Multicenter evaluation of the novel enzyme immunoassay based on P1-enriched protein for the detection of Mycoplasma pneumoniae infection

Pediatric clinical features of Mycoplasma pneumoniae infection are associated with bacterial P1 genotype

The present study evaluated the association between different Mycoplasma pneumoniae (M. pneumonia) genotypes and clinical features of pediatric patients. Subjects were children diagnosed with community-acquired pneumonia at the Children's Hospital of Soochow University (Suzhou, China) from January 2012 to December 2013. Clinical and laboratory tests were conducted and clinical samples positive for M. pneumoniae were genotyped by nested-multiplex polymerase chain reaction. Three type I strains and three type II strains were also randomly selected for sequencing. A total of 335 clinical samples positive for M. pneumoniae were obtained. The average age of M. pneumonia-infected pediatric patients was 4.8±3.3 (years). Genotyping results identified 304 positive samples as group I strains and 30 samples as group II strains, in which 1 sample was type II variant 2a. It was also observed that point mutations were more likely to occur in type I strains compared with type II strains. Although clinical pulmonary infection scores between patients with type I and type II strains did not significantly differ, patients with type I strains had a higher risk of developing severe M. pneumoniae pneumonia (SMPP) and extrapulmonary complications, and had significantly higher percentages of peripheral blood neutrophils than patients with type II strains (P<0.05). Collectively, these data indicate that the predominant strains of M. pneumoniae in Suzhou between 2012 and 2013 were type I, and that pediatric pneumonia patients with type I strains of M. pneumoniae were more likely to progress to SMPP.

Eosinophilic Fasciitis associated with Mycoplasma arginini infection

Eosinophilic fasciitis (EF) with generalized sclerodermiform skin lesions developed over a 19-month period in a previously healthy 23-year-old man. Although we confirmed EF by skin histology and laboratory tests, the recurrent fevers and the clinical observation of sclerotic prepuce with urethritis indicated further bacteriological analysis by conventional microbiological and DNA-based tests. Urethra cultures were positive for an arginine-hydrolyzing mycoplasma and Ureaplasma urealyticum. The patient also had serum IgM antibodies to Mycoplasma pneumoniae using enzyme-linked immunosorbent assay (ELISA)-based qualitative detection. Mycoplasma arginini was isolated from two independent venous blood serum samples and was identified by conventional microbiological tests and sequencing of the 16S rRNA and rpoB genes (GenBank sequence accession numbers HM179555 and HM179556, respectively). M. arginini genomic DNA also was detected by species-specific PCR in the skin lesion biopsy sample. Treatment with corticosteroids and long-term courses of selected antibiotics led to remission of skin symptoms and normalization of laboratory values. This report provides the first evidence of EF associated with mycoplasma infection and the second report of human infection with M. arginini and therefore suggests that this mycoplasma infection might have contributed to the pathogenesis of the disease.

Identification of an N-terminal 27 kDa fragment of Mycoplasma pneumoniae P116 protein as specific immunogen in M. pneumoniae infections

BACKGROUND

Mycoplasma pneumoniae is an important cause of respiratory tract infection and is increasingly being associated with other diseases such as asthma and extra-pulmonary complications. Considerable cross-reactivity is known to exist between the whole cell antigens used in the commercial serological testing assays. Identification of specific antigens is important to eliminate the risk of cross-reactions among different related organisms. Adherence of M. pneumoniae to human epithelial cells is mediated through a well defined apical organelle to which a number of proteins such as P1, P30, P116 and HMW1-3 have been localized, and are being investigated for adhesion, gliding and immunodiagnostic purposes.

METHODS

A 609 bp fragment P116(N-27), corresponding to the N-terminal region of M. pneumoniae P116 gene was cloned and expressed. A C-terminal fragment P1(C-40), of P1 protein of M. pneumoniae was also expressed. Three IgM ELISA assays based on P116(N-27), P1(C-40) and (P116 (N-27) + P1(C-40)) proteins were optimized and a detailed analysis comparing the reactivity of these proteins with a commercial kit was carried out. Comparative statistical analysis of these assays was performed with the SPSS version 15.0.

RESULTS

The expressed P116(N-27) protein was well recognized by the patient sera and was immunogenic in rabbit. P1(C-40) of M. pneumoniae was also immunogenic in rabbit. In comparison to the reference kit, which is reported to be 100% sensitive and 75% specific, ELISA assay based on purified P116(N-27), P1(C-40) and (P116(N-27) + P1(C-40)) proteins showed 90.3%, 87.1% and 96.8% sensitivity and 87.0%, 87.1% and 90.3% specificity respectively. The p value for all the three assays was found to be < 0.001, and there was a good correlation and association between them.

CONCLUSION

This study shows that an N-terminal fragment of P116 protein holds a promise for serodiagnosis of M. pneumoniae infection. The IgM ELISA assays based on the recombinant proteins seem to be suitable for the use in serodiagnosis of acute M. pneumoniae infections. The use of short recombinant fragments of P116 and P1 proteins as specific antigens may eliminate the risk of cross-reactions and help to develop a specific and sensitive immunodiagnostic assay for M. pneumoniae detection.

