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

Pinocembrin Relieves Mycoplasma pneumoniae Infection‑Induced Pneumonia in Mice Through the Inhibition of Oxidative Stress and Inflammatory Response

Pneumonia is a serious infectious disease with increased morbidity and mortality worldwide. The M. pneumoniae is a major airway pathogen that mainly affects respiratory tract and ultimately leads to the development of pneumonia. The current exploration was aimed to uncover the beneficial properties of pinocembrin against the M. pneumoniae-triggered pneumonia in mice via its anti-inflammatory property. The pneumonia was stimulated to the BALB/c mice via infecting them with M. pneumoniae (100 µl) for 2 days through nasal drops and concomitantly treated with pinocembrin (10 mg/kg) for 3 days. The azithromycin (100 mg/kg) was used as a standard drug. Then the lung weight, nitric oxide, and myeloperoxidase (MPO) activity was assessed. The content of MDA, GSH, and SOD activity was scrutinized using kits. The total cells and DNA amount present in the bronchoalveolar lavage fluid (BALF) was assessed by standard methods. The IL-1, IL-6, IL-8, TNF-α, and TGF contents in the BALF samples and NF-κB level in the lung tissues were assessed using kits. The lung histopathology was assessed microscopically to detect the histological alterations. The 10 mg/kg of pinocembrin treatment substantially decreased the lung weight, nitric oxide (NO) level, and MPO activity. The MDA level was decreased, and GSH content and SOD activity were improved by the pinocembrin treatment. The pinocembrin administered pneumonia animals also demonstrated the decreased total cells, DNA amount, IL-1, IL-6, IL-8, TNF-α, and TGF in the BALF and NF-κB level. The findings of histological studies also witnessed the beneficial role of pinocembrin against M. pneumoniae-infected pneumonia. In conclusion, our findings confirmed that the pinocembrin effectively ameliorated the M. pneumoniae-provoked inflammation and oxidative stress in the pneumonia mice model. Hence, it could be a hopeful therapeutic agent to treat the pneumonia in the future.

Geraniol relieves mycoplasma pneumonia infection-induced lung injury in mice through the regulation of ERK/JNK and NF-κB signaling pathways

BACKGROUND

Pneumonia is a serious pediatric lung injury disease caused by Mycoplasma pneumoniae (M. pneumoniae) with increasing global prevalence every year. The WHO has reported that nearly 19% of children die due to pneumonia worldwide.

OBJECTIVE

The present research was conducted to discover the ameliorative properties of geraniol against M. pneumoniae-provoked pneumonia in mice through the modulation of inflammatory responses.

METHODOLOGY

The pneumonia was provoked in the male Swiss albino mice via infecting animals with 100 µl of M. pneumoniae for 2 days and supplemented concurrently with 20 mg/kg of geraniol for 3 days. 100 mg/kg of azithromycin was used as a standard drug. The nitric oxide (NO) level and MPO activity were measured using kits. The SOD activity, GSH, and MDA levels were studied using standard methods. The polymerase chain reaction (PCR) study was performed to examine the M. pneumoniae DNA load. The inflammatory cytokines status was assessed by assay kits. The ERK1/2, JNK1/2, and NF-κB expressions were studied by reverse-transcription (RT-PCR). The lung tissues were analyzed microscopically to investigate the histological alterations.

RESULTS

Geraniol treatment effectively reduced lung weight, NO level, and MPO activity in the pneumonia mice. The total cells and M. pneumoniae DNA load were also decreased by the geraniol. The SOD activity and GSH level were improved and MDA was decreased by the geraniol treatment. The IL-1, IL-6, IL-8, TNF-α, and TGF status were appreciably depleted by the geraniol in the pneumonia mice. Geraniol also suppressed the ERK1/2 and NF-κB expressions in the lung tissues. Histological findings also suggest the therapeutic roles of geraniol against pneumonia in mice.

CONCLUSION

In summary, our results proved the beneficial roles of geraniol against the M. pneumoniae-provoked pneumonia. Geraniol could be a hopeful therapeutic agent to treat pneumonia in the future.

The investigation of P1 gene in Mycoplasma pneumonia isolated from atypic pneumonia by molecular methods, determine IgG antibody and MIC to ciprofloxacin antibiotic

Mycoplasma pneumoniae, which causes atypical pneumonia, is a well-established pathogen of the respiratory tract. This bacterium is intrinsically susceptible to fluoroquinolones. But recently, drug-resistant forms of this bacterium have been reported. This study aims to determine the prevalence of this bacterium by ELISA and PCR and MIC to ciprofloxacin. The clinical samples (blood and nasopharyngeal swab) were collected from 100 patients, who were referred to selective hospitals in Tehran with respiratory complaints, were enrolled in 2017. Nasopharyngeal swab sample collections were cultured on PPLO broth and PPLO agar. After culturing and DNA extraction, PCR was performed by specific P1 genes primers. Ciprofloxacin's MIC of Mycoplasma pneumonia isolated was determined by the Micro-broth dilution method. The serum of IgG antibody titers was also measured by ELISA Mycoplasma pneumonia. In this study, out of 100 samples, 12 bacteria were isolated on PPLO agar. Using specific primers, 7 samples of Mycoplasma speciesism-specific were positive for the presence of M.pneumoniae and 2 Ciprofloxacin resistant isolates were evaluated. ELISA results show that IgG titer antibody is existent in 19 samples and 5 samples are intermediate as well. IgG antibody titer average in the whole sample is 27/66 U/ml, but it is in Positive samples by P1 PCR is 45/75 U/ml. This study showed that PCR is a sensitive and reliable method for rapid detection of M. pneumoniae bacteria in respiratory infectious samples, but the results of this method are different from the ELISA method. Additionally, it seems that the resistance to ciprofloxacin is relatively common among M. pneumoniae.

Accurate, rapid and low-cost diagnosis of Mycoplasma pneumoniae via fast narrow-thermal-cycling denaturation bubble-mediated strand exchange amplification

Mycoplasma pneumoniae is a strong infectious pathogen that may cause severe respiratory infections. Since this pathogen may possess a latent period after infection, which sometimes leads to misdiagnosis by traditional diagnosis methods, the establishment of a rapid and sensitive diagnostic method is crucial for transmission prevention and timely treatment. Herein, a novel detection method was established for M. pneumoniae detection. The method, which improves upon a denaturation bubble-mediated strand exchange amplification (SEA) that we developed in 2016, is called accelerated SEA (ASEA). The established ASEA achieved detection of 1% M. pneumoniae genomic DNA in a DNA mixture from multiple pathogens, and the limit of detection (LOD) of ASEA was as low as 1.0 × 10^-17 M (approximately 6.0 × 10³ copies/mL). Considering that the threshold of an asymptomatic carriage is normally recommended as 1.0 × 10⁴ copies/mL, this method was able to satisfy the requirement for practical diagnosis of M. pneumoniae. Moreover, the detection process was finished within 20.4 min, significantly shorter than real-time PCR and SEA. Furthermore, ASEA exhibited excellent performance in clinical specimen analysis, with sensitivity and specificity of 96.2% and 100%, respectively, compared with the "gold standard" real-time PCR. More importantly, similar to real-time PCR, ASEA requires only one pair of primers and ordinary commercial polymerase, and can be carried out using a conventional fluorescence real-time PCR instrument, which makes this method low-cost and easy to accomplish. Therefore, ASEA has the potential for wide use in the rapid detection of M. pneumoniae or other pathogens in large numbers of specimens. Graphical abstract.

