Reduced lung diffusion capacity after Mycoplasma pneumoniae pneumonia

Primary symptoms of severe mycoplasma pneumoniae pneumonia with acute abdomen, scrotal swelling and pain, and fever: A case report

BACKGROUND INTRODUCTION

In recent years, there has been an increase in the number of patients diagnosed with pediatric diseases who have severe Mycoplasma pneumoniae (MP) pneumonia, and there has also been an increased attention to serious extrapulmonary complications. However, cases with abdominal pain, acute abdomen, scrotal swelling and pain, and fever as the primary symptoms have been rarely reported.

CASE DESCRIPTION

A 3-years-and-8-months-old male patient diagnosed with pediatric disease was reported with abdominal pain, scrotal swelling and pain, and fever as the primary symptoms in the present study. No respiratory symptoms were observed throughout the disease. Through computed tomography (CT) scanning, the patient was diagnosed with severe MP pneumonia based on the symptoms of abdominal pain and fever, as well as pulmonary infection, pleural effusion, and retroperitoneal exudation. Laboratory tests supported the diagnosis of MP infection, and the diagnosis was confirmed by severe MP pneumonia. The therapeutic effects of azithromycin were poor, and the symptoms were quickly alleviated with the addition of gamma globulin and methylprednisolone. After discharge, azithromycin sequential therapy was administered. The chest CT was normal at the follow-up 1-month later.

CONCLUSION

Severe MP pneumonia in patients with pediatric diseases may include abdominal pain, scrotal swelling and pain, and fever as the primary symptoms. Care should be taken to avoid missed diagnoses and misdiagnoses in clinical practice.

Mycoplasma pneumoniae in pediatric patients: Do macrolide-resistance and/or delayed treatment matter?

BACKGROUND

Mycoplasma pneumoniae is a common pathogen for pneumonia in children, especially in the post-pneumococcal conjugate vaccination era. Though self-limited disease was found in the majority of the patients, severe diseases occurred occasionally. The emergence of macrolide resistance was reported worldwide. It is important to delineate whether macrolide resistance or delayed treatment affects outcome.

METHODS

We retrospectively collected pediatric patients with M. pneumoniae infection confirmed by positive PCR in a tertiary medical center in Taiwan from 2010 to 2017. Patients' clinical characteristics, bacterial load, macrolide resistance and treatment outcome were analyzed.

RESULTS

Among 471 children with positive M. pneumoniae PCR, 95% were diagnosed with pneumonia. Seventeen percent of patients had extrapulmonary complications, and 1.5% had respiratory failure. Delayed treatment was associated with prolonged fever after appropriate treatment, fulminant disease, and extrapulmonary manifestations (p < 0.05). The mean rate of macrolide resistance was 24% and macrolide resistance was related to longer febrile duration, longer hospital stay, lung consolidation and impaired liver function tests (P < 0.05).

CONCLUSIONS

Macrolide resistance was fairly common and might lead to delayed appropriate antibiotic treatment. Delayed appropriate antimicrobial treatment, no matter macrolide resistance or not, was associated with more severe and/or prolonged diseases. Early diagnosis of M. pneumoniae as well as the awareness of macrolide resistance make early effective antibiotic treatment possible and may improve clinical outcomes.

Clinical and histologic features of Mycoplasma pneumoniae-related erythema multiforme: A single-center series of 33 cases compared with 100 cases induced by other causes

BACKGROUND

Mycoplasma pneumoniae infection has been documented in erythema multiforme (EM) and Stevens-Johnson syndrome-toxic epidermal necrosis (SJS-TEN). Clinical aspects of M pneumoniae-related EM have been poorly described in the literature.

OBJECTIVE

To highlight differences between M pneumoniae EM and non-M pneumoniae EM.

METHODS

This single-center, retrospective cohort study included all patients admitted to our dermatology department for EM during 2000-2015. We compared epidemiologic, clinical, and histologic data and follow-up for M pneumoniae EM and non-M pneumoniae EM cases.

