Detection of Staphylococcus aureus by a Sensitive Immuno-PCR Assay

Staphylococcus aureus causes a wide variety of diseases in humans, the clinical courses of which range from boils and furuncles to more serious diseases such as septicemia and pneumonia (1). Although a significant cause of community-acquired infection, most life-threatening cases of S. aureus disease are hospital-acquired and are associated, in many cases, with indwelling vascular devices or catheters (2). The standard method of diagnosing S. aureus is to culture an isolate from a blood agar plate and then use a latex test to identify S. aureus . A specific product of S. aureus is protein A (3). Protein A is a cell-wall constituent of S. aureus and is mainly covalently linked to the peptidoglycan structure (4); however, ∼8–30% of the protein is secreted into the medium during the exponential growth phase (5). This property has been used to develop a latex agglutination test and an ELISA to identify and detect S. aureus . We describe here a sensitive immuno-PCR assay to detect S. aureus protein A. After optimization of the reaction conditions and the use of flexible plates with 96 V-bottomed wells, which were compatible with both the ELISA washer and the thermal cycler for PCR, we automated both detection methods. Anti-protein A antisera were created by immunizing rabbits with …