Comparison of polyclonal antisera and anti-43kDa antigen monoclonal antibodies for the culture-amplified antigenic detection of Mycoplasma pneumoniae by immunoblotting

IgM anti-P1 immunoblotting. A standard for the rapid serologic diagnosis of Mycoplasma pneumoniae infection in pediatric care

STUDY OBJECTIVE

To prospectively evaluate the use of an IgM anti-P1 immunoblotting assay for the rapid diagnosis of Mycoplasma pneumoniae infection in a pediatric setting.

PATIENTS AND METHODS

Blood specimens from 107 children representing 108 predominantly respiratory illnesses were obtained for a prospective evaluation of the IgM anti-P1 assay. Primary patient diagnoses were determined by a combination of the complement fixation test and supplementary microbiologic and nonmicrobiologic diagnostic tests. The potential effect of the assay results on antibiotic therapy was assessed by observing concurrent therapy.

RESULTS

M pneumoniae was the primary etiologic agent of disease in 19 patients. The sensitivity, specificity, positive predictive value, and negative predictive value of the IgM test to determine a case of primary M pneumoniae disease was 84.2 percent, 95.5 percent, 80.0 percent, and 96.6 percent, respectively. Twenty-seven children may have had antimicrobial therapy appropriately modified if results of the assay were directly utilized. Three of four patients with positive assays, which would have been falsely indicative of primary disease, had evidence of a recent probable M pneumoniae infection shortly preceding the acute illness.

CONCLUSION

The rapid IgM anti-P1 assay is reasonably specific for the diagnosis of M pneumoniae infection. Apart from establishing prompt and accurate diagnosis, the results have the potential to change treatment measures in a significant proportion of patients.

Definition and application of a histopathological scoring scheme for an animal model of acute Mycoplasma pneumoniae pulmonary infection

A histopathological scoring system was developed to assess the pathology of acute Mycoplasma pneumoniae pulmonary infection in a hamster model. A final score per animal (ranging 0-26) is obtained by averaging scores from each lung which have been accumulated by the addition of subscores from the assessments of quantity and quality of peribronchiolar and peribronchial infiltrates, luminal exudates, perivascular infiltrates, and parenchymal pneumonia. The scoring scheme was then applied to test the ability of a heat-killed inoculum to induce pulmonary pathology and to the trial of a 43 kDa protein-associated antigen as a vaccine immunogen. A heat-killed inoculum delivered by both intratracheal and intranasal routes did not induce pulmonary pathology compared to a live inoculum (respective mean scores 0.1, 6.7; P less than 0.01). Animals prevaccinated with the 43 kDa antigen developed an accentuated pathological response after live challenge compared to those unvaccinated (respective mean scores 16.8, 5.8; P = 0.00007). Hypersensitization to growth medium components may, however, have contributed to the accentuated disease since the lungs of vaccinated animals challenged with culture-negative media also were affected (mean score 5.4). Reproducibility of the scoring system was measured by duplicate reading of histology slides which were randomized to the observer upon the second reading (r = 0.93; P = 0.000009). The scoring system has the ability to differentiate disease severity in small groups of animals.