Diagnostic utility of serology and polymerase chain reaction for detection of Mycoplasma pneumoniae and Chlamydophila pneumoniae in paediatric community-acquired lower respiratory tract infections

Purpose

Mycoplasma pneumoniae (M. pneumoniae) and Chlamydophila pneumoniae (C. pneumoniae) play a significant role in children of all ages with lower respiratory tract infections (LRTIs). This study was conducted to detect M. pneumoniae and C. pneumoniae in children with community-acquired LRTIs employing serology, polymerase chain reaction (PCR) and nested PCR analysis.

Material and Methods

This study included 75 children with acute LRTIs for detection of M. pneumoniae and C. pneumoniae. Blood was obtained for M. pneumoniae and C. pneumoniae antibodies and nasopharyngeal aspirates for M. pneumoniae PCR and C. pneumoniae nested PCR.

Results

M. pneumoniae infection was positive in 9 (64.21%) children aged 2-6 months and in 5 (35.79%) aged 7 months-12 years, and this difference was statistically significant (P = 0.002). C. pneumoniae infection was comparable within the age group and statistically insignificant (P = 0.43). Clinical and radiological profiles of M. pneumoniae- and C. pneumoniae-positive and negative patients were numerically comparable. Serology and PCR together detected M. pneumoniae infection in 14 (18.6%) children. The sensitivity, specificity and positive and negative predictive values of serology were 77.78%, 92.42%, 58.33% and 96.83%, respectively. C. pneumoniae infection was positive in 11 (14.6%) children by serology and nested PCR with 50% sensitivity, 87.67% specificity, 10% positive predictive value and 98.46% negative predictive value.

Conclusions

Our study confirms that M. pneumoniae and C. pneumoniae play a significant role in community-acquired LRTIs and a combination of serology and nested PCR is useful for its diagnosis.

The diagnostic value of serological tests and real-time polymerase chain reaction in children with acute Mycoplasma pneumoniae infection

Background

This study set out to evaluate the clinical significance and diagnostic effectiveness of serological tests and real-time polymerase chain reactions (RT-PCR) in children of different age groups and disease durations infected with Mycoplasma pneumoniae (MP).

Methods

Pediatric patients with lower respiratory tract infection (LRTI) confirmed by polymerase chain reaction (PCR) were enrolled and subjected to bronchoalveolar lavage fluid PCR (BALF-PCR) for MP infection. The diagnostic values of the serum immunoglobulin M (IgM) test, paired sera immunoglobulin G (IgG) test, RT PCR applied to nasopharyngeal aspirates (NPA-PCR), and combined IgM and NPA-PCR test were evaluated.

Results

When BALF PCR was used as the gold standard, the MP positivity rate of combined IgM and NPA PCR was 78.85%in children aged 3–5 years. The positivity rates of IgM, NPA PCR, and combined IgM and NPA PCR in children older than 5 years were 71.21%, 72.72%, and 84.85%, respectively. The detection rate of combined IgM and NPA PCR was consistent with BALF PCR (Kappa =0.727). The MP positivity rates of combined IgM and NPA PCR at 1–2 weeks was as high as 91.11%, and was consistent with the BALF PCR (Kappa =0.756). Moreover, the positivity rates of IgM or NPA PCR at 2-3 weeks were 63.16%, and were consistent with each other (Kappa =0.771).

Conclusions

Combined IgM and NPA PCR is the optimal test to confirm MP infection among children aged 3–5 years in cases with a disease duration of less than2 weeks, and either NPA PCR or IgM is recommended for children older than 5 years with a disease duration of 2–3 weeks.

Keywords

Mycoplasma pneumoniae pneumonia (MPP); diagnosis; children; age; disease duration

Detection of respiratory syncytial virus & Mycoplasma pneumoniae in paediatric lower respiratory tract infections

Background & objectives

Respiratory syncytial virus (RSV) and Mycoplasma pneumoniae are considered common cause of lower respiratory tract infections (LRTIs) in children. The present study was conducted to detect M. pneumoniae and RSV in paediatric LRTIs employing serology, polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) analysis.

Methods

Seventy five children aged one month to five years with acute LRTIs were investigated for M. pneumoniae antibodies and RSV antigen using immunochromatographic test, RT-PCR for RSV and M. pneumoniae by PCR on nasopharyngeal aspirates.

Results

RSV infection was observed in 33 (44%) and M. pneumoniae was positive in 26 (35%) children. No significant difference in infection was noted between male and female children. Clinical and radiological features among RSV and M. pneumoniae positive and negative cases were similar. Considering RT-PCR for RSV as gold standard, RSV antigen immunochromatography was 90.90 per cent sensitive and 100 per cent specific.

Interpretation & conclusions

Our study showed the presence of RSV and M. pneumoniae infection in 44 and 35 per cent children, respectively with community-acquired LRTIs and aged less than five years.

Mycoplasma pneumoniae infection and asthma in children

A clinical association between exacerbation of asthma symptoms and Mycoplasma pneumoniae ( M. pneumoniae) infection has long been suspected. We studied 80 children aged 5-15 years; 50 with asthma (Group 1) and 30 without an acute exacerbation of asthma (Group 2) for detection of M. pneumoniae by serology and polymerase chain reaction (PCR) on nasopharyngeal aspirates. Our study confirms that lower respiratory tract infections with M. pneumoniae are frequently associated with exacerbations of asthma in children.

Mycoplasma pneumoniae DNA detection and specific antibody class response in patients from two tertiary care hospitals in tropical Sri Lanka

PURPOSE

Respiratory tract infections are a major cause of global morbidity and mortality. Pneumonia is the ninth leading cause of mortality in Sri Lanka. Atypical pathogens cause about one-fifth of community-acquired pneumonia, while Mycoplasma pneumoniae accounts for about 50 %. This study aimed to determine the seroprevalence of M. pneumoniae respiratory tract infections in Sri Lanka while attempting to understand the relationships between the serology and PCR.

