Severe acute lung injury caused by Mycoplasma pneumoniae: potential role for steroid pulses in treatment

Treatment with Fluticasone Propionate Increases Antibiotic Efficacy during Treatment of Late-Stage Primary Pneumonic Plague

Severe and late-stage pneumonias are often difficult to treat with antibiotics alone due to overwhelming host inflammatory responses mounted to clear infection. These host responses contribute to pulmonary damage leading to acute lung injury, acute respiratory distress syndrome, and death. In order to effectively treat severe and late-stage pneumonias, use of adjunctive therapies must be considered to reduce pulmonary damage when antimicrobial agents can be administered. Pneumonic plague, a severe pneumonia caused by inhalation of Yersinia pestis, is a fatal disease that causes death within 6 days without antibiotic intervention. Late-stage pneumonic plague is difficult to treat, as antibiotics must be delivered within 24 h after onset of symptoms to be effective. Here, we use a murine model of primary pneumonic plague to examine how host inflammatory responses impact antibiotic treatment of late-stage pneumonic plague. We developed a murine infection model demonstrating the poor outcomes associated with delayed delivery of antibiotics. We show that pretreatment of mice with intranasal fluticasone propionate increased the efficacy of delayed antibiotic delivery and enhanced murine survival. Mice receiving fluticasone propionate also showed decreased bacterial burden and reduced inflammatory pathology in the lungs. Further, we show that treatment and survival correlated with decreased levels of interleukin-6 (IL-6) and reduced neutrophil infiltration to the lungs. This work demonstrates how host inflammatory responses complicate treatment of late-stage pneumonic plague and suggests that targeting of host inflammatory responses may improve treatment of severe, late-stage pneumonia.

Clinical Characteristics of Macrolide-Refractory Mycoplasma pneumoniae Pneumonia in Korean Children: A Multicenter Retrospective Study

Mycoplasma pneumoniae is a major causative pathogen of community-acquired pneumonia in children, and the treatment of choice is macrolides. There is an increasing trend in reports of refractory clinical responses despite macrolide treatment due to the emergence of macrolide-resistant M. pneumoniae. Early discrimination of macrolide-refractory M. pneumoniae pneumonia (MrMP) from macrolide-sensitive M. pneumoniae pneumonia (MSMP) is vital; however, testing for macrolide susceptibility at the time of admission is not feasible. This study aimed to identify the characteristics of MrMP in Korean children, in comparison with those of MSMP. In this multicenter study, board-certified pediatric pulmonologists at 22 tertiary hospitals reviewed the medical records from 2010 to 2015 of 5294 children who were hospitalized with M. pneumoniae pneumonia and administered macrolides as the initial treatment. One-way analysis of variance and the Kruskal-Wallis test were used to compare differences between groups. Of 5294 patients (mean age, 5.6 years) included in this analysis, 240 (4.5%), 925 (17.5%), and 4129 (78.0%) had MrMP, macrolide-less effective M. pneumoniae pneumonia, and MSMP, respectively. Compared with the MSMP group, the MrMP group had a longer fever duration, overall (13.0 days) and after macrolide use (8.0 days). A higher proportion of MrMP patients had respiratory distress, pleural effusion, and lobar pneumonia. The mean aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and C-reactive protein levels were the highest in the MrMP group, along with higher incidences of extrapulmonary manifestations and atelectasis (during and post infection). Pre-existing conditions were present in 17.4% (n = 725/4159) of patients, with asthma being the most common (n = 334/4811, 6.9%). This study verified that MrMP patients show more severe initial radiographic findings and clinical courses than MSMP patients. MrMP should be promptly managed by agents other than macrolides.

The value of interleukin-27 for differentiating tuberculous pleural effusion from Mycoplasma pneumoniae pneumonic effusion in children

OBJECTIVES

The early diagnosis of tuberculous pleural effusion (TPE) is challenging due to the difficulty of isolating Mycobacterium tuberculosis, and pleural biomarkers are an optional choice. Recent studies showed that interleukin-27 (IL-27) appears to be a new accurate biomarker for TPE in adults and no related studies were reported in children. In this study, we aimed to evaluate the potential value of IL-27 in pediatric tuberculous pleurisy by detecting its levels in pleural fluid and serum.

METHODS

A total of 48 children with TPE and 64 children with severe Mycoplasma pneumoniae (MP) pneumonic effusion (SMPPE) were enrolled in this study. IL-27 concentrations were measured in serum and pleural fluid. The diagnostic yield of IL-27 was evaluated using receiver operating characteristic (ROC) curves.

RESULTS

The level of p-IL-27 in TPE showed statistically no significant difference when compared with SMPPE (p > 0.05). However, pleural fluid IL-27 (p-IL-27) / serum IL-27 (s-IL-27) ratio in TPE were significantly much higher than those in SMPPE (p < 0.05). By the analysis of the ROC curves, the diagnostic sensitivity and specificity of the p-IL-27/s-IL-27 ratio were 100% and 48.44%, respectively (cutoff value of 1.0280). The area under the ROC curve for p-IL-27/s-IL-27 was 0.7295.

CONCLUSION

Pleural fluid IL-27 alone was not accurate in distinguishing pediatric TPE from SMPPE, which was different from the diagnostic value of IL-27 in adult studies due to the different disease spectra between children and adults. Our results implied that the p-IL-27/s-IL-27 ratio had a potential value in distinguishing TPE from SMPPE. However, the specificity of IL-27 was relatively lower and it is necessary to find a more specific marker in tuberculous pleurisy of children.

The critical function of miR-1323/Il6 axis in children with Mycoplasma pneumoniae pneumonia

OBJECTIVE

Mycoplasma pneumoniae pneumonia (MPP) is a common respiratory infection in children. Tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17), and IL-6 have correlation with Mycoplasma pneumoniae lung infection and MPP pathogenesis.

METHOD

miRNAs participate in the pathogenesis of various diseases by regulating the development and differentiation of the immune cell. Blood was collected and total RNA was isolated. miRNA microarrays were performed to identify differentially expressed miRNAs in MPP patients. The levels of relative miRNAs and mRNAs were evaluated by qRT-PCR.

RESULTS

There are 23 differentially expressed miRNAs in MPP children's plasma, 15 miRNAs had enhanced expression and 8 had depressed expression. MPP patients showed lower mir-1323 level in blood samples than healthy controls. MPP patients with pleural effusion had much higher Il6 and Il17a mRNA levels than those without pleural effusion. The expression level of Il6 had a negative correlation with miR-1323 level. In the human THP-1 cell line, the level of miR-1323 was significantly reduced through lipopolysaccharides treatment. In THP-1 cells, overexpression or silencing of miR-1323 significantly reduced or promoted Il6 expression.

CONCLUSION

In conclusion, miR-1323 targets the mRNA of Il6 and inhibits the expression of Il6. The pathogenesis of MPP inhibits the expression of miR-1323 in macrophages, triggers the overexpression of Il6, and enhances inflammation response.

Prediction model for prolonged fever in patients with Mycoplasma pneumoniae pneumonia: a retrospective study of 716 pediatric patients

Objective

To identify patients with Mycoplasma pneumoniae pneumonia (MPP) with a risk of prolonged fever while on macrolides.

