DNA-BASED METHODS FOR CLONE-SPECIFIC IDENTIFICATION OF STAPHYLOCOCCUS AUREUS
• Staphylococcus aureus strain CC398 now accounts for a significant percentage of all MRSA strains detected in Europe. • CC398 is an emerging zoonosis: it colonises livestock animals without clinical signs, but transmission to humans could undermine existing MRSA control programmes. • This diagnostic test for identification of CC398 is a single-step PCR, easily performed within a few hours. • This test is reliable, sensitive, specific and inexpensive to perform.
Methicillin-resistant Staphylococcus aureus (MRSA) strains belonging to a specific lineage designated CC398 have been identified in pigs, calves and other livestock and their human contacts world-wide. CC398 colonises the skin and mucosal surfaces of healthy animals without clinical signs, but the emergence of an MRSA clone in animals represents a major public health problem since animal carriers can contribute to the spread of MRSA among humans. Unlike other MRSA lineages, CC398 is likely to have animal origin and therefore is presently regarded as a zoonosis. MRSA CC398 is spreading throughout Europe and to North America, in fact it was recently established that CC398 accounted for 20% of all MRSA strains detected in the Netherlands. This underscores the need for fast, simple, inexpensive and reliable typing for this particular MRSA lineage. Generally, molecular typing of MRSA, in particular in hospital-acquired infections, is an important prerequisite for an effective and targeted use of infection control measures aimed at preventing further dissemination within hospitals, as well as from the community to hospitals. The identification of lineages for epidemiological typing and infection control is crucial at both local and global levels to facilitate intervention. Existing S. aureus typing methods such as MLST, spa and PFGE are laborious and/or expensive. However, this new diagnostic test for identification of MRSA CC398 employs a single-step PCR that is easily performed within a few hours. Preliminary validation of the test performed on a collection of CC398 and non-CC398 strains, has demonstrated that this test is reliable, accurate and sensitive