Asthma in children: are chlamydia or mycoplasma involved?

Progress in diagnosis and treatment of difficult-to-treat asthma in children

At present, medications containing inhaled corticosteroids (ICS-containing) are the keystones of asthma treatment. The majority of asthmatic children can significantly improve clinical outcomes with little worsening by standardized inhaled glucocorticoid treatment, but there is still a small proportion of children who are unable to achieve good symptom control even after the maximum standardized treatment, known as 'children with difficult-to-treat asthma (DA)'. The high heterogeneity of DA makes therapy challenging and expensive, which poses a serious risk to children's health and makes it extremely difficult for clinical physicians to accurately identify and treat children with DA. This article reviews the definition, evaluation, and treatment of this asthma in order to provide a reference for optimal clinical decision-making.

The remaining unsolved problems for rational antibiotic therapy use in pediatric community-acquired pneumonia

INTRODUCTION

Despite availability of several official guidelines, not all the problems related to the most effective and safe use of antibiotics in children with community-acquired pneumonia (CAP) have been solved. Presently, too many children receive unneeded antibiotics or, when antibiotics are mandatory, the choice of the drug is not appropriate.

AREAS COVERED

In this paper, the authors discuss the remaining unsolved problems for rational antibiotic therapy use in pediatric community-acquired pneumonia and provide their expert perspectives.

EXPERT OPINION

Further improvement in pediatric CAP management could be derived from physician education on antibiotic use and a larger use, particularly in office practice, of point of care testing or new technologies (i.e. artificial intelligence) to define etiology of a lower respiratory infection. However, recommendations regarding the duration of antibiotic therapy vary largely because of the absence of reliable data on the optimal CAP treatment according to the bacterial etiology of the disease, its severity, and child characteristics. Available evidence seems to confirm that a short course of antibiotics, approximately 5 days, can be effective and lead to results not substantially different from those obtained with prolonged-course antibiotic therapy, at least in patients with mild to moderate disease.

Effect of childhood BMI on asthma: a systematic review and meta-analysis of case-control studies

Background

Asthma is a multifactorial syndrome that threatens the health of children. Body mass index (BMI) might be one of the potential factors but the evidence is controversial. The aim of this study is to perform a comprehensive meta-analysis to investigate the association between asthma and BMI.

Methods

Electronic databases including, Web of Science, Pubmed, Scopus, Science Direct, ProQuest, up to April 2017, were searched by two researchers independently. The keywords “asthma, body mass index, obesity, overweight, childhood and adolescence” were used. Random and fixed effects models were applied to obtain the overall odds ratios (ORs) and standardized mean difference (SMD). Heterogeneity between the studies was examined using I² and Cochrane Q statistics.

Results

After reviewing 2511 articles, 16 studies were eligible for meta-analysis according to inclusion/exclusion criteria. A meta-analysis from 11 case-control studies revealed OR of asthma and overweight as OR = 1.64; (95% Confidence Interval (CI): 1.13–2.38) and from 14 case-control studies, OR for asthma and obesity was OR = 1.92 (95% CI: 1.39–2.65), which indicated that risk of asthma in overweight and obese children and adolescence was significantly higher (1.64 and 1.92 times) than that of individuals with (p-value < 0.01 for underweight/normal weight in both cases). Furthermore, there was a significant relationship between asthma and BMI > 85 percentile according to SMD SMD = 0.21; (95%CI: 0.03–0.38; p-value = 0.021).

Conclusions

The results showed a significant relationship between BMI (obesity/overweight) and asthma among children and adolescents. It is important to study the confounding factors that affect the relationship between asthma and BMI in future epidemiological researches.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1093-z) contains supplementary material, which is available to authorized users.

Inflammation and infections in asthma

INTRODUCTION

Asthma is driven by an inflammatory response against normally harmless environmental inorganic and organic compounds in the respiratory tract. Immune responses to airborne pathogens such as viruses and bacteria may reduce the allergic responses but are also known to trigger asthma attacks and eventually lead to severe disease condition.

OBJECTIVE

To investigate the role of respiratory pathogens concerning the induction or protection against acute or chronic asthma manifestations.

METHODS

We included 131 articles for the final review according to their relevance with the subject.

RESULTS

There is apparently contradictory interaction of respiratory germs in the airways of asthmatics which may be protective on one angle but deleterious on the other.

CONCLUSION

The relationship between inflammation and remodeling and the pathogenic role of viral and bacterial infection in the airways of asthmatic patients is still highly debatable and incompletely understood.

