Pediatric respiratory infections by Mycoplasma pneumoniae

Observational retrospective clinical study on clinical features of macrolide-resistant Mycoplasma pneumoniae pneumonia in Chinese pediatric cases

This study aimed to investigate differences in clinical characteristics and laboratory findings between children infected with Macrolide-Sensitive Mycoplasma pneumoniae (MSMP) and Macrolide-Resistant Mycoplasma pneumoniae (MRMP). Additionally, the research sought to identify laboratory markers for rapidly distinguishing refractory Mycoplasma pneumoniae pneumonia (RMPP) from ordinary Mycoplasma pneumoniae pneumonia (OMPP). In total, 265 Mycoplasma pneumoniae (MP) patients were included, with MRMP identified by specific point mutations in domain V of the 23S rRNA gene. A retrospective analysis compared the clinical courses and laboratory data, revealing that MRMP patients experienced prolonged febrile days (P = 0.004), elevated CRP levels (P < 0.001), and higher MP DNA loads than MSMP patients (P = 0.037). Based on clinical symptoms, MRMP was divided into RMPP (n = 56) and OMPP (n = 70), with RMPP demonstrating significantly increased IL-18, community-acquired respiratory distress syndrome (CARDS) toxins in nasopharyngeal aspirate, and serum CRP levels (P < 0.001; P = 0.006; P < 0.001). In conclusion, timely recognition of RMPP is crucial for enhancing prognosis. The identification of MRMP, coupled with proinflammatory cytokines such as IL-18, CARDS toxins, and CRP, emerges as promising markers with the potential to contribute significantly to diagnostic accuracy and prognosis assessment.

Association between Mycoplasma pneumoniae infection, high‑density lipoprotein metabolism and cardiovascular health (Review)

The association between Mycoplasma pneumoniae (M. pneumoniae) infection, high-density lipoprotein metabolism and cardiovascular disease is an emerging research area. The present review summarizes the basic characteristics of M. pneumoniae infection and its association with high-density lipoprotein and cardiovascular health. M. pneumoniae primarily invades the respiratory tract and damages the cardiovascular system through various mechanisms including adhesion, invasion, secretion of metabolites, production of autoantibodies and stimulation of cytokine production. Additionally, the present review highlights the potential role of high-density lipoprotein for the development of prevention and intervention of M. pneumoniae infection and cardiovascular disease, and provides suggestions for future research directions and clinical practice. It is urgent to explore the specific mechanisms underlying the association between M. pneumoniae infection, high-density lipoprotein metabolism, and cardiovascular disease and analyze the roles of the immune system and inflammatory response.

The molecular characteristics, diagnosis, and treatment of macrolide-resistant Mycoplasma pneumoniae in children

The purpose of this study is to review the molecular characteristics, the diagnosis, and treatment of the widespread infection of macrolide-resistant Mycoplasma pneumoniae (M. pneumoniae; MRMP) in children, thus providing a better knowledge of this infection and presenting the associated problems. Single point mutations in the V region of the 23S rRNA gene of M. pneumoniae genome are associated with macrolide resistance. P1-1, MLVA4-5-7-2, and ST3 are usually the predominated genetic types in the M. pneumoniae epidemics. The short-term two times serological IgM (or together with IgG) test in the acute stage can be used for confirmation. Combined serological testing and PCR might be a more prudent method to reduce macrolide consumption and antibiotic selective pressure in a clinical setting. Molecular methods for the detection of single-nucleotide mutations in the V region of the 23S rRNA gene can be used for the diagnosis of MRMP. The routine use of macrolide for the treatment of macrolide-sensitive Mycoplasma pneumoniae (MSMP) infections can get good effect, but the effects are limited for severe MRMP infections. Additional corticosteroids may be required for the treatment of severe MRMP infections in children in China during the era of MRMP.

Assessment of variables associated with prolonged admission duration in children with Mycoplasma pneumoniae pneumonia

Introduction

Macrolide‐resistant Mycoplasma pneumoniae (MRMP) has become prevalent in children. This study investigated the clinical and laboratory variables of MRMP and macrolide‐sensitive M. pneumoniae (MSMP) and identified factors associated with prolonged hospital admission in children.

Methods

A prospective multicenter study was conducted in 1063 children <18 years old in July 2018–June 2020. The 454 had a positive M. pneumoniae polymerase chain reaction assay.

Results

Most subjects had MRMP (78.4%), and all mutated strains had the A2063G transition. We defined MRMP* (n = 285) as MRMP pneumonia requiring admission and MSMP* (n = 72) as MSMP pneumonia requiring admission. Patients with MRMP pneumonia were older, more likely to have segmental/lobar pneumonia, and had more febrile days than those with MSMP pneumonia. C‐reactive protein (CRP), lactate dehydrogenase (LDH), and percentage neutrophils were more strongly associated with MRMP* than MSMP* groups. Percentage neutrophils, CRP, and alanine aminotransferase significantly changed between admission and follow‐up measurements in patients with MRMP* (P < 0.05). The duration of admission positively correlated with the number of febrile days after initiation of antibiotic medication and laboratory variables (white blood cell count, CRP, and aspartate aminotransferase [AST]) (P < 0.05). Random forest analysis indicated that the number of febrile days after initiation of antibiotic medication, AST, and percentage neutrophils at admission was over five.

Conclusions

This study indicated that children with M. pneumoniae pneumonia with a higher number of febrile days after initiation of antibiotic medication, AST, and percentage neutrophils at admission were more likely to have prolonged admission duration.

Refractory Mycoplasma pneumoniae Pneumonia in Children: Early Recognition and Management

Refractory Mycoplasma pneumoniae pneumonia (RMPP) is a severe state of M. pneumoniae infection that has attracted increasing universal attention in recent years. The pathogenesis of RMPP remains unknown, but the excessive host immune responses as well as macrolide resistance of M. pneumoniae might play important roles in the development of RMPP. To improve the prognosis of RMPP, it is mandatory to recognize RMPP in the early stages, and the detection of macrolide-resistant MP, clinical unresponsiveness to macrolides and elevated proinflammatory cytokines might be clues. Timely and effective anti-mycoplasmal therapy and immunomodulating therapy are the main strategies for RMPP.

Biomarkers of Mycoplasma pneumoniae pneumonia in children by urine metabolomics based on Q Exactive liquid chromatography/tandem mass spectrometry

RATIONALE

Mycoplasma pneumoniae has become one of the common pathogens causing pediatric respiratory infections. In clinical diagnosis, throat swabs are very difficult to obtain from children, and there is a possibility of false positive results; hence, there are few clinically available diagnostic methods.

METHODS

In this study, Q Exactive liquid chromatography/tandem mass spectrometry was used to analyze the metabolites in the urine of healthy children (HC) and M. pneumoniae pneumonia in children (MPPC) patients. A multivariate statistical analysis was performed to screen the differential metabolites. Based on the HMDB and KEGG, the possible metabolic pathways subject to biological alteration were identified.