METHODOLOGY

Paired sera from 418 adult patients (pneumonia, n=97; bronchitis, n=183; pharyngitis, n=138) and 87 healthy controls were studied. IgM, IgG and IgA antibodies were tested by M. pneumoniae enzyme-linked immunosorbent assay (ELISA). Positive IgM and or IgG seroconversion was considered to be seropositive. M. pneumoniae DNA were tested by PCR in age and gender-matched seropositives and seronegatives.

RESULTS

M. pneumoniae IgG was in 14.4 % (14/97), 6.0 % (11/183) and 1.5 % (2/138) of pneumonia, bronchitis and pharyngitis patients, respectively, whilst IgM was in 6.2 % (6/97), 1.1 % (2/183) and 0 % (0/138), respectively. Amongst the pneumonia seropositives, 64.7 % (11/17) showed IgG alone, 17.5 % (3/17) showed IgM alone and 17.5 % (3/17) showed IgM and IgG. Amongst the bronchitis seropositives, 84.6 % (11/13) had IgG alone and 15.4 % (2/13) had IgM alone. In the pharyngitis seropositives, only IgG was detected 100 % (2/2). M. pneumoniae DNA was in 52.2 % (12/23) of seropositives and 15.4 % (4/26) of seronegatives. In pneumonia or bronchitis patients, specific DNA was in 77.8 % (7/10) and 50 % (6/12) of patients, respectively. M. pneumoniae DNA was not found in pharyngitis patients. Of the seropositive PCR-negative pneumonia patients, 66.7 % (2/3) showed IgG alone and 33.3 % (1/3)showed IgM alone. In bronchitis patients, 83.3 % (5/6) showed IgG alone and 16.7 % (1/6) showed IgM alone. Of the seronegative PCR-positive patients, 16.7 % (2/12) had pneumonia and 18.2 % (2/11) had bronchitis.

CONCLUSION

The serological evidence for M. pneumoniae infection in Sri Lanka comprised the following prevalences: 17.5 % (17/97), 7.1 % (13/183) and 1.4 % (2/138) in adults with pneumonia, bronchitis or pharyngitis, respectively. M. pneumoniae DNA was in 52.2 % (12/23) of seropositives and 15.4 % (4/26) of seronegatives. IgG was predominant in PCR positives and negatives.

Mycoplasma pneumoniae in Community-Acquired Lower Respiratory Tract Infections

OBJECTIVE

To determine the role of Mycoplasma pneumoniae (M. pneumoniae) in pediatric lower respiratory tract infections (LRTIs) employing serological tests and polymerase chain reaction (PCR) analysis.

METHODS

In this prospective study, 200 children aged 6 mo to 12 y hospitalized with acute LRTIs were investigated for M. pneumoniae. Serum samples were collected for serological analysis of M. pneumoniae. Throat swab samples were obtained on admission to amplify 277-base pair region of 16S rDNA gene of M. pneumoniae by PCR.

RESULTS

In the present study, 40(26.1%) children <5 y and 28(59.5%) children ≥5 y age group were positive for M. pneumoniae infection and this difference was statistically significant (P < 0.001). M. pneumoniae was positive in 32(41%) female and 36(29.5%) male children though this difference was statistically insignificant (P = 0.12). The clinical profile across M. pneumoniae positive and negative cases were comparable except for presence of chest pain which was statistically significant (P = 0.023). None of the radiological findings was statistically associated with incidence of M. pneumoniae infection. Serological evidence of acute M. pneumoniae infection was observed in 64(32%) patients with sensitivity 66.6% and specificity 70.1% while PCR positivity in 12(6%) patients with sensitivity 12.5% and specificity 97%. Together, serology and PCR detected M.pneumoniae infection in 68(34%) patients.

CONCLUSIONS

The present study underlines the role of M. pneumoniae in children with community- acquired LRTIs and more particularly in ≥5 y of age.

Detection of Mycoplasma pneumoniae and Legionella pneumophila in Patients Having Community-Acquired Pneumonia: A Multicentric Study from New Delhi, India

Atypical pathogens including Mycoplasma pneumoniae and Legionella pneumophila are increasingly recognized as important causes of community-acquired pneumonia (CAP). Mycoplasma pneumoniae accounts for 20-40% of all CAP and L. pneumophila is responsible for 3-15% of cases. The paucity of data from India in this regard prompted us to conduct this prospective multicentric analysis to detect the prevalence of M. pneumoniae and L. pneumophila in our geographical region. A total of 453 patients with symptoms of pneumonia and 90 controls with no history of lower respiratory tract infections were included in the study. A duplex polymerase chain reaction (PCR) targeting 543 bp region of P1 adhesin gene of M. pneumoniae and 375 bp region of macrophage infectivity potentiator (mip) gene of L. pneumophila was standardized for simultaneous detection of these atypical pathogens. Respiratory secretions, blood, and urine samples were collected from each patient and control and were subjected to duplex PCR, culture and serology for M. pneumoniae and L. pneumophila. Urine samples were subjected for detecting L. pneumophila antigen. Among the 453 patients investigated for M. pneumoniae, 52 (11.4%) were positive for IgM antibodies, 17 were positive by culture, and seven tested positive by PCR (P1 gene). Similarly for L. pneumophila, 50 cases (11%) were serologically positive for IgM antibodies, one was positive by PCR (mip gene) and urine antigen detection. A total of eight samples were positive by duplex PCR for M. pneumoniae P1 gene (N = 7) and L. pneumophila mip gene (N = 1). Of the 90 controls, two samples (2.2%) showed IgM positivity, and 15 (16.7%) showed IgG positivity for M. pneumoniae. For L. pneumophila, three samples (3.3%) tested positive for IgM, and 12 (13.3%) tested positive for IgG antibodies. The study findings indicate the presence of M. pneumoniae and L. pneumophila in our geographical region, and a combination of laboratory approaches including PCR, culture, and serology is required for effective detection of these agents.

Enzymatic amplification-free nucleic acid hybridisation sensing on nanostructured thick-film electrodes by using covalently attached methylene blue

Amplification-free (referring to enzymatic amplification step) detection methodologies are increasing in biosensor development due to the need of faster and simpler protocols. However, for maintaining sensitivity without this step, highly detectable molecules or very sensitive detection techniques are required. The nanostructuration of transducer surfaces with carbon nanotubes (CNTs), gold nanoparticles (AuNPs) or both in nanohybrid configurations has been employed in this work for DNA hybridisation sensing purposes. Methylene blue (MB), covalently attached to single stranded DNA, (ssDNA) was incubated with a complementary sequence immobilized on nanostructured screen-printed electrodes (AuSPEs). Although CNTs can increase notoriously the signal of the marker, adsorptive properties should also be considered when bioassays are performed because non-specific adsorption (NSA) phenomena are magnified. In this work, strategies for decreasing NSA were thoroughly evaluated for the detection of Mycoplasma pneumoniae (MP) on CNTs-nanostructured screen-printed electrodes. Among them, the employ of UV-radiation or long incubation times (72h) allowed obtaining higher signals for the complementary strand with respect to the non-complementary one. The use of CNTs/AuNPs nanohybrids, together with the use of streptavidin-biotin (ST-B) interaction allows the higher differentiation (with a 3.5 ratio) in the genosensing of M. pneumoniae.

