Project description:Respiratory-tract infections are a predominant cause for clinical treatment, although, clinical assessments and standard clinical laboratory protocols are time-consuming and often inadequate for reliable diagnoses. Novel methods, preferably applied directly to clinical samples, excluding cultivation steps, are needed to improve diagnostics, provide adequate treatment and reduce the use of antibiotics and associated development of antibiotic resistance. This study applied nano-liquid chromatography coupled with tandem MS, with a bioinformatics pipeline and an in-house database of curated high-quality reference genome sequences to identify species-unique peptides as potential biomarkers for bacterial pathogens commonly found in respiratory tract infections: Staphylococcus aureus; Moraxella catarrhalis; Haemophilus influenzae and Streptococcus pneumoniae. The species-unique peptides were initially identified in pure-culture bacterial reference strains, reflecting the genomic variation in the four species and, furthermore in clinical respiratory tract samples, without prior cultivation, elucidating proteins expressed in clinical conditions of infection. Peptide biomarker candidates for each species is presented. As a proof-of-principle, the most promising species-unique peptides were applied in targeted tandem MS-analyses of clinical samples and their relevance for identifications of the pathogens, i.e. proteotyping, was validated, demonstrating their potential as effective peptide biomarker candidates for diagnostics of infectious diseases.