RESULTS

Thirty-three patients with M pneumoniae EM were compared with 100 patients with non-M pneumoniae EM. Disease onset in winter was more frequent with M pneumoniae EM (P = .003). Acrally distributed lesions (32% vs 88%, P < .0001) and typical targets (45% vs 74%, P = .01) were less common in M pneumoniae EM than non-M pneumoniae EM. Multiple (≥2) mucousal membrane involvement was more frequent in M pneumoniae EM than non-M pneumoniae EM (97% vs 60%; P < .0001), as were mucosal and respiratory tract sequelae (P < .05). The mean hospital stay was longer with M pneumoniae EM patients: 9.5 days versus 5.1 days (P = .0002). A TEN-like pattern was observed in all 14 (100%) M pneumoniae EM skin biopsies versus 10 of 27 (48%) non-M pneumoniae EM biopsies (P < .001).

LIMITATIONS

The retrospective design.

CONCLUSION

M pneumoniae EM has a distinctive presentation compared with non-M pneumoniae EM, with more diffuse and atypical targets, more mucositis and respiratory tract sequelae. Histologic data show a TEN-like pattern in all M pneumoniae EM skin samples.

Effects of low-dose clarithromycin added to fluticasone on inflammatory markers and pulmonary function among children with asthma: A randomized clinical trial

BACKGROUND

Macrolides exert anti-inflammatory and immunomodulatory effects beyond their purely antibacterial action, as demonstrated by several bronchial inflammatory disorders, including asthma.

METHODS

Fifty-eight children with newly diagnosed mild persistent asthma were selected by using the Global Initiative for Asthma guidelines and were randomly divided into the study (group I) (n = 36) and control (group II) (n = 22) groups. Mycoplasma pneumonia-specific immunoglobulin G and -specific immunoglobulin M antibody levels of each participant were measured by enzyme-linked immunosorbent assay. Clarithromycin 5 mg/kg daily and placebo were given to groups I and II, respectively, for 4 weeks. All of the children had maintenance inhaled corticosteroid (fluticasone propionate, one puff twice [50 μg/puff] daily). Forced expiratory volume in 1 second, forced expiratory flow at 25-75% of the pulmonary volume, exhaled nitric oxide value, total IgE level, absolute eosinophil count, and eosinophilic cation protein value were measured at baseline and at the end of the treatment.

RESULTS

There are significantly increased forced expiratory volume in 1 second and forced expiratory flow at 25-75% of the pulmonary volume levels and decreased exhaled nitric oxide values after the 4-week clarithromycin treatment. The study group also had a decreased peripheral blood absolute eosinophil count and eosinophilic cation protein level, but not for the total IgE level, after the treatment.

CONCLUSION

Four weeks of sub-antimicrobial doses of clarithromycin may improve pulmonary function and decrease eosinophilic inflammation in children with asthma.

Is asthma an infectious disease? New evidence

The pathogenetic mechanisms leading to asthma are likely to be diverse, influenced by multiple genetic polymorphisms as well as elements of the environment. Recent data on the microbiome of the airway have revealed intriguing differences between the number and diversity of microbial populations in healthy persons and asthmatics. There is convincing evidence that early viral infections, particularly with human rhinovirus and respiratory syncytial virus, are often associated with the development of chronic asthma and with exacerbations. Recent studies suggest that two unrelated types of atypical bacteria, Mycoplasma pneumoniae (Mpn) and Chlamydia pneumoniae, are present in the airways of a substantial proportion of the population, bringing up the possibility that the persistent presence of the organism may contribute to the asthmatic phenotype in a subset of patients. This review will examine the current data regarding a possible role for infection in chronic asthma with a particular focus on atypical bacterial infections.

Does a parent-reported history of pneumonia increase the likelihood of respiratory symptoms needing therapy in asthmatic children and adolescents?

BACKGROUND

Asthmatic children and adolescents attending outpatient clinics often have a history of pneumonia. Whether respiratory symptoms, lung function, and airway inflammation differ in asthmatic patients with and without a history of pneumonia remains controversial.

