Pathogenesis and association ofMycoplasma pneumoniaeinfection with cardiac and hepatic damage

A comparative study of general and severe mycoplasma pneumoniae pneumonia in children

OBJECTIVES

The increasing prevalence of severe Mycoplasma pneumoniae pneumonia (SMPP) poses a significant threat to the health of children. This study aimed to characterise and assess the outcomes in children with SMPP.

METHODS

We retrospectively analysed children hospitalised for M. pneumoniae pneumonia (MPP) between January and December 2022. Retrospectively, demographic, clinical, underlying diseases, laboratory and radiological findings, and treatment outcomes were collected and analysed. Disease severity was defined as severe or general according to the Guideline for diagnosis and treatment of community-acquired pneumonia in children (2019 version).

RESULTS

Over a 12-month observation period, 417 children with MPP were enrolled, 50.6% (211/417) of whom had SMPP, with the peak incidence observed in winter. Of the 211 children with SMPP, 210 were treated and discharged with improvement, while one child with congenital heart disease died of cardioembolic stroke. A significantly higher proportion of patients with SMPP had underlying diseases, extrapulmonary complications (myocardial and digestive system involvement), and bacterial co-infection. A total of 25 (12%) children with SMPP received mechanical ventilation. The median duration of mechanical ventilation was 3 days. All children were treated with macrolide antibiotic. A significantly higher proportion of patients with SMPP received antibiotic other than macrolides, methylprednisolone sodium succinate, intravenous immunoglobulin and anticoagulation, compared with patients with general MPP (GMPP). Children with SMPP had significantly higher levels of white blood cells, neutrophil percentage, C-reactive protein, procalcitonin, interferon-γ, interleukin (IL)-2, IL-5, IL-6, IL-8, IL-10 and significantly lower percentages of lymphocytes, monocytes, and natural killer cells, compared with GMPP group.

CONCLUSION

Our findings suggest that severely ill children have more pronounced inflammatory reaction and extrapulmonary complications. For effective management of children with SMPP, hormonal, prophylactic, anticoagulant therapy, as well as the use of antibiotics other than macrolides for bacterial co-infections, could be incorporated into treatment regimens.

A Case Report of Mycoplasma pneumoniae-induced fulminant myocarditis in a 15-year-old male leading to cardiogenic shock and electrical storm

Mycoplasma pneumoniae (M. pneumoniae) is a well-recognized pathogen primarily associated with respiratory tract infections. However, in rare instances, it can lead to extrapulmonary manifestations, including myocarditis. We present a case of a 15-year-old male who developed fulminant myocarditis, cardiogenic shock, and cardiac electrical storm attributed to M. pneumoniae infection. He underwent a combination of intra-aortic balloon pump (IABP) and veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for cardiac support, ultimately surviving despite the intracardiac thrombus formation and embolic stroke. Following comprehensive treatment and rehabilitation, he was discharged in stable condition. This case underscores the importance of considering atypical pathogens as potential etiological factors in patients presenting with cardiac complications, especially in the adolescents. It also emphasizes the need for clinical vigilance and effective support for potential cardiac complications arising from M. pneumoniae infection.

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.

Mechanism of Infantile Feire Kechuan Oral Solution against Mycoplasma pneumoniae infection of A549 cells

BACKGROUND

Mycoplasma pneumoniae is a leading cause of community-acquired respiratory infections. Infantile Feire Kechuan Oral Solution (IFKOS) is effective for treatment of M. pneumoniae infection. The aim of this study was to explore the potential mechanism of IFKOS against M. pneumoniae infection in basal epithelial human lung adenocarcinoma A549 cells.

METHODS

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the effects of IFKOS on the viability of A549 cells infected with M. pneumoniae. Optical microscopy was used to observe cell morphology and a Muse cell analyzer was used to assess apoptosis and the cell cycle phase. Enzyme-linked immunosorbent assays were employed to assess the expression levels of interleukin (IL)-4, IL-6, IL-8, IL-17, tumor necrosis factor (TNF)-α, interferon (IFN)-α, and IFN-γ.

