Nontypeable Haemophilus influenzae (NTHi) is a bacteria that is one of the leading causes of OM and respiratory infections in older people. NTHi carry substances on their surface called antigens. When antigens come into contact with the right kinds of cells in the body, an immune reaction is caused. This reaction is often the symptoms of sickness that a patient feels. One of the major antigens on the surface of NTHi is called lipooligosaccharide (LOS).