Bacteria associated with acute otitis media have high Clq binding capacity.

A simple, rapid and sensitive radioimmunologic method for demonstrating Clq binding to bacteria is described. Various bacteria were shown to bind Clq without the participation of antibodies. Great differences in Clq binding levels between different types and strains of S. pneumoniae were found. A high uptake of Clq was observed for many pneumococcal strains of type VI, XIX and XXIII and also for non-typable strains of H. influenzae and B. catarrhalis. Other bacteria tested, including H. influenzae types a-f, demonstrated less capacity to bind Clq.