RESULTS

Under certain conditions, M. pneumoniae infection reduced the viability and inhibited the proliferation of A549 cells, promoted early apoptosis, and arrested cells in the G0/G1 phase, thus shortening the S and G2/M phases (all p < 0.05). M. pneumoniae also upregulated expression of IL-8 and TNF-α and downregulated that of IL-6 (p < 0.05), which switched the immune balance of Th1/Th2 to Th1 cells. IFKOS (5.531 mg/mL) improved the viability and proliferation of M. pneumoniae-infected A549 cells, mitigated early apoptosis, and reversed cell cycle arrest in the G0/G1 phase, thereby extending the S and G2/M phases (all, p < 0.05). IFKOS downregulated expression of IL-8 and TNF-α and upregulated that of IL-6 (p < 0.01), thereby reversing the immune imbalance of Th1/Th2. Secretion of IL-4, IL-17, IFN-α, and IFN-γ was not observed.

CONCLUSION

IFKOS played a protective role in the regulation of cell viability, apoptosis, the cell cycle, and Th1/Th2 immune imbalance induced by M. pneumoniae infection and conveyed an anti-inflammatory effect in A549 cells.

A Previously Healthy 18-Year-Old Male With Fever, Arrhythmia, and Shock

A male individual aged 18 years with no significant past medical history presented with fever, headache, dry cough, and chest pain. On clinical examination, he had tachycardia and hypotension needing intravenous fluid resuscitation and inotropic support. A chest radiograph revealed streaky lung opacities, and he was treated with antibiotics for suspected community-acquired pneumonia complicated by septic shock. Significant elevation of cardiac enzymes was noted, and there was a continued need for inotropes to maintain normotension. He also developed intermittent bradycardia, with serial electrocardiograms showing first-degree atrioventricular block, low-voltage QRS complexes, and ST-T wave changes and telemetry demonstrating junctional and ventricular escape rhythm. A complete workup for sepsis and acute myocarditis were performed to find the etiologic agent. Intravenous immunoglobulins were started to treat myocarditis, with eventual clinical improvement. He was eventually diagnosed with an unusual etiology for his illness. He was noted to still have intermittent ventricular escape rhythm on electrocardiograms on follow-up 2 weeks after discharge but continues to remain asymptomatic and in good health.

Susceptibility Analysis in Several Mouse Strains Reveals Robust T-Cell Responses After Mycoplasma pneumoniae Infection in DBA/2 Mice

Mycoplasma pneumoniae (Mp) is a highly contagious respiratory pathogen responsible for human community-acquired pneumonia. The number of antibiotic-resistant Mp strains is increasing; therefore, to develop novel therapeutics, it is crucial to precisely understand the pathogenesis of mycoplasma pneumonia. Herein, we examined the susceptibility and response to Mp among eight inbred mouse strains. Following infection, the bacterial load in the bronchoalveolar lavage fluid (BALF) from DBA/2 mice was higher than that in the other tested strains such as BALB/c mice, which are frequently used in Mp research. In contrast, the numbers of CD45⁺ immune cells and neutrophils in BALF were comparable between BALB/c and DBA/2 mice, with lower numbers observed in C57BL/6J and CBA/N mice than in BALB/c mice. Among the tested strains, the BALF level of interleukin 12 subunit p40 was highest in DBA/2 mice; however, significant differences in other cytokines levels were not observed between BALB/c and DBA/2 mice. After Mp infection, Mp-specific Th1 and Th17 responses were significantly enhanced in DBA/2 mice when compared with BALB/c mice. Furthermore, prior infection with Mp increased the number of neutrophils in BALF after the reinfection of DBA/2 mice through an Mp-specific CD4⁺ T cell-dependent mechanism. Thus, DBA/2 may be an appropriate strain for evaluating Mp infection. Moreover, a comparison of responses revealed by various inbred mouse strains could be useful for elucidating the pathogenesis of Mycoplasma pneumonia.

Genetic polymorphisms of rs9313422 G>C and rs41297579 G>A at the promoter of TIM-1 gene contribute to the risk of community-acquired pneumonia in children

OBJECTIVE

To investigate the association of genetic polymorphisms of rs9313422 G>C and rs41297579 G>A at the promoter of TIM-1 gene with the risk of community-acquired pneumonia (CAP) in children.

METHODS

A total of 112 children with CAP were included as the case group. Another 120 healthy children were enrolled as the control group. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was applied for the genotyping of rs9313422 G>C and rs41297579 G>A in the promoter region of TIM-1.