Host factors and genetic susceptibility to infections due to intracellular bacteria and fastidious organisms

While genetic polymorphisms play a paramount role in tuberculosis (TB), less is known about their contribution to the severity of diseases caused by other intracellular bacteria and fastidious microorganisms. We searched electronic databases for observational studies reporting on host factors and genetic predisposition to infections caused by intracellular fastidious bacteria published up to 30 May 2014. The contribution of genetic polymorphisms was documented for TB. This includes genetic defects in the mononuclear phagocyte/T helper cell type 1 (Th1) pathway contributing to disseminated TB disease in children and genome-wide linkage analysis (GWAS) in reactivated pulmonary TB in adults. Similarly, experimental studies supported the role of host genetic factors in the clinical presentation of illnesses resulting from other fastidious intracellular bacteria. These include IL-6 -174G/C or low mannose-binding (MBL) polymorphisms, which are incriminated in chronic pulmonary conditions triggered by C. pneumoniae, type 2-like cytokine secretion polymorphisms, which are correlated with various clinical patterns of M. pneumoniae infections, and genetic variation in the NOD2 gene, which is an indicator of tubal pathology resulting from Chamydia trachomatis infections. Monocyte/macrophage migration and T lymphocyte recruitment defects are corroborated to ineffective granuloma formation observed among patients with chronic Q fever. Similar genetic polymorphisms have also been suggested for infections caused by T. whipplei although not confirmed yet. In conclusion, this review supports the paramount role of genetic factors in clinical presentations and severity of infections caused by intracellular fastidious bacteria. Genetic predisposition should be further explored through such as exome sequencing.

Chlamydia pneumoniae infection associated with uncontrolled asthma: a hospital based cross sectional study

OBJECTIVES

To evaluate the proportion of anti- Chlamydia pneumoniae (Cp) IgM positivity in patients with uncontrolled asthma and partly controlled childhood asthma and their clinical correlates.

METHODS

This was a hospital based cross sectional study. Children aged 1 to 12 y suffering from asthma were included after written informed parental consent. For diagnosis and classification of uncontrolled and partly controlled asthma, GINA guidelines 2009 were used. Anti-Cp IgM was tested by using an enzyme linked immunosorbent assay (ELISA) and value of antibody index ≥ 0.90 was considered positive. Data was collected on demographic, clinical and investigative variables including chest radiograph posterior-anterior view.

RESULTS

From August 2010 through August 2011 44 patients hospitalized with uncontrolled asthma in exacerbation and 45 patients with partly controlled asthma from ambulatory care settings were included. Anti-Cp IgM was positive in 25 % (n = 11/44) and 6.7 % (n = 3/45) patients with uncontrolled and partly controlled asthma, respectively (Odds ratio = 4.67, χ (2) = 5.64, 95 % CI 1.20-18.10, p 0.0 17). Among the patients of uncontrolled asthma, duration of hospital stay was longer in anti-Cp IgM positive patients (9 ± 2.19 vs. 7.19 ± 2.10 d, p 0.02).

CONCLUSIONS

Since anti-Cp IgM positivity was associated with age >5 y and radiological consolidation in uncontrolled asthma in exacerbation, specific treatment of Chlamydia pneumoniae must be actively considered.

Pneumocystis elicits a STAT6-dependent, strain-specific innate immune response and airway hyperresponsiveness

It is widely held that exposure to pathogens such as fungi can be an agent of comorbidity, such as exacerbation of asthma or chronic obstructive pulmonary disease. Although many studies have examined allergic responses to fungi and their effects on pulmonary function, the possible pathologic implications of the early innate responses to fungal pathogens have not been explored. We examined early responses to the atypical fungus Pneumocystis in two common strains of mice in terms of overall immunological response and related pathology, such as cell damage and airway hyperresponsiveness (AHR). We found a strong strain-specific response in BALB/c mice that included recruitment of neutrophils, NK, NKT, and CD4 T cells. This response was accompanied by elevated indicators of lung damage (bronchoalveolar lavage fluid albumin and LDH) and profound AHR. This early response was absent in C57BL/6 mice, although both strains exhibited a later response associated with the clearance of Pneumocystis. We found that this AHR could not be attributed exclusively to the presence of recruited neutrophils, NKT, NK, or CD4 cells or to the actions of IFN-γ or IL-4. However, in the absence of STAT6 signaling, AHR and inflammatory cell recruitment were virtually absent. Gene expression analysis indicated that this early response included activation of several transcription factors that could be involved in pulmonary remodeling. These results show that exposure to a fungus such as Pneumocystis can elicit pulmonary responses that may contribute to morbidity, even without prior sensitization, in the context of certain genetic backgrounds.

