Identification of risk factors for infection in an outbreak of Mycoplasma pneumoniae respiratory tract disease

Cigarette Smoke Particle-Induced Lung Injury and Iron Homeostasis

It is proposed that the mechanistic basis for non-neoplastic lung injury with cigarette smoking is a disruption of iron homeostasis in cells after exposure to cigarette smoke particle (CSP). Following the complexation and sequestration of intracellular iron by CSP, the host response (eg, inflammation, mucus production, and fibrosis) attempts to reverse a functional metal deficiency. Clinical manifestations of this response can present as respiratory bronchiolitis, desquamative interstitial pneumonitis, pulmonary Langerhans’ cell histiocytosis, asthma, pulmonary hypertension, chronic bronchitis, and pulmonary fibrosis. If the response is unsuccessful, the functional deficiency of iron progresses to irreversible cell death evident in emphysema and bronchiectasis. The subsequent clinical and pathological presentation is a continuum of lung injuries, which overlap and coexist with one another. Designating these non-neoplastic lung injuries after smoking as distinct disease processes fails to recognize shared relationships to each other and ultimately to CSP, as well as the common mechanistic pathway (ie, disruption of iron homeostasis).

Incidence of acute respiratory tract infections (2006-2015) and influenza (2006-2013) among French armed forces

OBJECTIVES

We aimed to assess the incidence of respiratory tract infections in military settings between 2006 and 2015.

PATIENTS AND METHODS

We performed a retrospective epidemiological study of the entire military population from 2006 to 2015. Comprehensive data was collected from all medical centers, operational medical units, naval services, and army training hospitals and provided by the epidemiological surveillance of the armies.

RESULTS

The annual average population of the study was 331,394 soldiers. For acute respiratory tract infections (2006-2015), 22,818 cases were reported in metropolitan France, 3,211 cases in French overseas territories, 1,595 cases in the French Navy, and 1,318 cases in external military operations for a total of 28,942 cases. For influenza (2006-2013), 934 cases were reported in metropolitan France, 101 cases in French overseas territories, and 23 cases in external operations, for a total of 1,058 cases. The mean incidence rate of acute respiratory tract infections expressed as case number per 1,000 person-years (PY) was 8.7 PY (95% CI [8.6-8.8]) with an exceptional increased incidence rate in 2009 (25.9 PY, 95% CI [25.4-26.4]). The mean incidence rate of influenza was 0.35 PY (95% CI [0.33-0.37]) with a peak incidence rate of 1.9 PY in 2009.

CONCLUSION

Acute respiratory tract infections are at the forefront of infectious episodes in the French armies. Although not necessarily severe, current prevention measures are not enough to reduce the incidence threshold of these infections and need to be improved.

<italic>Mycoplasma Pneumoniae</italic>-Associated Necrotizing Pneumonia in Children: a case-report

<p>Mycoplasma pneumoniae is the most common bacterial strain causing atypical pneumonia in children and adolencents. Although it is known to cause mild symptoms, it can also cause severe pulmonary or extrapulmonary complications in rare cases. Necrotizing pneumonia (NP) is often reported as a complication of Streptococcus pneumoniae and is very rarely caused by M. pneumoniae. We report a case in which a 5-year-old boy was diagnosed with lobar pneumonia with symptoms that aggravated even with macrolide antibiotic treatment. Anti-mycoplasma pneumoniae Ig-M test yielded high values, and direct polymerase chain reaction results were also positive. NP caused by M. pneumoniae was confirmed on computed tomography. After treatment involving tosufloxacin and systemic steroid, the lesion decreased in size and improved gradually when followed-up for more than 1 year. The patient did not have any predisposing or risk factors for NP.</p>

Pooled analysis of nuclear acid sequence-based amplification for rapid diagnosis of Mycoplasma pneumoniae infection

Background

Mycoplasma pneumoniae(M pneumoniae) is a common human etiology of respiratory infections. Nuclear acid sequence‐based amplification (NASBA) shows good value for the detection of M pneumoniae that surpasses PCR. However, the optimal detection technology still remains to be identified. The purpose of this meta‐analysis was to systematically evaluate the overall accuracy of NASBA for diagnosing M pneumoniae infections.

Methods

The databases PubMed, Cochrane Library, Google Scholar, CNKI, Wang Fang, and Baidu Scholar were comprehensively searched from their initiation date to December 2017 for NASBA in the diagnosis of M pneumoniae infection. Meta‐DiSc 1.4 statistical software was used to evaluate the sensitivity (SEN), specificity (SPE), negative likelihood ratio (−LR), positive likelihood ratio (+LR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC). RevMan 5.2 statistical software was used for quality evaluation of the included articles. Publication bias was evaluated by funnel plot.