RESULTS

Compared with HC, 73 different metabolites in MPPC patients disrupted nine metabolic pathways through different change trends; after integrating various parameters, 20 significantly different metabolites were identified as MPPC potential biomarkers. Through the above two analysis modes, acetylphosphate and 2,5-dioxopentanoate were both screened out and used as potential biomarkers for the early diagnosis of MPPC for the first time.

CONCLUSIONS

The characterization of 20 potential biomarkers provides a scientific basis for predicting and diagnosing MPPC. This article further indicates that urine metabolic profiling has great potential in diagnosing MPPC and can effectively prevent the disease from causing further deterioration.

Community-Acquired Respiratory Distress Syndrome Toxin: Unique Exotoxin for M. pneumoniae

Mycoplasma pneumoniae infection often causes respiratory diseases in humans, particularly in children and adults with atypical pneumonia and community-acquired pneumonia (CAP), and is often exacerbated by co-infection with other lung diseases, such as asthma, bronchitis, and chronic obstructive pulmonary disorder. Community-acquired respiratory distress syndrome toxin (CARDS TX) is the only exotoxin produced by M. pneumoniae and has been extensively studied for its ADP-ribosyltransferase (ADPRT) activity and cellular vacuolization properties. Additionally, CARDS TX induces inflammatory responses, resulting in cell swelling, nuclear lysis, mucus proliferation, and cell vacuolization. CARDS TX enters host cells by binding to the host receptor and is then reverse transported to the endoplasmic reticulum to exert its pathogenic effects. In this review, we focus on the structural characteristics, functional activity, distribution and receptors, mechanism of cell entry, and inflammatory response of CARDS TX was examined. Overall, the findings of this review provide a theoretical basis for further investigation of the mechanism of M. pneumoniae infection and the development of clinical diagnosis and vaccines.

Effects of four types of chinese medicines as concomitant drugs with azithromycin for the treatment of mycoplasma pneumonia in children in China: a network meta-analysis

OBJECTIVE

The purpose of this study was to evaluate the efficacy of the use of four concomitant Chinese medicines with azithromycin in the treatment of mycoplasma pneumonia in children (MPC) by using network meta-analysis (NMA) and ranking them according to their performances.

METHODS

There were a total of 130 randomly controlled trials of four different concomitant Chinese medicines with azithromycin for the treatment of MPC in many databases, and an NMA was conducted in them by using Stata (version 13.0) software to evaluate the odds ratio (OR) and sequence of the different combinations. The included studies were divided into two groups: control group (azithromycin alone) and observation group (one of four azithromycin combinations).

RESULTS

A total of 13119 cases were included in this study, and the results showed that the pooled OR and 95% confidence interval (CI) of MPC improvement compared with azithromycin alone were 4.76 (3.18-7.14) for azithromycin and Reduning, 5.66 (4.50-7.12) for azithromycin and Tanreqing, 4.84 (3.35-7.01) for azithromycin and Xiyanping, and 4.58 (3.59-5.83) for azithromycin and Yanhuning, respectively. This study shows the significant efficacy of Chinese concomitant drug. The combination of azithromycin with Tanreqing is the best candidate of concomitant drug in terms of clinical efficacy. Its surface under the cumulative ranking (SUCRA) score was 85.5, while the SUCRA score for the azithromycin and Yanhuning combination was the worst, which is 48.4.

CONCLUSIONS

The combination of azithromycin with Tanreqing is the most promising group among four combinations for the treatment of MPC.

Mutations in domain V of Mycoplasma pneumoniae 23S rRNA and clinical characteristics of pediatric M. pneumoniae pneumonia in Nanjing, China

OBJECTIVE

To investigate the prevalence of mutations in domain V of Mycoplasma pneumoniae (MP) 23S ribosomal RNA (rRNA) and the clinical characteristics of pediatric MP pneumonia (MPP) in Nanjing, China.

METHODS

Domain V of 23S rRNA was sequenced in MP strains collected from children diagnosed with MPP in Nanjing. Clinical and laboratory data were obtained.

RESULTS

Among the 276 MP strains, 255 (92.39%) harbored mutations, primarily A2063G in domain V of MP 23S rRNA. When children were stratified according to the presence or absence of mutations, no significant differences were found in sex, age, the MP DNA load at enrollment, lymphocyte counts, pulmonary complications, immunomodulator levels, fever duration, the duration of fever after macrolide therapy, and hospital stay. The prevalence of refractory MPP in the two groups was similar. Children with refractory MPP exhibited higher MP DNA loads than those with non-refractory MPP.

CONCLUSIONS

Despite the high prevalence of the A2063G mutation in domain V of MP 23S rRNA, mutations were not associated with the clinical characteristics of MPP. The MP DNA load significantly differed between refractory and non-refractory MPP.

Macrolide-Resistant and Macrolide-Sensitive Mycoplasma pneumoniae Pneumonia in Children Treated Using Early Corticosteroids

We have found that early corticosteroid therapy was effective for reducing morbidity during five Korea-wide epidemics. We evaluated the clinical and laboratory parameters of 56 children who received early corticosteroid treatment for pneumonia that was caused by macrolide-resistant Mycoplasma pneumoniae (M. pneumoniae) or macrolide-sensitive M. pneumoniae between July 2019 and February 2020. All subjects had dual positive results from a PCR assay and serological test, and received corticosteroids within 24–36 h after admission. Point mutation of residues 2063, 2064, and 2067 was identified in domain V of 23S rRNA. The mean age was 6.8 years and the male:female ratio was 1.2:1 (31:25 patients). Most of the subjects had macrolide-resistant M. pneumoniae (73%), and all mutated strains had the A2063G transition. No significant differences in clinical and laboratory parameters were observed between macrolide-resistant and macrolide-sensitive M. pneumoniae groups that were treated with early dose-adjusted corticosteroids. Higher-dose steroid treatment may be needed for patients who have fever that persists for >48 h or increased biomarkers such as lactate dehydrogenase concentration at follow-up despite a usual dose of steroid therapy.

Early Confirmation of Mycoplasma pneumoniae Infection by Two Short-Term Serologic IgM Examination

The aim of the present study is to re-evaluate the clinical application of two-times serologic immunoglobulin M (IgM) tests using microparticle agglutination assay (MAA), an enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) assay in diagnosing Mycoplasma pneumoniae (MP) infection. A retrospective analysis of 62 children with MP pneumonia during a recent epidemic (2019–2020) was conducted. The MAA and ELISA immunoglobulin M (IgM) and IgG measurements were conducted twice at admission and around discharge, and MP PCR once at presentation. Diagnostic rates in each test were calculated at presentation and at discharge. The seroconverters were 39% (24/62) of patients tested by MAA and 29% (18/62) by ELISA. At presentation, the diagnostic positive rates of MAA, ELISA, and PCR tests were 61%, 71%, and 52%, respectively. After the second examination, the rates were 100% in both serologic tests. There were positive correlations between the titers of MAA and the IgM values of ELISA. The single serologic IgM or PCR tests had limitations to select patients infected with MP in the early stage. The short-term, paired IgM serologic tests during hospitalization can reduce patient-selection bias in MP infection studies.