Antibody response to chlamydiae in children with asthma and respiratory illness

No relation between the occurrence of antibodies to chlamydial agents and asthma in children was found. In asthmatic children, the antibodies to Chlamydia trachomatis occurred in 3.1% and to Chlamydophila pneumoniae in 22.7%, whereas in a control group of children without asthma or other allergic disease in 2.3% and 24.0%, respectively. The occurrence of antibodies of IgA and IgG classes to C. pneumoniae was also very similar; its rise was age-dependent. On the other hand, in the group of children in a pre-school age with respiratory tract infection, anti-chlamydial antibodies were demonstrated significantly more often (18.5% of IgG antibodies to C. trachomatis, 20.0% of IgM antibodies to both C. trachomatis and C. pneumoniae) than in those suffering from other, non-respiratory illness (3.9% of the former and 5.9% of the latter antibodies). However, in these children, we did not succeed in detection of C. trachomatis in conjunctival and nasopharyngeal smears by PCR. Nevertheless, chlamydial agents (C. trachomatis in infants, C. pneumoniae in pre-school children) should be taken into consideration in a differential diagnosis of respiratory tract inflammation.

Corticosteroids for pneumonia

BACKGROUND

Pneumonia is an acute inflammation of the lungs and treatments differ depending on the type and severity. Corticosteroids can influence immune regulation, carbohydrate metabolism, protein catabolism, electrolyte balance and stress response. However, the benefits of corticosteroids for patients with pneumonia remains unclear.

OBJECTIVES

To assess the efficacy and safety of corticosteroids in the treatment of pneumonia.

SEARCH STRATEGY

We searched Cochrane Central Register of Controlled Clinical Trials (CENTRAL) (The Cochrane Library 2010, Issue 11) which contains the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to December week 4, 2010), EMBASE (1974 to December 2010), the China National Knowledge Infrastructure (CNKI) (1978 to December 2010) and VIP (1986 to December 2010).

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing the effectiveness of corticosteroids for pneumonia.

DATA COLLECTION AND ANALYSIS

Three review authors selected studies. We telephoned the trial authors to confirm the randomisation method used. We extracted and analysed the methodological details and data from the included studies.

MAIN RESULTS

We included six studies including 437 participants in the review. Two studies were of high methodological quality and three were of poor quality. All studies involved small numbers of participants. Two small studies provided weak evidence that corticosteroids did not significantly reduce mortality (Peto odds ratio (OR) 0.26; 95% CI 0.05 to 1.37), but accelerated the resolution of symptoms or time to clinical stability, and decreased the rate of relapse of the disease. Steroids can improve the oxygenation and reduce the need for mechanical ventilation in severe pneumonia. There was no significant difference between treatment groups with regards to the time to discharge from the intensive care unit (ICU). There were insufficient data to report the time to pneumonia resolution and admission to ICU. Typical adverse events associated with corticosteroid therapy were infrequent.

AUTHORS' CONCLUSIONS

In most patients with pneumonia, corticosteroids are generally beneficial for accelerating the time to resolution of symptoms. However, evidence from the included studies was not strong enough to make any recommendations.

Bacterial infections and pediatric asthma

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis seem to have no role in asthma in children. Mycoplasma pneumoniae and Chlamydophila pneumoniae can induce wheezing and cause asthma exacerbations in children, and chronic Chlamydophila infections may even participate in asthma pathogenesis. However, studies have failed to show any benefits from antibiotics for incipient or stable pediatric asthma, as well as for asthma exacerbations in children. Exposure to antibiotics in infancy has been an independent risk factor of later asthma in many studies. A recent study applying molecular biology methods to lower airway samples provided preliminary evidence that lower airways are not sterile but have their own protective microbiota, which can be disturbed in lung diseases like asthma.

Update on infection and antibiotics in asthma

Asthma pathogenesis seems to be a result of a complex mixture of genetic and environmental influences. There is evidence that Mycoplasma pneumoniae and Chlamydophila pneumoniae (formerly known as Chlamydia pneumoniae) play a role in promoting airway inflammation that could contribute to the onset and clinical course of asthma. Evidence also indicates that when antimicrobial therapy can eradicate or suppress these organisms, it may be possible to alter the course of the disease. Certain macrolide antibiotics have been shown to improve control of asthma symptoms and lung function in patients diagnosed with acute C. pneumoniae or M. pneumoniae infection. Positive polymerase chain reaction studies for C. pneumoniae or M. pneumoniae are needed to select asthma patients for chronic treatment. Macrolide antibiotics may also have independent anti-inflammatory activity that may be useful in the management of asthma and other inflammatory diseases.

Management of acute asthma exacerbations in children

The management of acute asthma exacerbations in children remains controversial and the latest guidelines (Expert Panel Report [EPR]-3 2007 and the Global Initiative of Asthma 2008) leave several questions unanswered. This review summarizes the most up-to-date information on the practical prevention and control of asthma attacks in children, and describes the 20-year experience of a major tertiary asthma clinic with the administration of inhaled corticosteroids in this setting. The following subjects are discussed: the knowledge and skills required by the parents regarding asthma and its treatment, how to prevent or minimize exacerbations in asthmatic children, the drugs used in the treatment of exacerbations and their order of administration, and the steps to follow after discharge from the emergency department or after a severe asthma exacerbation. The efficacy of inhaled corticosteroids in the management of acute asthma exacerbations in children, both at home and in the emergency department, is discussed in detail. The goal of asthma-management programs is to arm parents with the skills and knowledge to prevent, detect and successfully control most exacerbations of asthma in children at home.

