Diagnosis of Mycoplasma pneumoniae infection by microparticle agglutination and antibody-capture enzyme-immunoassay

Pediatric round pneumonia

"Round pneumonia" or "spherical pneumonia" is a well-characterized clinical entity that seems to be less addressed by pediatricians in Taiwan. We herein report the case of a 7-year-old boy who presented with prolonged fever, cough, and chest X-rays showing a well-demarcated round mass measuring 5.9 × 5.6 × 4.3 cm in the left lower lung field, findings which were typical for round pneumonia. The urinary pneumococcal antigen test was positive, and serum anti-Mycoplasma pneumoniae antibody titer measurement using a microparticle agglutination method was 1:160 (+). After oral administration of antibiotics including azithromycin and amoxicillin/clavulanate, which was subsequently replaced by ceftibuten due to moderate diarrhea, the fever subsided 2 days later and the round patch had completely resolved on the 18th day after the diagnosis. Recent evidence suggests treating classical round pneumonia with antibiotics first and waiving unwarranted advanced imaging studies, while alternative etiologies such as abscesses, tuberculosis, nonbacterial infections, congenital malformations, or neoplasms should still be considered in patients with atypical features or poor treatment response.

Pulmonary tuberculosis presenting as community-acquired pneumonia

OBJECTIVE AND BACKGROUND

The aims of this study were to investigate the frequency of Mycobacterium tuberculosis as a cause of community-acquired pneumonia (CAP) requiring hospitalization in Malaysia, and to define the clinical features of pulmonary tuberculosis (PTB) that distinguish it from non-TB CAP.

METHODS

A prospective study was performed on consecutive non-immunocompromised patients aged 12 years and older, who were hospitalized for CAP.

RESULTS

Of a total of 346 patients hospitalized for CAP, the aetiological agent was identified in 163 patients (47.1%). M. tuberculosis was isolated in 17 patients (4.9%). Multivariate analysis revealed that the following features were significantly associated with culture-positive PTB: duration of symptoms of more than 2 weeks before hospital admission (odds ratio (OR) 25.10; 95% confidence interval (CI) 4.63-136.05; P<0.001), history of night sweats (OR 5.43; 95% CI 1.10-26.79; P=0.038), chest radiograph showing upper lobe involvement (OR 8.23; 95% CI 1.59-42.53; P=0.012) or cavitary infiltrates (OR 19.41; 95% CI 2.94-128.19; P=0.002), total white blood cell count on admission of 12x10(9)/L or less (OR 6.28; 95% CI 1.21-32.52; P=0.029) and lymphopenia (OR 4.73; 95% CI 1.08-20.85; P=0.040).

CONCLUSION

Mycobacterium tuberculosis was not an uncommon cause of CAP requiring hospitalization in Malaysia. A longer duration of symptoms, history of night sweats, upper lobe involvement, cavitary infiltrates, lower total white blood cell count and lymphopenia were predictive of PTB.

Outbreak of Chlamydophila pneumoniae infection in long-term care facilities and an affiliated hospital

This paper reports an outbreak of Chlamydophila pneumoniae infection in long-term care facilities and an affiliated hospital. The outbreak involved rapid spread of infection, and was inconsistent with several outbreaks experienced among younger populations. In addition, there were differences in the incidences among facilities and the affiliated hospital in relation to mean age. Our findings indicate that it is possible that elderly residents may be more susceptible to acquiring this infection. Physicians and other health care providers in long-term care facilities should consider C. pneumoniae in the differential diagnosis of an outbreak of respiratory infection.

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.

Community-acquired pneumonia in southeast Asia: the microbial differences between ambulatory and hospitalized patients

STUDY OBJECTIVES

To determine microbial agents causing community-acquired pneumonia (CAP) in Southeast Asia.

DESIGN

A prospective study.

SETTING

Three general hospitals in Thailand.

PATIENTS

Two hundred forty-five adult patients fulfilling the clinical criteria of CAP from September 1998 to April 2001.

INTERVENTIONS

Investigations included sputum Gram stain and culture, blood culture, pleural fluid culture (if presented), urine antigen for Legionella pneumophila and Streptococcus pneumoniae, and serology for Mycoplasma pneumoniae, Chlamydia pneumoniae, and L pneumophila.

