Extra-pulmonary diseases related to Mycoplasma pneumoniae in children: recent insights into the pathogenesis. Curr Opin Rheumatol. 2018;30:380-387. [PMID: 29432224 DOI: 10.1097/bor.0000000000000494]

Serum inflammatory markers in children with Mycoplasma pneumoniae pneumonia and their predictive value for mycoplasma severity

BACKGROUND

Mycoplasma pneumoniae pneumonia (MPP) significantly impacts pediatric health, necessitating markers for early severe disease identification.

AIM

To investigate the correlation between serum inflammatory marker and the severity of MPP in children.

METHODS

A prospective study was carried out from January 2023 to November 2023. A total of 160 children with MPP who underwent treatment were selected: 80 had severe MPP and 80 had mild MPP. Clinical and laboratory data were collected at the time of hospital admission and during hospitalization. Receiver operating characteristic curves were utilized to assess the diagnostic and prognostic for severe MPP.

RESULTS

Fever duration and length of hospitalization in pediatric patients with severe MPP exceeded those with mild MPP. The incidence of pleural effusion, lung consolidation, and bronchopneumonia on imaging was markedly elevated in the severe MPP cohort compared to the mild MPP cohort. In contrast to the mild cohort, there was a notable increase in C-reactive protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate, lactic dehydrogenase, D-dimer, and inflammatory cytokines [interleukin (IL)-6, IL-8, IL-10 and tumor necrosis factor (TNF)-α] in the severe MPP group were significantly higher.

CONCLUSION

Serum inflammatory markers (CRP, PCT, IL-6, D-dimer, IL-10 and TNF-α) were considered as predictors in children with severe MPP.

Model based on the automated AI-driven CT quantification is effective for the diagnosis of refractory Mycoplasma pneumoniae pneumonia

The prediction of refractory Mycoplasma pneumoniae pneumonia (RMPP) remains a clinically significant challenge. This study aimed to develop an early predictive model utilizing artificial intelligence (AI)-derived quantitative assessment of lung lesion extent on initial computed tomography (CT) scans and clinical indicators for RMPP in pediatric inpatients. A retrospective cohort study was conducted on patients with M. pneumoniae pneumonia (MP) admitted to the Children's Hospital of Nanjing Medical University, China from January 2019 to December 2020. An early prediction model was developed by stratifying the patients with Mycoplasma pneumoniae pneumonia (MPP) into two cohorts according to the presence or absence of refractory pneumonia. A retrospective cohort of 126 children diagnosed with Mycoplasma pneumoniae pneumonia (MPP) was utilized as a training set, with 85 cases classified as RMPP. Subsequently, a prospective cohort comprising 54 MPP cases, including 37 instances of RMPP, was assembled as a validation set to assess the performance of the predictive model for RMPP from January to December 2021. We defined a constant Φ which can combine the volume and CT value of pulmonary lesions and be further used to calculate the logarithm of Φ to the base of 2 (Log2Φ). A clinical-imaging prediction model was then constructed utilizing Log2Φ and clinical characteristics. Performance was evaluated by the area under the receiver operating characteristic curve (AUC). The clinical model demonstrated AUC values of 0.810 and 0.782, while the imaging model showed AUC values of 0.764 and 0.769 in the training and test sets, respectively. The clinical-imaging model, incorporating Log2Φ, temperature(T), aspartate aminotransferase (AST), preadmission fever duration (PFD), and preadmission macrolides therapy duration (PMTD), achieved the highest AUC values of 0.897 and 0.895 in the training and test sets, respectively. A prognostic model developed through automated quantification of lung disease on CT scans, in conjunction with clinical data in MPP may be utilized for the early identification of RMPP.

Exploring the pathogenetic mechanisms of Mycoplasmapneumoniae (Review)

Mycoplasmas, the smallest self-replicating prokaryotes without a cell wall, are the most prevalent and extensively studied species in humans. They significantly contribute to chronic respiratory tract illnesses and pneumonia, with children and adolescents being particularly vulnerable. Mycoplasma pneumoniae (M. pneumoniae) infections typically tend to be self-limiting and mild but can progress to severe or even life-threatening conditions in certain individuals. Extrapulmonary effects often occur without pneumonia, and both intrapulmonary and extrapulmonary complications operate through separate pathological mechanisms. The indirect immune-mediated damage of the immune system, vascular blockages brought on by vasculitis or thrombosis and direct harm from invasion or locally induced inflammatory cytokines are potential causes of extrapulmonary manifestations due to M. pneumoniae. Proteins associated with adhesion serve as the primary factor crucial for the pathogenicity of M. pneumoniae, relying on a specialized polarized terminal attachment organelle. The type and density of these host receptors significantly impact the adhesion and movement of M. pneumoniae, subsequently influencing the pathogenic mechanism and infection outcomes. Adjacent proteins are crucial for the proper assembly of the attachment organelle, with variations in the genetic domains of P1, P40 and P90 surfaces contributing to the variability of clinical symptoms and offering new avenues for developing vaccines against M. pneumoniae infections. M. pneumoniae causes oxidative stress within respiratory tract epithelial cells by adhering to host cells and releasing hydrogen peroxide and superoxide radicals. This oxidative stress enhances the vulnerability of host cells to harm induced by oxygen molecules. The lack of superoxide dismutase and catalase of bacteria allows it to hinder the catalase activity of the host cell, leading to the reduced breakdown of peroxides. Lung macrophages play a significant role in managing M. pneumoniae infection, identifying it via Toll-like receptor 2 and initiating the myeloid differentiation primary response gene 88-nuclear factor κΒ signaling cascade. However, the precise mechanisms enabling M. pneumoniae to evade intracellular host defenses remain unknown, necessitating further exploration of the pathways involved in intracellular survival. The present comprehensive review delves into the pathogenesis of M. pneumoniae infection within the pulmonary system and into extrapulmonary areas, outlining its impact.

The Therapeutic Potential of Neutrophil Extracellular Traps and NLRP3 Inflammasomes in Mycoplasma pneumoniae Pneumonia

INTRODUCTION

Mycoplasma pneumoniae (MP) is the most common pathogen of community-acquired pneumonia in children. However, the role of neutrophil extracellular traps (NETs) in the pathogenesis of MP is unclear.

METHODS

Both the level of NETs were detected between the 60 MP pneumonia patients and 20 healthy controls, whose the clinical characteristics were compared. Additionally, NETs formation induced by community-acquired respiratory distress syndrome (CARDS) toxin was also analyzed through transcriptome sequencing.

RESULTS

The levels of cell-free DNA, Cit-H3, and MPO-DNA complexes were significantly increased in the patients with MP pneumonia. Importantly, both cell-free DNA and LDH were higher in hospitalized patients with severity than those without severity. In addition, CARDS toxin induced the NETs formation in vitro and in vivo. Transcriptomics GO and KEGG pathway analysis indicate that NOD like receptor signaling pathway and Toll-like receptor signaling pathway are significantly enriched. Finally, we found that DNase I significantly attenuated the higher levels of Cit-H3, and up-regulation of interleukin-1β (IL-1β) and interleukin-18 (IL-18) by down-regulating the expression of NLRP3 and Caspase1(p20) in the lung tissues.

DISCUSSION

These results indicate that inhibiting excessive activation of NLRP3 inflammasomes, and NETs formation may alleviate MP pneumonia.

Predictive value of bronchoscopy combined with CT score for refractory mycoplasma pneumoniae pneumonia in children

INTRODUCTION

Mycoplasma pneumoniae pneumonia (MPP) is prevalent in paediatric patients and can progress to refractory mycoplasma pneumoniae pneumonia (RMPP).

OBJECTIVE

To assess the predictive value of bronchoscopy combined with computed tomography (CT) score in identifying RMPP in children.

METHODS

A retrospective analysis was conducted on 244 paediatric patients with MP, categorising them into RMPP and general mycoplasma pneumoniae pneumonia (GMPP) groups. A paired t-test compared the bronchitis score (BS) and CT score before and after treatment, supplemented by receiver operating characteristic (ROC) analysis.

RESULTS

The RMPP group showed higher incidences of extrapulmonary complications and pleural effusion (58.10% and 40%, respectively) compared with the GMPP group (44.60%, p = 0.037 and 18.71%, p < 0.001, respectively). The CT scores for each lung lobe were statistically significant between the groups, except for the right upper lobe (p < 0.05). Correlation analysis between the total CT score and total BS yielded r = 0.346 and p < 0.001. The ROC for BS combined with CT score, including area under the curve, sensitivity, specificity, and cut-off values, were 0.82, 0.89, 0.64, and 0.53, respectively.

CONCLUSION

The combined BS and CT score method is highly valuable in identifying RMPP in children.

Characteristics and Outcomes of Mycoplasma Pneumoniae Pneumonia Associated with Pulmonary Embolism and Necrotizing Pneumonia in Children

Purpose

To explore the clinical characteristics, treatment, and long-term prognosis of mycoplasma pneumoniae pneumonia (MPP) combined with pulmonary embolism (PE) in children.

Patients and Methods

The medical records of 16 children who were diagnosed with MPP associated with PE between January 2016 and January 2023 at Children's Hospital, Zhejiang University School of Medicine were retrospectively reviewed.