Increased serum interleukin-5 and vascular endothelial growth factor in children with acute mycoplasma pneumonia and wheeze

Acute mycoplasma pneumonia may be accompanied by wheeze in some children considered not to have asthma. The aim of the present study was to evaluate cytokine secretion in children with acute mycoplasma pneumonia and wheeze. We studied 58 patients with mycoplasma pneumonia (12 with wheeze, Group 1; 46 without wheeze, Group 2) and 36 patients of non-mycoplasma pneumonia (Group 3). Serum levels of interleukin (IL)-4, IL-5, interferon (IFN)-gamma, and vascular endothelial growth factor (VEGF) were measured using an enzyme-linked immunosorbent assay kits. The mean +/- SD IL-5 level of Group 1 was 97.1 +/- 73.0 pg/ml, which was significantly higher than that of Group 2 (28.2 +/- 32.2 pg/ml) and that of Group 3 (35.7 +/- 42.0 pg/ml). The mean +/- SD VEGF level of Group 1 was 687.5 +/- 385.8 pg/ml, which was significantly higher than that of Group 2 (310.0 +/- 251.9 pg/ml) and that of Group 3 (402.3 +/- 279.5 pg/ml). No significant differences in serum levels of IL-4, IFN-gamma, and IgE were observed between the groups. Our results show that children with mycoplasma pneumonia and wheeze have significantly higher serum levels of IL-5 and VEGF. These increased immune responses may be associated with the pathophysiological mechanisms by which the Mycoplasma pneumoniae contribute to the development of wheeze during acute mycoplasma pneumonia.

Role of respiratory pathogens in infants hospitalized for a first episode of wheezing and their impact on recurrences

In order to evaluate the infectious agents associated with the first episode of severe acute wheezing in otherwise healthy infants and to define the role of each of them in recurrences, 85 patients in Italy, aged <12 months, hospitalized because of a first acute episode of wheezing, were prospectively enrolled between 1 October 2005 and 31 March 2006. Upon enrollment, nasopharyngeal swabs were collected for the real-time PCR detection of respiratory syncytial virus (RSV) types A and B, influenza virus types A and B, adenovirus, parainfluenza viruses types 1, 2, 3 and 4, rhinovirus, human metapneumovirus, human coronavirus types 229E, OC43, NL63, and HKU1, bocavirus, enterovirus, and paraechovirus; nasopharyngeal aspirates were also obtained to detect atypical bacteria. At least one infectious agent was identified in 76 children (89.4%). RSV was the most frequently detected pathogen and its prevalence was significantly higher than that of the other pathogens in both age groups, and significantly higher in the children aged 3-12 months than in those aged <3 months. Only the children with RSV infection experienced recurrent wheezing. Viral load was significantly higher in children with than in those without recurrent wheezing. This study shows that RSV is the main reason for hospitalization during the first wheezing episode in infants, and that it appears to be the only pathogen associated with a high frequency of recurrences. A high viral load seems to be strictly related to the likelihood of recurrence.

Asthmatic persons are prone to the persistence of Chlamydia pneumoniae antibodies

Acute Chlamydia pneumoniae infection may initiate asthma or worsen asthmatic symptoms. In crowded conditions, such as military service, young men are susceptible to respiratory infections, including C. pneumoniae. We recruited 127 asthmatic and 391 nonasthmatic military conscripts, followed up their respiratory tract infections and the kinetics of serum C. pneumoniae antibodies, and assessed the association between C. pneumoniae and asthma during 6 months of military service in 2 intake groups. During the 6-month period, in the July intake group, IgG antibody prevalence decreased from 60.3% to 43.8% in asthmatic and from 55.6% to 22.6% in nonasthmatic conscripts. In the January intake group, IgG antibody prevalence increased from 38.3% to 48.4% in asthmatic and from 37.2% to 43% in nonasthmatic recruits. IgG and IgA antibodies persisted more often in the asthmatic groups. In conclusion, the prevalence of IgG antibodies showed seasonal variation. Military recruits seem to be most vulnerable to C. pneumoniae infections during the period from January to June. The antibody titer changes were more rapid than previously thought.