Results

Six articles with high quality, including 10 studies, were finally included in this meta‐analysis. The combined statistics results for the diagnosis of M pneumoniae infection by NASBA were 0.77 (SEN, 95% CI: 0.71 to 0.82); 0.98 (SPE, 95% CI: 0.98 to 0.99); 0.22 (‐LR, 95% CI: 0.13 to 0.39); 50.38 (+ LR, 95% CI: 21.85 to 116.17); 292.72 (DOR, 95% CI: 95.02 to 901.75); and 0.9875 (the area under the curve of SROC).

Conclusion

Nuclear acid sequence‐based amplification is a reliable technique to diagnose M pneumoniae infection. However, whether it can replace PCR and serology need to be further studied.

Mycoplasma pneumoniae Pneumonia with Worsening Pleural Effusion Despite Treatment with Appropriate Antimicrobials: Case report

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia. As M. pneumoniae pneumonia is usually a mild and self-limiting disease, complications such as pleural effusion occur only rarely. We report a 22-year-old woman who presented to the Emergency Medicine Department of the Sultan Qaboos University Hospital, Muscat, Oman, in 2017 with an eight-day history of fever associated with coughing, chills and rigors. She was diagnosed with M. pneumoniae pneumonia, but subsequently developed pleural effusion which worsened despite treatment with appropriate antimicrobials. The pleural effusion required drainage, which revealed that it was of the more severe exudative type. Following drainage, the patient improved dramatically. She was discharged and advised to continue taking antibiotics.

An atypical case of atypical pneumonia

Atypical pneumonia has been thought to account for 7%-20% of community-acquired pneumonia (CAP). The treatment for the pathogens that cause atypical pneumonia is different from that of other bacterial pneumonia. Therefore, identification of the causative pathogen in a primary care situation is crucial for adequate treatment of CAP. Mycoplasma infection is prevalent in the general population, but Mycoplasma pneumoniae with extrapulmonary symptoms is relatively rare. Herein, we report a case of CAP because of M. pneumoniae that presented with a wide variety of extrapulmonary diseases. Delayed administration of appropriate antibiotics may contribute to development of extrapulmonary manifestations.

Control of a Mycoplasma pneumoniae Outbreak in an Institutional Setting Using Azithromycin Prophylaxis

Background

Mycoplasma pneumoniae is a major cause of respiratory infection of varying severity. Outbreaks of M. pneumoniae infection commonly occur in closed or semi-closed communities and settings. The control of such outbreaks is challenging, owing to delayed detection, long incubation period, and paucity of infection control guidelines.

Methods

Between May and July 2015, a residential facility for adults with developmental disabilities in Southern Israel witnessed an outbreak of acute respiratory infection, subsequently diagnosed as associated with M. pneumoniae. All relevant data were collected as a part of a formal outbreak investigation. Strict infection control procedures were implemented, and azithromycin prophylaxis was provided to all residents.

Results

Out of 215 residents, there were 29 suspected cases, 23 of which were confirmed as M. pneumoniae infection by serology or nucleic acid testing, for an attack rate of 11%. There were no cases of severe or fatal illness. An infection control strategy, including implementation of strict case isolation, enforcement of hygiene measures, a high index of suspicion for case detection, and use of azithromycin prophylaxis for all residents, led to rapid cessation of the outbreak.

Discussion

The use of azithromycin prophylaxis may be worthwhile in closed institutional settings in which M. pneumoniae infections are documented. The dynamics of this outbreak suggest that if spread between wards is anticipated, expanding prophylaxis beyond immediate contacts of affected individuals should be considered.

Rare complicated parapneumonic effusion, Mycoplasma pneumoniae with new-onset lupus flare: Case report and literature review

Mycoplasma pneumoniae has been associated with respiratory tract infections. Mycoplasma pneumoniae pneumonia–related pleural effusion is rarely reported. Extra-pulmonary abnormalities such as encephalitis, myocarditis, glomerulonephritis, and myringitis have been reported. However pulmonary manifestations in systemic lupus erythematosus include pneumonitis, pleurisy, interstitial lung disease, and thromboembolic disease. We present the case of a 26-year-old male who came for evaluation of fever, cough, and shortness of breath with right-sided chest pain. He was found to have right-side loculated complicated parapneumonic effusion and underwent drainage with a pleural catheter followed by fibrinolytic therapy. He was then found to have new-onset systemic lupus erythematosus concomitant with Mycoplasma pneumonia, leading to lupus flare and lupus nephritis. He responded well to levofloxacin, steroids, hydroxychloroquine, and mycophenolate, with complete resolution of loculated pleural effusion and symptom improvement. Our case describes the rare combination of Mycoplasma pneumoniae pneumonia, parapneumonic pleural effusion, and lupus flare with lupus nephritis. Early identification and treatment can lead to better out come in young patients.

