The specific IgM response toMycoplasma pneumoniaeinfection: interpretation and application to early diagnosis

Abstract

Specific IgM antibody production in patients with serologically proven Mycoplasma pneumoniae infection by the complement fixation (CF) test was studied using a mu-capture ELISA. Sera from 79% of patients were found to be IgM positive. Patients could be divided into two groups relating to the amount of specific antibody produced. High levels of specific IgM (greater than or equal to 10 units) were more commonly found in younger patients. Seventy-six per cent of patients under the age of 20 produced relatively high levels of IgM compared to 35% of patients over the age of 20. In contrast, the number of patients who produced low or undetectable levels of IgM (less than 10 units) was found to increase with age. This trend was found to be significant which suggests that low or undetectable levels of IgM may be due to reinfection with M. pneumoniae. Specific IgM was found to appear in the serum at approximately 7 days after the onset of symptoms, peaking at between 10 and 30 days, and then falling to undetectable levels at an estimated 12-26 weeks post onset of symptoms. Twenty-eight per cent of acute-phase sera (CF titres less than 256) from patients whose sera subsequently showed a fourfold or greater rise in M. pneumoniae CF antibody titre were IgM positive. Thus using mu-capture ELISA a diagnosis of M. pneumoniae infection may often be made more rapidly than by the complement fixation test.

Evaluation of Four Commercial Immunoglobulin G (IgG)- and IgM-Specific Enzyme Immunoassays for Diagnosis of Mycoplasma pneumoniae Infections

“…The -capture ELISA has previously been found to have a high sensitivity and specificity. It has been validated for early diagnosis of M. pneumoniae infection (13,23,37,39). Although IgM EIAs are more sensitive and specific than CFT, the IgM response may be nonspecific (3,19,26,29) or absent, particularly in the elderly with reinfection (2,14,22,23,30,33,37).…”

“…It has been validated for early diagnosis of M. pneumoniae infection (13,23,37,39). Although IgM EIAs are more sensitive and specific than CFT, the IgM response may be nonspecific (3,19,26,29) or absent, particularly in the elderly with reinfection (2,14,22,23,30,33,37). It has also been shown that healthy people often have a relatively high background of specific M. pneumoniae IgG antibodies in their sera, probably because of past M. pneumoniae infections (2,8,14,22,25,34,35).…”

Respiratory tract infections by Mycoplasma pneumoniae in children: a review of diagnostic and therapeutic measures

“…CFA does not discriminate in the acute phase whether MP is involved, but with paired sera for epidemiological studies or evaluation of new tests, it can be a useful tool. CFA is time-consuming (requires 2 days), laborious, has a low speci®city and has a lower sensitivity than immuno¯uorescence and enzyme linked immunosorbent assay (ELISA) [9,67,79,102,107,115]. False-positive results with CFA based on cross-reactivity with antigens in Streptococcus MG and Staphylococcus aureus have been reported [40].…”

Portación faríngea de Mycoplasma pneumoniae en niños chilenos

“…El diagnóstico oportuno de este microorganismo permite efectuar una terapia antimicrobiana específica y limitar su diseminación en la comunidad. La detección de IgM es el recurso de laboratorio más empleado actualmente en pediatría para el diagnóstico de neumonía por M. pneumoniae, pero su sensibilidad se aproxima solamente a 80%, siendo dependiente de la diná-mica de la respuesta inmune humoral y del momento de toma de la muestra de sangre 2,[5][6][7] . En la infección por M. pneumoniae, la IgM aparece entre los 7 y 10 días de iniciado el cuadro clínico y rápidamente asciende, alcanzando un título máximo a los 10 a 30 días 6 .…”

“…En la infección por M. pneumoniae, la IgM aparece entre los 7 y 10 días de iniciado el cuadro clínico y rápidamente asciende, alcanzando un título máximo a los 10 a 30 días 6 . Sin embargo, algunos pacientes no desarrollan IgM antes de las 2 semanas de iniciada la enfermedad, limitando la utilidad de este procedimiento diagnóstico 6,7 . Por otra parte, la especificidad de la detección de IgM mediante ELISA varía ampliamente entre 25 y 90%, dependiendo del kit comercial utilizado 3,4 .…”