Pediatric Mycoplasma pneumoniae Infection Presenting with Acute Cholestatic Hepatitis and Other Extrapulmonary Manifestations in the Absence of Pneumonia

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.

Cavitatory necrotising pneumonia with extrapulmonary multi-systemic involvement — a rare presentation of macrolide-resistant Mycoplasma pneumoniae

Background

Mycoplasma pneumoniae is one of the leading causes of community-acquired pneumonia. Due to its microbiological variation, clinical presentations of mycoplasma infections are atypical and diverse. Multiple pulmonary and extrapulmonary manifestations of Mycoplasma pneumoniae have been documented. Among pulmonary, common manifestations are fever, malaise, lymphadenopathy, pneumonia, upper respiratory tract infections, sinusitis, etc. Necrotising pneumonia leading to cavitation as a manifestation is rather an uncommon presentation.

Case presentation

We are reporting a rare case of a 5-year-old female child who presented with bilateral haemorrhagic pleural effusion and necrotising pneumonia with cavitation along with extrapulmonary manifestation in the form of maculo-papular rash, Coombs-positive haemolytic anaemia and serositis. The child was started on azithromycin and symptomatic management, but she did not respond to it; she had clinical worsening and evidence of radiological necrotising pneumonia. The child was treated as macrolide-resistant mycoplasma pneumonia with levofloxacin, steroids and rigorous physiotherapy.

Conclusions

Accurate clinical acumen along with timely radiological imaging is the need of the hour for early diagnosis of macrolide-resistant mycoplasma pneumonia (MRMP). This case also emphasises role of fluoroquinolones and steroids in treatment of macrolide-resistant mycoplasma pneumonia.

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.

Rhabdomyolysis and Neurological Manifestation With Progressive Weakness in a Young Adult: A Rare Extrapulmonary Presentation of Mycoplasma Pneumoniae

Mycoplasma pneumoniae (M. pneumoniae) is a common cause of community-acquired pneumonia. It has been associated with many extrapulmonary manifestations that can present even in the absence of pulmonary signs and symptoms. Rhabdomyolysis and central nervous system (CNS) manifestations are rare extrapulmonary manifestations. These are infrequently reported in adults. We present a case of a healthy 32-year-old male who initially presented with signs and symptoms of community-acquired pneumonia and was treated with antibiotics. However, he continued to have generalized malaise, night sweats, diffuse joint pain, and myalgias and was subsequently noted to have rhabdomyolysis with elevated creatine kinase (CK) and myoglobin levels. Rhabdomyolysis was attributed to M. pneumoniae based on the recent history of upper respiratory tract infection and M. pneumoniae immunoglobulin M (IgM) serology positivity along with high M. pneumoniae IgG titer. The other causes of rhabdomyolysis were diligently excluded based on patient history and laboratory and clinical data. This immune-mediated rhabdomyolysis improved with intravenous hydration, doxycycline, and prednisone therapy. However, the patient developed progressive weakness with neuropathy, which required treatment with intravenous immune globulin (IVIG). This case highlights the need to maintain a high index of suspicion for rare extrapulmonary manifestations of mycoplasma infection, which could be life-threatening or cause significant morbidity; and in cases of severe extrapulmonary manifestations, the appropriate use of immunosuppressive/immunomodulatory therapy may lead to a better outcome.

Rhabdomyolysis: A Case Report of an Extrapulmonary Presentation of Mycoplasma pneumoniae

Introduction

We present an unusual case of rhabdomyolysis secondary to Mycoplasma pneumoniae in a healthy 27-year-old female. M. pneumoniae is associated with numerous extrapulmonary manifestations, including acute hepatitis, Stevens-Johnson syndrome, and rhabdomyolysis. Most documented cases affect the pediatric population, with only five cases in adults reported in the literature.

Case Report

The patient presented with complaints of myalgia and intractable cough. In this case the initial presentation demonstrated hypoxia requiring supplemental oxygen, and a creatine kinase of 7,646 units per liter (U/L) (reference range 26–192 U/L) with a peak of 29,427. During her hospitalization, she also remained persistently hypoxic for several days but ultimately was successfully weaned off all supplemental oxygen. She was discharged home after a seven-day hospitalization.

Conclusion

This patient’s presentation of an insidious, upper respiratory infection along with the subsequent development of rhabdomyolysis with reactive antibodies to M. pneumoniae demonstrates a link between these two clinically important conditions.

Risk of Mycoplasma pneumoniae-related hepatitis in MP pneumonia pediatric patients: a predictive model construction and assessment

BACKGROUND

A predictive model for risk of Mycoplasma pneumoniae (MP)-related hepatitis in MP pneumonia pediatric patients can improve treatment selection and therapeutic effect. However, currently, no predictive model is available.