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.

A Rare Case of Cavitary Lesion of the Lung Caused by Mycoplasma pneumoniae in an Immunocompetent Patient

Mycoplasma pneumoniae is an atypical bacterium that most commonly causes upper respiratory tract infections, but it can also cause pneumonia, referred to as "walking pneumonia." Although cavitary lesions are present in a wide variety of infectious and noninfectious processes, those attributable to M. pneumoniae are extremely uncommon; thus, to date, epidemiological studies are lacking. Here, we present a rare case of a 20-year-old male, referred to us from a psychiatric facility for evaluation of a cough, who was found to have a cavitary lesion in the right upper lobe. An extensive workup for cavitary lesion was negative, but his mycoplasma IgM level was high. A computed tomography (CT) of the chest confirmed the presence of a cavitary lesion. After treatment with levofloxacin antibiotics, a follow-up CT showed complete resolution of the lesion. Our case is a rare presentation of mycoplasma pneumonia as a cavitary lesion in a patient without any known risk factors predisposing to mycoplasma infection. Early recognition and treatment with an appropriate antibiotic may lead to complete resolution of the cavitary lesion.

Pulmonary migratory infiltrates due to mycoplasma infection: case report and review of the literature

Pulmonary migratory infiltrates (PMI) are observed in a few diseases. We report here a case of PMI attributed to Mycoplasma pneumonia (Mp) infection. The patient's past medical history was characterized by fleeting and/or relapses of patchy opacification or infiltrates of parenchyma throughout the whole lung field except for left lower lobe radiographically. Serological assays revealed an elevation of IgG antibody specific to Mp and its fourfold increase in convalescent serum. Histopathological findings showed polypoid plugs of fibroblastic tissue filling and obliterating small air ways and interstitial infiltrates of mononuclear inflammatory cells in the vicinal alveolar septa. The patient was treated with azithromycin which resulted in a dramatic improvement clinically and imageologically. In spite of the increasing incidence of Mp, the possible unusual imaging manifestation and underlying mechanism haven't attracted enough attention. To our knowledge, there are rare reports of such cases.

Development of a Multilocus Sequence Typing Scheme for Molecular Typing of Mycoplasma pneumoniae

Mycoplasma pneumoniae is a major human respiratory pathogen causing both upper and lower respiratory disease in humans of all ages, and it can also result in other serious extrapulmonary sequelae. A multilocus sequence typing (MLST) scheme for M. pneumoniae was developed based on the sequences of eight housekeeping genes (ppa, pgm, gyrB, gmk, glyA, atpA, arcC, and adk) and applied to 55 M. pneumoniae clinical isolates and the two type strains M129 and FH. A total of 12 sequence types (STs) resulted for 57 M. pneumoniae isolates tested, with a discriminatory index of 0.21 STs per isolate. The MLST loci used in this scheme were shown to be stable in 10 strains following 10 sequential subculture passages. Phylogenetic analysis of concatenated sequences of the eight loci indicated two distinct genetic clusters that were directly linked to multilocus variable-number tandem repeat analysis (MLVA) type. Genetic MLST clustering was confirmed by genomic sequence analysis, indicating that the MLST scheme developed in this study is representative of the genome. Furthermore, this MLST scheme was shown to be more discriminatory than both MLVA and P1 typing for the M. pneumoniae isolates examined, providing a method for further and more detailed analysis of observed epidemic peaks of M. pneumoniae infection. This scheme is supported by a public Web-based database (http://pubmlst.org/mpneumoniae).

Molecular Epidemiology of Mycoplasma pneumoniae: Genotyping Using Single Nucleotide Polymorphisms and SNaPshot Technology

Molecular typing of Mycoplasma pneumoniae is an important tool for identifying grouped cases and investigating outbreaks. In the present study, we developed a new genotyping method based on single nucleotide polymorphisms (SNPs) selected from the whole-genome sequencing of eight M. pneumoniae strains, using the SNaPshot minisequencing assay. Eight SNPs, localized in housekeeping genes, predicted lipoproteins, and adhesin P1 genes were selected for genotyping. These SNPs were evaluated on 140 M. pneumoniae clinical isolates previously genotyped by multilocus variable-number tandem-repeat analysis (MLVA-5) and adhesin P1 typing. This method was also adapted for direct use with clinical samples and evaluated on 51 clinical specimens. The analysis of the clinical isolates using the SNP typing method showed nine distinct SNP types with a Hunter and Gaston diversity index (HGDI) of 0.836, which is higher than the HGDI of 0.583 retrieved for the MLVA-4 typing method, where the nonstable Mpn1 marker was removed. A strong correlation with the P1 adhesin gene typing results was observed. The congruence was poor between MLVA-5 and SNP typing, indicating distinct genotyping schemes. Combining the results increased the discriminatory power. This new typing method based on SNPs and the SNaPshot technology is a method for rapid M. pneumoniae typing directly from clinical specimens, which does not require any sequencing step. This method is based on stable markers and provides information distinct from but complementary to MLVA typing. The combined use of SNPs and MLVA typing provides powerful discrimination of strains.

