 infected persons were found in the same family, only the index person was included in the study.
The study comprised 21 cases and 81 controls. The median age of the cases was 29 years, 13 were females. Ten (48 %) had skin or soft tissue infections; in one case such infection was complicated by severe joint infection. Consequently, ST398 seems to present a clinical presentation identical to that of other community-acquired MRSA infections.
Compared with the CNR controls, the cases were more likely to have lived or worked on farms with livestock (odds ratio (OR) 35.4; 95% CI 2.7-469.8) and have been admitted to hospital (OR 11.4; 95% CI 1.4-94.8). Compared with the MRSA control group, cases were more likely to have lived or worked on farms with livestock (OR 14.5; 95% CI 2.7-76.7).
Thirteen (62%) cases and no controls had come into contact with swine. The owners of the farms which cases had been in contact with were contacted with a view to testing for MRSA in the current production animals.
Statens Serum Institut – News – EPI-NEWS – EPI-NEWS 2007 – No. 27-33, 2007.
