Improved sensitivity and specificity of enzyme immunoassays with P1-adhesin enriched antigen to detect acute Mycoplasma pneumoniae infection

An in-house P1-enriched (168-kDA protein) Mycoplasma pneumoniae antigen pre paration was compared in IgG, IgA and IgM enzyme immunoassays (EIAs) to the respective EIAs employing crude antigen lysate, antigen prepared by Triton X-114 partition and two commercial antigens, one of which was an ether-ext racted antigen and the other a P1-enriched antigen. In addition, three comm ercial kits from Sanofi Pasteur, Novum Diagnostica and Savyon Diagnostics w ere also assessed for comparison. Diagnostic sensitivity was studied with p aired samples from adults (n = 37) with acute respiratory illness interpret ed as acute, recent or past infection to M. pneumoniae on the basis of the results of complement fixation test (CFT). If the consensus of at least two methods is taken as the true positive for acute infection, the diagnostic sensitivities of combined IgG and IgM EIAs were 100% for the Platelia(R), S ero(TM) MP and in-house EIAs whereas for the Novum EIAs and CFT- 97% and 74 %, respectively. Moreover, the sensitivity of the P1-enriched antigen was p roven superior on the basis of systematically highest OD405 nm ratios betwe en convalescent and acute serum samples. Analytical specificity was studied by screening serum samples from 92 Finni sh blood donors and 111 serum samples from cord blood. Diagnostic specifici ty was studied in a blind testing of 30 paired serum samples from infants w ith pneumonia of variable etiology. No single misinterpretation of acute in fection from the group of samples with other respiratory diseases did occur . The present study confirmed and extended the earlier observations of the us efulness of P1-enriched antigen for reliable serologic diagnosis of acute M . pneumoniae infection. (C) 2001 Elsevier Science B.V. All rights reserved.