Risk factors for heat illness among British soldiers in the hot Collective Training Environment

Background

Heat illness is a preventable disorder in military populations. Measures that protect vulnerable individuals and contribute to effective Immediate Treatment may reduce the impact of heat illness, but depend upon adequate understanding and awareness among Commanders and their troops.

Objective

To assess risk factors for heat illness in British soldiers deployed to the hot Collective Training Environment (CTE) and to explore awareness of Immediate Treatment responses.

Methods

An anonymous questionnaire was distributed to British soldiers deployed in the hot CTEs of Kenya and Canada. Responses were analysed to determine the prevalence of individual (Intrinsic) and Command-practice (Extrinsic) risk factors for heat illness and the self-reported awareness of key Immediate Treatment priorities (recognition, first aid and casualty evacuation).

Results

The prevalence of Intrinsic risk factors was relatively low in comparison with Extrinsic risk factors. The majority of respondents were aware of key Immediate Treatment responses. The most frequently reported factors in each domain were increased risk by body composition scoring, inadequate time for heat acclimatisation and insufficient briefing about casualty evacuation.

Conclusions

Novel data on the distribution and scale of risk factors for heat illness are presented. A collective approach to risk reduction by the accumulation of ‘marginal gains’ is proposed for the UK military. This should focus on limiting Intrinsic risk factors before deployment, reducing Extrinsic factors during training and promoting timely Immediate Treatment responses within the hot CTE.

Particle exposures and infections

Particle exposures increase the risk for human infections. Particles can deposit in the nose, pharynx, larynx, trachea, bronchi, and distal lung and, accordingly, the respiratory tract is the system most frequently infected after such exposure; however, meningitis also occurs. Cigarette smoking, burning of biomass, dust storms, mining, agricultural work, environmental tobacco smoke (ETS), wood stoves, traffic-related emissions, gas stoves, and ambient air pollution are all particle-related exposures associated with an increased risk for respiratory infections. In addition, cigarette smoking, burning of biomass, dust storms, mining, and ETS can result in an elevated risk for tuberculosis, atypical mycobacterial infections, and meningitis. One of the mechanisms for particle-related infections includes an accumulation of iron by surface functional groups of particulate matter (PM). Since elevations in metal availability are common to every particle exposure, all PM potentially contributes to these infections. Therefore, exposures to wood stove emissions, diesel exhaust, and air pollution particles are predicted to increase the incidence and prevalence of tuberculosis, atypical mycobacterial infections, and meningitis, albeit these elevations are likely to be small and detectable only in large population studies. Since iron accumulation correlates with the presence of surface functional groups and dependent metal coordination by the PM, the risk for infection continues as long as the particle is retained. Subsequently, it is expected that the cessation of exposure will diminish, but not totally reverse, the elevated risk for infection.

Development of protective anti-Mycoplasma pneumoniae antibodies after immunization of guinea pigs with the combination of a P1-P30 chimeric recombinant protein and chitosan

The attachment organelle of the human respiratory tract pathogen Mycoplasma pneumoniae is essential for colonization of the host mucosa. Furthermore, adherence-related proteins such as the major adhesin P1 and protein P30 represent vaccine candidates. Using the chimeric recombinant protein HP14/30, which combines surface-localized and adherence-involved regions of both proteins, we developed an optimized strategy to immunize guinea pigs. The vaccination protocol includes subcutaneous prime immunization followed by presentation of the antigen directly to the respiratory mucosa by two intranasal (i.n.) administrations and combination of antigen with the mucosal adjuvant chitosan. The immunization scheme induced high, consistent and long-lasting IgA levels in respiratory tract samples (BAL, nasal and throat washing fluid) from the animals. In comparison with a preimmune serum, incubation of M. pneumoniae cells with sera from these animals reduced the mean adhesion of bacteria to HeLa cells to 6%. After i.n. infection, immunized animals showed significantly decreased numbers of M. pneumoniae-specific genome copies, especially in the upper respiratory tract, in comparison with the control group. The results demonstrated that optimized immunization with the chimeric protein HP14/30 is promising for further vaccination efforts to prevent host colonization with M. pneumoniae.