Absence of tooth staining with doxycycline treatment in young children

The aim of the study was to determine if doxycycline causes tooth staining in young children. A dentist examined 31 randomized children who had been treated with doxycycline and 30 children who had not received doxycycline. Mean age of the children was 10.4 -/+ 2.1 years. Mean age at receipt of the first doxycycline treatment was 4.1 -/+ 1.6 years, and mean number of doxycycline courses was 2.0 -/+ 1.3. No tooth staining was detected by the dentist in any of the children in either group. These findings indicate that treatment with doxycycline in children aged 2 to 8 years is not associated with tooth staining.

Differential effects of Chlamydia pneumoniae infection on cytokine levels in human T lymphocyte- and monocyte-derived cell cultures

Continuous cultures of human lymphocyte- and monocyte-derived cell lines were examined for levels of immunoregulatory cytokines important in resistance to the intracellular opportunistic bacterium Chlamydia pneumoniae (Cp), a ubiquitous pathogen widely disseminated in the population and hypothesized to be involved in chronic inflammatory diseases such as atherosclerosis and neurological diseases like multiple sclerosis and Alzheimer's disease. The results of this study showed that the continuous human T lymphocyte cell line MOLT-4 and the continuous monocytic cell line THP-1 were readily infected by Cp in vitro as shown by immunofluorescence microscopy for Cp lipopolysaccharide (LPS). The 16S rRNA expression determined by real-time RT-PCR increased rapidly after infection of either cell line with these bacteria. The THP-1 cells infected with Cp showed increased levels of the immunoregulatory cytokine IL-12 and also of TNFalpha and IL-10 compared to cultures stimulated with heat-killed Cp (KCp) or Escherichia coli LPS as a control. Stimulation of MOLT-4 cells with KCp or E. coli LPS also induced the Th1 cytokines IFNgamma and IL-12 and the Th2 cytokine IL-10, but infection with viable Cp induced higher Th1 cytokine levels. These results suggest that Cp infection induces a predominant Th1 cytokine profile by T cells, in addition to induction of TNFalpha by monocytes/macrophages. Such effects are likely involved in antibacterial immunity against Cp infection.

Azithromycin has a direct relaxant effect on precontracted airway smooth muscle

Macrolides have been proven to have beneficial bacteriostatic and anti-inflammatory properties, but very little is known about the potential value of their bronchodilatory effect. Therefore, in the present study we investigated the effect of azithromycin on contractile responses of isolated rabbit tracheal strips to carbachol or KCl. Azithromycin has a relaxant, concentration-dependent effect on tracheal strips precontracted with carbachol (300 nM), significant from the concentration of 1 muM. The mechanical removal of epithelium did not alter the effect of azithromycin. Azithromycin (100 microM) also relaxed tracheal strips precontracted with KCl (80 mM) even in the presence of atropine (100 microM). Moreover, azithromycin (100 microM) decreased contractions induced by 300 nM and 10 microM carbachol to 55.4% and 80.5% of initial contraction, respectively. The relaxant effect of azithromycin persisted in both calcium free solution and in the presence of the calcium channel antagonist, verapamil. The relaxant effect of azithromycin was not altered by the pre-treatment of preparations with the inhibitors of Ca(2+)-ATPase (cyclopiazonic acid), Na(+)-K(+) ATPase (ouabain), Rho-associated kinase [(R)-(+)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide dihydrochloride] (Y-27632) or the non-specific cAMP and cGMP phosphodiesterases inhibitor 3-isobutyl-1-methyl-2,6(1H,3H)-purinedione (IBMX). These results suggest that azithromycin has a concentration-dependent, epithelium-independent, direct relaxant effect on precontracted tracheal strips that is not mediated via inhibition of Ca(2+) influx or Ca(2+) release from intracellular stores. Also, it is not due to alteration of the function of Na(+)-K(+) ATPase and does not depend on the formation of cAMP/cGMP or the Rho/Rho-activated kinase pathway.

The relationship between serum endothelin (ET)-1 and wheezing status in the children with Mycoplasma pneumoniae pneumonia

Although Mycoplasma pneumoniae infection is known to be associated with acute wheezing and the exacerbation of asthma, the mechanism by which this pathogen contributes to the development of wheeze-related symptoms is not fully understood. The aim of our study was to examine serum endothelin (ET)-1 and other cytokines in acute M. pneumoniae pneumonia and investigate if there is any relation between these inflammatory mediators and the occurrence of wheezing. We studied 53 patients, aged 3-13 yr, who admitted with pneumonia. These patients were divided into three groups: M. pneumoniae pneumonia with wheeze (n=23) and without wheeze (n=19), and the patients without the evidence of M. pneumoniae infection (n=11). Age-matched controls (n=10) were also studied. The serum concentrations of ET-1, interleukin (IL)-5 and IL-18 were measured using ELISA kits in patient groups and controls. The patients with M. pneumoniae pneumonia had significantly higher serum ET-1 than those without evidence of M. pneumoniae infection. In the presence of M. pneumoniae pneumonia, ET-1 concentrations were significantly higher in the patients with wheeze than those without wheeze. IL-5 and IL-18 in each patient group were higher compared to controls. However, no significant between-group difference was observed. Total serum IgE levels were significantly higher in the patients with M. pneumoniae pneumonia and wheeze than in those without wheeze. A positive correlation was observed between serum ET-1 and total IgE in the patients with M. pneumoniae pneumonia and wheeze. Our results may suggest a role of ET-1 in the occurrence of acute wheezing or exacerbation of asthma associated with M. pneumoniae pneumonia.