The effect of vibrating positive expiratory pressure therapy on refractory Mycoplasma pneumoniae pneumonia prognosis in children

BACKGROUND

It is well documented that vibration techniques and positive expiratory pressure (PEP) can improve airway clearance, however, few clinical trials have studied the efficacy of vibrating PEP therapy on refractory Mycoplasma pneumoniae (M. pneumoniae) pneumonia (RMPP) in children. This study aimed to explore using vibrating PEP therapy in children with RMPP.

METHODS

Sixty participants in the remission stage of RMPP were recruited into this randomized study and divided into two groups. The Acapella group (n=30) used the Acapella^® Choice twice daily for 2 months to clear their airways. The control group (n=30) used traditional chest percussion or postural drainage to mediate sputum expectoration. The groups administered their respective treatments at home and were followed up weekly. Participants kept a record of their treatment and condition in a daily log. The primary outcome of this study was the resolution of chest images, and the secondary outcome was the sputum period.

RESULTS

There was no significant difference in sex or age distribution between the two groups. There were no significant differences at baseline between the groups in the location of their lesions (P=0.11). After 2 months of treatment, there was a better resolution of chest images in the Acapella group (P=0.00) compared with the control group. Additionally, the mean sputum period was significantly shorter for the Acapella group than for the control group (Acapella: 7.97±1.54 days; control: 11.90±1.64 days; P=0.00).

CONCLUSIONS

Vibrating PEP therapy is an effective therapy for children with RMPP, both in airway clearance and the resolution of lung abnormalities.

Immunopathogenesis of COVID-19 and early immunomodulators

The novel coronavirus disease 2019 (COVID-19) is spreading globally. Although its etiologic agent is discovered as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), there are many unsolved issues in COVID-19 and other infectious diseases. The causes of different clinical phenotypes and incubation periods among individuals, species specificity, and cytokine storm with lymphopenia as well as the mechanism of damage to organ cells are unknown. It has been suggested that in viral pneumonia, virus itself is not a direct cause of acute lung injury; rather, aberrant immune reactions of the host to the insults from viral infection are responsible. According to its epidemiological and clinical characteristics, SARS-CoV-2 may be a virus with low virulence in nature that has adapted to the human species. Current immunological concepts have limited ability to explain such unsolved issues, and a presumed immunopathogenesis of COVID-19 is presented under the proteinhomeostasis-system hypothesis. Every disease, including COVID-19, has etiological substances controlled by the host immune system according to size and biochemical properties. Patients with severe pneumonia caused by SARS-CoV-2 show more severe hypercytokinemia with corresponding lymphocytopenia than patients with mild pneumonia; thus, early immunomodulator treatment, including corticosteroids, has been considered. However, current guidelines recommend their use only for patients with advanced pneumonia or acute respiratory distress syndrome. Since the immunopathogenesis of pneumonia may be the same for all patients regardless of age or severity and the critical immune-mediated lung injury may begin in the early stage of the disease, early immunomodulator treatment, including corticosteroids and intravenous immunoglobulin, can help reduce morbidity and possibly mortality rates of older patients with underlying conditions.

Assessment of serum sialic acid correlated with C3 in children with Mycoplasma pneumoniae pneumonia

Background

Different from the diagnosis of bacterial infections, Mycoplasma pneumoniae pneumonia (MPP) is still lacking of convenient non‐specific laboratory parameters.

Method

A total of 125 children with MPP were included in the MPP group and 89 children with Mycoplasma‐negative pneumonia were included in the control group, and the sera were collected from the children at both the acute and recovery stages in the two groups.

Results

The sialic acid and C3 in the MPP group were significantly higher than those in the control group both at the acute and at the recovery stage. On the other hand, the sialic acid and C3 at the acute stage were significantly higher than those at the recovery stage in the MPP group. However, in the control group, the sialic acid and C3 demonstrated IgG exhibited no significant change between the acute stage and the recovery stage. Lastly, positive correlations between sialic acid level and C3 level were identified in the MPP group at both acute and recovery stages.

Conclusion

Our study demonstrated that the serum sialic acid correlated with C3 specifically increased in children with MPP, indicating that it might be the important non‐specific parameters in the diagnosis of MPP.

Low-Dose Corticosteroid Treatment in Children With Mycoplasma pneumoniae Pneumonia: A Retrospective Cohort Study

Background: The clinical value of corticosteroid treatment in Mycoplasma pneumoniae pneumonia (MPP) has been controversial. Our study aimed to identify the effects of low-dose corticosteroids on the recovery of children with MPP. Methods: In this retrospective cohort study, pediatric inpatients with MPP were included from the Shanghai Children's Mycoplasma pneumoniae pneumonia cohort study between August 2014 and July 2019. The multivariable logistic regression and propensity-score matching were used to investigate the effects of low-dose corticosteroid treatment on fever duration after admission, total fever duration, length of hospital stay, C-reactive protein recovery time, and imaging recovery time with the stratification of severe pneumonia, refractory pneumonia, inflammatory biomarkers, pulmonary images, and timing of corticosteroids. Results: There were 548 patients in the corticosteroid group and 337 in the no-corticosteroid group. The corticosteroid group showed severe clinical parameters such as more severe and refractory cases, higher laboratory values, and more abnormal imaging manifestations. The corticosteroid group also showed longer fever duration after admission [odds ratio (OR) = 1.9 (95% CI, 1.2-3.1), P = 0.008], longer total fever duration [OR = 1.6 (95% CI, 1.1-2.3), P = 0.011], longer hospital stay [OR = 2.8 (95% CI, 1.9-4.0), P < 0.001], and longer C-reactive protein (CRP) recovery time [OR = 2.1 (95% CI, 1.1-3.9), P = 0.021] in the regression model after the adjustment for severity. Although low-dose corticosteroids were associated with shortened imaging recovery time in patients with high level laboratory values, pulmonary imaging could be completely recovered in both groups. The trend of these results was consistent even after stratifications and a propensity scores matching analysis. Conclusions: Low-dose corticosteroids may not be beneficial in children inpatients with MPP, and further studies on proper treatment modality are needed in the MRMP era.

Risk factors of 90-day rehospitalization following discharge of pediatric patients hospitalized with mycoplasma Pneumoniae pneumonia

Background

Among pediatric patients hospitalized for Mycoplasma pneumoniae pneumonia (MPP), the risk factors for 90-day readmission after discharge is undefined.

Methods

We conducted a retrospective observational study of patients <14 years of age who were discharged with a diagnosis of MPP between January 2016 and February 2017. We collected clinical, laboratory and radiographic variables at the time of initial admission. We assessed pneumonia-related readmission within 90-day after discharge. Risk factors independently associated with rehospitalization were identified using multiple logistic regression models.