Detection of Mycoplasma pneumoniae by real-time PCR

Mycoplasma pneumoniae is a significant cause of respiratory disease, accounting for approximately 20% of cases of community-acquired pneumonia. Although several diagnostic methods exist to detect M. pneumoniae in respiratory specimens, real-time PCR has emerged as a significant improvement for the rapid diagnosis of this pathogen. The method described herein details the procedure for the detection of M. pneumoniae by real-time PCR (qPCR). The qPCR assay described can be performed with three targets specific for M. pneumoniae (Mp181, Mp3, and Mp7) and one marker for the detection of the RNaseP gene found in human nucleic acid as an internal control reaction. Recent studies have demonstrated the ability of this procedure to reliably identify this agent and facilitate the timely recognition of an outbreak.

Multilocus variable-number tandem-repeat analysis of Mycoplasma pneumoniae clinical isolates from 1962 to the present: a retrospective study

In this study, we evaluated a recently developed multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) method for the molecular typing of Mycoplasma pneumoniae. The method is based on GeneScan analysis of five VNTR loci throughout the genome which define a specific genotype based on the number of tandem repeats within each locus. A retrospective analysis of 154 M. pneumoniae clinical isolates collected over the last 50 years and a limited (n = 4) number of M. pneumoniae-positive primary specimens acquired by the CDC was performed using MLVA. Eighteen distinct VNTR types were identified, including two previously unidentified VNTR types. Isolates from several M. pneumoniae community outbreaks within the United States were also analyzed to examine clonality of a specific MLVA type. Observed in vitro variability of the Mpn1 VNTR locus prompted further analysis, which showed multiple insertions or deletions of tandem repeats within this locus for a number of specimens and isolates. To our knowledge, this is the first report showing variation within the Mpn1 locus, thus affecting precise and reliable classification using the current MLVA typing system. The superior discriminatory capability of MLVA provides a powerful tool for greater resolution of M. pneumoniae strains and could be useful during outbreaks and epidemiological investigations.

Role of Mycoplasma pneumoniae glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in mediating interactions with the human extracellular matrix

In different, phylogenetically unrelated micro-organisms, glycolytic enzymes play a dual role. In the cytosol they are involved in metabolic reactions whereas the surface-localized fraction of the enzymes contributes to adhesion and virulence. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a typical member of this group of multifunctional proteins. In this study, we characterized the GAPDH of Mycoplasma pneumoniae, a common pathogen of the human respiratory mucosa. Full-length GAPDH of M. pneumoniae was successfully expressed and used to produce a polyclonal antiserum. By immunofluorescence, colony blot and ELISA experiments with different fractions of the M. pneumoniae proteins, GAPDH was demonstrated to be present in the cytosol and at even higher concentrations at the surface of mycoplasmas. Nevertheless, antibodies against recombinant GAPDH were not detected in sera of immunized animals or of patients with confirmed M. pneumoniae infection. Recombinant GAPDH bound to different human cell lines in a concentration-dependent manner, and binding was inhibited by specific anti-GAPDH serum. In contrast, this antiserum did not significantly influence the adherence of M. pneumoniae to HeLa cells. When different human extracellular matrix proteins were tested in Western blot assays, GAPDH bound to fibrinogen. The results showed that the GAPDH of M. pneumoniae is a member of the family of cytosol-localized glycolytic enzymes, which also occur at the surface of the bacterium, and mediates interactions with the extracellular matrix proteins of the human host. Thus, the surface-exposed fraction of GAPDH may be a factor that contributes to the successful colonization of the human respiratory tract by M. pneumoniae.

Epidemiological characteristics and meteorological factors of childhood Mycoplasma pneumoniae pneumonia in Hangzhou

BACKGROUND

Mycoplasma pneumoniae (M. pneumoniae) is an important pathogen of pediatric respiratory infections and the relation of M. pneumoniae pneumonia (MPP) with meteorological factors remains obscure. This study aims to investigate the epidemiological characteristics of childhood MPP and observe if there is a relationship between epidemiological characteristics and meteorological factors in Hangzhou.

METHODS

M. pneumoniae DNA in nasopharyngeal aspirates of hospitalized pneumonia children were detected by polymerase chain reaction from January 1, 2007 to December 31, 2009. The positive rates of MPP (MPP rates) in different years, seasons and ages were compared. The relationship between MPP rates and meteorological data, including mean air temperature (°C), mean relative humidity (%), monthly precipitation (mm) and raining days were analyzed.

