A newly approved diagnostic test uses a bacteriophage technology based on bioluminescence to detect the presence of methicillin-resistant Staphylococcus aureus (MRSA) within 5 hours, as opposed to the 24 to 48 hours it takes conventional cultures to do the same. The US Food and Drug Administration (FDA) authorized marketing of the cobas vivoDx MRSA diagnostic test from Roche Molecular Systems last week. 

About 5% of hospital patients carry the MRSA bacteria. Although many who carry the bacteria do not develop MRSA, the bacteria can still cause serious illness and death, according to the US Centers for Disease Control and Prevention (CDC), which defines it as a serious antimicrobial threat. There were more than 323,000 MRSA cases in hospitalized patients in the US and more than 10,000 deaths in 2017, according to the CDC.

“Diagnostics that are able to provide accurate results more quickly can offer healthcare providers an advantage when trying to prevent and contain the spread of resistant bacteria,” said Tim Stenzel, MD, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health, in a press release. “Today’s authorization adds a new tool in the fight to prevent and control MRSA in high-risk settings. The FDA remains committed to supporting efforts to address antimicrobial resistance in order to better protect patients against this ongoing public health challenge.”

The cobas vivoDx MRSA test correctly identified MRSA in approximately 90% of samples where MRSA was present and correctly identified no MRSA in 98.6% of samples that did not have MRSA present, according to the performance studies reviewed by the FDA. When approving the diagnostic tool, the agency used its de novo premarket review pathway, a regulatory pathway for low-to-moderate-risk devices of a new type. 

The FDA says it is installing special controls for this type of test that include requirements relating to labeling and design verification and validation to address risks such as false positives. “This action also creates a new regulatory classification, which means that subsequent devices of the same type with the same intended use may go through the FDA’s 510(k) pathway, whereby devices can obtain clearance by demonstrating substantial equivalence to a predicate device,” the FDA states.

Kevin Kavanagh, MD, the founder of Health Watch USA, a not-for-profit patient advocacy group, has been an outspoken proponent for better approaches to MRSA detection. “The cobas vivoDx MRSA diagnostic test has great potential,” Kavanagh tells Infection Control Today. “Rapid testing and screening for MRSA is of utmost importance in the identifying of carriers and in the control of spread of this dangerous pathogen. The United States Department of Veterans Affairs and the United Kingdoms' National Health Service has reported great success in strategies aimed at carrier identification along with isolation and decolonization. These targeted strategies have the advantage of reducing the microbiome’s exposure to antiseptics and antibiotics which will lessen the changes of promoting the development of antibiotic resistance.”