The atypical pneumonias: clinical diagnosis and importance

The most common atypical pneumonias are caused by three zoonotic pathogens, Chlamydia psittaci (psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q fever), and three nonzoonotic pathogens, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella. These atypical agents, unlike the typical pathogens, often cause extrapulmonary manifestations. Atypical CAPs are systemic infectious diseases with a pulmonary component and may be differentiated clinically from typical CAPs by the pattern of extrapulmonary organ involvement which is characteristic for each atypical CAP. Zoonotic pneumonias may be eliminated from diagnostic consideration with a negative contact history. The commonest clinical problem is to differentiate legionnaire's disease from typical CAP as well as from C. pneumoniae or M. pneumonia infection. Legionella is the most important atypical pathogen in terms of severity. It may be clinically differentiated from typical CAP and other atypical pathogens by the use of a weighted point system of syndromic diagnosis based on the characteristic pattern of extrapulmonary features. Because legionnaire's disease often presents as severe CAP, a presumptive diagnosis of Legionella should prompt specific testing and empirical anti-Legionella therapy such as the Winthrop-University Hospital Infectious Disease Division's weighted point score system. Most atypical pathogens are difficult or dangerous to isolate and a definitive laboratory diagnosis is usually based on indirect, i.e., direct flourescent antibody (DFA), indirect flourescent antibody (IFA). Atypical CAP is virtually always monomicrobial; increased IFA IgG tests indicate past exposure and not concurrent infection. Anti-Legionella antibiotics include macrolides, doxycycline, rifampin, quinolones, and telithromycin. The drugs with the highest level of anti-Legionella activity are quinolones and telithromycin. Therapy is usually continued for 2 weeks if potent anti-Legionella drugs are used. In adults, M. pneumoniae and C. pneumoniae may exacerbate or cause asthma. The importance of the atypical pneumonias is not related to their frequency (approximately 15% of CAPs), but to difficulties in their diagnosis, and their nonresponsiveness to beta-lactam therapy. Because of the potential role of C. pneumoniae in coronary artery disease and multiple sclerosis (MS), and the role of M. pneumoniae and C. pneumoniae in causing or exacerbating asthma, atypical CAPs also have public health importance.

Antimicrobial therapy in childhood asthma and wheezing

There is an increasing number of viral and bacterial pathogens suspected of contributing to asthma pathogenesis in childhood, making it more difficult for the practitioner to make specific therapy decisions. This review discusses the role of viruses, e.g. respiratory syncytial virus, human metapneumovirus, influenza viruses and rhinoviruses, as well as the role of the atypical bacteria Chlamydophila pneumoniae and Mycoplasma pneumoniae, as contributors to childhood asthma. Diagnosis, prevention, and therapy are discussed, including a summary of drugs, i.e. macrolide antibacterials, antivirals, and vaccine regimens already available, or at least in clinical trials. For the practitioner dealing with patients every day, drug regimens are assigned to the individual pathogens and an algorithm for the management of atypical infections in patients with asthma or recurrent wheezing is presented.

The bronchial lavage of pediatric patients with asthma contains infectious Chlamydia

There has been a worldwide increase in the incidence of asthma, and the disease has greatly impacted the public health care system. Chlamydia pneumoniae has been reported as a possible contributing factor in asthma. The organism has been detected by polymerase chain reaction (PCR) in bronchial tissue, but there has been no direct evidence of viability. To determine the frequency of viable Chlamydia in children, blood and bronchoalveolar lavage were collected from 70 pediatric patients undergoing flexible fiberoptic bronchoscopy. Forty-two of these patients had asthma, whereas the remaining patients had various respiratory disorders. Fifty-four percent (38) of the bronchoalveolar lavage samples were PCR-positive for Chlamydia, and 31% (22) of the PCR-positive samples were positive when cultured on macrophages. Twenty-eight samples (40%) and 14 samples (20%) of the PCR- and culture-positive samples, respectively, were from patients with asthma. Culture of the blood samples revealed that 24 (34.3%) of 70 were positive for Chlamydia compared with 8 (11%) of 70 matched nonrespiratory control subjects (p < 0.01); 17 (24%) of the positive blood cultures from the respiratory group were from patients with asthma. Elevation of total IgE was strongly associated with lavage culture positivity for Chlamydia. We therefore conclude that viable Chlamydia pneumoniae organisms are frequently present in the lung lavage fluid from this cohort of predominantly asthmatic pediatric patients.