RESULTS

In 14 799 pneumonia cases found from 2007 to 2009, the MPP rate was 18.5%. Altogether 1610 boys (16.9%) and 1134 girls (21.4%) suffered from MPP with a significant difference between both genders (χ(2)=45.68, P<0.001). In children younger than 1 year, 1-2 years, 3-6 years, and older than 7 years, the MPP rates were 9.8%, 21.1%, 44.4% and 61.6%, respectively. The MPP rates were significantly higher in older children than in younger ones (trends test χ(2)=46.72, P<0.001). In a descending order, the MPP rates in summer, autumn, spring, and winter were 27.8%, 23.9%, 18.0% and 11.6%, respectively (χ(2)=372.75, P<0.001). The MPP rates in 2007 to 2009 were 12.9%, 19.3% and 23.6%, respectively (trends test χ(2)=13.72, P<0.001). Of the four meteorological factors, only monthly mean air temperature was included in the multiple linear regression model (P<0.001).

CONCLUSIONS

This study showed that the MPP rate was higher in older children than in younger ones. Girls had a higher positive rate of MPP than boys. In Hangzhou, MPP was more prevalent in summer and autumn. Air temperature was the only meteorological factor affecting the prevalence of MPP.

Detection of Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella spp. in clinical specimens using a single-tube multiplex real-time PCR assay

A multiplex real-time PCR assay for the detection of Mycoplasma pneumoniae (MP181), Chlamydia (Chlamydophila) pneumoniae (CP-Arg), Legionella spp. (Pan-Leg), and the human RNase P (RNase P) gene was developed for rapid testing of atypical bacterial respiratory pathogens in clinical specimens. This method uses 4 distinct hydrolysis probes to detect 3 leading causes of community-acquired pneumonia. The assay was evaluated for specificity and sensitivity by testing against 35 related organisms, a dilution series of each specific target and 197 clinical specimens. Specificity testing demonstrated no cross-reactivity. A comparison to previously validated singleplex real-time PCR assays for each agent was also performed. The analytical sensitivity for specific pathogen targets in both the singleplex and multiplex was identical (50 fg), while efficiencies ranged from 82% to 97% for the singleplex assays and from 90% to 100% for the multiplex assay. The clinical sensitivity of the multiplex assay was improved for the Pan-Leg and CP-Arg targets when compared to the singleplex. The MP181 assay displayed equivalent performance. This multiplex assay provides an overall improvement in the diagnostic capability for these agents by demonstrating a sensitive, high-throughput and rapid method. This procedure may allow for a practical and efficient means to test respiratory clinical specimens for atypical pneumonia agents in health care settings and facilitate an appropriate public health response to outbreaks.

The convergence of the global smoking, COPD, tuberculosis, HIV, and respiratory infection epidemics

At the beginning of the 21st century, we are facing the convergence of several epidemics. These include tobacco smoking, tuberculosis, HIV infection, influenza, and chronic obstructive pulmonary disease. These epidemics interact by way of increasing disease susceptibility and worsening outcomes. To control these interacting epidemics, we need to better understand each infection and how it influences the others. Multifaceted approaches will be necessary to reduce the impact on those in developing nations most likely to be affected by the convergence of all epidemics.

Control of Streptococcus pneumoniae serotype 5 epidemic of severe pneumonia among young army recruits by mass antibiotic treatment and vaccination

During an outbreak of severe pneumonia among new army recruits, an epidemiological investigation combined with repeated nasopharyngeal/oropharyngeal cultures from sick and healthy contacts subjects was conducted. Fifteen pneumonia cases and 19 influenza-like illness cases occurred among 596 recruits over a 4-week period in December 2005. Pneumonia attack rates reached up to 5.5%. A single pneumococcus serotype 5 clone was isolated from blood or sputum cultures in 4 patients and 30/124 (24.1%) contacts. Immunization with 23-valent polysaccharide vaccine supplemented with a 2-dose azithromycin mass treatment rapidly terminated the outbreak. Carriage rates dropped to <1%, 24 and 45 days after intervention.

Difference of clinical features in childhood Mycoplasma pneumoniae pneumonia

BACKGROUND

M. pneumoniae pneumonia (MP) has been reported in 10-40% of community-acquired pneumonia cases. We aimed to evaluate the difference of clinical features in children with MP, according to their age and chest radiographic patterns.

METHODS

The diagnosis of MP was made by examinations at both admission and discharge and by two serologic tests: the indirect microparticle agglutinin assay (>or=1:40) and the cold agglutinins titer (>or=1:32). A total of 191 children with MP were grouped by age: or=6 years of age (81 patients). They were also grouped by pneumonia pattern: bronchopneumonia group (96 patients) and segmental/lobar pneumonia group (95 patients).

RESULTS

Eighty-six patients (45%) were seroconverters, and the others showed increased antibody titers during hospitalization. Among the three age groups, the oldest children showed the longest duration of fever, highest C-reactive protein (CRP) values, and the most severe pneumonia pattern. The patients with segmental/lobar pneumonia were older and had longer fever duration and lower white blood cell (WBC) and lymphocyte counts, compared with those with bronchopneumonia. The patient group with the most severe pulmonary lesions had the most prolonged fever, highest CRP, highest rate of seroconverters, and lowest lymphocyte counts. Thrombocytosis was observed in 8% of patients at admission, but in 33% of patients at discharge.