RESULTS

rs9313422 G>C was related to the risk of CAP in children under codominant model, dominant model, recessive model, and allele model. Besides, the A allele of rs41297579 G>A could increase the risk of CAP in children. Besides, the haplotype GA (rs9313422-rs41297579) and GG reduced the risk of children CAP, while haplotype CA had an elevated risk. rs9313422 G>C and rs41297579 G>A polymorphisms were both associated with the severity of CAP in children, and the rs9313422 G>C was also related to the ICU admission rate. In addition, patients carried with the mutant homozygotes of rs9313422 G>C and rs41297579 G>A showed higher levels of white blood cell (WBC), procalcitonin (PCT), and C-reactive protein (CRP) than the wild type and heterozygous genotypes carriers.

CONCLUSION

rs9313422 G>C and rs41297579 G>A polymorphisms in the promoter region of TIM-1 could increase the risk of CAP in children and showed a relation with inflammatory responses and severity.

Cytokine signatures associate with disease severity in children with Mycoplasma pneumoniae pneumonia

Host immune response may be involved in the pathogenesis of children Mycoplasma pneumoniae pneumonia (MPP). In the current study, we investigated the alterations of cytokines levels among control, mild MPP and severe MPP children to determine whether cytokine signatures associate with MPP and correlate with disease severity. We measured 13 cytokines in bronchoalveolar lavage fluid (BALF) of 88 children with MPP and 26 children with foreign body aspiration (FB) using a Luminex system. Linear discriminant analyses were performed to develop predictive models of mild MPP and severe MPP on these children. We observed nearly complete separations of severe MPP group, mild MPP group and control group in linear discriminant analyses. Eleven cytokines significantly increased in children with MPP, and seven cytokines had statistically significant upward linear trends correlated with MPP severity. In addition, compared to control group, both IFNγ/IL4 ratio and IFNγ/IL13 ratio increased in mild MPP and severe MPP groups. Our results suggest that children MPP can alter BALF cytokines signatures which associate with disease severity and can be characterized by a distinct airway molecular phenotype that has elevated Th1/Th2 ratios.

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.

The role of mixed Mycoplasma and Herpesvirus infections in case of skin lesions in children

Numerous literature data show the role of mycoplasma infection in the development of non-respiratory lesions of various organs and systems, including the skin. Herpesvirus and mycoplasma infections can trigger the development of immune-mediated inflammatory reactions of the skin and mucous membranes — erythema multiforme exudative, Stevens-Johnson syndrome, vesicular pustular dermatosis — Sneddon-Wilkinson syndrome, etc.

In order to study the frequency and nature of skin lesions with mycoplasmosis combined with herpesvirus infection, 45 patients aged 3 to 15 years of life were observed. A comprehensive clinical and laboratory study revealed skin lesions in 27 patients associated with current mycoplasma and herpesvirus infections. Thus, multiforme exudative erythema in the small form variant was diagnosed in 13 patients, skin vasculitis in 4, hemorrhagic purpura in 3, urticaria rash in 3, erythema nodosum in 2, mucositis in 2 children. In 18 children, a combined mycoplasma and herpesvirus infection was established. In 9 children, a mono infection was detected (in 5 — herpes virus and in 4 — mycoplasma).

All observed patients showed antibodies to smooth muscle antigens in titers from 1:80 to 1:160 (normal 1:40) and in the vast majority (in 24 patients) — antibodies to vascular endothelial antigens in titers from 1:80 to 1:320 (with the norm of 1:40). Compaction of the intima-media complex was detected in 6 patients with monoinfection and in 16 patients with co-infection, according to ultrasound duplex scanning of the vessels of the brachiocephalic department.

Thus, for various immuno-inflammatory, allergic skin diseases, screening for infections, in particular, mycoplasma and herpesvirus, is necessary to optimize treatment.

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.

Mycoplasma pneumoniae and toll-like receptors: A mutual avenue

Mycoplasma pneumoniae is an intracellular bacterium leading to several complications in humans. M. pneumoniae is cleared in some cases and induces complications in others. The main responsible mechanisms regarding the controversy are yet to be cleared. Toll-like receptors (TLRs) are the important cell membrane and intracellular receptors which recognize a wide range of microbial macromolecules. The roles of TLRs in the eradication of several pathogens and also induction of their related complications have been demonstrated. This review article presents recent data about the roles of TLRs in the induction of immune responses which lead to M. pneumoniae eradication and related complications.