Methods

A retrospective study was performed with 716 children admitted for MPP. Refractory MPP (RMPP-3) was defined as fever persisting for > 72 h without improvement in clinical and radiologic findings after macrolide antibiotics (RMPP-3) or when fever persisted for > 120 h (RMPP-5) without improvement in clinical and radiologic findings. Radiological data, laboratory data, and fever profiles were compared between the RMPP and non-RMPP groups. Fever profiles included the highest temperature, lowest temperature, and frequency of fever. Prediction models for RMPP were created using the logistic regression method and deep neural network. Their predictive values were compared using receiver operating characteristic curves.

Results

Overall, 716 patients were randomly divided into two groups: training and test cohorts for both RMPP-3 and RMPP-5. For the prediction of RMPP-3, a conventional logistic model with radiologic grouping showed increased sensitivity (63.3%) than the model using laboratory values. Adding laboratory values in the prediction model using radiologic grouping did not contribute to a meaningful increase in sensitivity (64.6%). For the prediction of RMPP-5, laboratory values or radiologic grouping showed lower sensitivities ranging from 12.9 to 16.1%. However, prediction models using predefined fever profiles showed significantly increased sensitivity for predicting RMPP-5, and neural network models using 12 sequential fever data showed a greatly increased sensitivity (64.5%).

Conclusion

RMPP-5 could not be effectively predicted using initial laboratory and radiologic data, which were previously reported to be predictive. Further studies using advanced mathematical models, based on large-sized easily accessible clinical data, are anticipated for predicting RMPP.

Acute respiratory distress syndrome during the COVID-19 pandemic: not only SARS-CoV-2

A previously healthy 30-year-old woman developed severe ARDS at the beginning of the COVID-19 pandemic. SARS-CoV-2 infection was suspected, but testing was negative. Mycoplasma pneumoniae was detected by PCR in bronchoalveolar lavage fluid and blood. This case illustrates that M. pneumoniae infection can progress to septicemia and ARDS with severe respiratory failure in young healthy adults.

Risk factors for mortality from severe community-acquired pneumonia in hospitalized children transferred to the pediatric intensive care unit

BACKGROUND

Some children hospitalized due to severe community-acquired pneumonia (CAP) require to the pediatric intensive care unit (PICU) because of severe complications. The purpose of this study was to identify the risk factors for mortality in this patient population.

METHODS

This study evaluated the medical records of 113 hospitalized children with severe CAP, who were transferred to the PICU within 48 h of admission at the Guangzhou Women and Children's Medical Center between 2013 and 2017.

RESULTS

The study group consisted of 87 boys (77%) and 26 girls (33%), aged between 1 month and 9 years; 72.6% (82/113) of patients were aged <12 months. The mortality rate was 12.3% (14/113). The most common viral and bacterial pathogens isolated were adenovirus (17.7%, 20/113) and Haemophilus influenzae (8.8%, 10/113). Wheezing, cyanosis, oxygen saturation <90%, Pediatric Early Warning Score (PEWS) >3 on admission, not receiving corticosteroid therapy prior to admission, the need for mechanical ventilation, septic shock, multi-organ dysfunction (MODS), and acute renal failure (ARF) occurring prior to transfer to the PICU, increased alanine aminotransferase (ALT) and aspartate transaminase (AST) levels, and decreased hemoglobin and albumin (ALB) levels were associated with mortality (P < 0.05). Non-survivors were more likely to have an oxygen saturation <90% on admission and lower levels of ALB prior to transfer to the PICU than survivors (P < 0.05).

CONCLUSIONS

Our results showed that hospitalized children with severe CAP who were transferred to the PICU within 48 h of hospital admission were mainly aged <1 year. Additionally, an oxygen saturation <90% and decreased ALB levels were early prognostic variables independently associated with death.

Correlation Between the Clinical Severity, Bacterial Load, and Inflammatory Reaction in Children with Mycoplasma Pneumoniae Pneumonia

Given the lack of defining features in the clinical manifestations and radiographic findings for children with mycoplasma pneumoniae pneumonia (MPP), quantitative polymerase chain reaction (qPCR) has become a useful diagnostic method. This study was performed to explore the relationship between the qPCR findings, clinical symptoms, and inflammatory markers in children with MPP. Four hundred children with MPP have been enrolled in this retrospective analysis. All clinical and analytical information, including mycoplasma pneumoniae (MP) PCR results, has been collected. Based on the PCR results, the patients were divided into groups with load values (copy number) < 10⁵ (54 cases), ≥10⁵ and <10⁶ (71 cases), ≥10⁶ and <10⁷ (112 cases), ≥10⁷ and ≤10⁸ (114 cases), and >10⁸ (49 cases). The clinical features (including symptoms and signs) and inflammatory indicators were compared among the groups. The incidence of high fever (above 39°C), thermal peak during the entire hospitalization period, fever duration, days of hospitalization, and plasma lactate dehydrogenase (LDH) levels were statistically correlated with the MP PCR load value in children with MPP. The analysis of relevance degree showed the correlative order as a thermal peak of hospitalization > duration of fever > period of hospitalization > LDH value > C-reactive protein value. The host immune response was significantly greater in the complication group than in the non-complication group.

Early diagnosis and appropriate respiratory support for Mycoplasma pneumoniae pneumonia associated acute respiratory distress syndrome in young and adult patients: a case series from two centers

BACKGROUND

Mycoplasma pneumoniae (M. pneumoniae) is one of the most common causes of community acquired pneumonia (CAP). Establishing an early diagnosis of M. pneumoniae pneumonia in patients with acute respiratory distress syndrome (ARDS) may have important therapeutic implications.

METHODS

We describe diagnosis and management of M. pneumoniae pneumonia induced ARDS in a case series of adults and youth hospitalized with radiographically confirmed CAP prospectively enrolled in an observational cohort study in two university teaching hospitals, from November 2017 to October 2019.

RESULTS

In all 10 patients, early and rapid diagnosis for severe M. pneumoniae pneumonia with ARDS was achieved with polymerase chain reaction (PCR) or metagenomic next-generation sequencing (mNGS) testing of samples from the lower respiratory tract or pleural effusion. The average PaO₂/FiO₂ of all patients was 180 mmHg. Of the 10 cases, 4 cases had moderate ARDS (100 mmHg ≤ PaO₂/FiO₂ < 200 mmHg) and 3 cases had severe ARDS (PaO₂/FiO₂ < 100 mmHg). High flow nasal cannula (HFNC) was applied in all patients, though only two patients were sufficiently supported with HFNC. Invasive mechanical ventilation (IMV) was required in 5 patients. High resistance (median 15 L/cmH₂O/s) and low compliance (median 38 ml/cmH₂O) was observed in 4 cases. In these 4 cases, recruitment maneuvers (RM) were applied, with 1 patient demonstrating no response to RM. Prone positioning were applied in 4 cases. Two cases needed ECMO support with median support duration of 5.5 days. No patient in our case series received corticosteroid therapy. All patients were survived and were discharged from hospital.

CONCLUSIONS

Early and rapid diagnosis of severe M. pneumoniae pneumonia with ARDS can be achieved with PCR/mNGS tests in samples from the lower respiratory tract or pleural effusion. In our case series, half of M. pneumoniae pneumonia induced ARDS cases were adequately supported with HFNC or NIV, while half of cases required intubation. RM and prone position were effective in 30% of intubated cases, and 20% needed ECMO support. When early anti-mycoplasmal antibiotics were given together with sufficient respiratory support, the survival rate was high with no need for corticosteroid use.

