May 02, 2018
The end of antibiotics?
BY Jacqueline Mason
It was the real-life scenario physicians and pharmacists had feared.
A woman entered the ICU with a high fever and low white blood cell count.
Urgent laboratory testing revealed she had a bacterial blood infection highly resistant to antibiotics. On top of cancer, she was now also fighting to survive sepsis, a potentially fatal disorder that occurs when the body's immune system kicks in to fight an infection, but instead goes into overdrive and damages its own tissues and organs.
Antibiotic resistance among cancer patients like her is the focus of MD Anderson’s antibiotic stewardship team, which is dedicated to promoting the best use of antibiotics for our patients.
A quest to slow down the progression of antibiotics resistance
Frank Tverdek, Pharm.D., a clinical pharmacy services manager who’s part of the team, says stewardship became necessary as organisms evolved beyond antibiotics’ effectiveness.
Another team member, Micah Bhatti, M.D., Ph.D., assistant professor in Laboratory Medicine, explains it this way: The more antibiotics you put people on, the more likely future infections are resistant to antibiotics.
“Antibiotics have this long history of being relatively safe,” Bhatti says. “But we’re learning that’s not the case. They have repercussions.”
The type of bacteria infecting the ICU patient – Klebsilella oxytoca – is often associated with previous antibiotic therapy.
Like many cancer patients, the woman in the ICU likely received antibiotics to treat or prevent infection while undergoing chemotherapy, but the bacteria evolved to resist commonly used antibiotics.
“One of the hopes of stewardship is that it helps slow down the progression of antimicrobial resistance through appropriate use of antibiotics,” Bhatti says.
Eliminating the bug-drug mismatch
For cancer hospitals like MD Anderson, limiting antibiotics can be especially challenging.
Cancer therapies depend on the ability of antibiotics to fight infections. And because infections often originate from bacteria within the patient’s own gut or microbiome, patients with suppressed immune systems may experience recurrent infections that require multiple cycles of antibiotics.
This risk is so high that physicians often prescribe a general antibiotic even before laboratory tests have identified the microbe.
That’s a necessary approach in many cases, but the goal should be to quickly identify the pathogen and then adjust the antimicrobial treatment to prevent antibiotic resistance, says Victor Mulanovich, M.D., professor of Infectious Diseases and director of MD Anderson’s Antimicrobial Stewardship Program.
“The priority is to treat the patient with the right antibiotic, for the appropriate period of time, at the optimum dose,” Mulanovich says.
A tactical assault on resistance
The antibiotic stewardship team provides resources to help providers gain the upper hand on infections.
Step 1 – Quickly administering antimicrobials. Since this may be necessary while awaiting diagnostic results, MD Anderson uses a tool that removes much of the guesswork from choosing an early course of antibiotics.
Known as the antibiogram, it helps our doctors target the most common infections seen at MD Anderson with the most effective antibiotics.
The antibiogram identifies how often different types of bacteria are likely to be treatable with a particular antibiotic, helping a patient’s care team to choose the most appropriate antibiotic. The common antibiotic levofloxacin is only 20% effective against methicillin-resistant Staphylococcus aureus (MRSA), for instance. The antibiotic linezolid is 100% effective.
At least for now.
Step 2 – Quickly identifying the infectious organism. This is where Dr. Bhatti comes in.
He joined MD Anderson’s Microbiology Laboratory in 2015 following a fellowship in medical microbiology at Mayo Clinic in Rochester, Minnesota. Part of his laboratory role involves assessing the latest diagnostic technology to identify microorganisms in the shortest time.
Step 3 – Matching the appropriate drug to eradicate the bug. This begins when the Microbiology Laboratory notifies the physician of the positive culture. The physician will then modify the antibiotic treatment based on the findings. As part of a team effort, the antimicrobial stewardship team also monitors patients’ blood cultures and proposes recommendations when necessary.
The safety of antibiotics stewardship
Mulanovich identifies with our physicians who treat patients.
“Nobody wants to miss an infection,” he says.
So to avoid being perceived as a barrier to care, the Antimicrobial Stewardship Program has concentrated on quality improvement projects designed to give physicians the most up-to-date information on how to best treat and prevent infections.
The most recent project targets patients who tell their care teams that they’re allergic to penicillin. A penicillin allergy may limit many common antibiotic choices for patients and often requires the provider to choose an alternative antibiotic that is less effective against a particular infection or has more side effects.
Led by Mahnaz Taremi, M.D., assistant professor of Infectious Diseases, the team has discovered through screening and skin testing that up to 90% of hospitalized patients who believe they are allergic to penicillin in Leukemia and Genitourinary Medical Oncology do not have a true allergy.
That opens up more antibiotic treatment options, Mulanovich says.
Another initiative by our clinical pharmacists and the antimicrobial stewardship team involves alerting physicians when a patient has been on certain antibiotics for longer than five days. By reviewing the medication after five days (by which time cultures have identified the pathogen), the provider can end or adjust the treatment to best help the patient and simultaneously curb resistance.
“Stewardship isn’t a single event,” Tverdek says. “It’s now part of our considerations whenever we prescribe antibiotics in the 21st century.”
A longer version of this story originally appeared in Messenger, MD Anderson’s quarterly publication for employees, volunteers, retirees and their families.
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The priority is to treat the patient with the right antibiotic, for the appropriate period of time, at the optimum dose.
Victor Mulanovich, M.D.