Mycoplasma pneumoniae infection in children is a risk factor for developing allergic diseases

Mycoplasma pneumoniae (MP) infection is the dominant cause of pneumonia in children. We sought to determine the relationship between MP infection and secondary allergic disease and to clarify the associated mechanisms of inflammatory response. A prospective study was performed among 1330 patients diagnosed with pneumonia to investigate the patient immune status by determining the correlation between MP infection, immunoglobulin E (IgE) levels, and a spectrum of associated serum cytokines. Serum IgE, IL-4, IL-6, and IL-10 levels for MPP patients in the acute phase were obviously higher than those in the recovery phase (P < 0.01). MPP patients with allergic conditions had increased serum IgE levels and increased IL-4/INF-γ ratio, and IgE and Eosinophil Cationic Protein were further elevated in patients who eventually developed secondary asthma changes. Patients with severe pneumonia and high clinical pulmonary infection scores presented higher levels of IL-4 and IL-5 in serum than those with low scores (P < 0.01). The proportion of CD4+ and CD8+ T cells that secreted IL-4 was significantly increased in MPP patients with elevated IgE. Our data demonstrate a significant correlation between MP infection and IgE levels, which is associated with a Th1/Th2 cytokine imbalance.

Molecular detection of Mycoplasma pneumoniae by quantitative real-time PCR in patients with community acquired pneumonia

BACKGROUND & OBJECTIVES

Mycoplasma pneumoniae is the most important and common cause of community-acquired pneumonia (CAP). The conventional detection methods (culture and serology) lack sensitivity. PCR offers a better approach for rapid detection but is prone to carry over contamination during manipulation of amplification products. Quantitative real-time PCR (qRT-PCR) method offers an attractive alternative detection method. In the present study, qRT-PCR, PCR and serology methods were used to detect M. pneumoniae infection in cases of pneumonias and findings compared.

METHODS

A total of 134 samples consisting of blood (for serology) and respiratory secretions (for PCR and qRT-PCR) from 134 patients were collected. The blood samples were tested for IgG, IgM and IgA using commercially available kits. For standardization of PCR of M. pneumoniae P1 gene was cloned in pGEMTEasy vector. Specific primers and reporter sequence were designed and procured for this fragment. The qRT-PCR assay was performed to prepare the standard curve for M. pneumoniae positive control DNA template and detection in patient samples.

RESULTS

Of the 134 patients, 26 (19%) were positive for antibodies against M. pneumoniae. IgG was positive in 14.92 per cent (20) cases, IgM in 4.47 per cent (6) and IgA was positive in 5.22 per cent (7) cases. In the qRT-PCR assay 19 per cent (26) samples were positive. Of the 26 qRT-PCR positive samples, nine could be detected by serology. PCR was positive for 25 samples. An extra sample negative by PCR was detected by qRT-PCR. Thus, real-time PCR assay, PCR and serology in combination could detect M. pneumoniae infection in 43 patients.

INTERPRETATION & CONCLUSIONS

The study shows that 17 patients were detected by serology alone, 17 were detected by qRT-PCR only and nine patients were positive by both serology and real-time PCR. Of the 134 samples tested, 25 were positive by conventional PCR, but qRT-PCR could detect one more sample that was negative by PCR and serology. These results suggest that a combination of two or three methods may be required for reliable identification of CAP due to M. pneumoniae.

Rapid diagnosis of Mycoplasma pneumoniae by polymerase chain reaction in community-acquired lower respiratory tract infections

Two hundred children hospitalized for community-acquired lower respiratory tract infections (LRTIs) were investigated for Mycoplasma pneumoniae employing serological tests and a P1 adhesin gene-based polymerase chain reaction assay (PCR) on nasopharyngeal aspirates. Serological evidence of M. pneumoniae infection was observed in 68 (34%) patients and PCR was positive in 20 (10%) children. Together PCR and/or enzyme immuno assay detected M. pneumoniae in 71(35.5%) children. Our data underline the role of M. pneumoniae in Indian children with community-acquired LRTIs even in children aged < 24 months.

Critical role of macrophages and their activation via MyD88-NFκB signaling in lung innate immunity to Mycoplasma pneumoniae

Mycoplasma pneumoniae (Mp), a common cause of pneumonia, is associated with asthma; however, the mechanisms underlying this association remain unclear. We investigated the cellular immune response to Mp in mice. Intranasal inoculation with Mp elicited infiltration of the lungs with neutrophils, monocytes and macrophages. Systemic depletion of macrophages, but not neutrophils, resulted in impaired clearance of Mp from the lungs. Accumulation and activation of macrophages were decreased in the lungs of MyD88(-/-) mice and clearance of Mp was impaired, indicating that MyD88 is a key signaling protein in the anti-Mp response. MyD88-dependent signaling was also required for the Mp-induced activation of NFκB, which was essential for macrophages to eliminate the microbe in vitro. Thus, MyD88-NFκB signaling in macrophages is essential for clearance of Mp from the lungs.

Detection of Mycoplasma pneumoniae in children with lower respiratory tract infections

Mycoplasma pneumoniae is known to be a major cause of lower respiratory tract infections (LRTIs) in children. We studied 75 children who had been hospitalized for community-acquired LRTIs for the detection of M. pneumoniae by serological analysis and polymerase chain reaction (PCR) to amplify a 277-base pair region of 16S rDNA gene of M. pneumoniae applied to throat swab specimens. Serological and/or PCR positive results diagnosed M. pneumoniae infection in 23 (30.7%) patients.

Lung infections in cystic fibrosis: deriving clinical insight from microbial complexity

Lower respiratory tract bacterial infections, such as those associated with cystic fibrosis lung disease, represent a major healthcare burden. Treatment strategies are currently informed by culture-based routine diagnostics whose limitations, including an inability to isolate all potentially clinically significant bacterial species present in a sample, are well documented. Some advances have resulted from the introduction of culture-independent molecular assays for the detection of specific pathogens. However, the application of bacterial community profiling techniques to the characterization of these infections has revealed much higher levels of microbial diversity than previously recognized. These findings are leading to a fundamental shift in the way such infections are considered. Increasingly, polymicrobial infections are being viewed as complex communities of interacting organisms, with dynamic processes key to their pathogenicity. Such a model requires an analytical strategy that provides insight into the interactions of all members of the infective community. The rapid advance in sequencing technology, along with protocols that limit analysis to viable bacterial cells, are for the first time providing an opportunity to gain such insight.