Results

The average age patients were 8.24 ± 1.99 years. All cases were diagnosed with refractory mycoplasma pneumoniae pneumonia (RMPP) and presented complications in the form of necrotizing pneumonia (NP). The main symptoms observed were cough and fever (n = 16, 100%), chest pain (n = 8, 50%), dyspnea (n = 8, 50%), and hemoptysis (n = 4, 25%). In these cases, 12 patients had involvement of the pulmonary artery, 3 patients experienced issues with the pulmonary vein, and 1 patient had simultaneous involvement of both the pulmonary artery and pulmonary vein. Among the 12 pulmonary artery embolism cases, 6 involved the right pulmonary artery, 4 involved the left pulmonary artery, and 2 involved both the right and left pulmonary arteries. The mean D-dimer level was 8.50 ± 4.76 mg/L. All patients received anticoagulant therapy, and after treatment, there was a significant improvement in their symptoms and lung lesions.

Conclusion

Children with RMPP, chest pain, hemoptysis, and elevated D-dimer levels should be closely monitored for the potential development of PE. The co-occurrence of MPP and PE often involves the presence of NP. In cases of confirmed PE, anticoagulation therapy may be a suitable consideration. PE and NP resulting from MPP generally had a favorable overall prognosis.

Clinical characteristics and changes in serum CXCL10 and CXCL16 levels in patients with severe mycoplasma pneumonia

To explore the clinical characteristics and changes in serum CXCL10 and CXCL16 in patients with severe mycoplasma pneumonia, and to analyze the risk factors of severe mycoplasma pneumonia. About 258 children with acute mycoplasma pneumoniae pneumonia (MPP) admitted to the respiratory department of a certain hospital from January 2020 to December 2022 were selected as the study subjects. According to the severity of MPP, patients are divided into 2 groups, namely the mild illness group (Q group) and the severe illness group (Z group). The number of cases in these 2 groups of children is 167 and 91, respectively. The serum CXCL10, CXCL16, and other indicators of 2 groups are tested. Compared to group Q, patients in group Z have a higher proportion of extrapulmonary complications, longer cough time, longer shortness of breath, and longer wheezing time (P < .05). The serum CXCL16 is higher and the proportion of pleural effusion is higher (P < .01). There are more cases of fever, longer fever duration, longer hospital stay, higher serum CXCL10, and higher D-dimer levels (P < .001). The area under the curve of the probability curve for predicting severe mycoplasma pneumonia is 0.975 (P < .05). Children with severe mycoplasma pneumonia have significantly longer fever duration and hospital stay than those with mild symptoms. The serum levels of CXCL10 and CXCL16 are significantly elevated.

Association of anthropometric z score with complications and length of hospital stay in children with severe pneumonia aged 3 months to 5 years

BACKGROUND

Severe pneumonia in children accounts for a significant healthcare burden, involving prolonged hospitalization and increased risk of complications. The prognosis is closely related to the child's nutrition status. Anthropometric z scores are preferred to evaluate growth levels in children. This study aimed to investigate the association of anthropometric z scores with complications and length of hospital stay (LOS) in children with severe pneumonia.

METHODS

This study included 361 hospitalized children aged 3 months to 5 years with severe pneumonia in Tianjin, China. Anthropometry was performed, and anthropometric z scores were calculated. Blood laboratory indices were assessed, and complications and LOS were recorded.

RESULTS

The average anthropometric z scores were -0.10 ± 1.15 (body mass index for age z score), 0.00 ± 0.97 (upper arm circumference for age z score [ACAZ]), and -0.14 ± 1.00 (triceps skinfold thickness for age z score [TSAZ]). The prevalence of complications was 73.96% (n = 267), including 82 children with only respiratory complications, 71 with only extrapulmonary complications, and 114 with both. After adjusting for confounding factors, compared with the noncomplication group, only the extrapulmonary complication group had a lower TSAZ (odds ratio [OR] = 0.597; 95% CI = 0.405-0.880; P < 0.05), whereas the respiratory and extrapulmonary complication group had a lower ACAZ (OR = 0.674; 95% CI = 0.469-0.969; P < 0.05) and TSAZ (OR = 0.573; 95% CI = 0.389-0.843; P < 0.05). ACAZ (β = -0.368; 95% CI = -0.720 to 0.016; P < 0.05) and TSAZ (β = -1.123; 95% CI = -1.470 to -0.777; P < 0.05) were negatively correlated with LOS.

CONCLUSION

ACAZ and TSAZ were associated with complications and LOS of severe pneumonia in children aged 3 months to 5 years.

Mycoplasma invasion into host cells: An integrated model of infection strategy

Mycoplasma belong to the genus Mollicutes and are notable for their small genome sizes (500-1300 kb) and limited biosynthetic capabilities. They exhibit pathogenicity by invading various cell types to survive as intracellular pathogens. Adhesion is a crucial prerequisite for successful invasion and is orchestrated by the interplay between mycoplasma surface adhesins and specific receptors on the host cell membrane. Invasion relies heavily on clathrin- and caveolae-mediated internalization, accompanied by multiple activated kinases, cytoskeletal rearrangement, and a myriad of morphological alterations, such as membrane invagination, nuclear hypertrophy and aggregation, cytoplasmic edema, and vacuolization. Once mycoplasma successfully invade host cells, they establish resilient sanctuaries in vesicles, cytoplasm, perinuclear regions, and the nucleus, wherein specific environmental conditions favor long-term survival. Although lysosomal degradation and autophagy can eliminate most invading mycoplasmas, some viable bacteria can be released into the extracellular environment via exocytosis, a crucial factor in the prolonging infection persistence. This review explores the intricate mechanisms by which mycoplasma invades host cells and perpetuates their elusive survival, with the aim of highlighting the challenge of eradicating this enigmatic bacterium.

Insights into the defensive roles of lncRNAs during Mycoplasma pneumoniae infection

Mycoplasma pneumoniae causes respiratory tract infections, affecting both children and adults, with varying degrees of severity ranging from mild to life-threatening. In recent years, a new class of regulatory RNAs called long non-coding RNAs (lncRNAs) has been discovered to play crucial roles in regulating gene expression in the host. Research on lncRNAs has greatly expanded our understanding of cellular functions involving RNAs, and it has significantly increased the range of functions of lncRNAs. In lung cancer, transcripts associated with lncRNAs have been identified as regulators of airway and lung inflammation in a process involving protein complexes. An excessive immune response and antibacterial immunity are closely linked to the pathogenesis of M. pneumoniae. The relationship between lncRNAs and M. pneumoniae infection largely involves lncRNAs that participate in antibacterial immunity. This comprehensive review aimed to examine the dysregulation of lncRNAs during M. pneumoniae infection, highlighting the latest advancements in our understanding of the biological functions and molecular mechanisms of lncRNAs in the context of M. pneumoniae infection and indicating avenues for investigating lncRNAs-related therapeutic targets.

Research status and challenges of Mycoplasma pneumoniae pneumonia in children: A bibliometric and visualization analysis from 2011 to 2023

BACKGROUND

Mycoplasma pneumoniae (MP) infections occur in regional outbreaks every 3 to 7 years, lasting up to 2 years. Since this fall, there has been a significant rise in MP infections among children in China, indicating a regional epidemiological trend that imposes an increased national public health burden. To date, bibliometric methods have not been applied to studies on MP infection in children.

METHODS

We searched for all relevant English publications on MP pneumonia in children published from 2011 to 2023 using Web of Science. Analytical software tools such as Citespace and VOSviewer were employed to analyze the collected literature.

RESULTS

993 articles on MP pneumonia in children were published in 338 academic journals by 5062 authors affiliated with 1381 institutions across 75 countries/regions. China led in global productivity with 56.19%. Among the top 10 prolific organizations, 8 were Chinese institutions, with Soochow University being the most active, followed by Capital Medical University and Zhejiang University. Zhimin Chen from Zhejiang University School of Medicine exhibited the highest H-index of 32. Keyword co-occurrence network analysis revealed 7 highly relevant clusters.

CONCLUSION

The current research hotspots and frontiers in this field are primarily MP pneumonia, refractory MP pneumonia, lactate dehydrogenase, asthma, and biomarker. We anticipate that this work will provide novel insights for advancing scientific exploration and the clinical application of MP pneumonia in children.

Non-purulent myositis caused by direct invasion of skeletal muscle tissue by Leptospira in a hamster model

Myalgia is a common symptom of Leptospira infection in humans. Autopsies have reported that muscle tissue shows degeneration and necrosis of the myofibers and infiltration of inflammatory cells composed mainly of macrophages and lymphocytes. It remains unclear whether Leptospira directly infects the muscle and how the infiltrating inflammatory cells are involved in muscle fiber destruction. This study evaluated the relationship between histopathological changes and leptospiral localization in the muscle tissue of a hamster model. The influence of macrophages in skeletal muscle injury was also investigated, using selective depletion of macrophages by administration of liposomal clodronate. Hamsters infected subcutaneously with Leptospira interrogans serovar Manilae strain UP-MMC-SM showed myositis of the thighs adjacent to the inoculated area beginning at 6 days post-infection. The myositis was non-purulent and showed sporadic degeneration and necrosis of muscle fibers. The degeneration of myofibers was accompanied by aggregations of macrophages. Immunofluorescence staining revealed leptospires surrounding the damaged muscle fibers. Subcutaneous injection of formalin-killed Leptospira or intraperitoneal injection of live Leptospira caused no myositis in hamster thighs. Liposomal clodronate treatment in infected hamsters reduced macrophage infiltration in muscle tissue without impacting bacterial clearance. Muscle necrosis was still observed in the infected hamsters treated with liposomal clodronate, and there was no significant change in serum creatine kinase levels compared to those in animals treated with liposomes alone. Our findings suggest that leptospiral invasion of muscle tissue from an inoculation site leads to the destruction of muscle fibers and causes non-purulent myositis, whereas the infiltrating macrophages contribute less to muscle destruction.

