Laboratory diagnosis of Mycoplasma pneumoniae infection. 3. Detection of IgM antibodies to M. pneumoniae by a modified indirect haemagglutination test

Detection of Mycoplasma pneumoniae in adult community-acquired pneumonia by PCR and serology

Diagnosis of pneumonia caused by Mycoplasma pneumoniae in adults is hampered by a lack of rapid and standardized tests for detection. This prospective study was conducted to compare the diagnostic values of an indirect immunofluorescence assay and a 16S rRNA gene PCR for the diagnosis of M. pneumoniae pneumonia in adults. From February 2005 to January 2008, 357 patients (53.8 % males, median age 63 years, range 18-94) admitted for community-acquired pneumonia (CAP) to two hospitals in Santiago, Chile, were enrolled in the study. Thirty-two patients (9.0 %) met the criteria of current or recent M. pneumoniae infection, and laboratory diagnosis was definitive in 26 cases (81.2 %) and presumptive in six cases (18.8 %). Among the 32 M. pneumoniae infections, the PCR assay was positive in 23 (71.9 %) and the serology in 27 (84.4 %) of the cases. IgM was positive in acute-phase serum specimens in 13 cases (40.6 %) of M. pneumoniae infections. Using serology as the gold standard, the sensitivity, specificity, and positive and negative predictive values of the PCR were 66.7, 98.5, 78.3 and 97.3 %, respectively, whereas the global agreement of the methods was 343/357 (96.1 %). The frequency of M. pneumoniae CAP cases declined significantly during the second year of study, suggesting the end of an epidemic period. In conclusion, although good global agreement was found between PCR and serology, the lower sensitivity of the PCR leads us to recommend the use of both procedures in parallel to confirm M. pneumoniae in CAP in adults.

Mycoplasma pneumoniae and central nervous system complications: a review

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia. Little is known about the extrapulmonary manifestations of this organism. Numerous central nervous system (CNS) manifestations have been described with M. pneumoniae. CNS involvement is probably the most common site of involvement in addition to the respiratory system. Up to 7% of patients hospitalized with M. pneumoniae may have CNS symptoms. Common CNS presentations include encephalitis, aseptic meningitis, polyradiculitis, cerebellar ataxia, and myelitis. The mechanism behind these CNS manifestations remains unclear. Direct invasion, neurotoxin production, or an immune-mediated mechanism has been proposed. Newer diagnostic techniques for the direct detection of the antigen and the microorganism are proving useful for the detection of extrapulmonary disease. This review comprehensively reviews the CNS complications that have been reported with M. pneumoniae.

Diagnosis of Mycoplasma pneumoniae pneumonia in children

We evaluated a commercial immunoglobulin M (IgM)-capture immunoassay for the detection of Mycoplasma pneumoniae infections in 278 pediatric patients with community-acquired, radiographically defined pneumonia. Acute- and convalescent-phase serum samples were collected from all patients and were tested for M. pneumoniae-specific IgM and IgG antibodies by Platelia enzyme immunoassays (Sanofi Diagnostica Pasteur, Marnes la Coquette, France). Nasopharyngeal aspirates (NPAs) were collected at the time of admission to the hospital. A total of 227 NPAs were subjected to the detection of M. pneumoniae DNA by PCR, and 191 NPAs were cultured by using the Pneumofast kit (International Mycoplasma, Signeswere, France). Southern hybridization of PCR products and the IgM test with solid-phase antigen (Serion Immunodiagnostica, Würzburg, Germany) were used for additional confirmation of a positive result, which required agreement of at least two different methods. A total of 24 (9%) confirmed diagnoses of mycoplasma infection were made, 5 (21%) of which were in children <5 years of age. Of the positive children, 24 of 24 (sensitivity, 100%) were positive by the IgM-capture test with convalescent-phase serum, 19 of 24 (79%) were positive by the IgM-capture test with acute-phase serum, 19 of 24 (79%) were positive by IgG serology, 10 of 20 (50%) were positive by PCR, and 8 of 17 (47%) were positive by culture. An additional 5 (of 254) children were positive by the Platelia IgM test alone (specificity, 98%). When the PCR with Southern hybridization result was combined with the IgM-capture test result with the acute-phase sera, the sensitivity of rapid laboratory diagnosis increased to 95%. In conclusion, the IgM serology test was the single most valuable tool for the diagnosis of M. pneumoniae pneumonia in children of any age.

The detection of Mycoplasma pneumoniae in nasal polyps

The aetiology and microbial flora of nasal polyps is not well understood. No study in the literature has reported an association between the sub-bacterium Mycoplasma pneumoniae and nasal polyps. We have developed an assay method using the Polymerase Chain Reaction (PCR) to amplify a specific region of the M. pneumoniae DNA in extracts of clinical samples using species-specific primers designed to a region of the 16S rRNA. The presence of M. pneumoniae was detected in 13/14 (93%) nasal polyps, in 4/5 (80%) rhinosinusitis mucosal samples but only in 1/7 (14%) of control samples (obstructive turbinates). An epidemic of infections due to M. pneumoniae is expected to occur in 1995. We believe this assay could form the basis of a rapid technique for M. pneumoniae detection. We also propose that the presence of M. pneumoniae may be of importance in the aetiology of nasal polyps.

