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Lab-Based MDx Testing Lowers Use of Antibiotics at Tennessee Hospital


NEW YORK (360Dx) – Williamson Medical Center in Franklin, Tennessee has reduced hospital stays, and in some cases even avoided hospital admissions, through using rapid molecular diagnostics as part of its antibiotic stewardship program.

"Rapid diagnostics 24/7 in conjunction with antimicrobial stewardship 24/7 has proven to significantly decrease times to optimal therapy in our institution," said Patti Walton, laboratory administrative director at Williamson Medical Center, during a presentation at the Clinical Laboratory Management Association KnowledgeLab conference in Long Beach, California last week.

The hospital began implementing rapid PCR testing in 2013 for Clostridium difficile. In 2015, 2016, and 2017 more rapid PCR testing was added in conjunction with antibiotic stewardship based on hospital pathogen prevalence, according to Walton.

In 2015, a rapid PCR-based respiratory panel was introduced based on estimates that 75 percent of antibiotic prescriptions are written for ear aches, pharyngitis, sinusitis, bronchitis or upper respiratory infections, Walton said. A study of 295 pediatric patients given the respiratory panel over the course of one year, conducted in conjunction with the children's hospital affiliated with Williamson Medical Center, found that using a rapid PCR-based respiratory panel changed clinical management for half of the patients tested, according to Walton said.

"We avoided admission on 44 patients. We conservatively estimated that was about $105,000 in savings," Walton said. The cost estimate assumed a one-day stay for each admission, she noted.

The study found antibiotics were avoided for 89 patients tested with the panel, which matches Centers for Disease Control and Prevention estimates that approximately one-third of prescribed antibiotics are unnecessary, Walton said. In addition, the types of antibiotics that were used were narrowed in 20 patients, and another 14 patients were provided targeted antimicrobial therapy.

A rapid PCR meningitis panel, implemented in May 2016, resulted in a decrease in unnecessary hospital admissions, a decrease in hospital lengths of stay, and a decrease in the amount of antibiotics used, Walton said.

In a study of 29 patients tested for meningitis using rapid PCR testing, the hospital was able to discontinue antibiotics for 18.2 percent of patients based on test results. Among patients with negative test results, the hospital avoided antibiotics altogether in 21 percent and discontinued antibiotics within 48 hours for an additional 57 percent of patients. For the one patient in the study who tested positive for bacterial meningitis, physicians were able to narrow the antibiotic prescription to target selected bacteria types.

But Walton noted that implementing rapid molecular testing also has challenges. Although the hospital had no false positive results for the first year and a half of using the meningitis panel, there were two false positives within 48 hours in January of this year. One was with a child whose meningitis panel tested positive for strep pneumonia, but the emergency room doctor questioned the result and a second test came back negative. The following day, another child's meningitis panel tested positive for Haemophilus influenzae, or H. flu, but a repeat test came back negative.

"The three most common contaminants are strep pneumonia, H. flu, and the herpes virus. It's because these are things we carry," Walton said. "It was January, and healthcare workers are the worst about coming to work sick, so we took corrective action."

Following the two false-positive tests, rules were implemented mandating that hospital personnel wear masks if collecting samples or setting up panels. The lab provided education to hospital personnel, including ER staff, to stress that anyone who is, or has recently been sick, should not collect samples or set up the panel. In addition, the lab stressed the importance of using an unopened tube for meningitis panel collection if possible.

In 2016, Williamson Medical Center also implemented rapid PCR methicillin-resistant Staphylococcus aureus (MRSA) testing. For pneumonia patients prescribed vancomycin, the hospital has found that rapid PCR MRSA testing produces such a consistently high negative predictive value that the hospital has been able to create an automated protocol for using the test.

"If a patient comes in and they have a diagnosis of pneumonia; if they've been prescribed vancomycin; if they've had a length of stay less than 48 hours and they have been admitted to the critical care unit, there is an automatically generated order for MRSA by PCR," Walton said. "If the result is negative, then we de-escalate the vancomycin."The test typically allows the hospital to de-escalate vancomycin 48 hours faster than waiting on culture test results, according to Walton.

Other molecular rapid diagnostics that Williamson Medical Center has implemented as part of its antibiotic stewardship program include blood culture ID and a chlamydia and gonorrhea panel. Last year the hospital also added influenza A/B and RSV testing, Walton said.

Antibiotic stewardship has been rising concern of health officials and regulators in recent years. In 2015, a US government task force issued its National Action Plan for Combatting Antibiotic-Resistant Bacteria, in response to a 2014 presidential executive order. The National Action plan set specific goals including reducing incidences of overall C. diff infection and reducing overall MRSA bloodstream infections by 50 percent by 2020, in comparison to 2011 numbers.

The CDC estimates that each year in the US at least 2 million people become infected with bacteria that are resistant to antibiotics and at least 23,000 people die as a direct result of those infections.

At Williamson Medical Center, antibiotic stewardship began in 2009 when an infectious disease physician requested and received approval from the hospital's administration to work with a pharmacy clinical manager and an internal medicine pharmacist to review charts and make recommendations to physicians on antibiotic usage, Walton said.

In 2012 the hospital's first antibiotic stewardship committee was established, and in 2014 a more formal Antibiotic Stewardship Administrative Committee was established, which includes the hospital's lab director, chief operating officer, physicians, pharmacists, the chief nursing officer, the nursing informatics manager, and the hospital's director of patient safety and quality, Walton said. The administrative committee oversees the hospital's antibiotic stewardship program including developing antibiotic policies and goals, and reviewing goals annually, she said.

Currently, the hospital is working on a more extensive analysis of its meningitis panel that will study the use of the panel in conjunction with antibiotic stewardship, including studying appropriate therapies based on panel results, reviewing whether antibiotic usage has escalated or de-escalated, and assessing potential cost savings associated with the panel, Walton said. Physician score cards were also recently implemented to provide physicians with data on where they stand on antibiotic prescribing in comparison to their peers.

Measuring outcomes, and reviewing physician practices based on test results, are important steps in justifying the additional cost of rapid diagnostics, Walton said.

"Rapid diagnostics are most impactful for optimal patient care and patient safety if they are performed 24/7 and there is timely action in the form of change management," she said. "Rapid turnaround time in the lab is meaningless if there is not rapid turnaround in patient care decision-making."