AIMS

To compare clinical, lung functional, and inflammatory variables in asthmatic outpatients with and without a history of pneumonia. Methods. In 190 asthmatic outpatients, aged 6-18 years, we assessed respiratory symptoms, lung function (flows, volumes, and pulmonary diffusion capacity, DLCO/VA), and atopic-airway inflammation as measured by the fractional concentration of exhaled nitric oxide (FE(NO)). A previous medical and radiological diagnosis of pneumonia was defined as "recurrent pneumonia" if subjects had at least three pneumonia episodes or two episodes within a year.

RESULTS

Of the 190 outpatients studied, 38 (20%) had a history of pneumonia. These patients had more frequent upper-respiratory symptoms, nighttime awakenings in the past 4 weeks, daily use of inhaled corticosteroids, and lower FE(NO) than the 152 asthmatic children without previous pneumonia (FE(NO): 20.6 ppb, 95% CI: 15.2-28.0 vs. 31.1 ppb, 95% CI: 27.0-35.8; p < .05). Of the 38 patients with previous pneumonia, 14 had recurrent pneumonia. Despite comparable lung volumes and flows, they also had lower DLCO/VA than asthmatic children with no recurrent pneumonia and asthmatic children without previous pneumonia (DLCO/VA%: 91.2 ± 11.3 vs. 108.5 ± 14.7 vs. 97.9 ± 18.6, p < .05).

CONCLUSION

Respiratory assessment in asthmatic children and adolescents with a history of pneumonia, especially recurrent pneumonia, often discloses symptoms needing corticosteroid therapy, and despite normal lung volumes and flows, mild reductions in the variables reflecting gas diffusion and atopic-airway inflammation (DLCO/VA and FE(NO)). Whether these respiratory abnormalities persist in adulthood remains an open question.

Interstitial lung diseases in children

Interstitial lung disease (ILD) in infants and children comprises a large spectrum of rare respiratory disorders that are mostly chronic and associated with high morbidity and mortality. These disorders are characterized by inflammatory and fibrotic changes that affect alveolar walls. Typical features of ILD include dyspnea, diffuse infiltrates on chest radiographs, and abnormal pulmonary function tests with restrictive ventilatory defect and/or impaired gas exchange. Many pathological situations can impair gas exchange and, therefore, may contribute to progressive lung damage and ILD. Consequently, diagnosis approach needs to be structured with a clinical evaluation requiring a careful history paying attention to exposures and systemic diseases. Several classifications for ILD have been proposed but none is entirely satisfactory especially in children. The present article reviews current concepts of pathophysiological mechanisms, etiology and diagnostic approaches, as well as therapeutic strategies. The following diagnostic grouping is used to discuss the various causes of pediatric ILD: 1) exposure-related ILD; 2) systemic disease-associated ILD; 3) alveolar structure disorder-associated ILD; and 4) ILD specific to infancy. Therapeutic options include mainly anti-inflammatory, immunosuppressive, and/or anti-fibrotic drugs. The outcome is highly variable with a mortality rate around 15%. An overall favorable response to corticosteroid therapy is observed in around 50% of cases, often associated with sequelae such as limited exercise tolerance or the need for long-term oxygen therapy.

Tigecycline therapy significantly reduces the concentrations of inflammatory pulmonary cytokines and chemokines in a murine model of Mycoplasma pneumoniae pneumonia

Mycoplasma pneumoniae is one of the causative agents of atypical community-acquired pneumonia. Tigecycline belongs to a new class of glycylcycline antimicrobials that have activity against a wide range of microorganisms, including in vitro activity against M. pneumoniae. We investigated the effect of tigecycline on microbiologic, histologic, and immunologic indices in a murine model of M. pneumoniae pneumonia. BALB/c mice were inoculated intranasally with M. pneumoniae and treated subcutaneously with tigecycline or placebo for 6 days. Outcome variables included quantitative bronchoalveolar lavage (BAL) M. pneumoniae culture, lung histopathologic score (HPS), BAL cytokine and chemokine concentrations (tumor necrosis factor alpha [TNF-alpha], gamma interferon [IFN-gamma], interleukin 1beta [IL-1beta], IL-2, IL-4, IL-5, IL-6, IL-10, IL-12 [p40/p70], granulocyte-macrophage colony-stimulating factor, MIP-1alpha, MIG, KC, MCP-1, and IP-10). BAL M. pneumoniae concentrations in mice treated with tigecycline (MpTige) tended to be reduced compared with mice treated with placebo (MpPl); however this did not reach statistical significance. The lung HPS was significantly lower, as well as the parenchymal-pneumonia subscore, in the MpTige mice than in the MpPl mice. MpTige mice had significantly lower BAL cytokine concentrations of IL-1beta, IL-12 (p40/p70), IFN-gamma, and TNF-alpha; of the chemokines, MIG, MIP-1alpha, and IP-10 were statistically lower in MpTige mice. While tigecycline treatment demonstrated a modest microbiologic effect, it significantly improved lung histologic inflammation and reduced pulmonary cytokines and chemokines.