Results

Of the 424 MPP hospitalizations, 48 (11.3%) were readmitted within 90 days and were mainly diagnosed with pneumonia. Patients with younger age or coinfection with influenza A were more likely to be readmitted. In addition, compared with children without readmission, the readmission ones showed different clinical and laboratory characteristics at the index hospital admission. Multiple logistic regression analysis identified age (OR 0.815, 95%CI 0.706–0.940) and body temperature (OR 0.659, 95%CI 0.518–0.839) were significantly associated with lower risk of 90-day readmission. Coinfection with influenza was independently associated with a greater likelihood of 90-day readmission (OR 4.746, 95%CI 1.191–18.913).

Conclusions

Readmission after MPP are common and is related to patients’ age, body temperature and influenza A coinfection during initial hospital stay, indicating potential targets could be noticed to reduce the rehospitalization after pediatric MPP.

Early Corticosteroid Therapy for Mycoplasma pneumoniae Pneumonia Irrespective of Used Antibiotics in Children

Antibiotics’ effect on Mycoplasma pneumoniae (MP) infection still remains controversial. A prospective study of 257 children with MP pneumonia during a recent epidemic (2015–2016) was conducted. All MP pneumonia patients were treated with corticosteroids within 24–36 h after admission. Initially, oral prednisolone (1 mg/kg) or intravenous methylprednisolone (IVMP; 1–2 mg/kg) was administered for mild pneumonia patients, and IVMP (5–10 mg/kg/day) for severe pneumonia patients. If patients showed a persistent fever for 36–48 h or disease progression, additive IVMP (5 mg/kg or 10 mg/kg) was given. Thirty-three percent of patients received only a broad-spectrum antibiotic without a macrolide. The mean age and the male-to-female ratio was 5.6 ± 3.1 years and 1:1, respectively. Seventy-four percent of patients showed immediate defervescence within 24 h, and 96% of patients showed defervescence within 72 h with improvements in clinical symptoms. Three percent of patients (8/257) who received additive IVMP also showed clinical improvement within 48 h without adverse reactions. There were no clinical or laboratory differences between patients treated with a macrolide (n = 172) and without (n = 85). Early corticosteroid therapy might reduce disease morbidity and prevent disease progression in MP pneumonia patients without side effects, and antibiotics may have limited effects on MP infection.

Epidemiological relationship between Mycoplasma pneumoniae pneumonia and recurrent wheezing episode in children: an observational study at a single hospital in Korea

OBJECTIVE

This study was aimed to evaluate epidemiological and clinical relationship between Mycoplasma pneumoniae (MP) infection and childhood recurrent wheezing episode (RWE).

DESIGN

Retrospective case note review.

SETTING

Paediatric department at a single Korean institution.

PARTICIPANTS

Consecutive admitted patients with MP pneumonia and RWE (0-15 years of age) between 2003 and 2014.

METHODS

The retrospective medical records of patients with (MP) pneumonia (n=793 for epidemiological analysis and n=501 for clinical analysis) and those with RWE (n=384) from 2003 to 2014 were analysed. Diagnosis of MP pneumonia was made based on two-times titration of IgM antibody during hospitalisation. An RWE patient was defined as one with expiratory wheezing with at least one or more wheezing episodes based on medical records.

RESULTS

During three MP pneumonia epidemics, there were no corresponding increases of patients with RWE in the epidemic years. In the 501 MP pneumonia patients, 52 (10.4%) had wheezing at presentation and 15 (3%) had RWE. The MP pneumonia patients with wheezing at presentation (n=52) were younger and were more likely to have an allergic disease history than those without wheezing (n=449). Among wheezing patients at presentation, 10 patients had previously RWE history. In a follow-up study, 13 patients (including 5 RWE) with initial wheezing and 25 patients (including 2 RWE) without wheezing had wheezy episodes after discharge. Among the total 501 patients, it was estimated that at least 31 MP pneumonia patients (6.2%) showed recurrent wheezing after initial MP infection.

CONCLUSIONS

A small part of children with MP pneumonia showed recurrent wheezing after MP pneumonia, and patients with RWE had a greater likelihood of experiencing wheezing when they had an initial MP infection. However, there were no increased admitted patients with RWE in MP pneumonia epidemic periods because of rarity of MP reinfection in children including patients with RWE or asthma.

Transcriptome Analysis of Bronchoalveolar Lavage Fluid From Children With Mycoplasma pneumoniae Pneumonia Reveals Natural Killer and T Cell-Proliferation Responses

Background

Mycoplasma pneumoniae pneumonia (MPP) is one of the most common community-acquired pneumonia; this study is to explore the immune-pathogenesis of children MPP.

Methods

Next-generation transcriptome sequencing was performed on the bronchoalveolar lavage fluid cells from six children with MPP and three children with foreign body aspiration as control. Some of the results had been validated by quantitative real-time PCR in an expanded group of children.

Results

Results revealed 810 differentially expressed genes in MPP group comparing to control group, of which 412 genes including RLTPR, CARD11 and RASAL3 were upregulated. These upregulated genes were mainly enriched in mononuclear cell proliferation and signaling biological processes. Kyoto encyclopedia of genes and genomes pathway analysis revealed that hematopoietic cell linage pathway, natural killer cell-mediated cytotoxicity pathway, and T cell receptor signaling pathway were significantly upregulated in MPP children. In addition, significant alternative splicing events were found in GNLY and SLC11A1 genes, which may cause the differential expressions of these genes.

Conclusion

Our results suggest that NK and CD8+ T cells are over activated and proliferated in MPP children; the upregulated IFNγ, PRF1, GZMB, FASL, and GNLY may play important roles in the pathogenesis of children MPP.

Pattern and Significance of Asymptomatic Elevation of Liver Enzymes in Mycoplasma Pneumonia in Children

Mycoplasma infection is on the rise in recent times. It usually infects any system, including liver. This study aims to show the significance of elevated liver enzymes in mycoplasma pneumonia and to have a look at future prospects. This is a single-center retrospective study involving 105 children serologically positive for mycoplasma IgM and IgG antibodies and 50 with community-acquired pneumonia caused by organisms other than mycoplasma and Epstein-Barr virus from June 2015 to June 2016 and all without prior liver disease. The patients were followed after 10 days (7-14 days). The liver enzymes were significantly elevated in Mycoplasma pneumoniae infection. The mean levels of alanine transaminase and aspartate transaminase were 39.3 and 32.5 IU/L, respectively. There was a seasonal variation during the months of September and February. Liver involvement in mycoplasma pneumonia is mostly a benign condition and asymptomatic. It is insisted that children with continued elevation should be followed conservatively to avoid unnecessary diagnostic procedures in the future.

Lung Infections

A review of pulmonary infections of all types with diagnostic and morphological features.

