There are many commercially available rapid diagnostic tools that allow for early detection of infection. With early detection, healthcare practitioners everywhere hope to improve patient outcomes by linking them with appropriate treatment as quickly as possible.
At the Society of Infectious Diseases Pharmacists (SIDP) Program at ASM Microbe Society Day in New Orleans, Louisiana, Jerod Nagel, PharmD, infectious disease specialist at the University of Michigan Hospital and Health System, presented his team’s findings. He provided all members in attendance with an overview of such diagnostics, as well as how to incorporate them into effective antimicrobial stewardship programs in healthcare facilities, in order to reach that end goal—improving patient outcomes.
In his presentation, Dr. Nagel specifically focused on Staphylococcus aureus
infections. “We all know it’s a huge problem,” he said, pointing out that it ranks number one on the list of pathogen-associated hospital-associated infections (HAIs). Not surprisingly, when considering the burden of S. aureus
bacteremia, there is high morbidity and mortality.
“There’s 15% mortality, about 10% to 20% of those patients have deep-seated endocarditis or other metastatic disease, a lot of these patients have to go to the ICU [intensive care unit], the length of stay is incredibly long (10-20 days), and about half of the patients get an ID [identification and detection] consult,” he explained.
Dr. Nagel proceeded to share data showing that there was a significant reduction in mortality and length of hospital stay among patients who received early therapy for S. aureus
bacteremia. “So, that brings us to talking about what we could do to get patients on the right antibiotics right away,” he said.
Part of the answer lies in the new technologies available for rapid ID of these organisms. Here are the following rapid diagnostic tools that Dr. Nagel highlighted in his talk:
Mass spectrometry / [Matrix-Associated Laser Desorption/Ionization-Time Of Flight] MALDI-TOF:
MALDI-TOF utilizes mass spectrometry and “identifies bacteria based on unique protein sequences.” It reduces the time to organism ID by 24-36 hours—it takes about an hour. Unlike some of the other available tools, it can replace conventional or automated systems for organism ID for most organisms. It has a low reagent cost, but still makes for a costly initial investment, according to Dr. Nagel. Disadvantage? It’s “currently limited clinical utility in detecting methicillin resistance.” Regardless, it is commonly used in Europe but is also gaining popularity within the United States.
Nucleic acid hybridization / PNA-FISH, Quick-FISH, Xpress-FISH:
One of the biggest advantages of Quick-FISH is the extremely rapid testing process—it only takes about 20 minutes. This is one of the first products that came out, and as a result, many hospitals have clinical experience with this product. Not only that, but “it has proven benefit,” Dr. Nagel said. However, the initial product is limited to 3 targets, where other multiplex platforms have many more. It is also limited when it comes to detecting resistance mechanisms.