The impact of steroids given with macrolide therapy on experimental Mycoplasma pneumoniae respiratory infection

BACKGROUND

Systemic steroids have been advocated in addition to antimicrobial therapy for severe Mycoplasma pneumoniae pneumonia. We evaluated the efficacy of clarithromycin, dexamethasone, and combination therapy for M. pneumoniae respiratory infection.

METHODS

Mice infected with M. pneumoniae were treated with clarithromycin, dexamethasone, combined clarithromycin/dexamethasone, or placebo daily; mice were evaluated at baseline and after 1, 3, and 6 days of therapy. Outcome variables included M. pneumoniae culture, lung histopathologic score (HPS), and bronchoalveolar lavage cytokine, chemokine, and growth factor concentrations.

RESULTS

Clarithromycin monotherapy resulted in the greatest reductions in M. pneumoniae concentrations. After 3 days of treatment, combination therapy significantly reduced lung HPS compared with placebo, clarithromycin, and dexamethasone alone, whereas, after 6 days of therapy, clarithromycin alone and combination therapy significantly reduced lung HPS compared with placebo. Concentrations of interleukin (IL)-12 p40, RANTES, macrophage chemotactic protein-1, and cytokine-induced neutrophil chemoattractant were significantly lower in mice treated with clarithromycin alone and/or combination therapy compared with dexamethasone alone and/or placebo; combination therapy resulted in a significantly greater reduction than clarithromycin alone for IL-12 p40 and RANTES.

CONCLUSIONS

Although monotherapy with clarithromycin had the greatest effect on reducing concentrations of M. pneumoniae, combination therapy had the greatest effect on decreasing levels of cytokines and chemokines as well as pulmonary histologic inflammation.

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.

Lung function and bronchial responsiveness after Mycoplasma pneumoniae infection in early childhood

Mycoplasma (M.) pneumoniae has been associated with exacerbation of symptoms in asthmatic school children and adults; and an etiological role in asthma has been suggested. The purpose of this study was to investigate whether infection with M. pneumoniae in early childhood has a long-term influence on lung function and bronchial responsiveness. In a retrospective, clinical cohort-study children younger than 5 years-of-age when PCR-tested for M. pneumoniae were enrolled. Sixty-five children with clinical symptoms suggesting infection with M. pneumoniae during an epidemic season completed a clinical follow-up examination including lung function testing (28 PCR-positive and 37 PCR-negative). In addition to the PCR-test for M. pneumoniae all respiratory tract specimens were additionally tested for other atypical bacteria and for viruses by PCR. Lung function was measured as specific airway resistance by whole-body plethysmography and bronchial hyperresponsiveness was assessed by cold, dry air hyperventilation. Neither baseline lung function nor bronchial response to cold dry air hyperventilation differed between M. pneumoniae-positive and -negative children: mean baseline lung function were 1.17 versus 1.21 (kPa sec), P = 0.45; and mean change in specific resistance was 13% versus 9%, P = 0.42. In conclusion, M. pneumoniae infection in early childhood was not associated with long-term effects on lung function and bronchial hyperresponsiveness 2 years after infection.