Altered chemokine profile in Refractory Mycoplasma pneumoniae pneumonia infected children

BACKGROUND

Mycoplasma pneumoniae is one of the major pathogens causing community-acquired pneumonia in children. Although usually self-limited, Mycoplasma pneumoniae pneumonia (MPP) may lead to complicated morbidity that can even be life-threatening. Upon MPP infection, alveolar macrophage becomes attracted and activated and will induce subsequent cytokine and chemokine reaction. Refractory Mycoplasma pneumoniae pneumonia (RMPP) is manifested by clinical or radiological deterioration despite proper antibiotic therapy. RMPP is characterized with excessive inflammation and may need subsequent glucocorticoid treatment.

AIM

The aim of this study was to investigate the change of plasma chemokines in non-refractory Mycoplasma pneumoniae pneumonia (NRMPP) and RMPP before and after antibiotic or methylprednisolone treatment.

METHOD

A total of 42 children with MPP were enrolled in this study. Plasma specimens were collected at admission and one to two weeks after antibiotic or methylprednisolone treatment with declined fever. Plasma specimens were then indicated to chemokines detection.

RESULTS

Mycoplasma pneumoniae pneumonia altered the chemokine profile through the observation of decreased plasma M1 related chemokines (CCL2, CCL8 and CXCL10) and increased M2 related chemokines (CCL17 and CCL22) after treatment.When the patients were divided into RMPP and NRMPP groups and the chemokines before treatment were compared, the RMPP group showed higher CXCL10 but lower CCL3 and CCL11 than the NRMPP group.

CONCLUSION

Unique changes in macrophage related chemokines is observed in the course of MPP infection. NRMPP and RMPP infection in children showed distinct manifestation in chemokine profiles.

Development and validation of a simple-to-use nomogram for predicting refractory Mycoplasma pneumoniae pneumonia in children

OBJECTIVE

This study aimed to develop and validate a simple-to-use nomogram for predicting refractory Mycoplasma pneumoniae pneumonia (RMPP) in children.

METHODS

A total of 73 children with RMPP and 146 children with general Mycoplasma pneumoniae pneumonia were included. Clinical, laboratory, and radiological data were obtained. A least absolute shrinkage and selection operator (LASSO) regression model was used to determine optimal predictors. The nomogram was plotted by multivariable logistic regression. The performance of the nomogram was assessed by calibration, discrimination, and clinical utility.

RESULTS

The LASSO regression analysis identified lactate dehydrogenase, albumin, neutrophil ratio, and high fever as significant predictors of RMPP. This nomogram-illustrated model showed good discrimination, calibration, and clinical value. The area under the receiver operating characteristic curve of the nomogram was 0.884 (95% CI, 0.823-0.945) in the training set and 0.881 (95% CI, 0.807-0.955) in the validating set. Calibration curve and Hosmer-Lemeshow test showed good consistency between the predictions of the nomogram and the actual observations, and decision curve analysis showed that the nomogram was clinically useful.

CONCLUSION

A simple-to-use nomogram for predicting RMPP in early stage was developed and validated. This may help physicians recognize RMPP earlier.

Meta-analysis of the Clinical Efficacy and Safety of High- and Low-dose Methylprednisolone in the Treatment of Children With Severe Mycoplasma Pneumoniae Pneumonia

BACKGROUND

Mycoplasma pneumoniae pneumonia is generally a self-limiting disease, but it can develop into severe Mycoplasma pneumoniae pneumonia (SMPP). Immunologic mechanisms are thought to play an important role in the pathogenesis of SMPP. Therefore, the use of systemic glucocorticoids may have beneficial effects. However, to date, the use of glucocorticoid therapy in SMPP is limited to small case series, and the glucocorticoid dosage for children with SMPP has not been established.

METHODS

Here, we used a meta-analysis method to collect data from randomized control trials of different doses of methylprednisolone in SMPP to assess the safety and efficacy of treatment with low- versus high-dose methylprednisolone in children with SMPP.

RESULTS

We included 13 Chinese randomized control trials that included 1049 children. The high- and low-dose groups were comprised of 524 and 525 children, respectively. The high-dose group was significantly more effective than the low-dose group in clinical efficacy [risk ratio = 1.30, 95% confidence interval (CI) (1.23, 1.38), P < 0.05]. In addition, compared with low-dose methylprednisolone, high-dose methylprednisolone significantly shortened hospital stays and antipyretic therapy, pulmonary rales disappearance, cough disappearance and pulmonary shadow absorption times. There was no significant difference in adverse events between the high- and low-dose groups: risk ratio= 0.85, 95% CI (0.53, 1.36), P > 0.05.

CONCLUSIONS

We conclude that high-dose methylprednisolone is effective in the treatment of SMPP without increasing the incidence of adverse reactions.

Predictive Model for Discrimination of Tuberculous Pleural Effusion From Severe Mycoplasma pneumoniae Pneumonic Effusion in Children

BACKGROUND

Tuberculous pleural effusion (TPE) is often misdiagnosed as severe Mycoplasma pneumoniae pneumonic effusion (SMPPE) in children at early stage. The aim of this study was to develop a predictive model based on clinical and laboratory indices to make accurate differential diagnosis.

METHODS

Patients included in this study were 167 children (83 patients with TPE and 84 with SMPPE), containing 117 patients for predictive model development and 50 patients for external validation. Multivariate logistic regression analysis was conducted to select potentially useful characteristics for discrimination of TPEs. External validation was performed for model evaluation.

RESULTS

Multivariate analysis revealed that blood neutrophils and serum lactate dehydrogenase were significant independent factors to discriminate between TPEs and SMPPEs. The results indicated that blood neutrophils ≤69.6% and concentration of serum lactate dehydrogenase ≤297 U/L were the extremely important discrimination factors of TPEs. The area under the receiver operating characteristic curve of the model was 0.9839. The accuracy rate, sensitivity and specificity of the model were 94.02%, 98.28% and 89.83%, respectively. Meanwhile, the accuracy rate of the external validation from the 50 patients was 94.0%.

CONCLUSIONS

Applying a predictive model with clinical and laboratory indices can facilitate the differential diagnosis of TPE from SMPPE in children, which seems helpful when a microbiologic or histologic diagnosis of pleural tuberculosis could not be established.

Critical combination of initial markers for predicting refractory Mycoplasma pneumoniae pneumonia in children: a case control study

Background

It is unclear whether the responses of refractory and common Mycoplasma pneumoniae (MP) pneumonia to macrolides differ. Hence, this study aimed to identify biomarkers that may be used to distinguish refractory and common pneumonias caused by MP in children at hospital admission.

Methods

The study included 123 children divided into five groups according to infection agent and treatment protocol: Group I included those with MP infection without documented viral infection, treated with only macrolides; Group II included those with MP infection without documented viral infection, treated with a combination of macrolides and methylprednisolone; Group III included those with MP infection and documented viral infection, treated with only macrolides; Group IV included those with viral pneumonia without documented MP infection; Group V was the control group composed of admitted children without MP or a documented viral infection. These five groups were further subdivided into Groups A (including Groups I, III, IV, and V) and B (Group II) according to the responses to macrolide treatment. Concentrations of cytokines interleukin 6, interleukin 17, interleukin 18, and tumor necrosis factor-α, and lactate dehydrogenase, and ferritin of all children were evaluated, and these levels were compared among the groups. Statistical comparisons were made using Kruskal Wallis test and Mann-Whitney U test.