Mycoplasma pneumoniae as a cause of non-resolving pneumonia in a neonate

Mycoplasma pneumoniae is known to be the chief causative organism for community-acquired non-lobar pneumonia in children of 5–15 years of age. M. pneumoniae as an aetiological agent for pneumonia among neonates and infants has rarely been reported. We report here a case of persistent pneumonia due to M. pneumoniae in a 3-week-old neonate.

An economical tandem multiplex real-time PCR technique for the detection of a comprehensive range of respiratory pathogens

This study used real-time PCR assays to screen small sample volumes for a comprehensive range of 35 respiratory pathogens. Initial thermocycling was limited to 20 cycles to avoid competition for reagents, followed by a secondary real-time multiplex PCR. Supplementary semi-nested human metapneumovirus and picornavirus PCR assays were required to complete the acute respiratory pathogen profile. Potential pathogens were detected in 85 (70%) of pernasal aspirates collected from 121 children with acute respiratory symptoms. Multiple pathogens were detected in 29 (24%) of those samples. The tandem multiplex real-time PCR was an efficient method for the rapid detection of multiple pathogens.

Association of Mycoplasma pneumoniae and asthma among Indian children

The role of Mycoplasma pneumoniae infection as a trigger for asthma exacerbations is well supported in previous studies. This study was designed to investigate the role of M. pneumoniae infection in acute exacerbation of asthma in children. A total of 150 patients (110 males, 40 females) were studied and immunoglobulin M (IgM) antibodies to M. pneumoniae were detected by enzyme-linked immunosorbent assay (ELISA), and PCR amplification was performed for the P1 gene to associate M. pneumoniae infection with asthma. As compared with 33 children with asthma, only two of the control subjects had positive IgM titers for M. pneumoniae, which was statistically significant (P=0.002). A total of 15 children with asthma were positive by PCR for the P1 gene while none of the controls had a positive PCR. Of these positive cases, 24 cases were positive only by ELISA, six were positive only by PCR and nine patients were found to be positive by both ELISA and PCR. All the clinical characteristics of the patients at baseline were comparable between the moderate and the severe group of patients statistically, except for the peak expiratory flow rate. Mycoplasma pneumoniae infection was found to have a significant association with acute exacerbation in the moderate group of asthma patients by PCR (P=0.01). These data suggest that M. pneumoniae infection may contribute to asthma exacerbation.

Congenital Mycoplasma pneumoniae pneumonia in a neonate

A fatal case of vertical transmission of Mycoplasma pneumoniae manifesting as congenital pneumonia in a neonate is presented. The diagnosis was based on the detection of DNA by polymerase chain reaction on the neonatal nasopharyngeal aspirates and placenta and rising titers of maternal anti Mycoplasma antibodies by complement fixation test.

Evaluation of four commercial IgG- and IgM-specific enzyme immunoassays for detecting Mycoplasma pneumoniae antibody: comparison with particle agglutination assay

Diagnosis of Mycoplasma pneumoniae infection is important due to its variable clinical manifestations and absence of response to beta-lactams. Introduction of enzyme immunoassays (EIAs) for serologic diagnosis of M. pneumoniae has made it possible to separate the analyses of specific IgG and IgM antibodies. We compared four different commercial EIAs, ImmunoWELL IgG, IgM (GenBio), Medac IgG, IgA, IgM (Medac), Platelia IgG, IgM (Sanofi Pasteur), and Ridascreen IgG, IgA, IgM (r-Biopharm) with indirect particle agglutination assay (PA), Serodia-MycoII (Fujirebio). We tested 91 specimens from 73 pediatric patients (2-17 yr) hospitalized at a tertiary-care hospital between December 2005 and January 2006. The measurements of IgM EIAs were correlated with PA titers (Spearman's correlation coefficient, from 0.89 to 0.92) with high concordance rates, ranging from 82.4% to 92.3%. However, some negative IgM-EIA results in PA-positive specimens indicated that serial samplings with convalescent sera would be necessary to confirm M. pneumoniae infection.

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.

Design of a multiplex PCR for Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae and Chlamydophila pneumoniae to be used on sputum samples

A multiplex PCR (mPCR) was developed for simultaneous detection of specific genes for Streptococcus pneumoniae (lytA), Mycoplasma pneumoniae (P1), Chlamydophila pneumoniae (ompA), and Haemophilus influenzae (16S rRNA, with verification PCR for P6). When the protocol was tested on 257 bacterial strains belonging to 37 different species, no false negatives and only one false positive were noted. One Streptococcus mitis out of thirty was positive for lytA. In a pilot application study of 81 sputum samples from different patients with suspected lower respiratory tract infection (LRTI), mPCR identified S. pneumoniae in 25 samples, H. influenzae in 29, M. pneumoniae in 3, and C. pneumoniae in 1. All samples culture positive for S. pneumoniae (n=15) and H. influenzae (n=15) were mPCR positive for the same bacteria. In a pilot control study with nasopharyngeal swabs and aspirates from 10 healthy adults, both culture and mPCR were negative. No PCR inhibition was found in any of the mPCR-negative sputum or nasopharyngeal samples. Whether all samples identified as positive by mPCR are truly positive in an aetiological perspective regarding LRTI remains to be evaluated in a well-defined patient material. In conclusion, the mPCR appears to be a promising tool in the aetiological diagnostics of LRTI.

Molecular genetic methods in the diagnosis of lower respiratory tract infections

Molecular diagnostic techniques, such as PCR, have become useful tools for the rapid etiological diagnosis of lower respiratory tract infections. Nucleic acid amplification tests (NAATs) have been evaluated for detecting most respiratory pathogens, and commercial assays are available for some pathogens. However, standardized protocols are needed before these assays are introduced into routine diagnostic use. For pneumonia, NAATs offer advantages over conventional tests for the detection of Mycoplasma pneumoniae, Legionella spp. and Chlamydia pneumoniae. For pneumococcal pneumonia in adults, PCR adds little to existing diagnostic tests, and is unable to distinguish pneumococcal colonization from infection when testing respiratory samples. Although less sensitive than culture-based methods, several commercial molecular diagnostic assays have been developed for tuberculosis and are useful rapid tests for selected patients. PCR can now be considered the rapid diagnostic test of choice for pertussis and some respiratory virus infections. Further work is required to better characterize the role of molecular diagnostic tests for diagnosing lower respiratory tract infections, and to develop standard assays that can be readily adopted by routine diagnostic laboratories.

