Antibiotic ‘breathalyzer’ a promising alternative for therapeutic drug monitoring

Analysis of exhaled breath may be able to identify the presence of specific metabolites for four out of five antibiotics, offering a noninvasive approach to performing therapeutic drug monitoring.

In a single-centre, proof-of-concept study, breath analysis was able to distinguish unique antibiotic-related and antibiotic-regulated metabolites linked to meropenem, cefazolin, flucloxacillin, and ciprofloxacin, reported lead study author Dr Sarah Dräger of the Division of Internal Medicine, University Hospital Basel in Basel, Switzerland. [ESCMID Global 2024, abstract P2422]

No clear signal could be observed for piperacillin, Dräger added.

“Therapeutic drug monitoring of antibiotics is used to optimize and guide antibiotic dosing,” she said. “Currently, we use blood samples to do this. But the collection of blood is an invasive, time- and resource-consuming technique and leads to discomfort in patients.”

The lengthy wait time for test results, ranging from several hours to days, could hinder timely treatment adjustments for critically ill patients, according to Dräger.

In comparison, exhaled breath analysis offers a much more patient-friendly alternative: it is noninvasive, samples are easy to collect, and patient discomfort is eliminated entirely, she continued. “It also has the potential to decrease the turnaround time, especially when combined with real-time analyses, when … results [are available] in as little as 10 minutes.”

Exhaled breath analysis is already being used to monitor other drugs, such as antiseizure medications. Dräger and colleagues conducted their study to explore whether they could measure the levels of specific metabolites  to monitor antibiotic concentrations without taking blood samples.

A total of 10 adults (median age 63 years, 54.5 percent female) who received intravenous antibiotic treatment for respiratory infections (n=3), intravascular infections (n=3), abdominal infections (n=2), urinary tract infection (n=1), or skin and soft tissue infection (n=1) were recruited for the study. The antibiotics used were meropenem (n=3), piperacillin/tazobactam (n=3), cefazolin (n=2), flucloxacillin (n=1), and ciprofloxacin (n=1).

Exhaled breath samples were collected 30 minutes after antibiotic administration. Then, the samples were analysed for exogeneous metabolites and endogenous metabolites with the use of mass spectrometry.

In light of the overall data, Dräger pointed to exhaled breath analysis as a potentially game-changing method for therapeutic drug monitoring that eliminates the need for needles.

“We aim to confirm these very promising results in a larger cohort of patients, as well as look at how they relate to blood plasma concentrations of antibiotics and patient outcomes,” she said.