Results

Serum lactate dehydrogenase, interleukin 18, and ferritin concentrations were significantly higher in Group II than in Groups I, III, IV, and V and were significantly higher in Group B than in Group A. When the serum lactate dehydrogenase concentration was 350 IU/L or higher, the sensitivity and specificity for diagnosing refractory MP pneumonia were 73 and 80%, respectively. When the interleukin 18 level was 360 pg/mL or higher, the sensitivity and specificity for diagnosing refractory MP pneumonia were 93 and 70%, respectively. When the ferritin level was 230 pg/mL or higher, the sensitivity and specificity for diagnosing refractory MP pneumonia were 67 and 67%, respectively.

Conclusion

These results suggest that serum lactate dehydrogenase, interleukin 18, and ferritin constitute the critical combination of biomarkers useful for predicting refractory MP pneumonia in children at hospital admission.

High expression of HMGB1 in children with refractory Mycoplasma pneumoniae pneumonia

Background

Increasing numbers of refractory or severe, even fatal, cases of Mycoplasma pneumoniae infections have been reported in recent years. Excessive inflammatory responses play a vital role in the pathogenesis of refractory M. pneumoniae pneumonia (RMPP). HMGB1 is an actively secreted cytokine produced by macrophages and other inflammatory cells that participates in various infectious diseases. The present study aimed to explore the role and clinical significance of HMGB1 in children with RMPP and the potential mechanism of HMGB1 expression.

Methods

Four hundred and fifty-two children diagnosed with M. pneumoniae pneumonia, including 108 children with RMPP, were enrolled from January 2013 to December 2015 at the Children’s Hospital of Soochow University. HMGB1, TNF-α, and IL-6 in peripheral blood from RMPP and non-RMPP (NRMPP) cases were detected by real-time PCR and ELISA. Lipid-associated membrane proteins (LAMPs) were extracted from live M. pneumoniae and prepared at different concentrations for stimulation of THP-1 cells. After coculture with LAMPs, HMGB1, TNF-α, IL-6, RAGE, TLR2, and TLR4 in THP-1 cells were detected by real-time PCR.

Results

Occurrences of cough, fever, and abnormal lung signs were more frequent in RMPP cases compared with NRMPP cases (all p < 0.05). Children with RMPP had longer hospital stays than children with NRMPP (p < 0.05). Different distributions of lymphocytes were noted between RMPP and NRMPP cases. HMGB1, TNF-α, and IL-6 levels were significantly higher in RMPP cases compared with NRMPP cases (all p < 0.05). HMGB1 had good diagnostic ability to differentiate RMPP with AUC of 0.876, sensitivity of 0.833, and specificity of 0.824 compared with TNF-α and IL-6. HMGB1 expression in THP-1 cells was increased by stimulation with 10 μg/ml LAMPs. TLR2 expression was increased after stimulation with 6 μg/ml LAMPs. HMGB1 level was positively associated with TNF-α, IL-6, and TLR2 levels.

Conclusions

HMGB1 is a good diagnostic biomarker for differentiating RMPP and NRMPP. LAMPs from M. pneumoniae may induce HMGB1 expression in immune cells through the TLR2 pathway. Further in vitro and in vivo studies are needed for the development of a new treatment strategy to inhibit the HMGB1 pathway, thereby preventing the inflammation in RMPP.

The timing of azithromycin treatment is not associated with the clinical prognosis of childhood Mycoplasma pneumoniae pneumonia in high macrolide-resistant prevalence settings

BACKGROUND

Mycoplasma pneumoniae infection is a major cause of community-acquired pneumonia in children. We performed a retrospective study to evaluate the clinical impact of the timing of azithromycin treatment in children with Mycoplasma pneumoniae pneumonia in high macrolide-resistant prevalence settings.

METHODS AND FINDINGS

A total of 623 patients were enrolled in this study and were divided into 2 groups according to the timing of azithromycin therapy. Children who received azithromycin within 3 days (72 hours) after the onset of Mycoplasma pneumoniae pneumonia were classified into the early azithromycin treatment group (n = 174), whereas the late azithromycin treatment group (n = 449) comprised children treated with azithromycin more than 72 hours after symptom onset. We evaluated clinical prognosis according to demographic, clinical and laboratory characteristics. Although the early azithromycin treatment group exhibited a longer fever duration after azithromycin administration (7.17±4.12 versus 4.82±3.99 days, P<0.01), the total fever duration exhibited no significant difference (9.02±4.58 versus 9.57±4.91 days, P = 0.212). After azithromycin therapy, the two groups exhibited no significant differences with respect to improvements in the laboratory and radiological findings (all P>0.05).

CONCLUSION

The timing of azithromycin treatment is not associated with the clinical prognosis of Mycoplasma pneumoniae pneumonia in children in high macrolide-resistant Mycoplasma pneumoniae prevalence settings.

Low Bacterial Co-infection Invalidates the Early Use of Non-anti-Mycoplasma pneumoniae Antibiotics in Pediatric Refractory Mycoplasma pneumoniae Pneumonia Patients

Background: Childhood refractory mycoplasma pneumoniae (MP) pneumonia (RMPP) is a lung disease with elevated level of C-reactive protein and severe clinical and radiological deterioration. Whether bacterial co-infection contributes to disease of RMPP and whether inclusion of non-anti-MP antibiotics in treatment regimen would benefit RMPP patients remains elusive. Methods: We retrospectively reviewed the medical records of 675 RMPP children. Traditional bacterial culture and next generation sequencing (NGS) were used to detect bacteria in bronchoalveolar lavage fluid in all the 675 patients and 18 patients respectively. Antibiotics used and clinical outcomes were analyzed along with other clinical measurements. Results: Positive bacterial cultures were only found in 18 out of 675 cases (2.67%) and NGS analyses of another 18 cases did not revealed positive bacterial infection, which were consistent with the results of bacterial cultures. Non-anti-MP antibiotics were utilized in 630 cases (93.33%), even last-line antibiotics, such as glycopeptides or carbapenems, were frequently used. Conclusion: Bacterial co-infection in RMPP was rare and non-anti-MP antibiotics didn't show any efficacy for early treatment of RMPP patients, which may provide a rationale for restricting the use of non-anti-MP antibiotics in RMPP patients and preventing antibiotic resistance globally.

Adjunctive corticosteroid therapy for inpatients with Mycoplasma pneumoniae pneumonia

Background

There is conflicting evidence regarding the benefit of adjunctive corticosteroid therapy in patients with Mycoplasma pneumoniae pneumonia. We hypothesised that corticosteroid therapy could reduce mortality and length of stay (LOS) in such patients.

Methods

Adult patients with M. pneumoniae pneumonia from January 2010 to December 2013 were identified from the Japanese Diagnosis Procedure Combination inpatient database. The effects of low-dose and high-dose corticosteroid therapies on mortality, LOS, drug costs and hyperglycaemia requiring insulin treatment were evaluated using propensity score analyses.