[Mycoplasma pneumoniae, community-acquired pneumonia and asthma]

Mycoplasma pneumoniae is an intracellular pathogen, devoid of cell wall, able to invade airway epithelial cells. Infection may either remain asymptomatic or induce bronchitis and pneumonia. M. pneumoniae is the first-ranking aetiological agent of community-acquired pneumonias in children over five years of age. Clinical features are usually mild, but this should not preclude the initiation of a treatment, in order to avoid serious sequelae such as impairment of pulmonary gas exchange capacity. In children at high-risk of asthma, infection with M. pneumoniae can induce exacerbation. A survey was performed in children admitted to hospital Saint-Vincent-de-Paul (Paris) for an episode of severe asthma exacerbation with persistent hypoxemia. Mycoplasma infection was identified in 26% of children with a history of asthma and 50% of those for whom the exacerbation was the presenting manifestation of the disease. Furthermore, if the Mycoplasma infection was atypical, asthma exacerbation recurred within one month. M. pneumoniae should be considered not only as a preeminent agent of respiratory infection in children, but also as a triggering factor in exacerbation and even inception of asthma. As a consequence, it is mandatory to carefully search for and actively treat Mycoplasma infection in children.

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.

Impact of cethromycin (ABT-773) therapy on microbiological, histologic, immunologic, and respiratory indices in a murine model of Mycoplasma pneumoniae lower respiratory infection

Mycoplasma pneumoniae is a major etiologic agent of acute lower respiratory infections. We evaluated the antimicrobial and immunologic effects of cethromycin (ABT-773), a ketolide antibiotic, for the treatment of M. pneumoniae pneumonia in a mouse model. Eight-week-old BALB/c mice were inoculated intranasally once with 10(6) CFU of M. pneumoniae on day 0. Treatment was started 24 h after inoculation. Groups of mice were treated subcutaneously with cethromycin at 25 mg/kg of body weight or with placebo daily until sacrifice. Five to ten mice per group were evaluated at days 1, 4, 7, and 10 after inoculation. Outcome variables included bronchoalveolar lavage (BAL) for M. pneumoniae quantitative culture and cytokine and chemokine concentration determinations by enzyme-linked immunosorbent assay (tumor necrosis factor alpha [TNF-alpha], gamma interferon [IFN-gamma], interleukin-1beta [IL-1beta], IL-2, IL-4, IL-12, granulocyte-macrophage colony-stimulating factor, IL-8, monocyte chemoattractant protein 1 [MCP-1], and macrophage inflammatory protein 1alpha [MIP-1alpha]), histopathologic score of the lungs (HPS), and pulmonary function tests (PFT) using whole-body, unrestrained plethysmography at the baseline and post-methacholine exposure as indicators of airway obstruction (AO) and airway hyperresponsiveness (AHR), respectively. The cethromycin-treated mice had a greater reduction in M. pneumoniae culture titers than placebo-treated mice, reaching statistical significance on days 7 and 10 (P < 0.05). HPS was significantly reduced in cethromycin-treated mice compared with placebo-treated mice on days 4, 7, and 10 (P < 0.05). Cytokine concentrations in BAL samples were reduced in mice that received cethromycin, and the differences were statistically significant for 7 of the 10 cytokines measured (TNF-alpha, IFN-gamma, IL-1beta, IL-8, IL-12, MCP-1, and MIP-1alpha) on day 4 (P < 0.05). PFT values were improved in the cethromycin-treated mice, with AO and AHR significantly reduced on day 4 (P < 0.05). In this mouse model, treatment with cethromycin significantly reduced M. pneumoniae culture titers in BAL samples, cytokine and chemokine concentrations in BAL samples, histologic inflammation in the lungs, and disease severity as defined by AO and AHR.

Mycoplasma pneumoniae and asthma in children

The aim of this prospective study of a population of children (age, 2-15 years) hospitalized for severe asthma was to test them for acute infection due to Mycoplasma pneumoniae and acute infection due to Chlamydia pneumoniae. Of 119 patients with previously diagnosed asthma, acute M. pneumoniae infection was found in 24 (20%) and C. pneumoniae infection was found in 4 (3.4%) of the patients during the current exacerbation. Of 51 patients experiencing their first asthma attack, acute M. pneumoniae infection was proven in 26 (50%) of the patients (P<.01) and C. pneumoniae in 4 (8.3%). In the control group of 152 children with stable asthma or rhinitis, 8 (5.2%) had M. pneumoniae infection (P<.005). Of the 29 patients experiencing their first asthma attack and infected with M. pneumoniae or C. pneumoniae, 18 (62%) had asthma recurrences but only 6 (27%) of the 22 patients who did not have such infections had asthma recurrences (P<.05). M. pneumoniae may play a role in the onset of asthma in predisposed children and could be a trigger for recurrent wheezing.