Molecular characterization of genomic DNA in mycoplasma pneumoniae strains isolated from serious mycoplasma pneumonia cases in 2016, Yunnan, China

Mycoplasma pneumoniae (MP) is particularly prevalent in low-immunity school-age children. Few data have been reported on MP prevalence in Yunnan, China. This study was designed to investigate the prevalence and characterize genomic DNA of MP in a small outbreak in 2016, Southwest China. RepMP4 and RepMP2/3 genes of MP positive samples were amplified for molecular typing through sequence alignment and PCR-RFLP assay. Phylogenetic trees were constructed by MEGA5.0. The results showed that two distinct P1 types (type I and type II) were prevalent in this MP outbreak. Type I was the most prevalent type, and clustered in the same evolutionary branch of C26 (China, 2012). Only 1 MP isolate belonged to type II, and clustered in the branch of KCH405 (Japan, 2016). Fifty-nine nucleotide mutations were observed in P1 genes of type I isolates (51 in RepMP4, 8 in RepMP2/3). Ninety-five nucleotide mutations were observed in P1 genes of the type II isolates (33 in RepMP4, 62 in RepMP2/3). It is noteworthy that 31 mutation sites were clustered in an 84-bp fragment in the RepMP4 gene of type II isolates. One new fragment that appeared in two of the type I strains was not found in NCBI. Nucleotide diversity analyze results showed that RepMP4 was more likely to be genetically diverse than RepMP2/3. Two-tailed Z-test result of RepMP4 suggested positive selection between 6 P1 type I isolates and M29 (China, 2005). According to secondary structure prediction, 36 new possible protein binding sites were found and another 9 sites were lost, 2 helices were missed and 1 new helix appeared in type I isolates. As for type II isolates, 16 protein binding regions were gained and 31 were lost. This study may help to understand the intrinsic geographical relatedness and contributes further to the research of MP.

Mycoplasma Pneumoniae: A Cross-sectional Population-based Comparison of Disease Severity in Preschool and School-age Children

BACKGROUND

Mycoplasma pneumoniae causes epidemics of upper respiratory disease and pneumonia. It is thought that M. pneumoniae usually causes milder upper respiratory disease in preschool children, with a greater chance of pneumonia in school-age children. In this population-based cross-sectional study, we present evidence that severe M. pneumoniae infection is more common in preschool children than previously thought.

METHODS

During an M. pneumoniae epidemic in our area, widespread health service and public awareness lead to extensive testing for M. pneumoniae. Medical records of hospital-referred M. pneumoniae-positive children were assessed retrospectively for respiratory disease and chest radiographic results. Severe disease was defined as supplementary oxygen or fluid requirement, mechanical ventilatory support or neurologic disease. Age-specific population figures were used to calculate incidence during the study period. Those who were 0-5-year-olds were considered preschool, whereas 6-17-year-olds were considered school-aged.

RESULTS

Thirty-seven preschool and 55 school-age children were referred to the hospital and tested positive for M. pneumoniae. Twenty-two (60%) preschool and 23 (42%) school-age children had severe disease [incidence 56 vs. 29 per 100,000; relative risk: 1.9; 95% confidence interval (CI): 1.06-3.4; P = 0.03]. Twenty (54%) preschool and 19 (35%) school-age children had severe pneumonia (incidence 51 vs. 24 per 100,000; relative risk: 2.1; 95% CI: 1.1-3.9; P = 0.03).

CONCLUSIONS

During an M. pneumoniae epidemic in Akershus and North Oslo in 2011-2012, preschool children infected with M. pneumoniae had significantly higher risk of severe disease, particularly severe pneumonia, when compared with school-age children. M. pneumoniae should be considered a potential pathogen in younger children with respiratory distress, particularly during an epidemic period.

ATF3 inhibits the inflammation induced by Mycoplasma pneumonia in vitro and in vivo

OBJECTIVES

Activating transcription factor-3 (ATF3) is a key regulator of inflammatory responses. We aimed to investigate the effects and mechanisms of ATF3 on the inflammatory cytokines are induced by Mycoplasma pneumonia (MP).

STUDY DESIGN

RAW264.7 and mouse peritoneal macrophages were exposed to various time with or without MP infection (3, 6, 12, 24, and 48 h), and detect the expression of ATF3. Adenovirus-expression of ATF3 (Ad/ATF3) or Ad/βgal was transfected into cells which were exposed to MP for 48 h, RT-PCR and ELISA was used to evaluate the expression and secretion of TNF-α, IL-1β, IL-6, and IL-18. In addition, intravenous administration Ad/ATF3 or Ad/βgal into the mice, the secretion of inflammatory cytokines were detected using ELISA. ChIP assay was used to determine whether ATF3 can bind to the promoter of Early growth response protein 1 (Egr-1). Western blot was used to detect the expression of Egr-1 and Fyn.

RESULTS

ATF3 was increased at 3, 6, 12, and 24 h and the highest expression levels occurs in 6 h, there is no significant differences at 24 and 48 h compared with 0 h or CON group in RAW 264.7. Similar results were seen in mouse peritoneal macrophages. Overexpression of ATF3 resulted in the reduction of inflammatory cytokines. ChIP assay revealed that ATF3 can bind to the promoter of Egr-1. Overexpression of ATF3 inhibited the protein expression of Egr-1 and Fyn; conversely, ATF3-deficiency promoted the expression of Egr-1 and Fyn. Overexpression of Egr-1 reduced the anti-inflammatory action of ATF3.

CONCLUSIONS

ATF3 inhibit the expression and release of TNF-α, IL-1β, IL-6, and IL-18 induced by MP in vitro and in vivo, which is associated with its negative regulation of Egr-1/Fyn signaling pathway.

Effects of methylprednisolone or immunoglobulin when added to standard treatment with intravenous azithromycin for refractory Mycoplasma pneumoniae pneumonia in children

BACKGROUND

The prevalence of Mycoplasma pneumoniae pneumonia has increased considerably in recent years. To evaluate the efficacy of combined treatment of azithromycin with intravenous immunoglo-bulin (IVIG) or methylprednisolone in children with refractory Mycoplasma pneumoniae pneumonia (RMPP).

METHODS

Children with RMPP were randomly allocated to group A [intravenous azithromycin (IA)+ methylprednisolone], group B (IA+IVIG) or group C (IA alone). Following a 7-day treatment, group C patients were randomly separated into two sub-groups: group C₁ (IA+methylprednisolone) and group C₂ (IA+IVIG). Temperature, respiratory symptoms and signs were examined. The average febrile period after treatment (F₂), average total febrile period (F₃), infiltration absorption, atelectasis resolution, pleural effusion disappearance were determined. The levels of C-reactive protein (CRP), D-dimer, and lactate dehydrogenase (LDH) were measured.

