SEROLOGICAL CROSS-REACTIONS BETWEEN BARTONELLA AND CHLAMYDIA SPECIES - IMPLICATIONS FOR DIAGNOSIS

Diagnosis of Chlamydia or Bartonella infections continues to rely main ly on serology, However, serological cross-reactions between members o f these genera have recently been described. Sera from eight patients originally diagnosed as having Chlamydia pneumoniae endocarditis react ed with both Chlamydia sp. and Bartonella quintana antigens (microimmu nofluorescence technique). Adsorption of sera,vith B. quintana or C. p neumoniae antigens removed anti-C, pneumoniae antibodies, whereas adso rption with C. pneumoniae antigens did not change antibody titers to B . quintana. Western blot analysis confirmed the presence of cross-reac ting antigens and showed antibody patterns in all sera to be compatibl e with a Bartonella infection. These patients were therefore probably suffering from Bartonella-induced rather than Chlamydia-induced endoca rditis. In contrast, sera from 10 patients presumed to be suffering fr om C. pneumoniae pneumonia did not display anti-B. quintana antibodies , although cross-reacting antigens were revealed by Western blotting, This work highlights the possibility that cases of infective Bartonell a endocarditis are erroneously diagnosed as chlamydial infections.