Background: Mycoplasma pneumoniae (MP) is the most predominant pathogen causing pneumonia. The present study compares two serological assays, the indirect immunofluorescence assay (IFA) and the passive particle agglutination assay (PPA), in order to assist clinicians in selecting accurate diagnosis methods.
Methods: Sera from 127 patients suffering from mycoplasma pneumonia and 76 from the healthy group were analyzed simultaneously by PPA and IFA. Receiver operating characteristic analyses were performed to evaluate the detection value of PPA and IFA for mycoplasma pneumoniae. The kappa coefficient was analyzed to evaluate the agreement between the IFA and PPA assay.
Results: The AUC of PPA and IFA was more than 0.70, suggesting both assays were acceptable in clinical efficacy for detecting mycoplasma pneumoniae. When ± 1:40 antibody titers were interpreted as negative, PPA showed the highest specificity, Youden index, and AUC (86.84%, 65.58%, and 0.828, respectively), and the kappa coefficient between PPA and IFA was 0.360.
Conclusions: IFA and PPA assays have advantages and disadvantages in the detection of MP antibodies. MP anti-bodies ± 1:40 antibody titers should be interpreted as negative to improve PPA detection abilities, and the consistency of the two methods was regular agreement. Clinicians should detect MP antibodies simultaneously with two methods or analyze paired samples with one method for diagnosing whether or not MP infection is present.