Amplification of P1 and 16S rRNA genes by nested PCR for detection of Mycoplasma pneumoniae in paediatric patients

Mycoplasma (M.) pneumoniae is the most frequent atypical pathogen responsible for community-acquired respiratory infection in children and adults. The etiologic diagnosis of these infections still remains difficult. This is mainly due to the absence of characteristic clinical findings, and to the available detection methods (serology and culture) which are time consuming, insensitive and non-specific. To improve the detection of this infectious agent, nested polymerase chain reaction (PCR) analysis was developed. A total of 46 nasal aspirates, from children hospitalised with severe lower respiratory tract infection and in whom M. pneumoniae was suspected, were analysed for the presence of M. pneumoniae DNA by PCR. Routine microbiological investigations revealed no virus in these 46 samples. Using nested PCR, two targets were amplified: the sequences of 16S ribosomal (r) RNA gene (rDNA) and P1 adhesin gene. Evidence of M. pneumoniae infection was identified in four paediatric patients. The amplification of 16S rDNA was found to be more sensitive for the detection of M. pneumoniae. Our results suggest that amplification of the 16S rDNA by nested PCR and detection of the amplification products by visual inspection of the polyacrylamide gel should allow the rapid diagnosis of M. pneumoniae in respiratory tract infection in paediatric 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.

Diagnostic utility and clinical significance of naso- and oropharyngeal samples used in a PCR assay to diagnose Mycoplasma pneumoniae infection in children with community-acquired pneumonia

PCR assays of naso- and oropharyngeal samples among hospitalized children appear equally effective for the diagnosis of serologically confirmed community-acquired mycoplasmal pneumonia. However, the combination of results from both sites yields optimal sensitivity (57%), specificity (98%), and positive (92%) and negative (82%) predictive values when compared with Mycoplasma pneumoniae enzyme-linked immunosorbent assay.

Application of NucliSens Basic Kit for the detection of Mycoplasma pneumoniae in respiratory specimens

A commercially available nucleic acid sequence-based amplification (NASBA) NucliSens Basic Kit (NBK) assay for the detection of Mycoplasma pneumoniae 16S rRNA in respiratory specimens was developed and compared to standard NASBA and PCR assays previously developed in our laboratory. The specificity and sensitivity of the NBK assay was comparable to the specificity and sensitivity of the corresponding standard NASBA assay. The NBK offers standardized reagents for the development of a NASBA assay for the detection of M. pneumoniae in respiratory specimens and is easily adaptable to other amplification targets.

Nucleic acid amplification tests for the diagnosis of pneumonia

Molecular diagnostic techniques, such as polymerase chain reaction (PCR), are promising tools for the rapid etiological diagnosis of pneumonia. PCR offers potential advantages over conventional tests for the detection of Mycoplasma pneumoniae, Legionella species, and Chlamydia pneumoniae. For pneumococcal pneumonia in adults, PCR adds little to existing diagnostic tests and is unable to distinguish pneumococcal colonization from infection when testing respiratory samples. Although PCR is probably more sensitive than are conventional microscopy-based methods for diagnosing Pneumocystis carinii pneumonia, the specificity is uncertain, because P. carinii can occasionally be detected in the absence of clinical symptoms. PCR is useful for the diagnosis of viral pneumonia in immunocompromised patients. Further work is required to better characterize the role of PCR versus the role of other tests for diagnosing pneumonia and to develop standard PCR assays that can be readily adopted by routine diagnostic laboratories.

Polymerase chain reaction as a sensitive and rapid method for specific detection of Mycoplasma pneumoniae in clinical samples

The fast diagnosis of Mycoplasma primary atypical pneumonia is impaired by the lack of routinely available culture methods for isolation of Mycoplasma pneumoniae from clinical specimens. Likewise, serological methods commonly used for diagnosis are insensitive and non-specific. In this study, we have established and applied the polymerase chain reaction (PCR) technique to detect M. pneumoniae DNA in clinical samples originating from the respiratory tract. The PCR results were compared with those from culture and serology tests. To standardize the detection of M. pneumoniae by PCR, we first used DNA from culture grown organisms and clinical samples seeded with M. pneumoniae. PCR amplification was performed with M. pneumoniae-specific primers to amplify 144, 153 and 631 bp DNA fragments by using primer pairs MP5-1/MP5-2, P1-178/P1-331 and P1-178/P1-809, respectively. The amplification of the 631 bp DNA fragment was found to be most sensitive for the detection of M. pneumoniae. Using the most sensitive PCR, a total of 47 respiratory specimens from patients suspected of community acquired pneumonia were tested. While none of the specimens were positive for M. pneumoniae in culture, 6 specimens gave positive results by PCR. In 4 out of the 5 PCR positive samples tested serologically, the results were supported by elevated levels of anti-mycoplasma IgG/IgM/IgA. Thus, these results suggest that PCR is the most sensitive method to detect M. pneumoniae in clinical specimens.

Mycoplasma pneumoniae and Chlamydia pneumoniae in asthma: effect of clarithromycin

STUDY OBJECTIVES

To determine the effect of clarithromycin therapy in patients with asthma.

DESIGN

Randomized, double blind, placebo-controlled trial.

SETTING

A tertiary referral center.

PATIENTS OR PARTICIPANTS

Fifty-five subjects with chronic, stable asthma recruited from the general Denver, CO, community.

INTERVENTIONS

Patients underwent airway evaluation for Mycoplasma pneumoniae and Chlamydia pneumoniae by polymerase chain reaction (PCR) and culture, followed by treatment with clarithromycin, 500 bid, or placebo for 6 weeks.

MEASUREMENTS AND RESULTS

Outcome variables were lung function, sinusitis as measured by CT, and the inflammatory mediators tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, IL-4, IL-5, and IL-12 messenger RNA (mRNA) measured via in situ hybridization, in airway biopsies, and BAL. Mycoplasma or chlamydia were detected by PCR in 31 of 55 asthmatics. Treatment resulted in a significant improvement in the FEV(1), but only in the PCR-positive subjects (2.50 +/- 0.16 to 2.69 +/- 0.19 L, mean +/- SEM; p = 0.05). This was not appreciated in the PCR-negative subjects (2.59 +/- 0.24 to 2.54 +/- 0.18 L, p = 0.85) or the PCR-positive or PCR-negative subjects who received placebo. Sinus CTs revealed no change in sinusitis with clarithromycin treatment. In situ hybridization revealed no significant difference in baseline airway tissue or BAL-mediator expression between the PCR-positive and PCR-negative subjects. However, the PCR-positive subjects who received clarithromycin demonstrated a reduction in TNF-alpha (p = 0.006), IL-5 (p = 0.007), and IL-12 (p = 0.004) mRNA in BAL and TNF-alpha mRNA in airway tissue (p = 0.0009). The PCR-negative subjects who received clarithromycin only demonstrated a reduction in TNF-alpha (p = 0.01) and IL-12 (p = 0.002) mRNA in BAL and TNF-alpha mRNA in airway tissue (p = 0.004). There were no significant differences in cytokine expression in those subjects who received placebo.

