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Characterization of the Acinetobacter baumannii Secretome Using Size-Exclusion Chromatography and Raman Spectroscopy

Year: 2026

Type: article

Abstract: Acinetobacter baumannii, a multidrug-resistant pathogen of critical priority within the ESKAPE group, poses a significant threat to global healthcare, particularly in the context of nosocomial infections. Its pathogenesis is mediated not only by antibiotic resistance determinants but also by a complex repertoire of secreted virulence factors. However, comprehensive characterization of the A. baumannii secretome remains methodologically challenging due to spectral overlap in complex biological matrices. In this study, we applied a hybrid approach integrating size-exclusion chromatography with Raman spectroscopy to deconvolute the cell-free supernatant of A. baumannii. Chromatographic fractionation into seven fractions reduced spectral complexity and enabled the identification of unique metabolic profiles. Fraction 3 exhibited a distinct composition, containing specific markers for phosphatidylserine (~1724 cm−1), cysteine, phosphatidylinositol, and DNA (~770–806 cm−1), as well as CH2 groups of lipids and amino acids (~1450–1456 cm−1), while lacking signals corresponding to methionine-containing compounds, nucleic acid backbones, and polypeptide backbones characteristic of other fractions. Analysis revealed distinct biochemical specialization across fractions: Fraction 2 was enriched in glutamine/asparagine-associated signals (~990, ~998 cm−1), Fraction 4 contained a unique carotenoid marker (~1154 cm−1), Fraction 6 exhibited a phenylalanine-specific peak (~1104 cm−1), and Fraction 7 demonstrated the highest intensity of cysteine-containing protein, nucleotide, and phospholipid signals. These findings open new avenues for the discovery of biomarkers associated with virulence and antibiotic resistance in A. baumannii.

Source: International Journal of Molecular Sciences

DOI: 10.3390/ijms27135904