Neuroinfectious Diseases in Children: Pathophysiology, Outcomes, and Global Challenges

Pathogens with affinity for the central nervous system (CNS) in children are diverse in their mechanisms of infecting and attacking the brain. Infections can reach the CNS via hematogenous routes, transneurally thereby avoiding the blood-brain barrier, and across mucosal or skin surfaces. Once transmission occurs, pathogens can wreak havoc both by direct action on host cells and via an intricate interplay between the protective and pathologic actions of the host's immune system. Pathogen prevalence varies depending on region, and susceptibility differs based on epidemiologic factors such as age, immune status, and genetics. In addition, some infectious diseases are monophasic, whereas others may lie dormant for years, thereby causing a dynamic effect on outcomes. Outcomes in survivors are highly variable for each particular pathogen and depend on the vaccination and immune status of the patient as well as the speed by which the patient receives evidence-based treatments. Given pathogens cause communicable diseases that can cause morbidity and mortality on a population level when spread, the burden is often the greatest and the outcomes the worst in low-resource settings. Here we will focus on the most common infections with a propensity to affect a child's brain, the pathologic mechanisms by which they do so, and what is known about the developmental outcomes in children who are affected by these infections.

Investigating the occurrence of autoimmune diseases among children and adolescents hospitalized for Mycoplasma pneumoniae infections

Background

Mycoplasma pneumoniae infection is common in the general population and may be followed by immune dysfunction, but links with subsequent autoimmune disease remain inconclusive.

Objective

To estimate the association of M. pneumoniae infection with the risk of subsequent autoimmune disease.

Methods

This retrospective cohort study examined the medical records of South Korean children from 01/01/2002 to 31/12/2017. The exposed cohort was identified as patients hospitalized for M. pneumoniae infection. Each exposed patient was matched with unexposed controls based on birth year and sex at a 1:10 ratio using incidence density sampling calculations. The outcome was subsequent diagnosis of autoimmune disease, and hazard ratios (HRs) were estimated with control for confounders. Further estimation was performed using hospital-based databases which were converted to a common data model (CDM) to allow comparisons of the different databases.

Results

The exposed cohort consisted of 49,937 children and the matched unexposed of 499,370 children. The median age at diagnosis of M. pneumoniae infection was 4 years (interquartile range, 2.5-6.5 years). During a mean follow-up time of 9.0 ± 3.8 years, the incidence rate of autoimmune diseases was 66.5 per 10,000 person-years (95% CI: 64.3-68.8) in the exposed cohort and 52.3 per 10,000 person-years (95% CI: 51.7-52.9) in the unexposed cohort, corresponding to an absolute rate of difference of 14.3 per 10,000 person-years (95% CI: 11.9-16.6). Children in the exposed cohort had an increased risk of autoimmune disease (HR: 1.26; 95% CI: 1.21-1.31), and this association was similar in the separate analysis of hospital databases (HR: 1.25; 95% CI 1.06-1.49).

Conclusion

M. pneumoniae infection requiring hospitalization may be associated with an increase in subsequent diagnoses of autoimmune diseases.

Coronary artery dilation in children with febrile illnesses other than Kawasaki disease: A case report and literature review

Background

Coronary artery dilation (CAD) had rarely been described as a cardiac complication of febrile disease other than Kawasaki disease (KD). There are rare cases complicated by CAD reported in patients with Mycoplasma pneumoniae (MP) infection.

Case presentation

A 6-year-old boy with severe Mycoplasma pneumoniae pneumonia (MPP) was transferred to our hospital due to significant respiratory distress on the 11th day from disease onset. Nadroparin, levofloxacin, and methylprednisolone followed by oral prednisone were aggressively prescribed. His clinical condition gradually achieved remission, and the drugs were withdrawn on the 27th day. Regrettably, the recurrent fever attacked him again in the absence of infection-toxic manifestations. Necrotizing pneumonia (NP) was found on chest CT. And echocardiography revealed right CAD (diameter, 3.40mm; z-score, 3.8), however, his clinical and laboratory findings did not meet the diagnostic criteria of KD. CAD was proposed to result from MP infection, and aspirin was prescribed. Encouragingly, the CAD regressed one week later (diameter, 2.50mm; z-score, 1.4). Additionally, the child defervesced seven days after the initiation of prednisone and Nadroparin treatment. The patient was ultimately discharged home on the 50th day. During follow-up, the child was uneventful with normal echocardiography and fully resolved chest CT lung lesions.

Conclusions

CAD can develop in patients with severe MP infection. Pediatricians should be alert to the possibility of CAD in patients with severe MP infection and recognize that CAD might also develop in febrile disease rather than KD.

Development and validation of a simple-to-use nomogram for predicting the delayed radiographic recovery in children with mycoplasma pneumoniae pneumonia complicated with atelectasis

This study aimed to develop and validate a simple-to-use nomogram for predicting the delayed radiographic recovery in children with mycoplasma pneumoniae pneumonia (MPP) complicated with atelectasis. A retrospective study of 306 children with MPP complicated with atelectasis was performed at the Children's Hospital of Chongqing Medical University from February 2017 to March 2020.The patients were divided into recovery group and delayed recovery group based on chest CT scan 1 month after discharge. A least absolute shrinkage and selection operator (LASSO) regression model was used to identify the optimal predictors, and the predictive nomogram was plotted by multivariable logistic regression. The nomogram was assessed by calibration, discrimination, and clinical utility. LASSO regression analysis identified that lactate dehydrogenase (LDH), duration of illness prior to bronchoalveolar lavage (BAL), systemic glucocorticoid use and extrapulmonary complications were the optimal predictors for delayed radiographic recovery. The nomogram was plotted by the four predictors. The area under the Receiver Operating Characteristic (ROC) curve of the nomogram was 0.840 (95% CI = 784 ∼ 0.896) in the training set and 0.833 (95% CI = 0.8737 ∼ 0.930) in the testing set. The calibration curve demonstrated that the nomogram was well-fitted, and decision curve analysis (DCA) showed that the nomogram was clinically beneficial. This study developed and validated a simple-to-use nomogram for predicting delayed radiographic recovery in children with MPP complicated with atelectasis. This might be generally applied in clinical practice.

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

BACKGROUND INTRODUCTION

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

CASE DESCRIPTION

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

CONCLUSION

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

Clinical characteristics of community-acquired pneumonia in children caused by mycoplasma pneumoniae with or without myocardial damage: A single-center retrospective study

BACKGROUND

Mycoplasma pneumoniae (MP) is a prevalent pathogen that causes respiratory infections in children and adolescents.

AIM

To assess the differences in the clinical features of MP-associated community-acquired pneumonia (CAP) in children who presented with mild or severe mycoplasma pneumoniae pneumonia (MPP); to identify the incidence of myocardial damage between the two groups.

METHODS

This work is a retrospective study. We identified children between 2 mo and 16 years of age with clinical and radiological findings consistent with CAP. We admitted patients to the inpatient department of the Second Hospital of Jilin University, Changchun, China, from January 2019 to December 2019.

RESULTS

A total of 409 hospitalized patients were diagnosed with MPP. Among them were 214 (52.3%) males and 195 (47.7%) females. The duration of fever and cough was the longest in severe MPP cases. Similarly, plasma levels of highly sensitive C-reactive protein (t = -2.834, P < 0.05), alanine transaminase (t = -2.511, P < 0.05), aspartate aminotransferase (t = -2.939, P < 0.05), and lactate dehydrogenase (LDH) (t = -2.939, P < 0.05) were all elevated in severe MPP cases compared with mild MPP cases, and these elevations were statistically significant (P < 0.05). Conversely, the neutrophil percentage was significantly lower in severe MPP cases than in mild MPP cases. The incidence of myocardial damage was significantly higher in severe MPP cases than in mild MPP cases (χ² = 157.078, P < 0.05).

CONCLUSION

Mycoplasma pneumoniae is the main cause of CAP. The incidence of myocardial damage was higher and statistically significant in severe MPP cases than in mild MPP cases.

Analysis of cytokine levels, cytological findings, and MP-DNA level in bronchoalveolar lavage fluid of children with Mycoplasma pneumoniae pneumonia

BACKGROUND

The present study was conducted to determine the inflammatory response in the lungs of children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

This study retrospectively analyzed cytokine levels, cytological findings, and M. pneumoniae (MP)-DNA level in the bronchoalveolar lavage fluid (BALF) of 96 children with MPP. The study utilized Spearman's correlation method to evaluate the contribution of BALF and blood parameters in MPP children.