CONCLUSIONS

These observations support the hypothesis that clarithromycin therapy improves lung function, but only in those subjects with positive PCR findings for M pneumoniae or C pneumoniae.

Detection of Mycoplasma pneumoniae in spiked clinical samples by nucleic acid sequence-based amplification

Isothermal nucleic acid sequence-based amplification (NASBA) was applied to the detection of Mycoplasma pneumoniae. M. pneumoniae RNA prepared from a plasmid construct was used to assess the sensitivity of the assay, and an internal control for the detection of inhibitors was constructed. The sensitivity of the NASBA assay was 10 molecules of wild-type M. pneumoniae RNA generated in vitro and 5 color-changing units (CCU) of M. pneumoniae. An appropriate specimen preparation procedure was developed: after protease treatment of the respiratory specimens, guanidine thiocyanate lysis solution (4.7 M guanidine thiocyanate [Sigma-Aldrich NV], 46 mM Tris-HCl [Merck, Darmstadt, Germany], 20 mM EDTA [Sigma-Aldrich NV], 1.2% [wt/vol] Triton X-100 [Sigma-Aldrich NV], pH 6.2.) was added. With spiked throats, nasopharyngeal aspirates, bronchoalveolar lavage specimens, and sputum specimens, the sensitivity of the NASBA assay in the presence of the internal control was 2 x 10(4) molecules of in vitro-generated RNA or 5 CCU of M. pneumoniae. The sensitivity of the NASBA assay was comparable to that of a PCR targeted to the P1 adhesin gene. Fifteen clinical specimens positive for M. pneumoniae by PCR were also positive by NASBA. These results indicate that the sensitivity of detection of M. pneumoniae in spiked respiratory samples by NASBA is high. Together with the use of the internal control, the assay merits evaluation as a diagnostic tool.

Mycoplasma pneumoniae induces chronic respiratory infection, airway hyperreactivity, and pulmonary inflammation: a murine model of infection-associated chronic reactive airway disease

Because chronic Mycoplasma pneumoniae respiratory infection is hypothesized to play a role in asthma, the potential of M. pneumoniae to establish chronic respiratory infection with associated pulmonary disease was investigated in a murine model. BALB/c mice were intranasally inoculated once with M. pneumoniae and examined at 109, 150, 245, 368, and 530 days postinoculation. M. pneumoniae was detected in bronchoalveolar lavage fluid by culture or PCR in 70 and 22% of mice at 109 and 530 days postinoculation, respectively. Lung histopathology was normal up to 368 days postinoculation. At 530 days, however, 78% of the mice inoculated with M. pneumoniae demonstrated abnormal histopathology characterized by peribronchial and perivascular mononuclear infiltrates. A mean histopathologic score (HPS) at 530 days of 5.1 was significantly greater (P < 0.01) than that for controls (HPS score of 0). Serum anti-M. pneumoniae immunoglobulin G was detectable in all of the mice inoculated with M. pneumoniae and was inversely correlated with HPS (r = -0.95, P = 0.01) at 530 days postinoculation. Unrestrained whole-body plethysmography measurement of enhanced pause revealed significantly elevated airway methacholine reactivity in M. pneumoniae-inoculated mice compared with that in controls at 245 days (P = 0.03) and increased airway obstruction at 530 days (P = 0.01). Murine M. pneumoniae respiratory infection can lead to chronic pulmonary disease characterized by airway hyperreactivity, airway obstruction, and histologic inflammation.

A link between chronic asthma and chronic infection

BACKGROUND

Asthma is a prevalent disease with marked effects on quality of life and economic societal burden. However, the cause of asthma and its pathophysiology are not completely defined. Recently, the possibility that chronic infection may play a role has been suggested.

OBJECTIVE

We sought to define the association between Mycoplasma and Chlamydia species and chronic asthma.

METHODS

We performed a comparison study of asthmatic patients and normal control subjects. Fifty-five patients with chronic stable asthma were compared with 11 normal control subjects by using PCR, culture, and serology for Mycoplasma species, Chlamydia species, and viruses from the nasopharynx, lung, and blood. Bronchoalveolar lavage cell count and differential, as well as tissue morphometry, were also evaluated. Computer-generated scoring for the degree of chronic sinusitis in asthmatic patients was additionally evaluated.

RESULTS

Thirty-one of 55 asthmatic patients had positive PCR results for Mycoplasma (n = 25) or Chlamydia species (n = 6), which were mainly found on lung biopsy specimens or in lavage fluid. Only 1 of 11 normal control subjects had positive PCR results for Mycoplasma species. The distinguishing phenotype between asthmatic patients with positive and negative PCR results was the significantly greater number of tissue mast cells in the group with positive results.

CONCLUSION

A significant number of patients with chronic stable asthma demonstrate the presence of Mycoplasma species, Chlamydia species, or both in their airways, with the distinguishing feature of increased mast cell number. These findings need further delineation but may help us to understand the pathophysiology of asthma and new treatment options.

Development of a genomics-based PCR assay for detection of Mycoplasma pneumoniae in a large outbreak in New York State

A genomics-based PCR method was developed and used to test specimens from patients involved in a large outbreak of Mycoplasma pneumoniae in a closed religious community in New York State. New P1 adhesin gene primers were designed to bind to 9 of 10 target sequences in the repetitive-element sequences obtained from the whole genome sequence of M. pneumoniae. This PCR method had a sensitivity of 0.006 CFU and a specificity of 100% for M. pneumoniae. The PCR was validated by testing a subset of patient samples by culture and comparing the results to those obtained by PCR. Of the initial 280 samples tested, 73 were positive by PCR and 22 were positive by culture. All samples positive by culture were also positive by PCR. Follow-up testing of selected patients 3 to 6 weeks after antibiotic treatment revealed that eight samples remained positive by PCR and that three samples remained positive by culture. Additionally, no nonspecific PCR inhibition was detected as a result of the specimen type, transport medium, or sample preparation methodology. The study demonstrates that the PCR described here is a rapid, sensitive, and specific method for the identification of M. pneumoniae and was helpful for the detection and monitoring of the outbreak.