Results

Eligible patients (n = 2228) from 630 hospitals were divided into no-corticosteroid (n = 1829), low-dose corticosteroid (n = 267) and high-dose corticosteroid (n = 132) groups. The propensity score-matched pairs were generated from no-corticoid and low-dose corticoid groups (251 pairs), or no-corticoid and high-dose corticosteroid groups (120 pairs). Adjunctive corticosteroid therapy did not decrease 30-day mortality. In addition, both low-dose and high-dose corticosteroid therapies were associated with increases in LOS. Furthermore, hyperglycaemia requiring insulin treatment and drug cost increased with corticosteroid use.

Conclusions

Adjunctive treatment with low-dose or high-dose corticosteroids may not be beneficial in M. pneumoniae pneumonia.

The early examination of combined serum and imaging data under flexible fiberoptic bronchoscopy as a novel predictor for refractory Mycoplasma pneumoniae pneumonia diagnosis

The treatment role of flexible bronchoscopy (FOB) for pediatric refractory Mycoplasma pneumoniae pneumonia (RMPP) has been well documented. Besides, the application indication of FOB is also studied in patients with general MPP (GMPP), especially in those with large pulmonary lesions. This study was designed to examine the diagnostic value of bronchoscopic features for RMPP.The FOB and bronchoalveolar lavage (BAL) were adopted for pediatric patients who showed clinical and radiograph indications. On the basis of the final diagnosis on discharge, patients were divided into general and refractory MPP groups. The clinical, laboratory, and bronchoscopic imaging features were retrospectively investigated between these 2 groups.From June 2012 to May 2014, a total of 62 RMPP and 101 GMPP patients were treated with therapeutic bronchoscopy. The comparison analysis showed that the CRP, HBDH, LDH were significantly different between RMPP and GMPP groups (all P < .001). In the bronchoscopic imaging, the mucus plug was significantly more commonly seen in the RMPP group (P < .001). Receiver operating characteristic (ROC) analysis revealed that the combined serum, clinical, and FOB imaging data possessed greater specificity and sensitivity than serum and clinical data alone.Our data suggest that the combined serum, clinical, and bronchoscopic imaging data might serve as a promising predictor for early RMPP diagnosis for pediatric patients with large pulmonary lesions.

TIPE2 negatively regulates mycoplasma pneumonia-triggered immune response via MAPK signaling pathway

Excessive immune responses played an important role in pathophysiology of mycoplasma pneumonia (MP) infection. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a negative regulator of immune response. This study investigated the expression change of TIPE2 and its role in immune defense against MP infection, as well as the underlying mechanisms. Expressions of TIPE2 both in patients and in macrophages in vitro after MP infection were measured. We further studied cytokine production and mitogen-activated protein kinase (MAPK) signaling function in macrophages with interfered expression of TIPE2 upon MP infection. A significant decrease of TIPE2 mRNA expression was observed in peripheral blood mononuclear cells (PBMCs) from MP patients, which was correlated with the severity of infection. Accordingly we found down-regulation of TIPE2 expression in macrophages after MP infection. In vitro study further suggested that TIPE2 jeopardized inflammatory cytokine production trigged by MP infection via inhibiting MAPK signaling pathway. These findings provided evidences of the novel function of TIPE2 in anti-MP immunity and its possible clinical utility related clinical significance.

Cytokines as the good predictors of refractory Mycoplasma pneumoniae pneumonia in school-aged children

Excessive immune response against pathogens may play an important role in refracory Mycoplasma pneumoniae pneumonia (RMPP). The aim of this study was to elucidate the associations between cytokines and the prediction of RMPP in school-aged patients. Retrospective analysis was performed on school-aged children with Mycoplasma pneumoniae pneumonia (MPP) hospitalized in our hospital between January 1, 2011 and December 31, 2015. The clinical charcteristics, including the cytokines in serum between the RMPP group and the general Mycoplasma pneumoniae pneumonia (GMPP) group were compared and the predictive values of RMPP were explored. Of total 180 patients, 115 patients were in the GMPP group, 65 were in the RMPP group. We found the levels of cytokines, including nterleukin (IL)-6, IL-10, interferon gamma (IFN-γ) in RMPP group were significantly higher than those in GMPP group (P < 0.01). In ROC curve analysis, IL-10 and IFN-γ were useful for differentiating patients with RMPP from those with GMPP. Logistic regression analysis showed that the IL-10 ≥ 3.65 pg/ml and IFN-γ ≥ 29.05 pg/ml were significant predictors regarding to RMPP. Additionally, a positive correlation between serum IL-10 and IFN-γ concentrations was observed. Conclusions: IL-10 and IFN-γ could be used as the good predictors of RMPP in school-aged children.

Community-acquired pneumonia related to intracellular pathogens

Community-acquired pneumonia (CAP) is associated with high rates of morbidity and mortality worldwide; the annual incidence of CAP among adults in Europe has ranged from 1.5 to 1.7 per 1000 population. Intracellular bacteria are common causes of CAP. However, there is considerable variation in the reported incidence between countries and change over time. The intracellular pathogens that are well established as causes of pneumonia are Legionella pneumophila, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Chlamydophila psittaci, and Coxiella burnetii. Since it is known that antibiotic treatment for severe CAP is empiric and includes coverage of typical and atypical pathogens, microbiological diagnosis bears an important relationship to prognosis of pneumonia. Factors such as adequacy of initial antibiotic or early de-escalation of therapy are important variables associated with outcomes, especially in severe cases. Intracellular pathogens sometimes appear to cause more severe disease with respiratory failure and multisystem dysfunction associated with fatal outcomes. The clinical relevance of intracellular pathogens in severe CAP has not been specifically investigated. We review the prevalence, general characteristics, and outcomes of severe CAP cases caused by intracellular pathogens.

The Clinical Characteristics and Predictors of Refractory Mycoplasma pneumoniae Pneumonia in Children

Objective

To analyze the clinical characteristics of refracory Mycoplasma pneumoniae pneumonia (RMPP), and explore the related factors predicting RMPP.

Methods

Retrospective analysis was performed on 634 children with Mycoplasma pneumoniae pneumonia (MPP) hospitalized in our hospital between January 1, 2011 and December 31, 2014. The clinical features, laboratory data, radiological findings between the RMPP group and the general Mycoplasma pneumoniae pneumonia (GMPP) group were compared and the predictive values of related factors were analyzed.

Results

The median age of the RMPP patients (n = 145) was much older than that of the GMPP patients (n = 489) (P<0.01). We also found more severe presentations, higher incidence of extra-pulmonary complications and more serious radiological findings in RMPP group, which needed oxygen more often, longer antibiotics administration and intensive care (P<0.05). Meanwhile, the levels of C-reactive protein (CRP), lactic dehydrogenase (LDH), immunoglobulin A (IgM), interleukin (IL)-6, IL-10, interferon gamma (IFN-γ) and the percentage of neutrophils, CD8+ in RMPP group were significantly higher than those in GMPP group (P<0.05); while the levels of prealbumin (PAB) were lower than that in GMPP group (P<0.01). In ROC curve analysis, the percentage of neutrophil, CRP, LDH, PAB, IL-6, IL-10 and IFN-γ were useful for differentiating patients with RMPP from those with GMPP. Multiple logistic regression analysis showed that the CRP≥16.5mg/L, LDH ≥417IU/L and IL-6 ≥14.75pg/ml were significant predictors regarding to RMPP.

Conclusions

CRP≥16.5mg/L, LDH ≥417IU/L and IL-6 ≥14.75pg/ml might be the significant predictors of RMPP in children, which can aid in early recognition of RMPP.