RESULTS

There were 98 outpatients and 147 hospitalized patients included in the study, and an organism was identified in 74 of 98 outpatients (75.5%) and 105 of 147 of the hospitalized patients (71.4%). C pneumoniae (36.7%), M pneumoniae (29.6%), and S pneumoniae (13.3%) were the most frequent causative pathogens found in outpatients, while S pneumoniae (22.4%) and C pneumoniae (16.3%) were the most common in hospitalized patients. There was a significantly higher incidence of C pneumoniae (36.7% vs 16.3%, respectively; p < 0.001) and M pneumoniae (29.6% vs 6.8%; p < 0.001, respectively) in the outpatients than in the hospitalized patients. The incidence of S pneumoniae, L pneumophila, and mixed infections was not different between the groups. Mixed infections were presented in 13 of 98 outpatients (13.3%) and 9 of 147 hospitalized patients (6.1%), with C pneumoniae being the most frequent coinfecting pathogen.

CONCLUSIONS

The data indicate that the core organisms causing CAP in Southeast Asia are not different from those in the Western countries. The guidelines for the treatment of patients with CAP, therefore, should be the same.

Indirect enzyme-linked immunosorbent assay for detection of immunoglobulin G reactive with a recombinant protein expressed from the gene encoding the 116-kilodalton protein of Mycoplasma pneumoniae

Serology remains the method of choice for laboratory diagnosis of Mycoplasma pneumoniae infection. Currently available serological tests employ complex cellular fractions of M. pneumoniae as antigen. To improve the specificity of M. pneumoniae diagnosis, a recombinant protein was assessed as a serodiagnostic reagent. A panel of recombinant proteins were expressed from a cloned M. pneumoniae gene that encodes a 116-kDa surface protein antigen. The recombinant proteins were assessed for reactivity with patient sera and the most antigenic was further assessed for its serodiagnostic potential by indirect enzyme-linked immunosorbent assay (ELISA). The ELISA based on the recombinant protein was equivalent in sensitivity to the commercial test (Serodia Myco II; Fujirebio Inc.) to which it was compared. Southern and Western blotting data suggested that the recombinant protein derived from the 116-kDa protein of M. pneumoniae could provide a species-specific diagnostic tool, although further assessment is required.

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.

Legionella species community-acquired pneumonia. A review of 56 hospitalized adult patients

BACKGROUND

In a prospective study, Legionella species (Lsp) was identified as the causative agent in 56 (16.2%) of 346 adult patients hospitalized over the course of 1 year with community-acquired pneumonia (CAP), in the Soroka Medical Center, Beer-Sheva, Israel.

OBJECTIVE

To characterize patients with Lsp CAP in our study.

METHODS

The diagnosis of infection with Lsp was based on serologic testing of antibodies using the indirect immunofluorescent method.

RESULTS

In 35 (62.5%) of the patients, at least one other etiologic agent for CAP was identified in addition to Lsp. The patient population was relatively young, with relatively low rates of chronic comorbidity, and a broad spectrum of disease severity compared with previously published studies. No single epidemiologic, clinical, laboratory, or radiographic characteristic differentiated between Lsp CAP and other CAP patients in our study. Three patients (5.4%) who were not treated with erythromycin died. However, in contrast, nine patients who were treated with beta-lactam antibiotics recovered completely.

CONCLUSIONS

Lsp is a common cause of CAP in our region, usually as a coinfection with another causative agent. Lsp CAP, which cannot be characterized on the basis of clinical, routine laboratory, or radiographic data, requires specific microbiologic or serologic diagnosis. Treatment with erythromycin appears to be important to reduce mortality from this disease, but in a significant number of patients, the disease may be self-limited.

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.

Chlamydia pneumoniae community-acquired pneumonia: a review of 62 hospitalized adult patients

In a prospective study, Chlamydia pneumoniae was identified as the etiological agent in 62 (17.9%) of 346 adult patients hospitalized over the course of one year for community-acquired pneumonia at the Soroka Medical Center in Beer-Sheva, Israel. The diagnosis of C. pneumoniae infection was based on serological testing of antibodies by the MIF technique. In 43 of these patients (69.4%), at least one other etiological agent, in addition to C. pneumoniae for community-acquired pneumonia was identified. Streptococcus pneumoniae was identified in 34 patients with C. pneumoniae (54.8%), as an additional causative factor in infection. Community-acquired pneumonia patients with C. pneumoniae were significantly older than non-C. pneumoniae patients (p = 0.03), had a higher APACHE II score on admission (p < 0.05), a higher rate of positive blood cultures (p = 0.02), and longer periods of hospitalization (p = 0.022). Seven patients with pure C. pneumoniae infection recovered, despite treatment which is not considered to be specific for C. pneumoniae. It was concluded that C. pneumoniae is a common etiological agent for community-acquired pneumonia in our region, particularly in the elderly, and is characterized by a high rate of concomitant infections with other pulmonary pathogens. No specific clinical or radiological pattern was discerned that could distinguish between C. pneumoniae community-acquired pneumonia and non-C. pneumoniae community-acquired pneumonia.