CONCLUSIONS

In MP, older children had more prolonged fever and more severe pulmonary lesions. The severity of pulmonary lesions was associated with the absence of diagnostic IgM antibodies at presentation and lymphocyte count. Short-term paired IgM serologic test may be mandatory for early and definitive diagnosis of MP.

Clinical severity of Mycoplasma pneumoniae (MP) infection is associated with bacterial load in oropharyngeal secretions but not with MP genotype

BACKGROUND

Disease severity in Mycoplasma pneumoniae (MP) infection could potentially be related to bacterial factors such as MP genotype (MP1 or MP2; distinguished by different adhesions proteins) or bacterial load in airway secretions. We have compared these parameters in patients who were hospitalized for MP pneumonia, with outpatients with mild MP disease.

METHODS

MP bacterial load was measured by real-time PCR in 45 in- and outpatients ("clinical study group") in whom MP DNA had been detected in oropharyngeal secretions by PCR. In addition, genotype and phylogenetic relationships were determined. The phylogenetical assessment was done by partial DNA sequencing of the P1 gene on isolates from 33 patients in the clinical study-group where sufficient DNA was available. The assessment was further extended to isolates from 13 MP-positive family members and 37 unselected MP positive patients from the two subsequent years and two different geographical locations. In total 83 strains were molecular characterized.

RESULTS

Mean MP loads were significantly higher in 24 hospitalized patients than in 21 outpatients (1600 vs. 170 genomic equivalents/microL, p = 0.009). This difference remained significant after adjustment for age and days between disease onset and sampling. Hospitalized patients also had higher C-reactive protein levels. Mean levels were 188 vs 20 mg/L (p = 0,001). The genotype assessment showed MP genotype 1 in 17 of the 33 sequenced strains from the clinical study-group, and type 2 in 16 of these patients. Within each genotype, sequence differences were minimal. No association between disease severity and MP genotype was observed. In the extended genotype assessment, MP1 was found in similar proportions. In family contacts it was found in 53% and among patients from the two subsequent years 53% and 40%.

CONCLUSIONS

A higher MP bacterial load in throat secretions at diagnosis was associated with more advanced respiratory disease in patients, but MP genotype did not influence disease severity. Both MP genotypes co-circulated during recent outbreaks in Sweden.

Development of multiple-locus variable-number tandem-repeat analysis for molecular typing of Mycoplasma pneumoniae

In this study we report on the development of a multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) method for the molecular typing of Mycoplasma pneumoniae. The genomic content of M. pneumoniae M129 was analyzed for VNTRs, and 5 of the 17 VNTRs identified were selected for use in an MLVA assay. The method was based on a GeneScan analysis of VNTR loci labeled with fluorescent dyes by multiplex PCR and capillary electrophoresis. This approach was applied to a collection of 265 isolates from various European countries, Japan, and Tunisia; and 26 distinct VNTR types were found. The VNTR assay was compared to the P1 adhesin PCR-restriction fragment length polymorphism (RFLP) typing method and showed a far better resolution than the P1 PCR-RFLP method. The discriminatory power of MLVA (Hunter-Gaston diversity index [HGDI], 0.915) for the 265 isolates was significantly higher than that of the P1 PCR-RFLP method (HGDI, 0.511). However, there was a correlation between the typing results obtained by MLVA and the P1 gene PCR-RFLP method. The potential value of MLVA of M. pneumoniae as an epidemiological tool is discussed, and the use of the VNTR markers in further investigations of the potential use of MLVA in outbreaks of M. pneumoniae infections is proposed.

Respiratory tract infections in a military recruit setting: a prospective cohort study

BACKGROUND

Acute respiratory tract infections (RTIs) are an important cause of morbidity in the military setting. Respiratory viruses are the most frequently implicated pathogens, especially adenovirus and respiratory syncytial virus. We performed this study to investigate the role of factors such as obesity, cigarette smoking, and educational level on the development of respiratory tract infections in a military recruit setting.

METHODS

A cohort of 472 military recruits was prospectively followed up for the basic training period of 3 weeks. Symptoms of infections were monitored during this period.

RESULTS

Eighty-four of 472 recruits (17.8%) were diagnosed with infection; 55 (65.5%) with upper RTI (mainly rhinitis), 23 (27.4%) with flu-like syndrome, and 6 (7.1%) with tonsillitis. There was no association between age, BMI, or smoking status and symptomatic RTI (p>0.05).