Acute respiratory distress syndrome caused by Mycoplasma pneumoniae without elevated pulmonary vascular permeability: a case report

Sporadic patients with acute respiratory distress syndrome (ARDS) caused by Mycoplasma pneumoniae have been reported. However, knowledge about the pathophysiology and pharmacological treatment of this condition is insufficient. Moreover, the pulmonary vascular permeability in ARDS related to M. pneumoniae infection has not been reported. We report a case of ARDS caused by Mycoplasma pneumoniae without elevated pulmonary vascular permeability, which was successfully treated using low-dose short-term hydrocortisone, suggesting that pulmonary infiltration in ARDS caused by Mycoplasma pneumoniae does not match the criteria of permeability edema observed in typical ARDS.

Setting a standard for the initiation of steroid therapy in refractory or severe Mycoplasma pneumoniae pneumonia in adolescents and adults

Serum interleukin (IL)-18 level was thought to be a useful as a predictor of refractory or severe Mycoplasma pneumoniae pneumonia, and steroid administration is reported to be effective in this situation. The serum levels of IL-18 correlated significantly with those of lactate dehydrogenase (LDH). The purpose of this study was to set a standard for the initiation of steroid therapy in M. pneumoniae pneumonia using a simple serum marker. We analyzed 41 adolescent and adult patients with refractory or severe M. pneumoniae pneumonia who received steroid therapy, and compared them with 108 patients with M. pneumoniae pneumonia who responded to treatment promptly (control group). Serum LDH levels were significantly higher in the refractory and severe group than in the control group at the initiation of steroid therapy (723 vs 210 IU/L, respectively; p < 0.0001). From receiver operating characteristic curve analysis, we calculated serum LDH cut-off levels of 364 IU/L at initiation of steroid therapy and 302 IU/L at 1-3 days before the initiation of steroid therapy. The administration of steroids to patients in the refractory and severe group resulted in the rapid improvement of symptoms and a decrease in serum LDH levels in all patients. Serum LDH level can be used as a useful parameter to determine the initiation of steroid therapy in refractory or severe M. pneumoniae pneumonia. A serum LDH level of 302-364 IU/L seems to be an appropriate criterion for the initiation of steroid therapy.

Novel aspects on the pathogenesis of Mycoplasma pneumoniae pneumonia and therapeutic implications

Mycoplasma pneumoniae (Mp) is a leading cause of community acquired pneumonia. Knowledge regarding Mp pneumonia obtained from animal models or human subjects has been discussed in many different reports. Accumulated expertise concerning this critical issue has been hard to apply clinically, and potential problems may remain undiscovered. Therefore, our multidisciplinary team extensively reviewed the literature regarding Mp pneumonia, and compared findings from animal models with those from human subjects. In human beings, the characteristic pathological features of Mp pneumonia have been reported as alveolar infiltration with neutrophils and lymphocytes and lymphocyte/plasma cell infiltrates in the peri-bronchovascular area. Herein, we demonstrated the novel aspects of Mp pneumonia that the severity of the Mp pneumonia seemed to depend on the host innate immunity to the Mp, which might be accelerated by antecedent Mp exposure (re-exposure or latent respiratory infection) through up-regulation of Toll-like receptor 2 expression on bronchial epithelial cells and alveolar macrophages. The macrolides therapy might be beneficial for the patients with macrolide-resistant Mp pneumonia via not bacteriological but immunomodulative effects. This exhaustive review focuses on pathogenesis and extends to some therapeutic implications such as clarithromycin, and discusses the various diverse aspects of Mp pneumonia. It is our hope that this might lead to new insights into this common respiratory disease.

Characterization of macrolide resistance of Mycoplasma pneumoniae in children in Shenzhen, China

Macrolide-resistant Mycoplasma pneumoniae (MR-M. pneumoniae) was isolated from clinical specimens in Shenzhen, China from November 2010 to July 2011. A comparative study was conducted to determine whether macrolides are effective in treating patients infected with MR-M. pneumoniae. Of 57 M. pneumoniae strains, 36 harbored point mutations on A2063G in the 23S ribosomal RNA gene. A total of 36 (63%) strains were classified as MR-M. pneumonia and 21 (37%) as macrolide-susceptible M. pneumoniae (MS-M. pneumoniae). The clinical courses of MR-M. pneumoniae-infected patients (MR patients) treated with macrolides were compared with those of MS-M. pneumoniae-infected patients (MS patients). The patient demographics (sex, age), most laboratory findings, and diagnosis did not show significant differences between the two groups. The MR patients had higher mean total febrile days compared with MS patients (6.56 ± 6.17 days vs. 3.57 ± 3.80 days, P = 0.05). The MR patients were more likely to be have levels of high-sensitivity C-reactive protein than MS patients (42% (15/36) vs. 14% (3/21), P = 0.03). Although the febrile period was prolonged in MR patients treated with macrolides, the fever resolved even when the initial prescription was unchanged. Therefore, these results suggest that macrolides are less effective in MR patients than in MS patients.

Increased risk of refractory Mycoplasma pneumoniae pneumonia in children with atopic sensitization and asthma

Purpose

A nationwide outbreak of Mycoplasma pneumoniae pneumonia (MP) refractory to macrolide antibiotics occurred in Korea during 2011. Steroid therapy has been reported to be both efficacious and well tolerated in pediatric patients with refractory MP. We compared clinical features and laboratory characteristics between children with refractory MP requiring steroid treatment and those with macrolide-responsive MP and evaluated the risk factors associated with refractory MP.

Methods

We investigated 203 children who were admitted to our institution with MP from June to November 2011. Refractory MP was defined by persistent fever over 38.3℃ with progressive pulmonary consolidation or pleural effusion despite administration of appropriate macrolide antibiotics for 5 days or longer after admission. Steroid therapy was initiated on the fifth day after admission for refractory cases.

Results

There were 26 patients with refractory MP requiring steroid therapy. The mean duration of steroid therapy was 5.4 days and most of the patients were afebrile within 24 hours after initiation of steroid therapy. The prevalence of refractory MP was higher in patients with pleural effusion, lobar pneumonia affecting more than 2 lobes, higher levels of serum lactate dehydrogenase, increased oxygen requirements, and longer duration of hospitalization. Atopic sensitization and history of asthma were also associated with refractory MP after adjusting for age and gender.

Conclusion

Children with refractory MP had more severe pneumonia. Atopic sensitization and history of asthma may be risk factors for refractory MP requiring steroid therapy in Korean children.

Effects of prednisolone on refractory mycoplasma pneumoniae pneumonia in children

OBJECTIVES

To prospectively evaluate prednisolone treatment in children with refractory Mycoplasma pneumonia pneumonia (MPP).

METHODS

Fifty-eight refractory children with MPP were enrolled to receive either azithromycin combined with prednisolone (treatment group, n = 28) or azithromycin alone (control group, n = 30). Temperature, respiratory symptoms and signs were examined at the time of study entry and every 8 hr after enrollment, infiltration absorption, atelectasis resolution, pleural effusion disappearance, and serum ferritin and LDH levels were assessed on seventh day after enrollment.