Cytokines in Mycoplasma pneumoniae infections

Mycoplasma pneumoniae (M. pneumoniae) is one of the smallest free-living bacteria known. Along with other unique characteristics of this genus, it lacks the typical peptidoglycan cell wall of most eubacteria. Best known for causing tracheobronchitis and atypical pneumonia in humans, this pathogen also causes a number of extrapulmonary syndromes such as meningitis/encephalitis and arthritis. Recent studies also suggest that infection may be associated with chronic conditions such as asthma. Although the mechanisms of M. pneumoniae pathogenesis remain to be elucidated, one important component of M. pneumoniae infections is the induction of proinflammatory and other cytokines in both acute and chronic conditions. In this review, we survey the induction of cytokines by M. pneumoniae in different model systems, and we discuss the possible role of induced cytokines in M. pneumoniae pathogenesis.

Antibiotics in asthma

Asthma pathogenesis appears to be a result of a complex mixture of genetic and environmental influences. There is evidence that Mycoplasma pneumoniae and Chlamydia pneumoniae play a role in promoting airway inflammation that could contribute to the onset and clinical course of asthma. If antimicrobial therapy can eradicate these organisms, it might be possible to alter the course of the disease. Although antibiotics have no role in the routine management of acute exacerbations of asthma, certain macrolide antibiotics have been shown to have anti-inflammatory activity. Part of this effect is due to their known inhibition of steroid and theophylline metabolism, but through a myriad of mechanisms that are incompletely understood, macrolide antibiotics have additional broad anti-inflammatory properties that might prove useful in the management of asthma and other inflammatory diseases.

Chlamydia pneumoniae and newly diagnosed asthma: a case-control study in 1 to 6-year-old children

OBJECTIVE

The aim of the study was to evaluate the association between antibodies to Chlamydia pneumoniae and the onset of asthma in children.

METHODOLOGY

In 1996-2000, 122 children aged 1-6 years, who were treated for new asthma as inpatients or outpatients in our hospital, were recruited. For each patient, two controls, matched by age, sex and municipality, were randomly selected from the same population. In 2000, 104 serum samples were available from patients (85%) and 120 from controls (49%) for microimmunofluorescence (MIF) assay for C. pneumoniae and C. trachomatis antibodies, and for enzyme immunoassay (EIA) for C. pneumoniae antibodies.

RESULTS

In EIA, the median IgG concentrations were 20 EIU (EIA units) in the patients, and 16 EIU in the controls. IgG was positive (> 30 EIU) in 37 (36%) patients and in 36 (31%) controls. IgA was positive (> 12 EIU) in four (4%) patients and in eight (7%) controls. In MIF, four (4%) patients and seven (6%) controls were IgG positive, and seven were also IgA positive. IgM antibodies were detected in four children by EIA, and in none by MIF.

CONCLUSION

IgG antibodies to C. pneumoniae, though common in 1 to 6-year-old children as detected by EIA, did not differ between newly diagnosed asthma patients and controls in this case-control study.

Role of atypical bacterial infection of the lung in predisposition/protection of asthma

Asthma is a common inflammatory disease of the airways that results in airway narrowing and wheezing. Allergic asthma is characterised by a T-helper cell-type (Th) 2 response, immunoglobulin (Ig) E production, and eosinophilic influx into the airways. Recently, many clinical studies have implicated Mycoplasma pneumoniae and Chlamydia pneumoniae in the development and exacerbation of both chronic and acute asthma. It is widely accepted that M. pneumoniae and C. pneumoniae infections require Th1 immunity for clearance; therefore, according to the hygiene hypothesis, these infections should be protective against asthma. Here, we review the clinical evidence for the association and mechanisms of predisposition to and protection against asthma by these infections. We will examine the following question: Is it the absence of infection or the age of the individual on infection that confers susceptibility or resistance to asthma and does this vary between normal and predisposed individuals? We put forward a hypothesis of the effects of these infections on the development and prevention of asthma and how novel preventative and treatment strategies involving these microbes may be targeted against asthma.

