Researchers at the Zhejiang University conducted a pilot study to validate a simple breath test that could help clinicians diagnose and correctly distinguish a bacterial infection from bacterial colonization. The test, demonstrated in patients with ventilator-associated pneumonia, also has the potential of accurately assessing the necessity for antibiotic treatment, thereby slowing antibiotic resistance.
The research paper, titled “Breath analysis for noninvasively differentiating Acinetobacter baumannii ventilator-associated pneumonia from its respiratory tract colonization of ventilated patients,” was published in the Journal of Breath Research.
Ventilator-associated pneumonia (VAP), a type of hospital-acquired pneumonia (HAP), is associated with significant levels of morbidity and mortality. The condition is most critical due to infection with multiresistant pathogens such as Acinetobacter baumannii (A. baumannii). Respiratory tract colonization with these bacteria is common in intubated patients, constituting a high risk factor for VAP. Distinguishing between colonization and infection is clinically important, as failure to do this can result in the unnecessary use of antibiotics.
Breath volatile organic compound (VOC) analysis is of increasing interest in medical settings for diagnosis and screening purposes. VOC profiles have been studied in several respiratory diseases, such as pneumonia, chronic obstructive pulmonary disease (COPD), asthma, cystic fibrosis, cancer, and tuberculosis.
The researchers aimed to test the hypothesis that exhaled A. baumannii-derived VOCs could be used for the early detection of lower respiratory tract (LRT) bacteria in ventilated patients in intensive care units (ICUs). Moreover, the scientists assessed if concentration profiles could be associated with different states of A. baumannii infection and colonization.
In total, 20 patients with A. baumannii VAP (infection group), 20 ventilated patients with LRT A. baumannii colonization (colonization group), and 20 ventilated patients as the control group were enrolled. The analyses of VOCs were performed through gas chromatography–mass spectrometry and adsorptive preconcentration. Results indicated that the selected VOC profile in vivo could be used in the clinic to efficiently differentiate the presence of LRT A. baumannii from its absence, and LRT A. baumannii infection from its colonization.
The scientists, however, emphasize that it is not possible to simply transfer biomarkers from an in vitro experiment to in vivo use. “The direct detection of exhaled A. baumannii-derived VOCs may be adopted for an early alert of the LRT bacterial presence in ventilated ICU patients, and even in different parasitic states of A. baumannii (i.e. infection and colonization). However, further refinement and validation are required before its clinical use,” they concluded.