Rapid detection of Mycoplasma pneumoniae in clinical samples by real-time PCR

M. pneumoniae is a common causative agent of community-acquired pneumonia in children. The diagnosis of such infections is usually based on serology using complement fixation or, more recently, enzyme-immuno assays. PCR has been shown to be a promising alternative. We have evaluated a real-time PCR assay targeting the P1 adhesion protein gene and compared it to a conventional semi-nested PCR assay with the 16S rDNA as target. Comparison of 147 specimens from 48 patients showed an overall agreement of 97.4%. Real-time PCR proved to be of equal value on clinical specimens as conventional PCR regarding sensitivity and specificity, but is clearly advantageous regarding speed, handling and number of samples that can be analyzed per run.

Incidence of upper respiratory tract Mycoplasma pneumoniae infections among outpatients in Rhône-Alpes, France, during five successive winter periods

In this prospective study, nasal swab samples from patients with acute respiratory infections were evaluated for the presence of Mycoplasma pneumoniae. This PCR-plus-hybridization-based detection was associated with the detection of other viral agents. During the five winter surveillance periods, 3,897 samples were collected by 75 medical practitioners participating in the Groupe Régional d'Observation de la Grippe surveillance network in Rhône-Alpes (France). M. pneumoniae was detected in 283 samples (7.3%); its rate of detection ranged from 10.1 to 2.0% over the five periods, and it was the second most frequently isolated pathogen during the survey, after influenza A. Three high-prevalence winters were observed, yielding an early winter peak of M. pneumoniae infection which was observed in all age groups. No statistically significant difference was detected between rates of infections in the different age groups, but M. pneumoniae infection was significantly related to lower respiratory tract infection during periods of high prevalence. This study defined the frequency of M. pneumoniae detection from nasal swab specimens in patients with acute respiratory infections, confirming its high prevalence and the presence of large outbreaks due to this pathogen.

Detection of Mycoplasma pneumoniae in the airways of adults with chronic asthma

Infection with Mycoplasma pneumoniae has been shown to exacerbate asthma in humans. However, the role of M. pneumoniae in the pathogenesis of chronic asthma has not been defined. Eighteen asthmatics with chronic, stable asthma and 11 nonasthmatic control subjects underwent evaluation of the upper and lower airways and serologic analysis to determine the presence of M. pneumoniae, Chlamydia pneumoniae, and seven respiratory viruses through culture, enzyme-linked immunoassay (EIA) and polymerase chain reaction (PCR). M. pneumoniae was detected by PCR in 10 of 18 asthmatics and one of 11 control subjects (p = 0.02). In nine of the 10 patients, the organism was detected in bronchoalveolar lavage or bronchial biopsies. Seven of 18 asthmatics and one of 11 control subjects were also positive for M. fermentans and M. genitalium by PCR. All patients' cultures, EIAs, and serology were negative for M. pneumoniae. All PCR and cultures were negative for C. pneumoniae, and all EIAs for respiratory viruses were negative in all subjects. Nine asthmatics and one control subject exhibited positive serology for C. pneumoniae (p = 0.05). M. pneumoniae was present in the lower airways of chronic, stable asthmatics with greater frequency than control subjects, and may play a role in the pathogenesis of chronic asthma.

Molecular approaches to diagnosis of pulmonary diseases due to Mycoplasma pneumoniae

In this prospective study, the use of a culture-enhanced PCR assay for the detection of Mycoplasma pneumoniae, followed by hybridization with a specific probe (MP-HPCR) or without hybridization (MP-PCR), and the use of a nested PCR (MP-NPCR) were evaluated. Clinical samples (190 specimens) from 190 patients with respiratory complaints were incubated in culture broth overnight and then subjected to PCR. The results of the PCR were compared to those obtained by culture, the direct antigen test, and serologic testing by microparticle agglutination and by immunoblotting in unclear cases. The sensitivities were 19 CFU for MP-PCR, 1.9 CFU for MP-HPCR, and 0.019 CFU for MP-NPCR. PCR amplification of the beta-globin gene was possible in 98% of cases: after dilution of the beta-globin-negative samples, all samples were reactive. Correlation between negative MP-NPCR results and negative serology results was found in 89% of cases; a positive correlation was found with 10% of the patients. Samples from three immunocompromised patients were MP-NPCR positive but serologically negative. High respiratory colonization by M. pneumoniae (>10(5) CFU/ml) in patients with acute respiratory disease could be detected by culture, MP-PCR, and MP-NPCR. These results indicate that MP-PCR and MP-NPCR are reliable methods for the detection of M. pneumoniae in respiratory tract samples of patients with respiratory complaints.

Detection of Mycoplasma pneumoniae by polymerase chain reaction in lung aspirates from patients with community-acquired pneumonia

STUDY OBJECTIVE

This study was designed to evaluate the usefulness of polymerase chain reaction (PCR) to detect Mycoplasma pneumoniae DNA in samples obtained by transthoracic needle aspiration (TNA).

DESIGN

Prospective study of cases.

SETTING

A university hospital in Lleida, Spain.

PATIENTS

A total of 101 unselected patients, admitted between January 1993 and March 1994 in the emergency department, with a clinical and radiologic picture of community-acquired pneumonia, and without contraindications for TNA application.

INTERVENTIONS

Patients were studied with conventional diagnostic techniques for community-acquired pneumonia. In addition, a sample obtained by TNA was processed by the following methods: culture in standard media, culture in selective media for Legionella, detection of capsular antigens for Streptococcus pneumoniae and Haemophilus influenzae, and detection of M pneumoniae specific genome by PCR.

RESULTS

Serologic data were not available in eight patients and were excluded from this analysis. M pneumoniae PCR amplification was possible in eight cases, well correlated with serologic responses indicating current infection. Samples from ten additional patients, negative by PCR, were found to be demonstrative of recent M pneumoniae infection by serologic study. Finally, in all the remaining 75 cases, including the 59 patients for whom a different microbial diagnosis was established, M pneumoniae PCR test gave negative results.

CONCLUSION

This study indicates that PCR, applied to samples obtained by TNA, appears to be a moderately sensitive and highly specific method for rapid detection of M pneumoniae lung infection.

The role of nucleic acid amplification and detection in the clinical microbiology laboratory

Clinical microbiology is in the midst of a new era. Methodology that is based on nucleic acid detection has slowly appeared in the diagnostic laboratory, and is revolutionizing our ability to assist physicians in the diagnosis and management of patients suffering from infectious diseases. Much like the introduction of immunoassays built around hybridoma technology in the 1980s, considerable doubt and promise exist hand in hand in the 1990s. Conventional testing that is technically straight forward, informative, and timely will always be a part of clinical microbiology; however, considerable room for improvement exists with organisms/diseases for which laboratory methods are limited. Nucleic acid methodology will have its greatest and long-awaited impact in this arena.