Immune Thrombocytopenia Associated with Mycoplasma pneumoniae Infection

Real-world experience of thrombopoietin receptor agonists in pediatric immune thrombocytopenia: a report from a Chinese tertiary children's hospital

Background

Primary immune thrombocytopenia (ITP) is the most common bleeding disorder in children. There are approximately 20% pediatric ITP patients respond poor to corticosteroids as first-line treatment. Recently thrombopoietin receptor agonists (TPO-RAs) have been used to treat refractory ITP and have achieved certain therapeutic effects. To investigate the efficacy and safety of TPO-RAs in the treatment of pediatric ITP, we conducted this real-world study.

Methods

Fifty-three pediatric patients with ITP who did not respond well to corticosteroids were treated with TPO-RAs. Clinical data, including therapeutic response rate, changes in platelet (PLT) count, and adverse events (AEs) were collected.

Results

Of the 51 evaluable patients, 37 (72.5%) responded to TPO-RAs. Patients aged >4 years had a higher response rate than those aged ≤4 years (81.1% vs. 50.0%, P=0.04). There was no effect of sex, duration of disease, prior therapy, Mycoplasma pneumoniae (MP) immunoglobulin M (IgM) positivity, antinuclear antibody (ANA) positivity, CD4/CD8 ratio or baseline PLT count on the response rate (P>0.05). Other than 10 patients with PLT counts that exceeded the upper limit of normal, AEs were sporadic, including increased aminotransferase levels, cough, headache, and vomiting.

Conclusions

TPO-RAs exhibited good clinical efficacy in pediatric ITP patients who failed to respond to first-line treatment, especially patients aged >4 years, and the side effects were minor.

Secondary Immune Thrombocytopenia Due to Mycoplasma pneumoniae Without Clinically Significant Evidence of Active Infection

Immune thrombocytopenia (ITP) is a leading cause of isolated thrombocytopenia characterized by autoantibody-mediated destruction of platelets, impaired megakaryocyte function, and pathologic T-cell recognition of platelet antigens. Several triggers for ITP have been identified. Treatment of the inciting cause decreases the antibodies responsible for molecular mimicry, and these cases are usually associated with a better outcome with a decreased probability of progression to chronic ITP. Mycoplasma pneumoniae infection is known to have extrapulmonary manifestations, and growing evidence suggests it can be a cause of secondary ITP. Many of the described cases report evidence of a pulmonary infection with severe mucosal bleeding. Here, we describe an interesting case of a patient presenting with isolated thrombocytopenia with mild mucosal bleeding, later found to be positive for Mycoplasma immunoglobulin M without clinically significant evidence of active infection. Currently, mycoplasma testing is not routinely performed as a workup for ITP. However, clinicians may consider this before proceeding with more aggressive treatment for refractory ITP (i.e., prolonged immunosuppression, splenectomy). This case illustrates that mild/asymptomatic Mycoplasma infection can also be associated with ITP.

Mycoplasma pneumoniae Associated Acute Transverse Myelitis: An Atypical Clinical Presentation in an Adolescent Child

We report an atypical case of a 15-year-old pediatric patient diagnosed with Mycoplasma pneumoniae associated acute transverse myelitis (ATM). The patient had no prodromal or pulmonary symptoms that are commonly associated with mycoplasma infection. Yet, the patient exhibited acute bilateral lower extremity paralysis, paresthesia, decreased sensation at the level of T11 and below, bowel and bladder dysfunction, and thrombocytopenia. Magnetic resonance imaging of the spinal cord revealed transverse myelitis from T10 to the end of the conus medullaris. The patient showed only slow clinical improvement despite therapy consisting of azithromycin, high-dose intravenous methylprednisolone, intravenous immunoglobulin, and plasmapheresis. This report calls attention to the importance of early identification of mycoplasma as an underlying cause of ATM and the potential consequences of delayed detection and treatment: more severe neurologic complications, prolonged hospitalization, and unfavorable clinical outcomes.