RESULTS

Seven days after enrollment, the average F₂ after treatment of group A was the shortest. Compared with the control group C, the combined treatment group A and B showed higher rates of infiltration absorption, atelectasis resolution and pleural effusion disappearance, while lower levels of serum CRP, D-dimer and LDH. Fourteen days after enrollment, all children with combined therapy clinically improved, and presented better laboratory results. Group C₁ showed shorter F₃ and lower levels of CRP and LDH than those of group C₂. Overall, group A showed the shortest F₃, also has the lowest CRP and LDH.

CONCLUSIONS

Azithromycin with IVIG or methylprednisolone was better treatment for children with RMPP than azithromycin alone. IVIG treatment may be beneficial, especially when the efficacy of corticosteroids is insecure, thus could be considered as an alternative of primary therapeutic approaches.

Mycoplasma pneumoniae 23S rRNA A2063G mutation does not influence chest radiography features in children with pneumonia

Objective

To measure the rate of the A2063G mutation in the Mycoplasma pneumoniae (M. pneumoniae) 23S rRNA domain V in children with pneumonia and to determine the correlation between radiographic findings and the presence of the A2063G mutation.

Methods

Patients who were hospitalized with a confirmed diagnosis of M. pneumoniae pneumonia were enrolled in this study. M. pneumoniae strains were collected for genotype analysis. Chest radiography was performed on all children prior to and following macrolide treatment. Clinical and imaging data were obtained.

Results

Of 211 patients, 195 (92.42%) harboured M. pneumoniae with the A2063G mutation. No significant differences were identified in inflammation score, chest radiography inflammation absorption grade before and after macrolide treatment, or pulmonary complications (atelectasis, hydrothorax, or pleuritis) prior to macrolide treatment when children were stratified based on the presence or absence of the A2063G mutation.

Conclusions

A high proportion of children with pneumonia harboured strains of M. pneumoniae with the A2063G mutation in the 23S rRNA domain V. However, no obvious chest radiographic features of M. pneumoniae pneumonia were associated with the A2063G variant.

A comparison study between GeXP-based multiplex-PCR and serology assay for Mycoplasma pneumoniae detection in children with community acquired pneumonia

Background

Diagnosis of community-acquired pneumonia (CAP) caused by Mycoplasma pneumoniae (Mp) in children has been hampered by difficulty in obtaining convalescent serum and time constraints. In this study, the two diagnostic assays that targeted respectively on Mp-antibody and Mp-DNA were retrospectively investigated.

Methods

A total of 3146 children were clinically diagnosed to have CAP and were confirmed by chest X-ray during March 2015 to February 2016 in Children’s hospital of Hebei Province (China). Both of the sera and sputum samples were collected in 24 h after their admission. The Mp-antibody was examined by the passive particle agglutination assay and a fourfold or greater increase of antibody titers of paired sera or≧1:160 titer of single serum was set as the serology positive. Mp-DNA in the sputum samples was tested by a multiplex-PCR method named GeXP assay (multiplex PCR combined with automated capillary electrophoresis). In order to eliminate the false positive results caused by the asymptomatic carriage after infected by M. pneumoniae, the inconsistent samples were tested by the real-time isothermal transcription-mediated RNA amplification assay (SAT).

Results

The inter-rated agreement test was performed in 3146 CAP patients, with a highest kappa value in the school-age children as 0.783. There were 6.29% (198/3146) cases showed inconsistent results determined by GeXP and serology assay. All of the 19 GeXP(+)/Serology (−) samples and a randomly chosen 27 from 179 GeXP(−)/Serology (+) samples were tested by SAT assay, and a 97.8% diagnosis agreement was observed between SAT and GeXP assay, but not with the serology assay. In addition, patients who were detected only by serology or only by multiplex-PCR were significantly younger than those with both methods positive (3.0 and 1.5 years vs. 5.0 years, p < 0.01). The Viral-Mp coinfection accounted for 37.0% (97/262), which was more common in winter and spring (p < 0.05) and in the infantile group (p < 0.01), compared to the pure Mp positive ones.

Conclusion

In some children CAP cases, the Mp laboratory diagnosis was inconsistent between serology and multiplex-PCR assay. Verified by the SAT assay, the GeXP showed a more sensitive and reliable performance compared with the serology assay. Furthermore, employing the multiplex-PCR could provide more information on the associated pathogens for clinical assessment of CAP.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2614-3) contains supplementary material, which is available to authorized users.

Pneumonia, Acute Respiratory Distress Syndrome, and Early Immune-Modulator Therapy

Acute respiratory distress syndrome (ARDS) is caused by infectious insults, such as pneumonia from various pathogens or related to other noninfectious events. Clinical and histopathologic characteristics are similar across severely affected patients, suggesting that a common mode of immune reaction may be involved in the immunopathogenesis of ARDS. There may be etiologic substances that have an affinity for respiratory cells and induce lung cell injury in cases of ARDS. These substances originate not only from pathogens, but also from injured host cells. At the molecular level, these substances have various sizes and biochemical characteristics, classifying them as protein substances and non-protein substances. Immune cells and immune proteins may recognize and act on these substances, including pathogenic proteins and peptides, depending upon the size and biochemical properties of the substances (this theory is known as the protein-homeostasis-system hypothesis). The severity or chronicity of ARDS depends on the amount of etiologic substances with corresponding immune reactions, the duration of the appearance of specific immune cells, or the repertoire of specific immune cells that control the substances. Therefore, treatment with early systemic immune modulators (corticosteroids and/or intravenous immunoglobulin) as soon as possible may reduce aberrant immune responses in the potential stage of ARDS.

Macrolide Resistance and Its Impacts on M. Pneumoniae Pneumonia in Children: Comparison of Two Recent Epidemics in Korea

PURPOSE

The aim of this study was to investigate the change in macrolide resistance rate in pediatric Mycoplasma pneumoniae pneumonia and to evaluate the influence of macrolide-resistant M. pneumoniae (MRMP) on the clinical course of disease, by comparing 2 recent, consecutive epidemics in Korea.

METHODS

A total of 250 patients with M. pneumoniae pneumonia admitted to a single tertiary hospital were enrolled in this study. Detection of MRMP was based on specific point mutations in domain V of the 23S rRNA gene. The medical records of enrolled patients were reviewed retrospectively, and the clinical courses and laboratory data were compared.

RESULTS

The macrolide resistance rate of M. pneumoniae was 51.1% (48/94) in the 2011 epidemic, and 87.2% (136/156) in the 2015 epidemic. All MRMP isolates had the A2063G point mutation. In comparison of 2 epidemics, the mean age of patients with M. pneumoniae pneumonia was increased, and the total febrile days and febrile days after initiation of macrolides were prolonged in the 2015 epidemic. Overall severity of MRMP or macrolide-susceptible M. pneumoniae (MSMP) pneumonia over 2 epidemics was not significantly changed. However, the proportion of patients who had a fever lasting more than 72 hours after initiation of macrolides and who received corticosteroid treatment were higher in MRMP pneumonia during 2 epidemics.

