PURPOSE OF REVIEW: Breath testing has developed over the last 20 years. New 
techniques that can identify fingerprints for specific diseases and specific 
markers of respiratory pathogens have been applied to breath analysis. This 
review discusses the recent advances in breath analysis for the diagnosis of 
bacterial and fungal lower respiratory tract infections.
RECENT FINDINGS: The current techniques continue to develop rapidly, but 
preconcentration techniques are needed to analyse many target volatile organic 
compounds for most systems. Breath testing with an electronic nose is promising 
for the diagnosis of tuberculosis (TB), and specific volatiles identifiable by 
gas chromatography with mass spectrometry have been identified in breath for 
Mycobacterium tuberculosis, Pseudomonas aeruginosa and Aspergillus fumigatus, 
but are found at very low concentrations in breath. Contamination from the 
environment is an ongoing confounding influence. Exhaled breath condensate (EBC) 
is disappointing as a diagnostic sample.
SUMMARY: Careful attention needs to be paid to the sensitivity and specificity 
of a technique and confounding from the environment. The role of technologies 
such as selected ion flow tube-mass spectrometry is emerging. The electronic 
nose requires further validation for TB. The identification of specific 
microbial biomarkers aids the quest for improved accuracy. EBC is currently of 
limited value.