Thrombosis associated with mycoplasma pneumoniae infection (Review)

Mycoplasma pneumoniae is a common pathogen causing respiratory infections in children and adults. In addition to respiratory diseases, Mycoplasma pneumoniae is also involved in numerous extrapulmonary diseases. Thrombosis is an extrapulmonary manifestation associated with Mycoplasma pneumoniae infection. In recent years, an increasing number of case reports have been published identifying thrombosis secondary to Mycoplasma pneumoniae infection. In the present study, the available relevant literature in English available on PubMed, Medline and Web of Science was consulted. The results of the present study demonstrated that in patients with thrombosis caused by Mycoplasma pneumoniae infection, some of the factors causing thrombosis are transient and some are due to hereditary thrombophilia. Following timely treatment, the majority of patients recovered completely but some patients had a poor prognosis. The present review focuses on the pathogenesis, clinical features, treatment and prognosis of this crucial issue, which contributes toward the understanding of the disease.

[Clinical implications of the genus Mycoplasma]

Dentro del género Mycoplasma, las especies que tradicionalmente se han relacionado con cuadros infecciosos han sido principalmente M. pneumoniae, M. genitalium, M. hominis o U. urealyticum. Sin embargo, existen otras muchas que están implicadas y, que muchas veces, son desconocidas para los profesionales sanitarios. El objetivo de esta revisión es identificar todas las especies del género Mycoplasma que se han aislado en el hombre y determinar su participación en la patología infecciosa humana.

Low arterial oxygen partial pressure induces pulmonary thrombocytopenia in patients and a mouse model

BACKGROUND

Recent basic studies demonstrate that the lung is a primary organ of platelet biogenesis. However, whether the pathophysiological state of the lung affect the platelets is little known. We aim to investigate the incidence of thrombocytopenia in patients with pulmonary infection (PIN) and risk factors associated with pulmonary thrombocytopenia.

METHODS

In total, 11,941 patients with pulmonary infection (PIN) were enrolled, and patients with other three infectious diseases were collected as controls. The incidence of thrombocytopenia was compared, and the risk factors associated with thrombocytopenia in PIN patients were investigated by multivariate analysis. To explore the mechanism of thrombocytopenia, hypoxic model was constructed. Blood platelet counts from the angular vein (PLTs), left ventricle (PLT_post) and right ventricle (PLT_pre) were determined. Megakaryocytes identified by anti-CD41 antibody were detected through flow cytometry and immunofluorescence.

RESULTS

The incidence of thrombocytopenia in PIN was higher than that in other three infectious diseases (9.8% vs. 6.4% ~ 5.0%, P < 0.001). Low arterial oxygen partial pressure (PaO₂) was an important risk factor for thrombocytopenia (OR = 0.88; P < 0.001). In a hypoxic mouse model, PLTs decreased (518.38 ± 127.92 vs 840.75 ± 77.30, P < 0.05), which showed that low PaO₂ induced thrombocytopenia. The difference between the PLT_post and PLT_pre (∆PLT_post-pre), representing the production of platelets in the lungs, was significantly attenuated in hypoxic mice when compared with normoxic mice (F = 25.47, P < 0.05). Additionally, proportions of CD41-positive megakaryocytes in the lungs, marrow, spleen all decreased in hypoxic mice.

CONCLUSION

There is a high incidence for thrombocytopenia in PIN patients. Low PaO₂-induced thrombocytopenia is associated with impaired generation of platelet in the lungs.

Immune Thrombocytopenic Purpura: A Sequelae of Mycoplasma pneumoniae Infection

Our patient presented with a mild upper respiratory infection, which quickly developed into atypical pneumonia. Although atypical pneumonia is a common clinical presentation, our case is unique due to the rare hematologic complications associated with the underlying etiology of this atypical pneumonia case. Most cases of atypical pneumonia are simple, but ours developed immune thrombocytopenic purpura (ITP), which is a rare complication associated with an acute Mycoplasma pneumoniae infection (evidenced by positive IgM titers). Although our patient did not develop significant bleeding, our review of the literature demonstrated that ITP associated with M. pneumoniae infection can be fatal. Platelet count should be closely monitored and promptly treated.