CONCLUSIONS

The macrolide resistance rate of M. pneumoniae has risen rapidly over 2 recent, consecutive epidemics, and this has been associated with a prolonged clinical course and increased use of corticosteroids to treat pediatric M. pneumoniae pneumonia.

The epidemiology and clinical features of Mycoplasma pneumoniae infection in neonates

OBJECTIVES

This retrospective study was aimed to explore the epidemiological and clinical profiles of Mycoplasma pneumoniae infection in neonates.

METHODS

From 2011 to 2014, 1322 hospitalized neonates with lower respiratory tract infections were screened for Mycoplasma pneumoniae by detection of Mycoplasma pneumoniae antibodies using Serion ELISA classic Mycoplasma pneumoniae kits.

RESULTS

Mycoplasma pneumoniae was identified in 89 (6.7%) patients. The age ranged from 1 day to 28 days with a median of 22 days. The male to female ratio was 1.15:1. Mycoplasma pneumoniae infection peaked in spring (from March through May) and winter (from December through February). Compared with non-Mycoplasma pneumoniae infected neonates, those with Mycoplasma pneumoniae infection were older, presented fever more frequently, and had less tachypnea.

CONCLUSIONS

Mycoplasma pneumoniae could be an important etiologic agent for respiratory tract infection in neonates. In neonates Mycoplasma pneumoniae infection was usually associated with older age, presence of fever, and less tachypnea. Mycoplasma pneumoniae infection in neonates tends to be a mild process.

Early Serologic Diagnosis of Mycoplasma pneumoniae Pneumonia: An Observational Study on Changes in Titers of Specific-IgM Antibodies and Cold Agglutinins

There have been some limitations on early diagnosis of Mycoplasma pneumoniae (MP) infection because of no immunoglobulin M (IgM) responses and variable detection rates of polymerase chain reaction in the early stage of the disease. We wanted to discuss regarding early diagnostic method using short-term paired titration of MP-specific IgM and cold agglutinins (CAs) in the early stage of MP pneumonia.The participants of this study were 418 children with MP pneumonia during 2 recent epidemics (2006-2007 and 2011), and they were diagnosed by an anti-MP IgM antibody test (Serodia Myco II) examined twice during hospitalization at presentation and around discharge (mean of 3.4 ± 1.3 days apart). CA titers were simultaneously examined twice during study period. Anti-MP IgM antibody titer ≥1:40 and CA titer ≥1:4 were considered positive, respectively. The relationships between 2 IgM antibodies in the early stage were evaluated.Regarding MP-specific antibody titers, 148 patients showed a seroconversion, 245 patients exhibited increased titers, and 25 patients had unchanged higher titers (≥1:640) during hospitalization. The median MP-specific antibody titers at each examination time were 1:80 and 1:640, respectively; those of CAs were 1:8 and 1:32, respectively. Illness duration prior to admission showed a trend of association with both titers, and patients with shorter illness duration had a higher rate of negative titers or lower titers at each examination time. CAs and MP-specific antibody titers were correlated in the total patients at presentation and at 2nd examination (P < 0.001, respectively), and the diagnostic corresponding rates of CAs to IgM antibody test were 81% to 96% in patient subgroups.Short-term paired MP specific-IgM determinations in the acute stage may be used as a definitive diagnostic method for MP pneumonia. Paired CA titers showed a correlation with MP-specific antibody titers, suggesting they can be used as an adjuvant diagnostic method.

Mononuclear syndrome with acute hepatitis diagnosed as Mycoplasma pneumoniae infection without lung involvement

Although pneumonia is the hallmark of Mycoplasma pneumoniae infections, it has been associated with protean manifestations such as extrapulmonary involvement. Herein, a rare case of mononuclear syndrome with acute hepatitis and erythema multiforme revealed as M pneumoniae infection without lung involvement is reported. A 30-year-old man, previously healthy, presented with fever and rash with acute hepatitis: AST 603 IU/L, ALT 747 IU/L, prothrombin time 52%. Peripheral blood smears indicated monocytosis with atypical lymphocyte. Bone marrow biopsy revealed increased plasma cell infiltration. M pneumoniae infection was detected by serology testing. After treatment with macrolide, clinical symptoms and signs and serological tests were fully resolved. Diagnosis of this etiologic association is important when patients present with various clinical syndromes without pneumonia, because only specific antimicrobial therapy is effective against M pneumoniae.

Epidemiological comparison of three Mycoplasma pneumoniae pneumonia epidemics in a single hospital over 10 years

Purpose

Mycoplasma pneumoniae (MP) pneumonia epidemics have occurred in 3- to 4-year cycles in Korea. We evaluated the epidemiologic characteristics of MP pneumonia in Daejeon, Korea, from 2003 to 2012.

Methods

We retrospectively analyzed 779 medical records of children (0-15 years of old) with MP pneumonia admitted to our institution and compared the data from 3 recent epidemics.

Results

In 779 patients, the mean age and male-to-female ratio were 5.0±2.2 years and 1:1, and most cases were observed in autumn. There were three epidemics during the study period, in 2003, 2006-2007, and 2011. In our comparison of the three epidemics, we found no differences in mean age, the male-to-female ratio, hospital stay, or the rate of seroconverters during hospitalization. All three epidemics began in early summer and peaked in September 2003 and 2011 and in October 2006 and then gradually decreased until the next year's spring season, although the 2006 epidemic extended further into 2007. The peak age groups in the children in 2003 and 2006 were 3-6 year-olds (57.5% and 56%, respectively), but in the 2011 epidemic, the peak group was 1-4 year-olds (46.5%). The proportion of the <2 years of age group was 20%, 15.7% and 28.8%, and >10 years of age group was 5.2%, 13.8%, and 14.8% of total patients, respectively.

Conclusion

MP pneumonia outbreaks occurred every 3-4 years. The pattern of 3 recent epidemics was similar in demographic characteristics and seasonality with some variations in each outbreak.

A common immunopathogenesis mechanism for infectious diseases: the protein-homeostasis-system hypothesis

It was once believed that host cell injury in various infectious diseases is caused solely by pathogens themselves; however, it is now known that host immune reactions to the substances from the infectious agents and/or from the injured host cells by infectious insults are also involved. All biological phenomena in living organisms, including biochemical, physiological and pathological processes, are performed by the proteins that have various sizes and shapes, which in turn are controlled by an interacting network within the living organisms. The author proposes that this network is controlled by the protein homeostasis system (PHS), and that the immune system is one part of the PHS of the host. Each immune cell in the host may recognize and respond to substances, including pathogenic proteins (PPs) that are toxic to target cells of the host, in ways that depend on the size and property of the PPs. Every infectious disease has its own set of toxic substances, including PPs, associated with disease onset, and the PPs and the corresponding immune cells may be responsible for the inflammatory processes that develop in those infectious diseases.