Identification, expression and serological evaluation of the recombinant ATP synthase beta subunit of Mycoplasma pneumoniae

Background

Mycoplasma pneumoniae is responsible for acute respiratory tract infections (RTIs) common in children and young adults. As M. pneumoniae is innately resistant to β-lactams antibiotics usually given as the first-line treatment for RTIs, specific and early diagnosis is important in order to select the right treatment. Serology is the most used diagnostic method for M. pneumoniae infections.

Results

In this study, we identified the M. pneumoniae ATP synthase beta subunit (AtpD) by serologic proteome analysis and evaluated its usefulness in the development of a serological assay. We successfully expressed and purified recombinant AtpD (rAtpD) protein, which was recognised by serum samples from M. pneumoniae-infected patient in immunoblots. The performance of the recombinant protein rAtpD was studied using a panel of serum samples from 103 infected patients and 86 healthy blood donors in an in-house IgM, IgA and IgG enzyme-linked immunosorbent assay (ELISA). The results of this assay were then compared with those of an in-house ELISA with a recombinant C-terminal fragment of the P1 adhesin (rP1-C) and of the commercial Ani Labsystems ELISA kit using an adhesin P1-enriched whole-cell extract. Performances of the rAtpD and rP1-C antigen combination were further assessed by binary logistic regression analysis. We showed that combination of rAtpD and rP1-C discriminated maximally between the patients infected with M. pneumoniae (children and adults) and the healthy subjects for the IgM class, performing better than the single recombinant antigens or the commercial whole-cell extract.

Conclusion

These results suggest that AtpD can be used as an antigen for the immunodiagnosis of early and acute M. pneumoniae infection in association with adhesin P1, providing an excellent starting point for the development of point-of-care diagnostic assays.

Evaluation of 12 commercial tests and the complement fixation test for Mycoplasma pneumoniae-specific immunoglobulin G (IgG) and IgM antibodies, with PCR used as the "gold standard"

Serology and nucleic acid amplification are the main diagnostic tools for the diagnosis of Mycoplasma pneumoniae infection. Since no reference standard is generally accepted, serologic assays for M. pneumoniae have not been evaluated on a broad scale. In this study, 12 commercially available serologic assays (for immunoglobulin G [IgG] and IgM) and the complement fixation test (CFT) were evaluated by using M. pneumoniae DNA detection by real-time PCR as the "gold standard." The assays tested were Platelia EIA (Bio-Rad), SeroMP EIA (Savyon), Serion classic EIA (Virion/Serion), Biotest EIA (Biotest), Ridascreen EIA (r-Biopharm), AniLabsystems EIA (Labsystems), Novum EIA (Novum Diagnostica), Diagnosys EIA (MP products), Genzyme/Virotech EIA, ImmunoWell EIA (Genbio), ImmunoCard EIA (Meridian), and SerodiaMycoII microparticle agglutination (Fujirebio). Serum samples (n = 46) from 27 PCR-positive patients with a known first day of disease and sera (n = 33) from PCR-negative controls were obtained from prospective studies of acute lower respiratory tract infections. Additionally, control sera (n = 63) from patients with acute viral or bacterial respiratory infections other than those caused by M. pneumoniae were tested. The results showed low specificities for both the Novum and the ImmunoCard IgM assays. The IgM assays with the best performances in terms of sensitivity and specificity were AniLabsystems (77% and 92%, respectively), SeroMP (71% and 88%, respectively), and CFT (65% and 97%, respectively). Good receiver operating characteristic areas under the curve were found for CFT (0.94), the Platelia assay (0.87), and the AniLabsystems assay (0.85). We conclude that there are few commercial serologic assays for the detection of M. pneumoniae infections with appropriate performances in terms of sensitivity and specificity and that PCR has become increasingly important for the diagnosis of M. pneumoniae infections in defined groups of patients.

Mycoplasma pneumoniae and its role as a human pathogen

Mycoplasma pneumoniae is a unique bacterium that does not always receive the attention it merits considering the number of illnesses it causes and the degree of morbidity associated with it in both children and adults. Serious infections requiring hospitalization, while rare, occur in both adults and children and may involve multiple organ systems. The severity of disease appears to be related to the degree to which the host immune response reacts to the infection. Extrapulmonary complications involving all of the major organ systems can occur in association with M. pneumoniae infection as a result of direct invasion and/or autoimmune response. The extrapulmonary manifestations are sometimes of greater severity and clinical importance than the primary respiratory infection. Evidence for this organism's contributory role in chronic lung conditions such as asthma is accumulating. Effective management of M. pneumoniae infections can usually be achieved with macrolides, tetracyclines, or fluoroquinolones. As more is learned about the pathogenesis and immune response elicited by M. pneumoniae, improvement in methods for diagnosis and prevention of disease due to this organism may occur.

Use of quantitative and objective enzyme immunoassays to investigate the possible association between Chlamydia pneumoniae and Mycoplasma pneumoniae antibodies and asthma

Sera from 150 consecutive patients with established asthma and 150 matched controls were examined for Chlamydia pneumoniae IgG and IgA with commercially available enzyme immunoassays (EIAs) detecting immune response solely to surface proteins of elementary bodies. The assays were also modified to measure combined immune response to surface proteins and family-specific lipopolysaccharide antigen. Mycoplasma pneumoniae IgG and IgA were measured with new commercial EIAs utilising P1-enriched protein fraction as an antigen. No statistically significant differences between the patient groups in terms of prevalence or levels of antibodies to either organism were found with these methods.