METHODS

Three hundred seventy-four pneumonia pediatric patients with/without serologically-confirmed MP infection and ninety-three health controls were enrolled. Logistic regressions were performed to identify the determinant variables and develop predictive model. Predictive performance and optimal diagnostic threshold were evaluated using area under the receiver operating characteristic curve (AUROC). Stratification analysis by age and MP-IgM titer was used to optimize model's clinical utility. An external validation set, including 84 MP pneumonia pediatric patients, was used to verify the predictive efficiency. After univariate analysis to screen significant variables, monocyte count (MO), erythrocyte distribution width (RDW) and platelet count (PLT) were identified as independent predictors in multivariate analysis.

RESULTS

We constructed MRP model: MO [^109/L] × 4 + RDW [%] - PLT [^109/L] × 0.01. MRP achieved an AUROC of 0.754 and the sensitivity and specificity at cut-off value 10.44 were 71.72 and 61.00 %, respectively in predicting MP-related hepatitis from MP pneumonia. These results were verified by the external validation set, whereas it merely achieved an AUROC of 0.540 in pneumonia without MP infection. The AUROC of MRP was 0.812 and 0.787 in infants and toddlers (0-36 months) and low MP-IgM titer subgroup (1:160-1:320), respectively. It can achieve an AUROC of 0.804 in infants and toddler with low MP-IgM titer subgroup.

CONCLUSIONS

MRP is an effective predictive model for risk of MP-related hepatitis in MP pneumonia pediatric patients, especially infants and toddlers with low MP-IgM titer.

Mycoplasma pneumoniae-related hepatitis in children

Mycoplasma pneumoniae (M. pneumoniae) is a small bacterium characterized by the absence of cell wall. It is a human pathogen causing upper and lower respiratory infections, both in adults and children. However, it is also considered to be implicated in the pathogenesis of several types of extra-respiratory diseases, including some gastrointestinal disorders. The liver involvement in children during or after M. pneumoniae infections is analyzed and discussed in this review. Through a systematic literature search, it is evidenced that M. pneumoniae is not infrequently associated with alteration of liver function, but rarely causes acute and severe hepatitis in children. M. pneumoniae should be considered as an unusual cause of acute hepatitis in children, whenever the most common hepatotropic viruses have been excluded. The pathogenesis of M. pneumoniae-related hepatitis is likely to be immune-mediated: both the innate and adaptive immune responses may play a fundamental role. However, the exact pathological mechanisms have to be elucidated yet. Further clinical studies are needed in order to understand the actual relevance of this microorganism in liver disease and its pathogenesis.

Extra-pulmonary diseases related to Mycoplasma pneumoniae in children: recent insights into the pathogenesis

PURPOSE OF REVIEW

Providing an overview on Mycoplasma pneumoniae-related extra-pulmonary diseases (MpEPDs) in children, who represent the preferred target population by those complications, and discussing the main pathogenic mechanisms implicated or potentially involved.

RECENT FINDINGS

Recent evidences supported the fact that M. pneumoniae is more than an extra-cellular pathogen colonizing epithelial cells of the respiratory tract. It is able to penetrate the cell membrane of host cells and to invade the respiratory mucosa, leading to pronounced inflammatory responses and also spreading outside the respiratory system, to some extent. Thus, direct and indirect (immune-mediated) mechanisms have been described in M. pneumoniae infections, but the latter ones have been mainly implicated in MpEPDs, as reviewed here. Recently, interesting insights have been provided, especially as concern neurologic complications, and new potential mechanisms of disease have been emerging for autoimmunity.

SUMMARY

The awareness of the occurrence of MpEPDs, showing very variable clinical expressions, could promote a correct diagnosis and an appropriate treatment. The knowledge of disease mechanisms in MpEPDs is largely incomplete, but recent advances from clinical studies and murine models might promote and direct future research.

A systematic review on the definition of rhabdomyolysis

BACKGROUND

Rhabdomyolysis (RML) is an interdisciplinary condition due to muscle cell injury followed by the release of cell components into circulation. Etiology of RML has a broad range; a serious complication is acute kidney injury (AKI). Despite its high relevance, there is no established formal definition for RML.

OBJECTIVES

A systematic review, focusing on RML definition, providing a recommendation for clinicians.

METHOD

Systematic literature research in PubMed and Embase (1968-07/2018).

RESULTS

The database research presented 8136 articles in PubMed and 2151 in Embase. After screening, 614 papers were retained for statistical analysis. A retrospective study was the most used design (44%). A definition of RML was stated in 231 studies (37.6%), including a precise creatine kinase level (CK) cut-off most frequently (67.1%). In 53/231 (22.9%) studies the CK cut-off was > 5 × upper limit of normal (ULN), and in 64/231 (27.7%) studies > 1000 IU/L. Further components of definitions were elevated CK without specific thresholds, and clinical symptoms. Exclusion criteria referring to the definition of RML were established in 113 studies, including myocardial, renal, cerebral and neuromuscular characteristics.

CONCLUSION

At present, we recommend a clinical syndrome of acute muscle weakness, myalgia, and muscle swelling combined with a CK cut-off value of > 1000 IU/L/ or CK > 5 × ULN for the standard definition of a mild RML. Additionally measured myoglobinuria and AKI indicate a severe type of RML. Exclusion criteria as well as the chronological sequence need to be considered for a conclusive RML definition.