Community outbreak of acute respiratory infection by Mycoplasma pneumoniae

We present the results of the investigation of an epidemic outbreak of Mycoplasma pneumoniae infection which affected 95 schoolchildren from certain village in Catalonia. The investigation took an epidemiological, clinical and microbiological approach, detecting by capture enzyme-immunoassay technique the presence of IgM antibodies against M. pneumoniae. All cases occurred over a 9 week period. The attack rate in children under five was 18% and 8.2% in those from 5-14 years. The age mean and standard deviation of the cases was 5.2 +/- 3.5 years, the range being from 9 months to 14 years. Cough was the most common clinical manifestation (87.4%), followed by fever (67.4%), asthenia (21.1%), abdominal pain (18.9%), vomiting (13.7%), earache (8.4%) and sore throat (6.3%). There was no significant difference in the distribution of symptoms according to age groups. IgM anti M. pneumoniae was positive in 36 (37.9%) of the samples analysed. Treatment chosen in most cases (90) was eritromicin and there was a correct evolution in all cases except for two clinical and radiological recurrences. Hospitalization was only necessary in 5 cases. The present findings are important to emphasize the high incidence of M. pneumoniae respiratory disease in children under 5, and suggests that with respiratory processes affecting very young children, a possible Mycoplasma pneumoniae infection should also be considered and the necessary action taken in the form of early and appropriate treatment.

Laboratory diagnosis of Mycoplasma pneumoniae infection. 4. Antigen capture and PCR-gene amplification for detection of the Mycoplasma: problems of clinical correlation

Direct detection assays for Mycoplasma pneumoniae were established by PCR amplification of short sequences within the foot protein/adhesin (P1) gene and the 16S ribosomal RNA gene. Specificity and sensitivity was excellent, no hybridization was observed with M. genitalium and other human Mycoplasma species. In nose and throat washings from subjects with respiratory infection a pattern of high counts (c.f.u./ml) of M. pneumoniae (deduced from the amount of amplified PCR product), and a positive antigen capture assay, was found in 83% of subjects with serological evidence of current infection with M. pneumoniae. A small proportion of subjects with serological patterns suggesting infection in the more distant past had positive PCR assays. This was considered to represent either persistence of the organism from a previous infection or perhaps transient carriage during a reinfection, without substantial change in antibody response. PCR-based assay of M. pneumoniae offers a powerful, rapid, and sensitive substitute for culture of the mycoplasma. Antigen capture, while less sensitive than PCR, offers the advantage that it is more often positive with samples from current infection and requires less stringent laboratory organization to contain false positive results. We conclude however that the laboratory diagnosis of a chosen clinical episode should not rest on the PCR or Ag-EIA assays alone, but must also include antibody assays to confirm whether infection is current or represents persistence from past exposure.

Detection of Mycoplasma pneumoniae in clinical samples from pediatric patients by polymerase chain reaction

The polymerase chain reaction (PCR) technique was used to detect Mycoplasma pneumoniae DNA in clinical samples (nasopharyngeal aspirations or bronchoalveolar lavages) obtained from 100 children, 1 month to 16 years old. PCR allowed the detection of M. pneumoniae DNA from 20 out of the 100 patients studied. In 16 cases, PCR positivity was associated with acute respiratory symptomatology. For five PCR-positive patients, a positive culture or a serological response evidenced acute M. pneumoniae infections. A lack of antibody response was observed particularly with immunocompromised children and infants less than 12 months old. The amount of M. pneumoniae DNA in the PCR was estimated in a semiquantitative way by comparison of its hybridization signal with those obtained for 100, 10, and 1 color-changing unit (CCU) of the M. pneumoniae FH strain. Small amounts (less than or equal to 10(2) CCU/ml) of M. pneumoniae were found in samples from asymptomatic patients, while larger amounts (greater than or equal to 10(2) to greater than or equal to 10(4) CCU/ml) were found for 8 out of 10 patients with acute pneumonia.

Application of an indirect immunofluorescence test for detection of Mycoplasma pneumoniae in respiratory exudates

We prepared polyclonal antibody specific to Mycoplasma pneumoniae and examined the conditions influencing the ability of an indirect immunofluorescence test to detect the specific antigen in respiratory exudates. The antibody did not cross-react with normal human serum or with respiratory exudates from 10 healthy persons. Cross-reactivity of the antibody with species of mycoplasmas other than M. genitalium was fully diminished when absorbed with horse serum and yeast extract, components of the culture medium. Though the absorbed antibody cross-reacted with M. genitalium, the titer was significantly lower than when tested against M. pneumoniae. Two types of antigen-specific fluorescence were observed in clinical specimens: one is large or small fluorescent granular aggregates found in mucus, and the other is fine fluorescent particles diffused on the entire surface of small epithelial cells. Throat smears from 49 patients with serologically confirmed M. pneumoniae infections were examined by our indirect immunofluorescence method. Positive results were obtained in 42 cases, many of which were positive before a rise in serum antibody titer could be demonstrated, indicating that the method is useful for a preliminary diagnosis at an early stage of the infection.