Rapid Test Is Promising Tool for Antibiotic Stewardship

December 19, 2013

Time is a critical factor in antibiotic resistance. The longer bacteria have to be exposed to a drug, the more opportunities they have to develop ways to resist it. But a rapid lab test is emerging as a promising tool in helping doctors and hospitals cut that time short.

The testing method is called MALDI-TOF – short for matrix-assisted laser desorption/ionization time of flight – which identifies bacteria based on the weight of their microscopic particles. And it does so very quickly. While traditional lab methods can take up to five days to identify a specific germ, MALDI-TOF can deliver results in 24 to 48 hours.

Eileen Burd, Ph.D., director of clinical microbiology at Emory University Hospital in Atlanta, said every hour counts when it comes to fighting antibiotic resistance, a problem identified by the Centers for Disease Control and Prevention (CDC) as one of the gravest threats to public health today.

“If you can identify the bacteria you’re dealing with sooner, then you can make educated, appropriate decisions about which drugs you should use to treat the patient,” Burd said. “That really helps our efforts to be good stewards of antibiotics.”

Typically, when a patient develops an infection, doctors will begin treating them with a broad-spectrum antibiotic -- one that targets a wide range of bacteria – until lab tests can identify the specific type of germ that’s making the patient sick.

When that diagnosis comes, doctors can switch to a narrower antibiotic, one that targets only the problem bacteria. Burd said this is where MALDI-TOF testing can make a difference: allowing doctors to get a faster diagnosis and make the switch sooner, minimizing the time bacteria are exposed – and potentially developing resistance – to the broad-spectrum drugs.

In 2013, two studies reported the potential impact of MALDI-TOF technology. In one study, pharmacists at Methodist Hospital in Houston, Texas, used MALDI-TOF to analyze bacteria from infections in more than 100 patients. MALDI-TOF allowed the team to identify the problem bacteria in 10.2 hours on average, compared with 36.6 hours in samples analyzed with traditional methods. It took about 29 hours for patients in the MALDI-TOF group to start effective antibiotic treatment, compared with 75 hours in the traditional group. The MALDI-TOF patients were released from the hospital an average of two days before those in the traditional group, saving about $20,000 per patient in hospital costs.

In another study, a team at the University of Michigan Hospitals used MALDI-TOF to analyze bacteria from nearly 250 patients; using the rapid test allowed staff to identify the bacteria nearly 30 hours sooner and give patients optimal antibiotic therapy nearly 43 hours sooner than traditional lab testing methods.

In August, the U.S. Food and Drug Administration approved the first MALDI-TOF system for identifying bacteria in humans. Some hospital labs in Georgia are already using the technology for bacterial analysis, including those at Emory, Children’s Healthcare of Atlanta and the Grady Health System.

“We are fortunate that providers in Georgia have started to adopt these newer technologies and to share their experiences with their peers,” said Jeanne Negley, health care-associated infections surveillance director at the Georgia Department of Public Health. “As we work with providers in the state to encourage antibiotic stewardship, I am confident that these new, rapid laboratory methods, such as MALDI-TOF, will be an important tool to improve antibiotic use.”

Burd notes that it’s not enough for hospitals to use MALDI-TOF in their labs. The technology should also be part of a broader antibiotic stewardship program, ideally one in which doctors, nurses, pharmacists and lab technicians work together to make sure patients receive the appropriate antibiotics as rapidly as possible.

The lab can do a really fast, cool new test, but if nobody knows about it, then it doesn’t have an impact,” Burd said. “The technology should be used to facilitate a discussion about antibiotic use between the stewardship team and a patient’s doctor.”

It may take time before labs everywhere can use the technology. The machines that do the MALDI-TOF analysis are expensive –about $200,000 on average. And not all hospitals have antibiotic stewardship teams in place for the technology to be most effective.  But Burd said she thinks MALDI-TOF testing has the potential to alleviate the threat posed by drug-resistant bacteria.

“I am certain that it will help us turn the tide on antibiotic resistance,” she said. “This could really blow things out of the water.”

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