Nontypeable Haemophilus influenzae (NTHi) is a Gram-negative cocco-baccillus pathogen that is host adapted exclusively to humans. It is a major pathogen infecting both adults (bronchitis, COPD) and children (otitis media). NTHi utilises and incorporates sialic acid Neu5Ac (N-acetylneuraminic acid) from the host as a terminal sugar on lipooligosaccharide (LOS)(1). Sialic acid is critical in NTHi biofilm formation and evading the host immune system. Neu5Gc (N-glycolylneuraminic acid) is found in most vertebrates but is absent in humans owing to a mutation in the Neu5Ac hydroxylase (CMAH) gene (2). Thus when "non-human" Neu5Gc is presented as a cell surface glycan, it is recognized by the immune system as a "foreign antigen" triggering the generation of xeno-autoantibodies(3). Its been proposed that anti-Neu5Gc antibodies contribute to chronic inflammation, possibly contributing to tumour progression and vascular inflammation(4)(5). Recent literature have hypothesised that anti-Neu5Gc antibody production in humans occur during infancy whereby dietary Neu5Gc is taken up by NTHi and presented on LOS(6). In this study we examined Neu5Gc uptake and presentation on NTHi LOS to determine whether the transient, low levels of dietary Neu5Gc are preferentially utilized and displayed on NTHi LOS. NTHi strain 2019 was grown on media supplemented with various ratios of Neu5Ac and Neu5Gc. LOS was purified and Neu5Ac:Neu5Gc ratio determined by treatment with mild acidic hydrolysis followed by analysis and quantification using high performance anion exchange chromatography with amperometric detection. Results obtained show that Neu5Gc is not utilized as efficiently or preferred to Neu5Ac, when equal amounts of Neu5Gc and Neu5Ac are provided to NTHi in culture media. Molecular basis of NTHi preference for Neu5Ac, and its implication for the dietary Neu5Gc, and the Neu5Gc-LOS generation of anti-Neu5Gc antibody hypothesis are the subjects of our current studies.