RESULTS

(1) A total of 96 MPP children were classified into the Low MP-DNA MPP group (BALF MP-DNA ≤ 105 copies/mL) and the High MP-DNA MPP group (BALF MP-DNA > 105 copies/mL); the Non-fever MPP group (no fever during the entire course of pneumonia) and the Fever MPP group; the Defervescence MPP group (fever had subsided at the time of bronchoscopy) and the Fervescence MPP group; and the Mild MPP group and the Severe MPP group. (2) The High MP-DNA MPP, Fever MPP, Fervescence MPP, and Severe MPP groups had higher levels of interleukin (IL)-6, IL-10, and tumor necrosis factor-α (TNF-α) in their BALF (all p < .05). (3) The proportions of neutrophils and macrophages in the BALF of the High MP-DNA MPP and Fever MPP groups increased and decreased, respectively (all p < .05). (4) In the BALF of MPP children, MP-DNA, IL-6, IL-10, TNF-α, and interferon gamma (IFN-γ) levels positively correlated with neutrophil proportion while negatively correlated with macrophage proportion (all p < .05). (5) The MP-DNA, IL-6, IL-10, TNF-α, and IFN-γ levels in the BALF of MPP children were positively correlated with the levels of C-reactive protein, procalcitonin, lactic dehydrogenase, fibrinogen, and d-dimer, while they were negatively correlated with the albumin level (all p < .05).

CONCLUSIONS

In children with MPP, the pulmonary inflammatory immune response was stronger in the High MP-DNA MPP, Fever MPP, Fervescence MPP, and Severe MPP groups. The relationship between pulmonary cytokine levels, MP-DNA load, and serum inflammatory parameters were found to be weak.

Insight into the Pathogenic Mechanism of Mycoplasma pneumoniae

Mycoplasma pneumoniae, an obligate parasitic pathogen without cell wall, can cause severe upper and lower respiratory tract symptoms. It is the pathogen of human bronchitis and walking pneumonia, and named community-acquired pneumonia. In addition to severe respiratory symptoms, there are clinical extrapulmonary manifestations in the skin, brain, kidney, musculoskeletal, digestive system, and even blood system after M. pneumoniae infection. Hereby, we comprehensively summarized and reviewed the intrapulmonary and extrapulmonary pathogenesis of M. pneumoniae infection. The pathogenesis of related respiratory symptoms caused by M. pneumoniae is mainly adhesion damage, direct damage including nutrient predation, invasion and toxin, cytokine induced inflammation damage and immune evasion effect. The pathogenesis of extrapulmonary manifestations includes direct damage mediated by invasion and inflammatory factors, indirect damage caused by host immune response, and vascular occlusion. The intrapulmonary and extrapulmonary pathogenic mechanisms of M. pneumoniae infection are independent and interrelated, and have certain commonalities. In fact, the pathogenic mechanisms of M. pneumoniae are complicated, and the specific content is still not completely clear, further researches are necessary for determining the detailed pathogenesis of M. pneumoniae. This review can provide certain guidance for the effective prevention and treatment of M. pneumoniae infection.

Acute Pancreatitis Associated with Atypical Bacterial Pneumonia: Systematic Literature Review

BACKGROUND

Extra-pulmonary features sometimes occur in association with atypical bacterial pneumonia and include neurologic manifestations, diarrhea, rashes, altered liver enzymes, or kidney injury, among other conditions. Acute pancreatitis has been associated with atypical pneumonias since 1973.

METHODS

We performed a systematic review of the literature in the Excerpta Medica, National Library of Medicine, and Web of Science databases. We retained 27 reports published between 1973 and 2022 describing subjects with an otherwise unexplained pancreatitis temporally associated with an atypical pneumonia.

RESULTS

The reports included 33 subjects (19 males, and 14 females; 8 children and 25 adults) with acute pancreatitis temporally associated with atypical pneumonia caused by Mycoplasma pneumoniae (n = 18), Legionella species (n = 14), or Coxiella burnetii (n = 1). Approximately 90% of patients (n = 29) concurrently presented with respiratory and pancreatic diseases. No cases associated with Chlamydophila pneumoniae, Chlamydophila psittaci, or Francisella species were found.

CONCLUSIONS

Acute pancreatitis has been associated with various infectious agents. The present review documents the association with atypical pneumonia induced by Mycoplasma pneumoniae, Legionella species, and Coxiella burnetii.

The CARDS toxin of Mycoplasma pneumoniae induces a positive feedback loop of type 1 immune response

Background

Within the past 3-5 years, Mycoplasma pneumoniae has become a major pathogen of community-acquired pneumonia in children. The pathogenic mechanisms involved in M. pneumoniae infection have not been fully elucidated.

Methods

Previous protein microarray studies have shown a differential expression of CXCL9 after M. pneumoniae infection. Here, we conducted a hospital-based study to explore the clinical significance of the type 1 immune response inflammatory factors interferon (IFN)-γ and CXCL9 in patients with M. pneumoniae pneumonia (MPP). Then, through in vitro experiments, we explored whether CARDS toxin stimulated F-DCs (dendritic cells incubated with Flt3L) to promote Th-cell differentiation; we also investigated the IFN-γ-induced CXCL9 secretion pathway in macrophages and the role of CXCL9 in promoting Th1 cell migration.

Results

The CXCL9 expression level was upregulated among patients with a higher fever peak, fever duration of greater than 7 days, an imaging manifestation of lobar or segmental, or combined pleural effusion (P<0.05). The peripheral blood levels of IFN-γ and CXCL9, which were higher in patients than in the healthy control group, were positively correlated with each other (r=0.502, P<0.05). In patients, the CXCL9 expression level was significantly higher in the bronchoalveolar lavage fluid (BALF) than in the peripheral blood, and the BALF CXCL9 expression level was higher than that in the healthy control group (all P<0.05). Our flow cytometry analysis revealed that M1-phenotype macrophages (CD16 ⁺ CD64 ⁺ CD163^-) were predominant in the BALF from children with MPP. In in vitro experiments, F-DCs stimulated with CARDS toxin promoted the differentiation of CD4 ⁺ IFN-γ ⁺ Th (Th1) cells (P<0.05). Moreover, IFN-γ induced high levels of CXCL9 expression in M1-type macrophages in a dose-dependent and time-dependent manner. Additionally, macrophages transfection with STAT1-siRNA-1 downregulated the expression of CXCL9 (P<0.05), and CXCL9 promoted Th1 cell migration (P<0.05).

Conclusions

Our findings suggest that CARDS toxin induces a type 1 immune response positive feedback loop during M. pneumoniae infection; this putative mechanism may be useful in future investigations of immune intervention approaches for M. pneumoniae pneumonia.

Eating the Enemy: Mycoplasma Strategies to Evade Neutrophil Extracellular Traps (NETs) Promoting Bacterial Nucleotides Uptake and Inflammatory Damage

Neutrophils are effector cells involved in the innate immune response against infection; they kill infectious agents in the intracellular compartment (phagocytosis) or in the extracellular milieu (degranulation). Moreover, neutrophils release neutrophil extracellular traps (NETs), complex structures composed of a scaffold of decondensed DNA associated with histones and antimicrobial compounds; NETs entrap infectious agents, preventing their spread and promoting their clearance. NET formation is triggered by microbial compounds, but many microorganisms have evolved several strategies for NET evasion. In addition, the dysregulated production of NETs is associated with chronic inflammatory diseases. Mycoplasmas are reduced genome bacteria, able to induce chronic infections with recurrent inflammatory symptoms. Mycoplasmas' parasitic lifestyle relies on metabolite uptake from the host. Mycoplasmas induce NET release, but their surface or secreted nucleases digest the NETs' DNA scaffold, allowing them to escape from entrapment and providing essential nucleotide precursors, thus promoting the infection. The presence of Mycoplasma species has been associated with chronic inflammatory disorders, such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, Crohn's disease, and cancer. The persistence of mycoplasma infection and prolonged NET release may contribute to the onset of chronic inflammatory diseases and needs further investigation and insights.

Comprehensive virome analysis of the viral spectrum in paediatric patients diagnosed with Mycoplasma pneumoniae pneumonia

Background

Among hospitalized children suffering from community-acquired pneumonia, Mycoplasma pneumoniae (MP) is one of the most common pathogens. MP often exists as a co-infection with bacteria or viruses, which can exacerbate the clinical symptoms. We investigated the pathogen spectrum in MP-positive and MP-negative samples from hospitalized children with respiratory tract infections in Beijing, China.

Method

This study included 1038 samples of nasopharyngeal aspirates obtained between April, 2017 and March, 2018 from hospitalized children under 6 years of age with respiratory tract infections. To explore the impact of MP infection on the composition of the pathogen spectrum, 185 nasopharyngeal aspirates (83 MP-positive/102 MP-negative) were randomly selected for next-generation sequencing and comprehensive metagenomics analysis. Real-time PCR was used to detect and verify common respiratory viruses.

Results

Of the 1038 samples, 454 (43.7%) were infected with MP. In children < 6 years of age, the MP infection rate gradually increased with age, with the highest rate of 74.2% in 5–6-year-olds. The results of metagenomics analysis revealed 11 human, animal and plant virus families, and bacteriophages, including common respiratory viruses, enteroviruses and anelloviruses. The virus family with the highest number of reads in both MP-positive and MP-negative samples was the Pneumoviridae, and the number of reads for human respiratory syncytial virus (HRSV) in MP-positive samples was higher than that in MP-negative samples. Among the 83 MP-positive samples, 47 (56.63%) were co-infected with viruses, the most common of which was influenza virus (IFV). The durations of hospitalization and fever were higher in patients with MP co-infection than MP single infection, but the difference was not statistically significant.

Conclusion

The viral family with the highest number of reads in both groups was Pneumoviridae, and the number of reads matched to HRSV in MP-positive samples was much higher than MP-negative samples. Co-infection of MP and IFV infection were the most cases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01914-y.