CONCLUSIONS

Occurrence of respiratory tract infections in military recruits is common, at least in some populations and settings. We did not find an association between risk factors such as BMI and smoking and symptomatic respiratory infection in our population, a result that may be associated with the limited power of this study.

Pediatric respiratory infections by Mycoplasma pneumoniae

Mycoplasma pneumoniae is one of the most common agents of community-acquired pneumonia in children and young adults. Although M. pneumoniae is a small bacterium that can reproduce in an artificial culture medium and is known to be sensitive to certain antibiotics in vitro as well as in vivo, the immunopathogenesis of M. pneumoniae in the human host is not fully understood. The epidemiologic characteristics, including periodic epidemics, and some clinical characteristics of M. pneumoniae are similar to those observed in systemic viral infections. Many experimental and clinical studies have suggested that the pathogenesis of lung injuries in M. pneumoniae infection is associated with a cell-mediated immune reaction, including high responsiveness to corticosteroid therapy. This paper presents an overview of M. pneumoniae infections, with emphasis on epidemiology, pathogenesis and treatment.

Detection of macrolide resistance in Mycoplasma pneumoniae by real-time PCR and high-resolution melt analysis

Mycoplasma pneumoniae is a significant cause of community-acquired pneumonia, which is often empirically treated with macrolides or azalides such as erythromycin or azithromycin. Recent studies have discovered the existence of macrolide-resistant strains within the population that have been mapped to mutations within the domain V region of the 23S rRNA gene. Currently, identification of these resistant strains relies on time-consuming and labor-intensive procedures such as restriction fragment length polymorphism, MIC studies, and sequence analysis. The current study reports two distinct real-time PCR assays that can detect the A2063G or A2064G base mutation (A2058G or A2059G by Escherichia coli numbering) conferring macrolide resistance. By subjecting the amplicon of the targeted domain V region of the 23S rRNA gene to a high-resolution melt curve analysis, macrolide-resistant strains can quickly be separated from susceptible strains. Utilizing this method, we screened 100 clinical isolates and found 5 strains to possess mutations conferring resistance. These findings were concordant with both sequencing and MIC data. This procedure was also used successfully to identify both susceptible and resistant genotypes in 23 patient specimens. These patient specimens tested positive for the presence of M. pneumoniae by a separate real-time PCR assay, although the bacteria could not be isolated by culture. This is the first report of a real-time PCR assay capable of detecting the dominant mutations that confer macrolide resistance on M. pneumoniae, and these assays may have utility in detecting resistant strains of other infectious agents. These assays may also allow for clinicians to select appropriate treatment options more rapidly and may provide a convenient method to conduct surveillance for genetic mutations conferring antibiotic resistance.

Evaluation of three real-time PCR assays for detection of Mycoplasma pneumoniae in an outbreak investigation

We compared the performances of three recently optimized real-time PCR assays derived from distinct genomic regions of Mycoplasma pneumoniae during an outbreak. Comprehensive evaluation established that a newly described toxin gene represents a superior target for detecting M. pneumoniae DNA in clinical specimens, although use of multiple targets may increase testing confidence.

[Pathogenesis and laboratory diagnosis of Mycoplasma pneumoniae infections]

Mycoplasma pneumoniae is the only mycoplasma clearly involved in respiratory tract infections in man. Implicated most often in tracheobronchitis, it is the second most frequent agent responsible for community-wide bacterial pneumonia, and in addition it probably causes asthma exacerbations. M. pneumoniae infection occurs endemically, with epidemic peaks every four to seven years, mostly in children above five years of age. The laboratory diagnosis of these infections, mainly by serology, is made only in severe cases because of the fastidious growth of this microorganism. M. pneumoniae can, however, be detected easily by molecular amplification techniques. Macrolides and related antibiotics are considered the treatment of choice for M. pneumoniae infection in both adults and children. Antibiotic sensitivity testing of M. pneumoniae is not done routinely because resistant isolates have only rarely been described, the results are delayed, and they have no immediate therapeutic consequence.

Mycoplasma pneumoniae-an emerging extra-pulmonary pathogen

Mycoplasma is a well-recognised pathogen that colonises mucosal surfaces of humans and animals. Mycoplasma pneumoniae infects the upper and lower respiratory tracts of children and adults, leading to a wide range of respiratory and non-respiratory clinical conditions. M. pneumoniae infection is frequently considered in the differential diagnosis of patients with respiratory illnesses, and is commonly managed empirically with macrolides and fluoroquinolones. This contrasts with patients who present with non-respiratory symptoms in the context of a recent or current unrecognised M. pneumoniae infection, for whom this pathogen is rarely considered in the initial differential diagnosis. This review considers the microbiological, epidemiological, pathogenic and clinical features of this frequent pathogen that need to be considered in the differential diagnosis of respiratory and non-respiratory infections.