Multiple pathogens in adult patients admitted with community-acquired pneumonia: a one year prospective study of 346 consecutive patients

BACKGROUND

The purpose of this study was to assess the causes of community-acquired pneumonia in adult patients admitted to hospital.

METHODS

A prospective study was performed on 346 consecutive adult patients (54% men) of mean (SD) 49.3 (19.5) years (range 17-94) admitted to a university affiliated regional hospital in southern Israel with community-acquired pneumonia over a period of one year. Convalescent serum samples were obtained from 308 patients (89%). The aetiological diagnosis for community-acquired pneumonia was based on positive blood cultures and/or significant changes in antibody titres to Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, respiratory viruses, Coxiella burnetii, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella sp.

RESULTS

The aetiology of community-acquired pneumonia was identified in 279 patients (80.6%). The distribution of causal agents was as follows: S pneumoniae, 148 patients (42.8%); M pneumoniae, 101 (29.2%); C pneumoniae, 62 (17.9%); Legionella sp, 56 (16.2%); respiratory viruses, 35 (10.1%); C burnetii, 20 (5.8%); H influenzae 19 (5.5%); and other causes, 21 patients (6.0%). In patients above the age of 55 years C pneumoniae was the second most frequent aetiological agent (25.5%). In 133 patients (38.4%) more than one causal agent was found.

CONCLUSIONS

The causal agents for community-acquired pneumonia in Israel are different from those described in other parts of the world. In many of the patients more than one causal agent was found. In all these patients treatment should include a macrolide antibiotic, at least in the first stage of their illness.

Microparticle agglutination versus antibody-capture enzyme immunoassay for diagnosis of community-acquired Mycoplasma pneumoniae pneumonia

Community-acquired Mycoplasma pneumoniae pneumonia is a common disease which is usually diagnosed by serological methods. The objective of the present study was to understand the diagnostic significance and test characteristics of two different serological tests used to identify current Mycoplasma pneumoniae infection. Three hundred sixty-six patients who suffered from community-acquired pneumonia served as the study population. Six hundred ninety-four (328 paired and 38 unpaired) sera were examined for the presence of antibodies to Mycoplasma pneumoniae with commercial kits based on two serological methods, microparticle agglutination and antibody-capture EIA. Agreement between the two kits was 85.2% when individual sera were compared (kappa = 0.62) and 88.5% when patients were compared (Kappa = 0.69). The positive predictive value and the specificity for the identification of current Mycoplasma pneumoniae infection using a single acute-phase serum were 49.3% and 86.9%, respectively, for the microparticle agglutination method, compared to 91.3% and 97.7% for the antibody-capture EIA method (p < 0.001). The negative predictive value and the sensitivity were 86.3% and 48.1% for the microparticle agglutination, not significantly different from the corresponding values of 86.5% and 61.2% for the antibody-capture EIA. It is concluded that the overall agreement between the two methods tested is good, but not perfect. The methods complement each other in the identification of Mycoplasma pneumoniae as the causative agent in patients with community-acquired pneumonia.

16S rRNA based polymerase chain reaction compared with culture and serological methods for diagnosis of Mycoplasma pneumoniae infection

The use of a 16S rRNA based polymerase chain reaction (PCR) for the detection of Mycoplasma pneumoniae infection was investigated. Sputum samples from 34 patients with respiratory illness and evidence of pneumonia as judged by chest X-ray were analyzed by PCR and microbiological culture. Throat swabs from 14 healthy individuals were used as controls. For serology, an enzyme immunoassay for the detection of immunoglobulin M antibodies and a complement fixation assay were performed. Evidence of Mycoplasma pneumoniae infection was obtained in ten patients (29%), eight of whom were found positive by both PCR and serology. Two of the sputum samples from these eight patients were negative by culture. Of the remaining two patients positive for Mycoplasma pneumoniae, one was positive by PCR and culture but negative by serology, and one was found positive by serology but negative by PCR and culture. Thirteen of the 14 controls were negative by both PCR and serology. One control, however, was negative by serology but positive by PCR, which was probably due to asymptomatic carriage of Mycoplasma pneumoniae. The results of this study indicate the suitability of the PCR for the detection of Mycoplasma pneumoniae in clinical samples as well as its potential value as an additional tool for the diagnosis of infection.