Risk Factors for the Development of Post-Infectious Bronchiolitis Obliterans in Children: A Systematic Review and Meta-Analysis

Post-infectious bronchiolitis obliterans (PIBO), one of the major complications of respiratory tract infection, is commonly underdiagnosed. To identify the risk groups that may develop PIBO and avoid misdiagnoses, we investigated the risk factors associated with the development of PIBO. We searched PubMed, Embase, and MEDLINE databases for studies that included risk factors for the development of PIBO published from inception to 13 June 2022. We limited our search to studies that reported the estimates of odds ratio (OR), hazard ratio (HR), or relative risks for developing PIBO. A fixed-effect and a random-effect model were used. We included seven studies reporting data on the risk factors for PIBO in 344 children with PIBO and 1310 control children. Twenty-two variables, including sex, age, respiratory pathogens, symptoms, laboratory and radiologic findings, and mechanical ventilation, were mentioned in at least one study. The significant risk factors mentioned in two or more studies included elevated lactate dehydrogenase levels, pleural effusion, hypoxemia, sex, and mechanical ventilation. The significance of the duration of hospitalization and fever as risk factors for PIBO differed when the studies were classified according to the statistical method. In addition, the risk factors differed according to respiratory infection pathogens. This meta-analysis identified potential risk factors associated with the development of PIBO. The results of this study highlight the importance of avoiding misdiagnosis and help establish management strategies for patients at a high risk of developing PIBO.

Clinical Usefulness of Serum Lactate Dehydrogenase Levels in Mycoplasma pneumoniae Pneumonia in Children

OBJECTIVE

To elucidate the clinical usefulness of lactate dehydrogenase (LDH) levels in children with Mycoplasma pneumoniae (MP) pneumonia and identify cut-off levels in various clinical conditions.

METHODS

The study was retrospectively performed in 145 children who were hospitalized with MP pneumonia. Laboratory findings, including LDH levels at admission and clinical features were retrospectively reviewed from patients' electronic medical records.

RESULTS

The mean age of the study population was 5.9 y, and the mean value of LDH was 809.7 U/L. Poor response to treatment for MP pneumonia, respiratory virus coinfection, severe MP pneumonia, development of postinfectious bronchiolitis obliterans (PIBO) after MP pneumonia, pleural effusion, and oxygen need during illness were significantly associated with serum LDH levels. The cutoff levels of LDH for predicting poor response to treatment for MP pneumonia and respiratory virus coinfection were 1058 U/L [area under the curve (AUC), 0.729] and 803 U/L (AUC, 0.682), respectively. Those for pneumonic lesions involving at least one-third of the total lung volume, prediction of PIBO development, and extrapulmonary manifestations were 1098 U/L (AUC, 0.715), 676 U/L (AUC, 0.714), and 859 U/L (AUC, 0.710), respectively. The cutoff levels for pleural effusion during illness and for the prediction of oxygen need were 894 U/L (AUC, 0.699) and 1114 U/L (AUC, 0.771), respectively.

CONCLUSION

LDH levels are elevated in diverse clinical conditions in children with MP pneumonia and may be useful in the identification of severe clinical courses of MP pneumonia in children.

Epidemic characteristics of Mycoplasma pneumoniae infection: a retrospective analysis of a single center in Suzhou from 2014 to 2020

BACKGROUND

Mycoplasma pneumoniae (M. Pneumoniae) is a common pathogen of respiratory tract infections, but there is still a lack of detailed investigation on the large sample of M. Pneumoniae infection in the all age population. And patients with severe M. Pneumoniae pneumonia (SMPP) still have a certain risk of death. How to identify the clinical characteristics and population of patients with SMPP as soon as possible is still an urgent problem in clinical practice.

METHODS

Demographic characteristics, patient clinical information, and laboratory data of 81,131 patients with respiratory tract infections (RTIs) in the Affiliated Suzhou Hospital of Nanjing Medical University from 2014 to 2020 were retrospectively collected from all patient records. The serum particle agglutination (PA) test was used to determine M. Pneumoniae infection by detecting specific antibodies. The white blood cell count, the proportion of neutrophils and lymphocytes, C-reactive protein (CRP) and lactate dehydrogenase (LDH) levels between children and adults with SMPP were compared by Student's t-test; other clinical features were analyzed by χ² test or Fisher's exact test.

RESULTS

A total of 81,131 patients with RTIs were included, and 21,582 (26.60%) M. Pneumoniae immunoglobulin M (IgM)-positive patients were detected. From 2014 to 2020, the annual proportions of M. Pneumoniae RTIs were 23.60%, 28.18%, 38.08%, 27.05%, 23.44%, 25.26%, and 18.33%, respectively. In terms of seasonal distribution, April-June and September-November were the peak seasons of M. Pneumoniae infection each year. Children and women have a high proportion of M. Pneumoniae infection. The peak age of M. Pneumoniae infection was between 4 and 14 years old. There were 301 cases of SMPP, including 281 children and 20 adults (8 cases of pregnant women). Children and pregnant women accounted for a high proportion of SMPP. Children with SMPP had more extrapulmonary symptoms, multilobar infiltrates, and increased CRP and LDH levels compared with adults.

CONCLUSIONS

M. Pneumoniae infection has seasonal, sex, and age distribution trends. Children and pregnant women accounted for a high proportion of SMPP. Extrapulmonary symptoms, multilobar infiltrates, and increased CRP and LDH levels may be helpful to identify SMPP in children than in adults.

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.

Clinical significance of Mycoplasma pneumoniae specific IgM titer in children hospitalized with Mycoplasma pneumoniae pneumonia

BACKGROUND

The present study aimed to identify the clinical significance of Mycoplasma pneumoniae (MP)-specific immunoglobulin M (IgM) titer, in addition to a diagnosis of MP infection, in children with MP pneumonia.

METHODS

This study was performed in 155 children hospitalized with MP pneumonia. The clinical features and laboratory and radiographic findings on admission in children with positive or negative MP-specific IgM titers were retrospectively reviewed from the electronic medical records.

RESULTS

The mean age of the included children was 6.0 years, and 118 (76.1%) of the children were positive for MP-specific IgM. A longer duration between symptom onset and admission (adjusted odds ratio [aOR] 1.47, 95% confidence interval [CI] 1.24-1.75), longer duration of symptoms during the illness (aOR 1.15, 95% CI 1.02-1.30), and development of extra-pulmonary manifestations (aOR 9.16, 95% CI 1.96-42.81) were significantly associated with a positive MP-specific IgM titer. Serum lactate dehydrogenase levels (aOR 1.00, 95% CI 1.00-1.01) and pneumonic infiltration involving > 50% of the total lung volume on chest radiography (aOR 4.68, 95% CI 1.12-19.55) were associated with positive MP-specific IgM in children with MP pneumonia. A poor response to stepwise treatment for MP pneumonia was more common in children with a positive MP-specific IgM titer than those with a negative MP-specific IgM titer on admission.

CONCLUSIONS

A positive MP-specific IgM titer at diagnosis of MP pneumonia may partially suggest an exaggerated immune response with a higher disease burden compared to children with MP pneumonia with a negative MP-specific IgM titer.

Ultrasensitive, Specific, and Rapid Detection of Mycoplasma pneumoniae Using the ERA/CRISPR–Cas12a Dual System

Mycoplasma pneumoniae can cause severe respiratory tract infections and extrapulmonary diseases, which pose a significant threat to the health of children. Diagnostic methods for M. pneumoniae include isolation and culture, antibody detection, fluorescence quantitative PCR, and so on, but there are various shortcomings in time, cost, convenience, and sensitivity. In this study, we developed a rapid, sensitive, specific, and economical method for the detection of M. pneumoniae, termed the ERA/CRISPR–Cas12a dual system. The system used the high specificity and collateral cleavage activity of the LbCas12a protein, combined with enzymatic recombination amplification (ERA) technology with strong amplification ability, allowing the results to be observed by a portable fluorometer or visualized by the naked eye with a dipstick, which could be obtained in approximately 30 min. The ERA/CRISPR–Cas12a fluorescence and dipstick system were able to detect M. pneumoniae at titers as low as 1 and 100 copies/μL, respectively. The specificity of the two interpretation methods was 100%, and no cross-reaction with other pathogens was observed. In the evaluation of 92 clinical samples, the positive predictive agreements of the ERA/CRISPR–Cas12a fluorescence and dipstick systems with qPCR detection were 100% and 92.86%, respectively. The negative predictive agreements of both methods were 100%. In conclusion, this study established a portable, rapid, low-cost, ultrasensitive, and specific method for the early and rapid diagnosis of M. pneumoniae to meet the needs of on-site rapid detection in primary health institutions.

Mycoplasma pneumonia Infection Is Associated With an Increased Risk of Systemic Lupus Erythematosus: A Nationwide, Retrospective Cohort Study

Background

Infections may play a role in the development of systemic lupus erythematosus (SLE).

Objective

To assess the link between Mycoplasma pneumonia (M. pneumonia) infection and the incidence of SLE.

Method

We conducted a retrospective cohort study, which identified 116,043 hospitalized patients with M. pneumoniae between 2000 and 2012 from the Taiwan National Health Insurance Research Database and compared them with 447,839 matched inpatients who had never been diagnosed with M. pneumonia infection (at a 1:4 ratio, matched by age, gender, and index year). Their comparative risk of developing SLE was evaluated. The follow-up period was defined as the time from the initial diagnosis of M. pneumonia infection to the date of SLE diagnosis, or December 31, 2013. The incidence rates of SLE were assessed in people with and without M. pneumoniae infection. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs), with the uninfected group used as the reference.