An atypical case of atypical pneumonia

Atypical pneumonia has been thought to account for 7%-20% of community-acquired pneumonia (CAP). The treatment for the pathogens that cause atypical pneumonia is different from that of other bacterial pneumonia. Therefore, identification of the causative pathogen in a primary care situation is crucial for adequate treatment of CAP. Mycoplasma infection is prevalent in the general population, but Mycoplasma pneumoniae with extrapulmonary symptoms is relatively rare. Herein, we report a case of CAP because of M. pneumoniae that presented with a wide variety of extrapulmonary diseases. Delayed administration of appropriate antibiotics may contribute to development of extrapulmonary manifestations.

Pneumonia as a cardiovascular disease

Community-acquired pneumonia (CAP) is an important cause of death around the globe. Up to 30% of patients admitted to hospital for CAP develop cardiovascular complications (i.e. new/worsening heart failure, new/worsening arrhythmias, myocardial infarctions and/or strokes), acutely and up to 10 years thereafter. Cardiac complications result from complex interactions between preexisting conditions, relative ischaemia, upregulation of the sympathetic system, systemic inflammation and direct pathogen-mediated damage to the cardiovascular system. The exact mechanisms underlying the direct host-pathogen interactions are of great interest to identify potential therapeutic and preventative targets for CAP. In this review, we summarize the epidemiological data, risk factors and the pathogen-driven cardiovascular damage affecting patients with CAP.

Insights into the pathogenesis of Mycoplasma pneumoniae (Review)

Mycoplasma are the smallest prokaryotic microbes present in nature. These wall-less, malleable organisms can pass through cell filters, and grow and propagate under cell-free conditions in vitro. Of the pathogenic Mycoplasma Mycoplasma pneumoniae has been examined the most. In addition to primary atypical pneumonia and community-acquired pneumonia with predominantly respiratory symptoms, M. pneumoniae can also induce autoimmune hemolytic anemia and other diseases in the blood, cardiovascular system, gastrointestinal tract and skin, and can induce pericarditis, myocarditis, nephritis and meningitis. The pathogenesis of M. pneumoniae infection is complex and remains to be fully elucidated. The present review aimed to summarize several direct damage mechanisms, including adhesion damage, destruction of membrane fusion, nutrition depletion, invasive damage, toxic damage, inflammatory damage and immune damage. Further investigations are required for determining the detailed pathogenesis of M. pneumoniae.

Classification of Extrapulmonary Manifestations Due to Mycoplasma pneumoniae Infection on the Basis of Possible Pathogenesis

The list of extrapulmonary manifestations due to Mycoplasma pneumoniae infection can be classified according to the following three possible mechanisms derived from the established biological activity of M. pneumoniae; (1) a direct type in which the bacterium is present at the site of inflammation and local inflammatory cytokines induced by the bacterium play an important role (2) an indirect type in which the bacterium is not present at the site of inflammation and immune modulations, such as autoimmunity or formation of immune complexes, play an important role, and (3) a vascular occlusion type in which obstruction of blood flow induced either directly or indirectly by the bacterium plays an important role. Recent studies concerning extrapulmonary manifestations have prompted the author to upgrade the list, including cardiac and aortic thrombi as cardiovascular manifestations; erythema nodosum, cutaneous leukocytoclastic vasculitis, and subcorneal pustular dermatosis as dermatological manifestations; acute cerebellar ataxia, opsoclonus-myoclonus syndrome, and thalamic necrosis as neurological manifestations; pulmonary embolism as a respiratory system manifestation; and renal artery embolism as a urogenital tract manifestation. Continuing nosological confusion on M. pneumoniae–induced mucositis (without skin lesions), which may be called M. pneumoniae-associated mucositis or M. pneumoniae-induced rash and mucositis separately from Stevens-Johnson syndrome, is argued in the dermatological manifestations. Serological methods are recommended for diagnosis because pneumonia or respiratory symptoms are often minimal or even absent in extrapulmonary manifestations due to M. pneumoniae infection. Concomitant use of immunomodulators, such as corticosteroids or immunoglobulins with antibiotics effective against M. pneumoniae, can be considered as treatment modalities for most severe cases, such as encephalitis. Further studies would be necessary to construct a comprehensive therapeutic strategy, covering microbiology (antibiotics), immunology (immunomodulators), and hematology (anticoagulants). The possible influence of the emergence of macrolide-resistant M. pneumoniae on extrapulmonary manifestations, which can be considered of limited clinical threat in Japan where the resistant rate has currently decreased, is discussed on the basis of unique biological characteristics of M. pneumoniae, the smallest self-replicating organism.