Mycoplasma disease and acute chest syndrome in sickle cell disease

BACKGROUND

Acute chest syndrome (ACS) is the leading cause of hospitalization, morbidity, and mortality in patients with sickle cell disease. Radiographic and clinical findings in ACS resemble pneumonia; however, etiologies other than infectious pathogens have been implicated, including pulmonary fat embolism (PFE) and infarction of segments of the pulmonary vasculature. The National Acute Chest Syndrome Study Group was designed to identify the etiologic agents and clinical outcomes associated with this syndrome.

METHODS

Data were analyzed from the prospective study of 671 episodes of ACS in 538 patients with sickle cell anemia. ACS was defined as a new pulmonary infiltrate involving at least 1 complete segment of the lung, excluding atelectasis. In addition, the patients had to have chest pain, fever >38.5C, tachypnea, wheezing, or cough. Samples of blood and deep sputum were analyzed for evidence of bacteria, viruses, and PFE. Mycoplasma pneumoniae infection was determined by analysis of paired serologies. Detailed information on patient characteristics, presenting signs and symptoms, treatment, and clinical outcome were collected.

RESULTS

Fifty-one (9%) of 598 episodes of ACS had serologic evidence of M pneumoniae infection. Twelve percent of the 112 episodes of ACS occurring in patients younger than 5 years were associated with M pneumoniae infection. At the time of diagnosis, 98% of all patients with M pneumoniae infection had fever, 78% had a cough, and 51% were tachypneic. More than 50% developed multilobar infiltrates and effusions, 82% were transfused, and 6% required assisted ventilation. The average hospital stay was 10 days. Evidence of PFE with M pneumoniae infection was seen in 5 (20%) of 25 patients with adequate deep respiratory samples for the PFE assay. M pneumoniae and Chlamydia pneumoniae was found in 16% of patients with diagnostic studies for C pneumoniae. Mycoplasma hominis was cultured in 10 (2%) of 555 episodes of ACS and occurred more frequently in older patients, but the presenting symptoms and clinical course was similar to those with M pneumoniae.

CONCLUSIONS

M pneumoniae is commonly associated with the ACS in patients with sickle cell anemia and occurs in very young children. M hominis should be considered in the differential diagnosis of ACS. Aggressive treatment with broad-spectrum antibiotics, including 1 from the macrolide class, is recommended for all patients as well as bronchodilator therapy, early transfusion, and respiratory support when clinically indicated.

[Community-acquired pneumonia in children: etiology and treatment]

Due to their very different etiological agents, community-acquired pneumoniae in children frequently require empiric antibiotic therapy in emergency. Streptococcus pneumoniae represents between 15 to 30% of the etiologies and has unspecific diagnostic procedures; as a matter of fact radiological lobar consolidation is seen in less than half of cases, and laboratory data, except for high procalcitonin level, are poorly reliable. Pneumonia due to Mycoplasma pneumoniae is frequent after 2 years of age, reaching 40 to 60% of causes in ambulatory teenagers; it must be treated with macrolides as sequellae are possible. The exact number of viral pneumonia is difficult to establish because of the lack of reliable diagnostic methods. If bacterial superinfections are probably overestimated during acute phase, viral infections may lead to bacterial pneumonia 2 to 4 weeks after the initial episode. Empiric antibiotic treatment must take into account pneumococci and their penicillin-resistant strains. Amoxicillin is the antibiotic of choice, having a higher efficacy on resistant pneumococci than oral cephalosporins. In case of clinical failure of amoxicillin, mycoplasma infection must be considered and patient must receive macrolides. Future epidemiology will be affected by anti-pneumococcal immunisation but difficulties in diagnosis and empiric antibiotic treatment will probably remain. Studies in immunised children are needed to evaluate the importance of pneumococcal infections due to serotypes not included in the vaccine.

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.