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Phosphorylcholine-containing antigens in bacteria from the mouth and respiratory tract
S H Gillespie1, S Ainscough, A Dickens
1Department of Microbiology, Royal Free Hospital School of Medicine, London.
Abstract:
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.
Insights
Phosphorylcholine (PC) antigens were found in 15% of bacterial isolates. Most PC-positive bacteria were Haemophilus influenzae, potentially causing false positives in Streptococcus pneumoniae tests.
Area of Science:
- Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- Phosphorylcholine (PC) is a component of bacterial cell walls.
- PC-containing antigens can cause cross-reactions in diagnostic assays.
- Haemophilus influenzae is a common respiratory tract bacterium.
Purpose of the Study:
- To investigate the prevalence of phosphorylcholine (PC)-containing antigens in oral and respiratory bacterial isolates.
- To identify bacterial species possessing PC-containing antigens.
- To assess the potential for cross-reactivity in diagnostic tests for Streptococcus pneumoniae.
Main Methods:
- Enzyme immunoassay (EIA) was used to detect PC-containing antigens.
- 269 bacterial isolates from the mouth and respiratory tract were tested.
- Isolates were identified to the species level.
Main Results:
- 15% (41/269) of bacterial isolates were positive for PC-containing antigens.
- Haemophilus influenzae was the most common PC-positive species (29/41 isolates).
- Other PC-positive species included Gemella haemolysans, Micrococcus spp., Bacillus sp., Corynebacterium jeikeium, and Lactococcus sp.
Conclusions:
- Haemophilus influenzae frequently expresses phosphorylcholine (PC)-containing antigens.
- The presence of PC in H. influenzae may lead to false-positive results in Streptococcus pneumoniae antigen detection assays.
- This cross-reactivity has implications for respiratory specimen diagnostics.