Results

The adjusted HR of SLE for the M. pneumoniae group was 2.97 with 95% CI = 2.18–4.05 compared with the uninfected group. The risk was most significantly higher within 0.5 years after the M. pneumoniae infection with an adjusted HR of 6.18 (95% CI = 3.82–9.97, p < 0.01). The adjusted HR for SLE from 0.5 to 2 years and from 2 to 5 years after M. pneumoniae infection was 1.59 (95% CI = 0.70–3.59, p = 0.27) and 2.42 (95% CI = 1.22–4.81, p = 0.01), respectively.

Conclusion

The incidence of SLE was significantly higher in subjects infected with M. pneumoniae.

Recent Trends in the Epidemiology, Diagnosis, and Treatment of Macrolide-Resistant Mycoplasma pneumoniae

Among Mycoplasma pneumoniae (MP) is one of the major pathogens causing lower respiratory tract infection. Macrolide-resistant Mycoplasma pneumoniae (MRMP) isolates have been increasing and has become a global concern, especially in East Asian countries. This affects the treatment of MP infection; that is, some patients with MRMP infections fever cannot be controlled despite macrolide therapy. Therefore, alternative therapies, including secondary antimicrobials, including tetracyclines, fluoroquinolones, or systemic corticosteroids, were introduced. However, there are insufficient data on these alternative therapies. Thus, this article provides reviews of the recent trends in the epidemiology, diagnosis, and treatment of MRMP.

Serum amyloid a, C-reactive protein, and procalcitonin levels in children with Mycoplasma pneumoniae infection

Background

Mycoplasma pneumoniae (MP) is a common pathogen of community‐acquired pneumonia in children. In the present study, serum amyloid A (SAA), C‐reactive protein (CRP), and procalcitonin (PCT) levels in children with MP infection were analyzed and the differential diagnoses of MP evaluated.

Methods

The study included 152 children with MP infection hospitalized in Tai’an Central Hospital in Shandong Province and 50 healthy children as controls. SAA, CRP, and PCT, as well as serum immunoglobulins and T lymphocyte subsets were analyzed during the acute and convalescent phases. Among the MP‐infected children, 30 cases were selected to monitor the SAA, immunoglobulins, and T lymphocyte subset levels for a week.

Results

The SAA, CRP, PCT, IgA, and IgM levels were significantly higher in the MP‐infected group than in the control group (F_(SAA) = 83.91, p < 0.05; F_(CRP) = 40.79, p < 0.05; F_(PCT) = 60.58, p < 0.05; F_(IgA) = 43.45, p < 0.05; F_(IgM) = 233.88, p < 0.05). In addition, the levels of these factors were significantly higher in the acute phase than in the convalescent phase (p < 0.05). However, significant difference was not observed in the IgG level between these two groups (p > 0.05). The CD3⁺ and CD4⁺ levels in the MP‐infected group were lower than in the control group ( F_(CD3+)= 60.58, P < 0.05; F_(CD4+) = 89.05, p < 0.05), and the CD8⁺ level was higher than in the control group ( F_(CD8+)= 96.96, p < 0.05). The CD3⁺, CD4⁺, and CD8⁺ levels were significantly different between the acute phase and the convalescent phase (CD3⁺: acute phase vs. convalescent phase, q = 2.79, p < 0.05; CD4⁺: acute phase vs. convalescent phase, q = 2.83, p < 0.05; CD8⁺: acute phase vs. convalescent phase, q = 3.15, p < 0.05). The changes in serum SAA levels in the MP‐infected group positively correlated with the changes in IgA, IgM, and CD8⁺ levels and negatively correlated with CD3⁺, CD4⁺, and CD4⁺/CD8⁺.

Conclusion

SAA, CRP, and PCT were specific markers for diagnosing early MP infection in children. These findings are important in the differential diagnosis of MP infection and clinical guidance for MP treatment.

Combined therapy of Xiaoer Feire Kechuan oral liquid and azithromycin for mycoplasma Pneumoniae pneumonia in children: A systematic review & meta-analysis

BACKGROUND

Mycoplasma pneumoniae pneumonia (MPP) has high morbidity with an increased global burden. Xiaoer Feire Kechuan (XEFRKC) oral liquid comprises multiple herbal medicines and possesses numerous broad-spectrum antibacterial activities for MPP. Therefore, treatment options with XEFRKC to provide new clinical evidence for children with MPP needs to be explored.

PURPOSE

This study aimed to evaluate the clinical efficacy and safety of combined treatment of XEFRKC with azithromycin (XEFRKC + azithromycin) for treating the MPP in children.

METHODS

We conducted a comprehensive search in 7 databases to find the randomized controlled trials (RCTs) of XEFRKC + azithromycin treatment. Two researchers independently review the retrieval, extraction, and quality assessment of the dataset. In addition, we conducted the effect model to analyze the data and performed the meta-regression with sensitivity analysis to assess the heterogeneity and stability.

RESULTS

A total of 30 RCTs with 2997 participants were included in this review. The results of primary outcomes showed that the XEFRKC + azithromycin therapy was significantly different with the azithromycin in response rate (RR = 1.18, 95% CI: 1.13 to 1.22), fever disappearance time (MD = -1.01, 95% CI: -1.18 to -0.84), cough disappearance time (MD = -2.18, 95% CI: -2.69 to -1.67), and pulmonary rales disappearance time (MD = -1.3, 95% CI: -1.71 to -0.88). For secondary outcomes and safety as well, XEFRKC + azithromycin had a significant difference compared with azithromycin. Meta-regression results showed that multiple covariables were not the source of heterogeneity. Moreover, sensitivity analysis showed that the stability of the meta-analysis results remained robust.

CONCLUSIONS

For MPP in children, the XEFRKC + azithromycin therapy may be the better option compared with azithromycin alone. However, the accuracy of safety needs to be confirmed and verified with more high-quality RCTs.

Characteristics of Lung Microbiota in Children's Refractory Mycoplasma pneumoniae Pneumonia Coinfected with Human Adenovirus B

Background

Both M. pneumoniae and human adenovirus (HAdV) are common causative agents of lower respiratory tract infection in children; nonetheless, the lung microbiota in patients with coinfection of HAdV and M. pneumoniae remain unexplored.

Methods

Thirty-two children, diagnosed with refractory M. pneumoniae pneumonia (RMPP), entered into the one-year study from July 1, 2019 to June 30, 2020. Among them, twenty-one entered into the M. pneumoniae monoinfection (MP) group and eleven entered into the M. pneumoniae and HAdV coinfection (MP&ADV) group. The characteristics of the clinical findings were examined, and the lung microbiota was analyzed by metagenomic next generation sequencing (mNGS).

Results

Eleven patients in the MP&ADV group were coinfected with human mastadenovirus species B. The fever days lasted for significantly longer periods in the MP&ADV group than in the MP group (P < 0.05). The percentage of CD16⁺CD56⁺ cells was significantly higher in the MP&ADV group than that in the MP group (P < 0.05). There were no significant differences in α-diversity between the MP and MP&ADV groups, but the β-diversity was clearly higher in the MP&ADV group than that in the MP group (P < 0.05). At the microbial level, the top phylum of the MP BALF microbiota was Tenericutes; in contrast, it was Preplasmiviricota in the MP&ADV BALF. There were significant differences in the relative abundance of Tenericutes and Preplasmiviricota between the two groups (P < 0.001). There was a strong positive correlation between human mastadenovirus B and fever days, M. pneumoniae and level of IgA, and a strong negative correlation between Mycoplasma pneumoniae and PCT.

Conclusions

In RMPP, the BALF microbiota in children with mono M. pneumoniae infection was simpler than those with coinfection with human mastadenovirus B. Prolonged fever days were associated with human mastadenovirus B coinfection.

Association of Tandem Repeat Number Variabilities in Subunit S of the Type I Restriction-Modification System with Macrolide Resistance in Mycoplasma pneumoniae

Mycoplasma pneumoniae is one of the major pathogens responsible for pneumonia in children. Modern molecular genetics has advanced both the management and the epidemiologic study of this disease. Despite these advancements, macrolide resistance remains a global threat in the management of M. pneumoniae infection, for which the genetic background remains unrevealed. In this study, the result of whole genome analysis of 20 sequence type 3 (ST3) M. pneumoniae strains were examined to investigate the gene(s) associated with macrolide resistance. Overall, genetic similarities within M. pneumoniae, and especially ST3, were very high (over 99.99 %). Macrolide resistant ST3 strains shared 20 single nucleotide polymorphisms, of which one gene (mpn085) was found to be associated with resistance. BLAST comparison of M. pneumoniae revealed regular tandem repeat number variabilities between macrolide-susceptible and resistant strains for genes coding the Type I restriction-modification (R-M) system of subunit S (HsdS). Of the ten known HsdS genes, macrolide resistance was determined by the unique tandem repeat of mpn085 and mpn285. In conclusion, the use of whole genome sequencing (WGS) to target macrolide resistance in M. pneumoniae indicates that the determinant of macrolide resistance is variabilities in the tandem repeat numbers of the type I R-M system in subunit S.