RESULTS

All patients in treatment group achieved defervescence during 8-48 hr after enrollment versus no patient in the control group. The mean duration of hypoxemia was 1.9 ± 0.9 days in treatment group and 2.7 ± 1.1 days in the control group (P < 0.05), and the dyspnea resolved time was 1.5 ± 0.7 days and 2.9 ± 0.6 days (P < 0.05), respectively. Seven days after enrollment, 80% of patients in treatment group showed infiltration absorption versus 21.4% in control group (P < 0.05); the figures for atelectasis resolution were 71.4% versus 12.5% (P < 0.05), and for pleural effusion disappearance 88.9% versus 20.0% (P < 0.05). The serum ferritin and LDH level was lower in the treatment than that in control group (P < 0.05).

CONCLUSIONS

Azithromycin combined with prednisolone is a better treatment for children with refractory MPP than azithromycin alone.

More complications occur in macrolide-resistant than in macrolide-sensitive Mycoplasma pneumoniae pneumonia

We sought to understand the situation of macrolide-resistant genotypes of Mycoplasma pneumoniae, and analyze the relationship between macrolide-resistant genotypes and clinical manifestations of Mycoplasma pneumoniae pneumonia (MPP). Full-length sequencing of the 23S rRNA gene of M. pneumoniae was performed in 235 nasopharyngeal aspirates (NPAs) from children with MPP. We also retrospectively compared the clinical characteristics of macrolide-resistant (MR) M. pneumoniae infections and macrolide-sensitive (MS) M. pneumoniae infections. A total of 206 patients had point mutations in the M. pneumoniae 23S rRNA gene, and these patients are referred to as MR patients. The remaining 29 patients without point mutations are referred to as MS patients. Among 206 MR patients, 199 (96.6%) had A2063G mutations, 6 had A2063T mutations, and the remaining patients had an A2064G mutation. Among the clinical manifestations, we found that the median fever durations were 8 days (range, 0 to 42 days) and 6 days (0 to 14 days) (P < 0.01), the median hospitalization durations were 8 days (2 to 45 days) and 6 days (3 to 16 days) (P < 0.01), and the median fever durations after macrolide therapy were 5 days (0 to 42 days) and 3 days (0 to 10 days) (P < 0.01), respectively, in the MR and MS groups. We also found that the incidence of extrapulmonary complications in the MR group was significantly higher than that in the MS group (P < 0.05). Moreover, the radiological findings were more serious in the MR group than in the MS group (P < 0.05). The increasing prevalence of MR M. pneumoniae has become a significant clinical issue in the pediatric patients, which may lead to more extrapulmonary complications and severe clinical features and radiological manifestations.

Effects of Methylprednisolone Pulse Therapy on Refractory Mycoplasma pneumoniae Pneumonia in Children

Purpose

Mycoplasma pneumoniae (M. pneumoniae) is one of the most common causes of community-acquired pneumonia in children. The clinical course is typically self-limited and benign; however, rare cases of severe pneumonia can develop despite appropriate antibiotic therapy. We studied the effects of methylprednisolone pulse therapy on severe refractory M. pneumoniae pneumonia in children.

Methods

The clinical effects of methylprednisolone therapy were evaluated retrospectively in 12 children with severe refractory M. pneumoniae pneumonia, which was diagnosed serologically. All patients developed respiratory distress, high fever, and initial lobar pneumonic consolidation based on radiological findings. All clinical symptoms deteriorated despite appropriate antibiotic therapy. Thus, children were treated with intravenous methylprednisolone pulse therapy in addition to antibiotics.

Results

The average febrile period before admission was 4.9±1.7 days, and fever persisted in all children until steroid administration. Methylprednisolone pulse therapy (30 mg/kg) was given 5.4±2.5 days after admission. After methylprednisolone pulse therapy, clinical symptoms improved in all patients without adverse events. The fever subsided 0-2 h after initiation of corticosteroid therapy. The abnormal radiological findings resolved within 2.6±1.3 days, and the high C-reactive protein levels (6.7±5.9 mg/dL) on admission decreased to 1.3±1.7 mg/dL within 3.0±1.1 days after starting corticosteroid therapy.

Conclusions

Three-day methylprednisolone pulse therapy could be applied to treatment of refractory M. pneumoniae pneumonia despite appropriate antibiotic therapy and appeared to be efficacious and well-tolerated.

Mycoplasma pneumoniae extract induces an IL-17-associated inflammatory reaction in murine lung: implication for mycoplasmal pneumonia

Mycoplasma pneumoniae (Mp) may cause immune cell reactions as pivotal aspects of this clinically common respiratory pathogen. Our aim is to determine if Mp extract induces a cellular immune response associated with interleukin (IL)-17, leading to lung inflammation and lung injury. BALB/c mice were immunized with Mp extract intraperitoneally followed by its intratracheal administration, to mimic repeated Mp infection found in humans (repeated inoculation, RI group). Those with a single inoculation were compared as single inoculation group (SI group). Analysis of bronchoalveolar lavage fluid (BALF) demonstrated that keratinocyte-derived cytokine, tumor necrosis factor-α, and IL-6 were produced and peaked on days 0.5 or 1, followed by IL-17 on day 2. Levels of these mediators in BALF were higher in RI group than SI group (P < 0.05). Further, significantly more neutrophils were recruited to the lungs of the RI group (P < 0.05). These observations suggest that IL-17 is involved in the prolonged induction of neutrophils in mice treated with Mp extract.

Cluster of diffuse alveolar hemorrhage cases after the 2011 Tohoku Region Pacific Coast Earthquake

BACKGROUND

Diffuse alveolar hemorrhage (DAH) is a clinical syndrome that presents with progressively hemorrhagic bronchoalveolar lavage fluid (BALF) in serial samples and generally has a poor prognosis. The South Miyagi Medical Center, located on the inland side of southern Miyagi Prefecture, documented an increase in the number of patients with DAH after the 2011 Tohoku Region Pacific Coast Earthquake.

METHODS

We describe the clinical features of post-earthquake DAH in comparison to pre-earthquake DAH. We analyzed the data of the DAH patients we have been able to follow for at least 6 months since we started performing bronchoscopy and bronchoalveolar lavage (BAL) for all patients with interstitial lung disease in August 2009 until September 2011, and separated these patients into pre- and post-earthquake groups according to the earthquake date of March 11, 2011.

RESULTS

Post-earthquake DAH patients tended to test positive for infectious agents and showed higher serum IgE titers, with BALF that exhibited a tendency to higher silica concentrations. Post-earthquake DAH generally had a better prognosis than pre-earthquake DAH.

CONCLUSIONS

In describing the clinical features of post-earthquake cases of DAH, this report documents the possibility of an infection- and/or dust-induced, partially allergic, and relatively benign form of DAH.

