Missed opportunities for treatment: How FilmArray can boost acute gastroenteritis diagnosis

On July 28, BioFire sponsored a webinar titled "The Clinical IMPACT of the FilmArray GI Panel."

The webinar featured Kimberle Chapin, MD, DABMM, FCAP, Director of Microbiology and ID Molecular Diagnostics and Professor of Medicine and Pathology at Lifespan Hospitals and Brown Medical School; and Rangaraj Selvarangan, BVSc., PhD, DABMM, Professor at the UMKC School of Medicine and Director of Research Affairs, Division of Laboratory Medicine, and Director of Microbiology Laboratory at Children's Mercy Hospital in Kansas City, Mo.

Diagnosing diarrhea is difficult because there are a lot of multiples: multiple ways the disease is transmitted, multiple symptoms and 15 to 25 different pathogens for acute gastroenteritis.

"Multiples in healthcare usually mean confusion, inefficiency and duplication of processes," said Dr. Chapin. The method for collecting samples and processing them is also complex, especially if samples aren't collected in the ER and the patient has to return them. Then the multi-step process to identify the different bacteria for a diagnosis becomes confusing; some tests deliver results within hours while others take weeks.

The complaint Dr. Chapin hears most from providers is the need to order multiple tests for suspected organisms at various points in the continuum of care before they can deliver a diagnosis. "They get different reports at different times which makes it difficult to keep track of what they know and don't know," said Dr. Chapin.

Physicians are only able to deliver a diagnosis 25 percent of the time for acute gastroenteritis. But the FilmArray technology from BioFire identifies additional bacteria and toxins, parasites and viruses when compared to the standard-of-care. The FilmArray Gastrointestinal (GI) Panel includes 12 bacteria and toxins, four parasites and five viruses. The testing method is also simplified:

• Simultaneous tests for all bacteria, viral and parasitic targets
• 98.5 percent overall sensitivity
• 99 percent overall specificity

The system is also time-efficient; it takes two minutes of hands-on time and about an hour to run the test.

A prospective evaluation of the FilmArray technology for acute gastroenteritis (AGE) including five ER sights across the United States compared the technology to the standard-of-care practices in pediatric patients with AGE. The stool collections were taken in the ER or delivered within 48 hours of the ER visit and patients also answered a questionnaire at the time the test was taken as well as seven to 10 days later.

With the standard-of-care testing, 2.5 tests were done per patient and stool culture and Shiga toxin were most common requests; Giardia/Cryptosporidium screen and the O&P Exam were second most requested. Around 35 percent of patients had C. difficile toxin test requested. Seventeen percent had stool tests. The researchers found:

• 30 percent of tests were positive by conventional tests, compared with 70 percent by FilmArray test
• At least 25 percent had more than one pathogen by FilmArray; 0 percent reported more than one analyte in the conventional tests
• Potentially treatment modifying pathogens were identified in 25 percent of patients with FilmArray; most were shigella and parasitic organisms not detected by the standard of care

"There were a lot of shigella that weren't found by the standard care that could have been treated or have implications for public health," said Dr. Chapin.

The study investigators found about 20 percent of the patients received antibiotics inappropriately when they either had viruses or no pathogens. Patients who had negative results most often reported return visits to the ER.

Dr. Selvarangan discussed the impact of the FilmArray GI Panel on shigella outbreaks in various communities, including San Francisco and Kansas City. Shigella accounts for 500,000 cases of diarrheal illness, 5,400 hospitalizations and 38 deaths each year in the United States. The CDC considers drug-resistant Shigella a serious threat to public health, and it's expected that nearly 27,000 drug resistant Shigella infections occur per year.

"Many state regulations involve cohorting convalescing children and excluding them from interacting with well children," he said. Dr. Selvarangan and his colleagues conducted a study enrolling patients who presented in the emergency department and submitted their specimen within 48 hours. The specimens were collected and batched and the results weren't available for clinicians. However, the clinicians could order a standard of care culture tests for bacterial isolation.

The post intervention period went from November 2015 to June 2016 for a second study, but this time the stool samples were received in a lab and tested by the FilmArray GI Panel. Results were relayed to parents along with a treatment plan if one was provided. There were 139 patients enrolled in the pre-intervention and 151 in the intervention period; 229 submitted samples and 238 completed follow-up interviews.

Shigella was detected in 27 percent of the patients in the pre-intervention period and 19 percent in the intervention period.

The researchers also examined the economic impact on patients and families. They found the number of children with parents who missed work was similar in both groups; the number of missed work days was also similar and the percentage that reported disease spread among family members was similar. However, patients within the intervention period were less likely to contact additional providers.

However, the antibiotic treatment for shigella was higher in the intervention period than the pre-intervention period and the most common treatment was azithromycin, which was significantly higher in the intervention period.

"The FilmArray GI Panel resulted in a significant increase in appropriate azithromycin treatment during the intervention phase," concluded Dr. Selvarangan. "Time to targeted therapy with azithromycin was improved by the rapid test results available from FilmArray GI Panel."

Please click here to view the webinar.


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