Phosphorylcholine-containing antigens in bacteria from the mouth and respiratory tract

Phosphorylcholine (PC)-containing antigens were sought in 269 bacterial isolates from the mouth and respiratory tract by an enzyme immunoassay method. Only 41 (15%) isolates were PC-positive and of these 29 (70%) were strains of Haemophilus influenzae. Other species that produced positive results included two of five isolates of Gemella haemolysans, two of five isolates of Micrococcus spp., and a single strain each of Bacillus sp., Corynebacterium jeikeium, Lactococcus sp. and H. parainfluenzae. The presence of PC-containing antigens in H. influenzae may be an important source of cross-reaction in antigen detection techniques that detect the C-polysaccharide antigen of Streptococcus pneumoniae in respiratory specimens and would result in false positive results.