Dexamethasone downregulates the systemic cytokine response in patients with community-acquired pneumonia

The influence of adjunctive corticosteroids on the cytokine response in community-acquired pneumonia (CAP) is largely unknown. In this study, we analyzed the effect of dexamethasone on the cytokine response in patients with CAP and evaluated whether this effect is dependent on the causative microorganism. We hypothesized that dexamethasone has a larger effect on the cytokine response in patients with pneumococcal pneumonia than in patients with pneumonia caused by an atypical bacterium. A total of 304 hospitalized, nonimmunocompromised patients with CAP were randomized to an adjunctive 4-day course of 5 mg dexamethasone once a day (n = 151) or a placebo (n = 153). Serum concentrations of interleukin-1 receptor antagonist (IL-1Ra), IL-6, IL-8, IL-10, IL-17, tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), macrophage inflammatory protein-1 alpha (MIP-1α), and monocyte chemotactic protein-1 (MCP-1) were measured on days 0, 1, 2, and 4 and at a control visit. Overall, the concentrations of IL-6 (P < 0.01), IL-8 (P < 0.01), MCP-1 (P < 0.01), and TNF-α (P < 0.01) were significantly lower on day 2 in the dexamethasone group than in the placebo group. In patients with pneumococcal pneumonia (n = 72), both treatment groups showed a rapid decrease of cytokine concentrations; only the concentration of TNF-α (P = 0.05) was significantly lower in the dexamethasone group on day 2. In patients with CAP caused by an atypical pathogen (Legionella pneumophila, Chlamydophila species, Coxiella burnetii, or Mycoplasma pneumoniae; n = 58), IL-1Ra (P < 0.01), IL-6 (P < 0.01), and MCP-1 (P = 0.03) decreased more rapidly in the dexamethasone group than in the placebo group. In conclusion, dexamethasone downregulates the cytokine response during CAP. This effect seems to be dependent on the causative microorganism. This study provides insight into which patients with CAP might benefit most from adjunctive dexamethasone.

Life-threatening pneumonia caused by macrolide-resistant Mycoplasma pneumoniae

Two siblings had pneumonia caused by macrolide-resistant Mycoplasma pneumoniae as determined by polymerase chain reaction and serology. One of them developed adult respiratory distress syndrome and required extracorporeal membrane oxygenation therapy. This report highlights the need for studies to evaluate the optimal treatment in severe cases of macrolide-resistant M. pneumoniae pneumonia.

Persistently elevated IgA antibodies to Mycoplasma pneumoniae in patients with internal carotid artery stenosis

Background: It has been suggested that Mycoplasma pneumoniae may play a role in the development of atherosclerosis, but to date this association is still a matter of debate due to conflicting findings.

Methods: We have investigated the levels of specific IgA antibodies to M. pneumoniae in 91 patients with internal carotid artery (ICA) stenosis using a commercial kit (SeroMP™ IgA; Savyon Diagnostics, Israel; cut-off value: 20 binding units; BU). All patients underwent surgery for ICA stenosis. From each patient, the first serum sample (S1) was taken before surgery, and the second after an interval of 6 month (S2).

Results: The S1 seroprevalence was 18.7% (17/91). Thirteen of the 17 patients with positive S1 levels also remained positive after six month, whereby no decrease of IgA level was seen (median S1 level: 34 BU, range: 22–65 BU; median S2 level: 37 BU, range: 22–58 BU). Specifically, six of the patients showed an increased level after 6 months, and six a decrease, with the level remaining constant in one patient. In contrast, only 3 of the 74 S1 negative patients became positive for anti-M. pneumoniae IgA between the taking of the first and the second serum specimen (p<0.01). None of the assessed demographic factors or risk factors for atherosclerosis was associated with IgA seropositivity, neither were the degree CAVK or the degree of stenosis.

Conclusion: These findings cannot be explained throughout by the general seroprevalence, or by past respiratory tract infections with the pathogen, and therefore may suggest a role for M. pneumoniae in the development of atherosclerosis, since a chronic infection must be assumed.

Combined treatment for child refractory Mycoplasma pneumoniae pneumonia with ciprofloxacin and glucocorticoid

OBJECTS

To evaluate the efficacy of combined treatment of ciprofloxacin and glucocorticoid for child refractory Mycoplasma pneumoniae (M. pneumoniae) pneumonia.

METHODS

Clinical and laboratory characteristics of six pediatric refractory M. pneumoniae pneumonia cases treated with ciprofloxacin and glucocorticoids were reported.

RESULTS

Five cases complicated with pleural effusion. The average febrile period prior to admission was 8.5 ± 2.0 days, the average total febrile period was 14.6 ± 7.6 days, and the average febrile period after treatment was 3.3 ± 3.0 days. The average time in hospital for patients was 23.6 ± 4.8 days. The initial mean WBC count was 10,100 ± 2,400/mm(3) . The erythrocyte sedimentation rate (ESR), lactate dehydrogenase (LDH), and C-reactive protein (CRP) in all cases were elevated during the course of illness. After combined therapy, all children clinically improved, with resolution of radiographic findings and normal laboratory items. We analyzed the 23S rRNA gene in four nasopharyngeal secretions, and found mutations in A2063G of domain V in three cases, and mutation in A2064G in the other case.

CONCLUSION

Combined treatment of ciprofloxacin and glucocorticoids can significantly ameliorate child refractory M. pneumoniae pneumonia further comparative study is needed to well evaluate the treatment efficacy.

Acute respiratory distress syndrome caused by Mycoplasma pneumoniae in a child: the role of methylprednisolone and clarythromycin

Mycoplasma pneumoniae is recognized as an important agent of pneumonia in pediatric population. In rare situations, severe pulmonary injury can develop. The use of corticoids in these cases remains controversial. A case of a girl with acute respiratory distress syndrome and bilateral pleural effusion secondary to pneumonia due to Mycoplasma pneumoniae is described, with good recovery after appropriate use of methylprednisolone and clarythromicyn.

Stevens-Johnson syndrome in a boy with macrolide-resistant Mycoplasma pneumoniae pneumonia

Mycoplasma pneumoniae is a highly specialized parasitic bacterium that is a significant cause of community-acquired pneumonia in children. Although most such respiratory infections are mild, a minor percentage of patients require hospitalization and, occasionally, intensive treatment for respiratory failure. A variety of extrapulmonary sequelae of M pneumoniae infections have been described, including Stevens-Johnson syndrome. Macrolide resistance in M pneumoniae has developed rapidly in Asia, particularly in China, over the past decade and is now appearing in the United States. Emerging resistance to macrolides creates a therapeutic conundrum, particularly for pediatricians caring for young children in whom absolute or relative contraindications exist for the use of tetracyclines or fluoroquinolones, the 2 other main classes of drugs shown to be efficacious for M pneumoniae. We describe here the case of a child with a prolonged febrile illness associated with Stevens-Johnson-like mucocutaneous involvement who was found to have a respiratory infection with macrolide-resistant M pneumoniae.

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.

Macrolide-resistant Mycoplasma pneumoniae: characteristics of isolates and clinical aspects of community-acquired pneumonia

Mycoplasma pneumoniae is one of the main pathogens causing community-acquired respiratory tract infections in children and adults. Macrolide (ML) antibiotics are recognized generally as first-choice agents for M. pneumoniae infections, and these antibiotics were thought to have excellent effectiveness against M. pneumoniae for many years. In 2000, however, M. pneumoniae showing resistance to macrolides was isolated from clinical samples obtained from Japanese pediatric patients with community-acquired pneumonia (CAP). Since then, prevalence of ML-resistant M. pneumoniae isolates in pediatric patients has increased rapidly. In 2007, ML-resistant M. pneumoniae isolates were obtained from Japanese adults with CAP; numbers of such isolates also have gradually increased in Japan. Recently, similar antimicrobial resistance in M. pneumoniae has begun to emerge worldwide. In this review, we focus on changes of ML-resistant M. pneumoniae from year to year and consider resistance mechanisms as well as clinical features of patients with resistant M. pneumoniae infection.