Case Report and Literature Review: Clinical Characteristics of 10 Children With Mycoplasma pneumoniae-Induced Rash and Mucositis

Mycoplasma pneumoniae-induced rash and mucositis (MIRM) is a rare disease, which has not been reported in northern China previously. We retrospectively analyzed the clinical characteristics, diagnosis and treatment of 10 cases of MIRM in order to help clinicians to identify MIRM and to distinguish it from the similar mucositis and cutaneous characteristics of Stevens-Johnson syndrome. All 10 children included in the study had MIRM with skin and mucosal symptoms, but the characteristics of the skin and mucosal lesions differed by age. Most of the older children had sparse erythema and a vesicular rash, but the younger children had dense erythema without blisters but with purulent exudation. The mucositis was relatively mild in the younger children. The erythrocyte sedimentation rate, the levels of C-reactive protein, lactate dehydrogenase, and D-dimer were significantly elevated in most children with MIRM. Concomitant treatment of glucocorticoids and/or IVIG with macrolides may shorten the duration of fever and accelerate the clinical recovery. Additional case reports are needed to improve knowledge of the characteristics of MIRM and its response to therapy.

Mycoplasma pneumoniae Infections and Primary Immune Deficiencies

Mycoplasma pneumoniae (M. pneumoniae) is one of the leading causes of community-acquired pneumonia in children and is also implicated in a variety of reactive extrapulmonary diseases. Recurrent and/or severe respiratory infections are one of the most frequent manifestations of several types of primary immunodeficiency. Here, we reviewed the medical literature to assess the potential relevance of M. pneumoniae in the infections observed in children affected with combined, humoral, and innate primary immune deficiencies. M. pneumoniae does not result to be epidemiologically prevalent as a cause of pneumonia in children affected by primary immunodeficiencies, but this infection can have a persistent or severe course in this category of patients. Indeed, the active search of M. pneumoniae could be useful and appropriate especially in children with humoral immune deficiencies. Indeed, most cases of M. pneumoniae infection in primary immunodeficiencies are described in patients affected by a/hypo-gammaglobulinemia.

Pulmonary and Extrapulmonary Manifestations in Hospitalized Children with Mycoplasma Pneumoniae Infection

Mycoplasma pneumoniae (MP) is one of the main causes of both upper and lower respiratory infections in school-aged children, accounting for up to 40% of community-acquired pneumonia. Younger children are also affected, and extrapulmonary manifestations have been recently reported in the pediatric population. We carried out a retrospective analysis of MP-positive patients admitted to the Pediatric Emergency Unit of S. Orsola Malpighi University Hospital in Bologna, the largest tertiary pediatric referral center in the Emilia–Romagna region, Northern Italy, between 2012 and 2020. We identified 145 patients with MP infection (82 males and 63 females), 27% of which were younger than 2 years; the median age was 5 years (interquartile range 1–9). The clinical presentation partially differed between age groups. School-aged children were more likely to have a chest X-ray-confirmed pneumonia (p = 0.013), while younger children required oxygen therapy more often (p = 0.048). Seventy-four children (51%) showed extrapulmonary manifestations, mainly gastrointestinal (30%) and dermatological (14%). Neurological symptoms were more frequent in children older than 6 years (p = 0.006). The rate of other extrapulmonary manifestations did not differ significantly between age groups. This study shows that MP infection is a frequent cause of pediatric hospitalization, including of children younger than 2 years. Clinicians should be aware of the variable clinical expressions of MP, including extrapulmonary manifestations, to achieve a correct diagnosis and determine appropriate treatment.

Increased Total Serum Immunoglobulin E Is Likely to Cause Complications of Mycoplasma pneumoniae Pneumonia in Children

Objective

To investigate the correlation between serum immunoglobulin E (IgE) levels and the complications in children with Mycoplasma pneumoniae pneumonia (MPP).

Methods

A retrospective study of MPP patients hospitalized from May 2019 to July 2021 was performed. We analyzed the clinical manifestations, complications, laboratory findings, and treatments.

Results

A total of 275 patients who met the inclusion criteria were enrolled in the study. We divided patients into two groups based on whether there were complications. Complications occurred in 147 patients, of which pulmonary complications were more common than extrapulmonary complications. The IgE level in the complication group was higher than that in the non-complication group with p = 0.041. Patients with complications of necrotizing pneumonitis, pneumothorax, skin rash, or bronchiolitis obliterans had higher IgE levels. There was no statistically significant difference in IgE levels between pulmonary complications and extrapulmonary complications. The older the age, the greater the probability of complications (p = 0.001). The group with complications was more likely to have chest pain (p = 0.000), while the group without complications was more likely to have wheezing (p = 0.017). The use of bronchoscopy and glucocorticoids was higher in the complication group than in the non-complication group (p = 0.000).

Conclusions

MPP patients with higher IgE levels had more severe clinical symptoms and complications. We speculated that IgE might be a biomarker for complications after MP infection.

Mycoplasma pneumoniae Seroprevalence and Total IgE Levels in Patients with Juvenile Idiopathic Arthritis

Background

Mycoplasma pneumoniae (M. pneumoniae) is implicated in several immune-mediated extrapulmonary manifestations, including reactive arthritis. Recently, increased total serum IgE were reported in children developing M. pneumoniae-related extrapulmonary diseases (MpEPDs). Here, we aimed at analyzing these aspects in children affected with rheumatic disorders and, in detail, Juvenile Idiopathic Arthritis (JIA).

Methods

M. pneumoniae serology (IgG and IgM) and total serum IgE were concomitantly analyzed in 139 pediatric patients diagnosed with: JIA (Group 1, n = 85), or any rheumatic disease other than JIA (Group 2, n = 27), or non-inflammatory endocrinological disorders (Group 3, n = 27).

Results

Overall, 19.4% M. pneumoniae seroprevalence was observed in this hospitalized pediatric population, without signicant differences among the three groups. No significant differences in total serum IgE levels were noted among these groups; however, a second analysis excluding children with very high (and clearly abnormal) IgE levels suggested that JIA patients and, in detail, those with oligopolyarticular forms may have higher serum IgE concentrations. This relative difference among groups in serum IgE level seems to be more pronounced in M. pneumoniae seropositive children.

Conclusions

M. pneumoniae infection should be actively sought in children developing immune-mediated diseases, including patients affected with JIA and, especially, in oligopolyarticular forms. There is some evidence that total serum IgE levels may tend to be increased in patients with oligopolyarticular JIA subtype and especially in those resulting as M. pneumoniae seropositive. However, further and focused research is needed to confirm these preliminary results and to clarify the relation between M. pneumoniae infection, atopic status, and immune-mediated arthritis.

IL-17 stimulates neutrophils to release S100A8/A9 to promote lung epithelial cell apoptosis in Mycoplasma pneumoniae-induced pneumonia in children

Mycoplasma pneumoniae-induced pneumonia (MPP) is a common cause of community-acquired respiratory tract infections, increasing risk of morbidity and mortality, in children. However, diagnosing early-stage MPP is difficult owing to the lack of good diagnostic methods. Here, we examined the protein profile of bronchoalveolar lavage fluid (BALF) and found that S100A8/A9 was highly expressed. Enzyme-linked immunosorbent assays used to assess protein levels in serum samples indicated that S100A8/A9 concentrations were also increased in serum obtained from children with MPP, with no change in S100A8/A9 levels in children with viral or bacterial pneumonia. In vitro, S100A8/A9 treatment significantly increased apoptosis in a human alveolar basal epithelial cell line (A549 cells). Bioinformatics analyses indicated that up-regulated S100A8/A9 proteins participated in the interleukin (IL)-17 signaling pathway. The origin of the increased S100A8/A9 was investigated in A549 cells and in neutrophils obtained from children with MPP. Treatment of neutrophils, but not of A549 cells, with IL-17A released S100A8/A9 into the culture medium. In summary, we demonstrated that S100A8/A9, possibly released from neutrophils, is a new potential biomarker for the clinical diagnosis of children MPP and involved in the development of this disease through enhancing apoptosis of alveolar basal epithelial cells.

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.

The Level of D-Dimer Is Positively Correlated With the Severity of Mycoplasma pneumoniae Pneumonia in Children

Objective

Mycoplasma pneumoniae pneumonia (MPP) is an important disease in children. Studies have demonstrated that the levels of D-dimer are elevated in some children with MPP, especially those with thrombotic complications. However, the potential association between MPP and D-dimer remains unclear. In our study, we sought to explore the relationship between the levels of plasma D-dimer and clinical characteristics of MPP patients.

Methods

Retrospective analysis was conducted on 356 patients who were hospitalized in our hospital for MPP between January 1, 2017, and December 31, 2019. According to the peak value of D-dimer, patients were divided into three groups: the normal group (D-dimer<0.55 mg/L), the mild-moderately elevated group (D-dimer 0.55–5.5 mg/L) and the severely elevated group (D-dimer >5.5 mg/L). The demographic and clinical information, radiological findings, laboratory data, and treatments of patients were compared among different groups.

Results

106 patients were in the normal group, 204 patients were in the mild-moderately elevated group, and 46 patients were in the severely elevated group. More severe clinical and radiographic manifestations, longer length of fever, hospital stay and antibiotic therapy duration, higher incidences of extra-pulmonary complications, refractory MPP (RMPP), severe MPP (SMPP) were found in the elevated group, when compared with the normal group (P<0.01). Meanwhile, we found that the percentage of neutrophil (N%) and CD₈⁺ lymphocyte (CD₈⁺%), C-reactive protein (CRP), lactate dehydrogenase (LDH), interleukin (IL)-6, IL-10, and interferon-gamma (IFN-γ) trended higher with increasing D-dimer, whereas the percentage of lymphocyte (L%) and prealbumin (PAB) trended lower (P<0.01). In addition, the proportions of patients requiring oxygen therapy, glucocorticoid, bronchoscopy, immunoglobulin use, thoracentesis, or ICU admission were significantly higher in the severely elevated group than those in the other two groups (P<0.01). Correlation analysis showed that N%, L%, CRP, LDH, IL-10, length of fever, length of stay, and length of antibiotic therapy had strong correlations with the level of D-dimer.