Early Additional Immune-Modulators for Mycoplasma pneumoniae Pneumonia in Children: An Observation Study

Background

Mycoplasma pneumoniae (MP) pneumonia is a self-limiting disease, but some patients complain of progressive pneumonia, despite of appropriate antibiotic treatment. We aimed to introduce the role of immune-modulators (corticosteroid and/or intravenous immunoglobulin, IVIG) treatment for childhood MP pneumonia based on previous our experiences.

Materials and Methods

A retrospective case series analysis for 183 children with MP pneumonia was performed. MP pneumonia patients were diagnosed by two Immunoglobulin M (IgM) tests: the micro-particle agglutination method (≥1:40) and the cold agglutination test (≥1:4), and were examined twice at the initial admission and at discharge. Among 183 MP pneumonia patients, 90 patients with persistent fever for over 48 hours after admission or those with severe respiratory symptoms and signs received additional prednisolone (82 patients, 1 mg/kg/day) or intravenous methylprednisolone (8 patients, 5-10 mg/kg/day) with antibiotics. Four patients with aggravated clinical symptoms and chest radiographic findings after corticosteroid treatment received IVIG (1 g/kg/day, 1-2 doses).

Results

Mean age of 183 patients was 5.5 ± 3.2 years (6 months-15 years), and the male: female ratio was 1.1:1 (96:87). Fifty-seven patients (31%) were seroconverters and 126 seropositive patients showed increased diagnostic IgM antibody titres during admission (over 4 folds). The majority of the patients who received corticosteroids (86/90 cases) showed rapid defervescence within 48 hours with improved clinical symptoms, regardless of the used antibiotics. Also, 4 patients who received additional IVIG improved both clinically and radiographically within 2 days without adverse reaction.

Conclusions

In the era of macrolide-resistant MP strains, early additional immune-modulator therapy with antibiotics might prevent from the disease progression and reduce the disease morbidity without adverse reaction.

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.

Typical or atypical pneumonia and severe acute respiratory symptoms in PICU

Background and Aims

Mycoplasma pneumoniae (MP) is a common childhood pathogen associated with atypical pneumonia (AP). It is often a mild disease and seldom results in paediatric intensive care (PICU) admission. In 2003, World Health Organization (WHO) coined the word SARS (severe acute respiratory syndrome) in patients with severe acute respiratory symptoms (sars) for an outbreak of AP in Hong Kong due to a novel coronavirus. In 2012, another outbreak of coronavirus AP occurred in the Middle East. Confusing case definitions such as MERS (Middle East respiratory syndrome) and SARI (severe acute respiratory infections) were coined. This paper aims to present a case of MP with sars, ARDS, pneumonia and pleural effusion during the MERS epidemics, and review the incidence and mortality of severe AP with MP.

Methods

We presented a case of MP with sars, acute respiratory distress syndrome (ARDS), pneumonia and pleural effusion during the MERS epidemics, and performed a literature review on the incidence and mortality of severe AP with MP requiring PICU care.

Results

In early 2013, an 11‐year‐old girl presented with sars, ARDS (acute respiratory distress syndrome), right‐sided pneumonia and pleural effusion. She was treated with multiple antibiotics. Streptococcus pneumoniae was not isolated in this girl with ‘typical’ pneumonia by symptomatology and chest radiography, but tracheal aspirate identified MP instead. The respiratory equations are computed with PaO₂/FiO₂ consistent with severe lung injury. Literature on the incidence and mortality of severe AP with MP requiring PICU care is reviewed. Six, 165 and 293 articles were found when PubMed (a service of the U.S. National Library of Medicine) was searched for the terms ‘mycoplasma’ and ‘ICU’, ‘mycoplasma’ and ‘mortality’, and ‘mycoplasma' and ‘severe’. Mortality and PICU admission associated with MP is general low and rarely reported. Experimental and clinical studies have suggested that the pathogenesis of lung injuries in MP infection is associated with a cell‐mediated immune reaction, and high responsiveness to corticosteroid therapy has been reported especially for severe disease. Management of severe mycoplasma infection in the PICU includes general cardiopulmonary support and specific antimicrobial treatment. Macrolide resistance genotypes have been detected.

Conclusion

We urge health organizations to refrain from the temptation of coining unnecessary new terminology to describe essentially the same conditions each and every time when outbreaks of AP occur.

Predictive value of C-reactive protein in response to macrolides in children with macrolide-resistant Mycoplasma pneumoniae pneumonia

Purpose

The prevalence of macrolide-resistant Mycoplasma pneumoniae (MRMP) has increased worldwide. The aim of this study was to estimate the proportion of MRMP in a tertiary hospital in Korea, and to find potential laboratory markers that could be used to predict the efficacy of macrolides in children with MRMP pneumonia.

Methods

A total of 95 patients with M. pneumoniae pneumonia were enrolled in this study. Detection of MRMP was based on the results of specific point mutations in domain V of the 23S rRNA gene. The medical records of these patients were reviewed retrospectively and the clinical course and laboratory data were compared.

Results

The proportion of patients with MRMP was 51.6% and all MRMP isolates had the A2063G point mutation. The MRMP group had longer hospital stay and febrile period after initiation of macrolides. The levels of serum C-reactive protein (CRP) and interleukin-18 in nasopharyngeal aspirate were significantly higher in patients who did not respond to macrolide treatment. CRP was the only significant factor in predicting the efficacy of macrolides in patients with MRMP pneumonia. The area under the curve for CRP was 0.69 in receiver operating characteristic curve analysis, indicating reasonable discriminative power, and the optimal cutoff value was 40.7 mg/L.

Conclusion

The proportion of patients with MRMP was high, suggesting that the prevalence of MRMP is rising rapidly in Korea. Serum CRP could be a useful marker for predicting the efficacy of macrolides and helping clinicians make better clinical decisions in children with MRMP pneumonia.

Clinical significance of different bacterial load of Mycoplasma pneumoniae in patients with Mycoplasma pneumoniae pneumonia

Objective

This retrospective study was conducted to investigate the clinical significance of different Mycoplasma pneumoniae bacterial load in patients with M. pneumoniae pneumonia (MP) in children.

Methods

Patients with MP (n = 511) were identified at the Children's Hospital Affiliated to Soochow University database during an outbreak of MP between January 2012 and February 2013.

Results

Comparing patients with high and low bacterial load those with higher loads were significantly older (p < 0.01) and had fever significantly more frequently (p = 0.01). Presence of wheezing at presentation was associated with low bacterial load (p = 0.03). Baseline positive IgM was present in 93 (56.4%) patients with high bacterial load compared to 46 (27.8%) patients with low bacterial load (p < 0.001). Co-infection with viruses was found significantly more frequent among patients with low bacterial load (24.2%) than those with high bacterial load (8.5%) [p < 0.001]. Bacterial co-infection was also more frequently detected among patients with low bacterial load (22.4%) than in those with high bacterial load (12.1%) [p = 0.01].

Conclusion

M. pneumoniae at a high bacterial load could be an etiologic agent of respiratory tract disease, whereas the etiologic role of MP at a low bacterial load remains to be determined.

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.