[Cross-reactivity between Chlamydia psittaci and Acinetobacter in indirect immunofluorescence assays]

Cross reactivity between Chlamydia psittaci and a strain from genus Acinetobacter was investigated by indirect fluorescent antibody (IFA) technique. Two groups of serum samples were tested: 64 belonged to patients diagnosed as psittacosis and 64 (control group) were non reactive to Chlamydia psittaci by IFA. Samples were incubated on smears prepared with an Acinetobacter suspension for detecting IgG and IgM. 100% reactivity to IgG was found in 1:16 serum dilution among anti-psittacosis sera, whereas 6.25% of control sera reacted at the same dilution. When testing IgM, high rates of reactivity were found in both serum groups, thus it has been discarded as a marker for cross reactivity. Fluorescence pattern suggests that antigens are located at the cell wall.