Feasibility of using volatile urine fingerprints for the differentiation of sexually transmitted infections

Sexually transmitted infections (STIs) are a public health problem worldwide, and current diagnostic methods have certain limitations. In recent years, volatile organic compounds (VOCs) have been studied as an alternative diagnostic method. Due to this, this study aimed to detect, in vaginal swabs and urine samples, VOCs emitted by highly prevalent STIs-causing bacteria (Chlamydia trachomatis, Mycoplasma genitalium, and Neisseria gonorrhoeae) to identify potential biomarkers that allow the detection of these STIs. VOCs detected in urine samples showed a better differentiation of patients with STIs due to C. trachomatis from those not infected, with 2,6-dimethyl-4-heptanone as the volatile compound most related to the presence of this bacterium. Among the VOCs most related to M. genitalium in urine, 4-methyltetradecane and 2-methylpentadecane stood out, while 3,4,4-trimethyl-2-cyclohexen-1-one was the VOC most closely related to N. gonorrhoeae infection. Moreover, C₁₂ alcohols were the main VOC family associated with positive samples in all three bacteria, which could indicate the presence of aldehyde reductases in their metabolism. In contrast, alcohols such as 3-methyl-1-heptanol and 1-octanol, as well as dimethyl esters, were more associated with negative samples and may be useful in ruling out an STI caused by one of these three bacteria. In short, the VOCs identified as potential biomarkers in patients with infection by C. trachomatis, M. genitalium, or N. gonorrhoeae could be used in the early diagnosis of these STIs, quickly interrupting the chain of transmission, especially interesting in asymptomatic patients. KEY POINTS: • Sexually transmitted infections are a serious public health problem worldwide. • The study of VOCs in multiple infections is increasing in recent years. • The identification of volatile biomarkers could allow new diagnostic methods.