Direct PCR enables detection of Mycoplasma pneumoniae in patients with respiratory tract infections

The sensitivities of three methods of detection of Mycoplasma pneumoniae by a 16S rDNA PCR were compared by using a serial dilution of M. pneumoniae. These methods consisted of a PCR performed directly on cells after a proteinase K pretreatment (direct PCR), a PCR after purification of nucleic acids (DNA-PCR), and a PCR with rRNA sequences as the target after reverse transcription. The direct PCR and the reverse transcription PCR had a sensitivity of 1.5 CFU (approximately 250 genomes). By purification, a 10-fold loss of target DNA occurred, as shown by a 10-fold decrease in sensitivity (15 CFU) of the DNA-PCR. The presence of an excess of human background DNA did not influence the sensitivity of either PCR. The direct PCR was evaluated on samples from patients with respiratory complaints. Direct PCR amplification was possible in 94.9% of the samples, which were tested by amplification of a 326-bp fragment of the beta-globin gene, which was performed to test for the suitability of amplification. Nucleic acid purification was performed on the beta-globin-negative samples, after which only 2% remained negative. A positive correlation between the direct M. pneumoniae PCR and serology, as tested by the microparticle agglutination assay (MAG assay), was found in 88.1% of the cases. A positive MAG assay result was found for samples from 10 (17%) of the patients; samples from 6 (10.2%) of these patients were also positive by PCR. Samples from three patients were found to be positive by the M. pneumoniae PCR and negative by the MAG assay. Persistence of M. pneumoniae, as detected by PCR was observed in three patients. These results indicate that the direct PCR with 16S rDNA could prove to be useful in the detection of M. pneumoniae in respiratory tract samples, although more studies are needed to evaluate the correlation between clinical symptoms and positive test results.

Diagnosis of Mycoplasma pneumoniae infection by specific IgM antibodies using a new capture-enzyme-immunoassay

A total of 1226 sera from 1055 patients with respiratory tract infections were tested. IgM antibodies were detected by an antibody-capture enzyme-immunoassay (Mp TEST, Diatech Diagnostica Ltd, Israel). Acute infection with IgM antibodies to Mycoplasma pneumoniae was detected in 211 patients. Presence of IgM was closely associated to some or all pneumonia-related symptoms. Eighty-one of IgM-positive patients treated with tetracycline or erythromycin responded positively. Of the 211 patients, 63 (30%) had low levels and 23 (11%) had moderate levels of IgM antibodies already in the first serum sample. In these 86 patients (41%) the complement fixation (CF) test was negative or very low positive. Thus in these cases, the CF test would have missed the early diagnosis in the first serum samples.

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.

A latex agglutination test for the detection of Mycoplasma pneumoniae in respiratory exudates: a comparative study with a commercially available DNA-probe test

We prepared polyclonal antibody specific to Mycoplasma pneumoniae. Using this antibody, we developed a latex agglutination test (LAT) for detecting the organism in respiratory exudates as rapid diagnosis of M. pneumoniae infection. Further, LAT was compared with DNA-probe test (DP) which was the only commercially available test for the rapid detection of the organism. In LAT, both M. pneumoniae and M. genitalium give positive agglutination, but the titer of M. genitalium was significantly lower than that of M. pneumoniae. The detection limit of LAT was 2 x 10(5) CFU/ml and that of DP was 5 x 10(4) CFU/ml in vitro. It was considered that target molecules in LAT were accumulated in the pharyngeal portion of the patients, because of their long half-life at 37 C. However, ribosomal RNA which was target molecule in DP was destroyed at 37 C much sooner, and the accumulation could not be expected. Actually, positive rate in LAT was higher than that in DP among clinical specimens in which M. pneumoniae was detected by culture method. The procedure of LAT is much easier and more rapid than that of DP in which radioactive isotope is required. LAT could be the choice of test for rapid diagnosis of M. pneumoniae infection.

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.

Enzyme-linked immunosorbent assays and developments in techniques using latex beads

Not surprisingly, most of the publications on enzyme immunoassays or latex agglutination tests in 1990 have been applications for specific antigens or antibodies. Nevertheless, a large number of studies of considerable interest to all users have been reported. In this short review, we have chosen to highlight investigations into: factors affecting assay performance; enzyme immunoassay design and statistical analysis; novel approaches in enzyme immunoassays and related techniques; immunohistochemistry; and latex agglutination tests.