Conclusions

MPP patients with higher levels of D-dimer had more severe clinical manifestations and needed longer duration of treatment, which might be closely related to the severity of lung inflammation after MP infection.

Risk factors for delayed radiographic resolution in children with refractory Mycoplasma pneumoniae pneumonia

OBJECTIVE

To determine the risk factors for delayed radiographic resolution in children with refractory Mycoplasma pneumoniae pneumonia (RMPP) and explore the most suitable time for interventional bronchoscopy.

METHODS

This retrospective study involved 142 children with RMPP who were admitted to our hospital from 1 January 2015 to 31 December 2017. They were divided into a common resolution group and a delayed resolution group based on their chest radiograph series.

RESULTS

Among the 142 patients, 67 showed common resolution on chest radiographs and 75 showed delayed resolution. Independent risk factors for delayed resolution were a clinical course of ≥11.5 days before the performance of interventional bronchoscopy, mucus plug formation, corticosteroid resistance, and atelectasis. When bronchoscopy was performed before the disease had been present for <11.5 days, the length of hospitalization, total fever duration, and duration of time until disappearance of coughing were shorter than those in children who underwent bronchoscopy after the disease had been present for ≥11.5 days.

CONCLUSIONS

Corticosteroid resistance, the time to interventional bronchoscopy, atelectasis, and mucus plug formation were associated with delayed resolution on chest radiographs. Performance of interventional bronchoscopy before the clinical course has reached 11.5 days may help alleviate clinical symptoms and improve radiographic resolution.

Infantile giant cell hepatitis with autoimmune hemolytic anemia

Giant cell hepatitis (GCH) is characterized by large and multinucleated (syncytial) hepatocytes in the context of liver inflammation. Infantile GCH is typically associated with autoimmune hemolytic anemia in the absence of any other systemic or organ-specific autoimmune comorbidity. The etiology is unknown; concomitant viral infections (as potential trigger factors) have been identified in a few patients. The pathogenesis reportedly relies upon immune-mediated/ autoimmune mechanisms. This condition should be considered in any infant developing Coombs-positive anemia; indeed, anemia usually precedes the development of hepatitis. The clinical course is usually aggressive without the appropriate immunosuppressive therapy, which may include steroids, conventional immunosuppressors (e.g., azathioprine and cyclophosphamide as first-line treatments), intravenous immunoglobulin, and biologics (rituximab). Improvements in medical management (including the availability of rituximab) have significantly reduced the mortality of this condition in the last decade.

Expression of Serum miR-155 in Children with Mycoplasma pneumoniae Pneumonia and Its Role in Immunity to Mycoplasma pneumoniae

Objective

To investigate the expression of serum miR-155 in children with Mycoplasma pneumoniae pneumonia (MPP).

Methods

A total of 100 children at our hospital with pneumonia caused by Mycoplasma pneumoniae infection were enrolled as a study group, including 45 cases in the acute phase (acute phase group) and 55 in the recovery phase (recovery phase group). An additional 30 healthy children were enrolled during the same period as the control group. The expression levels of miR-155, tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), IL-10, IL-13, immunoglobulin (Ig) G, IgA, complements (C3 and CH50), and T lymphocyte subsets (CD₃⁺, CD₄⁺, CD₈⁺, and CD₄⁺/CD₈⁺) were determined. Multivariate logistic regression analysis was performed to identify risk factors affecting MPP in children.

Results

miR-155, IL-10, IgG, IgA, CD₃⁺, CD₄⁺, and CD₄⁺/CD₈⁺ were poorly expressed in children with MPP, and their expression in the acute phase group was significantly lower than that in the recovery phase group. TNF-α, IL-13, C3, and CH50 were highly expressed in the children, and their expression was significantly higher in the acute  phase group than in the recovery phase group. In the acute phase group, the expression of IL-8 was significantly higher than that in the control and recovery phase groups but without any significant differences between the recovery phase and control groups. Age, season, low complement state, epidemiological contact history, and antibiotic use time were independent risk factors affecting MPP in children.

Conclusion

Serum miR-155 is poorly expressed in children with MPP, and it can regulate inflammatory disorders and immune responses.

The clinical characteristics of Mycoplasma pneumoniae pneumonia and its relationship between hypokalemia in west China

BACKGROUND

Mycoplasma pneumoniae (MP) is one of the most common respiratory pathogens of community acquired pneumonia (CAP) in children. The purpose of this study was to identify epidemics of Mycoplasma pneumoniae pneumonia (MPP) and to determine the relationship between hypokalemia and MPP.

METHODS

This study was retrospectively conducted from 1 August 2016 to 31 July 2018 at Bishan People's Hospital in Chongqing, China. We analyzed the demographic characteristics (age, gender), extra-pulmonary manifestations, fever duration, length of hospital stay, whole blood cell (WBC) count, C-reactive protein (CRP) levels, and lactate dehydrogenase (LDH) levels.

RESULTS

The total number of children with pneumonia was 3,385, including 570 (16.84%) patients in the MP infection group. The male-to-female ratio was 1.34:1. The peak time of MPP incidence was in autumn. The MP infection group had a significantly higher ratio of fever, higher body temperature, and longer fever duration. The number of MP-infected patients with hypokalemia was highest in spring. The length of hospital stay in the mild hypokalemia group was longer than in the normokalemia group. Furthermore, severe hypokalemia cases were all in the severe MP infection group, and the severity of MP infection and hypokalemia were positively correlated.

CONCLUSIONS

In this study, we concluded that children infected with MP were more susceptible to fever, and had a longer duration of fever. The number of MP-infected patients with mild hypokalemia peaked in spring, and affected more boys than girls. Furthermore, patients with severe hypokalemia had longer fever duration, and a correlation was found between the severity of MP infection and hypokalemia.

Atypical Bacterial Pathogens and Small-Vessel Leukocytoclastic Vasculitis of the Skin in Children: Systematic Literature Review

Leukocytoclastic small-vessel vasculitis of the skin (with or without systemic involvement) is often preceded by infections such as common cold, tonsillopharyngitis, or otitis media. Our purpose was to document pediatric (≤18 years) cases preceded by a symptomatic disease caused by an atypical bacterial pathogen. We performed a literature search following the Preferred Reporting of Systematic Reviews and Meta-Analyses guidelines. We retained 19 reports including 22 cases (13 females and 9 males, 1.0 to 17, median 6.3 years of age) associated with a Mycoplasma pneumoniae infection. We did not find any case linked to Chlamydophila pneumoniae, Chlamydophila psittaci, Coxiella burnetii, Francisella tularensis, or Legionella pneumophila. Patients with a systemic vasculitis (N = 14) and with a skin-limited (N = 8) vasculitis did not significantly differ with respect to gender and age. The time to recovery was ≤12 weeks in all patients with this information. In conclusion, a cutaneous small-vessel vasculitis with or without systemic involvement may occur in childhood after an infection caused by the atypical bacterial pathogen Mycoplasma pneumoniae. The clinical picture and the course of cases preceded by recognized triggers and by this atypical pathogen are indistinguishable.

Clinical Predictors of Wheezing Among Children Infected With Mycoplasma Pneumoniae

Background: Mycoplasma pneumoniae (MP) not only was a common pathogen of respiratory tract infections, but also could trigger the exacerbation of asthmatic symptoms in children with or without asthma. Objective: This study aimed to identify possible risk factors associated with wheezing among children diagnosed with MP infection. Methods: A retrospective analysis of medical records of children aged 28 days to 18 years old who visited the Shanghai Children's Hospital between January 2019 and January 2020 was carried out, and all children were then classified into three groups: two wheezing groups (with or without MP infection) and a non-wheezing group with MP infection. Information including patient's demographics, clinical features, laboratory data, and radiography findings was extracted from the electronic medical record system. Chest radiographs were reviewed independently by two board-certified, blinded pediatric radiologists. Results: A total of 1,512 patients were included in our study, and 21.9% of them belonged to the wheezing group without MP infection. Among 1,181 patients with MP infection, 295 people (25.0%) suffered from wheezing, and males accounted for 61%. Through the multivariable logistic regression analyses, we found that six variables were positively associated with wheezing attacks in children with MP infection: male gender (likelihood ratio [LR] = 2.124, 95% confidence interval [CI]: 1.478-3.053), history of allergy (LR= 3.301, 95% CI: 2.206-4.941), history of wheezing (LR = 7.808, 95% CI: 5.276-11.557), autumn in reference to summer (LR = 2.414, 95% CI: 1.500-3.885), non-end-point infiltration in reference to consolidation or pleural effusion (LR = 1.982, 95% CI: 1.348-2.914), and infiltration scope (LR = 1.773, 95% CI: 1.293-2.432). However, the model showed that the probability of wheezing after MP infection decreased as age increased (LR = 0.257, 95% CI: 0.196-0.337). Moreover, the area under the curve (AUC) of the regression model was as high as 0.901 (0.847-0.955). Conclusion: The model integrated with factors including gender, age, season, radiological patterns, infiltration scope, and history of allergy performed well in predicting wheezing attack after MP infection in children.