A test used to detect methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (SA) DNA is being recalled by the Food and Drug Administration (FDA) after an increasing number of complaints for false negative MRSA results were reported. MRSA, also referred to as multidrug-resistant Staphylococcus aureus or oxacillin-resistant Staphylococcus aureus (ORSA), is a bacterium responsible for several difficult-to-treat infections in humans. False negative MRSA results could lead to incorrect treatment or delay of care for patients with MRSA infection, which could cause serious injury or death.

The recalled test is the Cepheid Xpert MRSA/SA Blood Culture Assay used with the GeneXpert Dx System, and was distributed from October 21, 2008 through June 21, 2010. On July 1, 2010, Cepheid issued a press release and sent its customers a revised Corrective Action Notice letter instructing them not to report the MRSA negative result when a MRSA negative/SA positive result is generated on the Cepheid MRSA/SA Blood Culture Assay. Instead, customers were instructed to conduct further antimicrobial susceptibility testing to determine the MRSA result. The MRSA positive/SA positive results generated on the Cepheid MRSA/SA Blood Culture Assay can still be reported. The new instructions will be incorporated in future product labeling. 

An investigation by Cepheid has not fully determined the remaining causes of the false-negative MRSA results. To date, one adverse event has been reported to the FDA. Any adverse reactions to this or any other product should be reported to the FDA MedWatch Adverse Event Reporting Program at www.FDA.gov/MedWatch.