Chlamydia pneumoniae infections in asthma: clinical implications

Chlamydia pneumoniae is an intracellular pathogen that has been suggested to play a role in the pathology of asthma. However, so far none of the studies have provided clear evidence for a causative role of C. pneumoniae infections in asthma, although there is little doubt that chronic C. pneumoniae infection does aggravate asthma and should be treated. The diagnosis of C. pneumoniae infection is still a matter of concern for it is dependent on trained skilled personnel and can vary significantly between different diagnostic laboratories. This fact is also one of the major problems encountered when comparing epidemiological studies investigating the possible role of C. pneumoniae infections and their impact on the pathogenesis of other diseases. With regard to therapy, long-term treatment with macrolides is the best available method to eradicate C. pneumoniae. Successful therapy for C. pneumoniae, however, can also be complicated by the high possibility of de novo infection as epidemiological studies have shown that the prevalence of antibodies to C. pneumoniae increases with age in all populations studied. In the northern hemisphere the prevalence of C. pneumoniae is also affected by seasonal conditions. It is too early to draw any conclusions from the equatorial belt countries. The available data on C. pneumoniae in tropical countries indicate a much faster infection rate during early adulthood with 100% serological prevalence at an age greater than 25 years. This data, if confirmed, would argue against C. pneumoniae causing asthma since the asthma prevalence in those countries does not increase in a parallel pattern. An alternative interpretation of most studies could be that the increased rate of C. pneumoniae infections in patients with asthma results from a modified susceptibility towards the microorganism, due to yet unknown changes of the host cell's physiology. It should be kept in mind that increased prevalence of C. pneumoniae infection is not restricted to asthma. Further studies are needed to understand the role of C. pneumoniae, especially of chronic infection, in the pathogenesis of inflammatory diseases with a specific focus on the effect that the microorganism triggers in the infected host cell. Only when we understand what C. pneumoniae does to its host cell will we be able to judge its impact on the overall status of an affected patient, and this knowledge will help us to develop a successful therapy.

Cytokine secretion in children with acute Mycoplasma pneumoniae infection and wheeze

The aim of this study was to evaluate cytokine secretion in children with acute Mycoplasma pneumoniae infection and wheeze. We studied 25 patients aged 2-14 years with an acute episode of wheezing (15 with acute M. pneumoniae infection) and 16 healthy controls of similar gender and age (8 with laboratory evidence of asymptomatic acute M. pneumoniae infection). Serum interleukin (IL)-2, interferon (IFN)-gamma, IL-4, and IL-5 concentrations were measured in samples obtained at enrollment, using enzyme-linked immunosorbent assay kits. In the presence of wheezing, IL-5 concentrations were significantly higher in subjects with acute M. pneumoniae infection (33.415 +/- 22.138 pg/mL) than in those without such infection (2.320 +/- 1.846 pg/mL, P < 0.0001). The children with acute M. pneumoniae infection and wheeze had higher IL-5 concentrations (33.415+/-22.138 pg/mL) than those with asymptomatic acute infection and without wheeze (1.740 +/- 2.299 pg/mL, P < 0.0001). No significant between-group differences were observed in terms of IL-2, IFN-gamma, or IL-4 levels, or the prevalence of atopy. Our results show that children with wheezing and acute M. pneumoniae infection have a specific cytokine profile characterized by a significant increase in serum levels of IL-5. This immune response may be important for understanding the pathophysiological mechanisms by which this pathogen contributes to the development of wheeze-related symptoms, and for identifying new treatment strategies.

Mycoplasma pneumoniae and Chlamydia pneumoniae cause lower respiratory tract disease in paediatric patients

New studies suggest that Mycoplasma pneumoniae and Chlamydia pneumoniae play a more significant role as causes of lower respiratory tract infections in childhood than was previously thought. In particular, the incidence of infections caused by these pathogens is high in children aged less than 5 years, the infections themselves seem to be a possible cause of wheezing, and may present a more complicated course when not treated with adequate antimicrobial agents. However, despite the increasing pathogenic significance of M. pneumoniae and C. pneumoniae, progress in fighting them is hampered by the lack of rapid and standardized diagnostic methods. This not only makes it practically impossible for practitioners to make a specific microbiological diagnosis, but has also had an adverse effect on treatment trials and has generated some questionable results. Carefully randomized and controlled trials are clearly needed to examine the effectiveness of different antibiotics against M. pneumoniae or C. pneumoniae and the optimal duration of therapy in various patient populations.

Emerging role of Mycoplasma pneumoniae and Chlamydia pneumoniae in paediatric respiratory-tract infections

Increased use of specialised diagnostic techniques over the past 10 years has allowed considerable new information to be obtained concerning Mycoplasma pneumoniae and Chlamydia pneumoniae infections. In children, these pathogens seem to have a more important role in causing respiratory-tract infections than previously thought; they have been associated with wheezing, and they are also frequent in children aged under 5 years. Contrary to original belief, no clinical, laboratory, or radiological findings seem to be unique to M. pneumoniae or C. pneumoniae; furthermore, there is no rapid and cost-effective diagnostic test capable of identifying these pathogens. Appropriate antimicrobial treatment of the infections they cause is needed to reduce the recurrent episodes of wheezing and other respiratory symptoms, to decrease morbidity, and to avoid the spread of the pathogens. However, a number of therapeutic issues remain unsolved.