Professor Dong Jianping
Chief Physician, Vice President of Beijing Haidian Hospital. Member of the Infection Branch of Beijing Medical Association, Standing Member of the Infection Professional Committee of the Beijing Society of Integrated Traditional Chinese and Western Medicine, Standing Member of the Infectious Diseases Professional Committee of the Beijing Society of Integrated Traditional Chinese and Western Medicine, Deputy Director of Beijing Infectious (Infectious) Disease Treatment Quality Control and Improvement Centre, Chairman of Haidian District Infectious (Infectious) Disease Treatment and Quality Control Centre, Deputy Chairman of Haidian District Hospital Infection Management Quality Control Centre.

Introduction: Mycoplasma pneumoniae pneumonia (MPP) is speculated to hit a peak this year. As MPP is spreading globally, it is crucial to zero in on the differential diagnosis and treatment of this condition.

While China adjusts to its first year of post-pandemic life, a large-scale epidemic of Mycoplasma pneumoniae (MP) has attracted widespread attention. Research indicates that MPP epidemics occur every 3–7 years. As it has been four years since the peak in 2019, experts speculate that MPP may peak again in 2023. ¹ The ‘Medical Community’ is honoured to have Professor Dong Jianping from Beijing Haidian Hospital introduce the differential diagnosis, prevention, and treatment of MPP to us.

MPP is Widespread Globally; But Why is it Particularly Prevalent in China?
In 2019, the European Society of Clinical Microbiology and Infectious Disease initiated a global prospective surveillance plan for MPP, which initially focused on European countries but is now adopted worldwide. Currently, the surveillance data is gathered from 45 locations spanning 24 countries across Europe, Asia, America, and Oceania. ² The data showed that the incidence rate of MPP was still very low, at 0.82% in the past three years from April 2020 to March 2023. However, from April to September 2023, the incidence rate of MPP surged from less than 1.00% to 4.12%. This data indicates that over three years after the global implementation of COVID-19 prevention and control measures, MPP epidemics have resurfaced in Europe and Asia. ³

Professor Dong Jianping stated that during the pandemic, non-pharmaceutical isolation measures have reduced the incidence of various infectious diseases. However, incidences of infections such as influenza, syncytial virus, adenovirus, etc., exhibited occasional fluctuations. In contrast, the onset of MPP appears to exhibit a noticeable trend of delay. China has a large population size, and there has been an extended duration of isolation measures implemented for COVID-19. MP infections in China have entered a high-incidence state after July 2023. Improved testing capabilities and an increased number of tests conducted could have contributed to a rise in the incidence rate.

Key Considerations for Diagnosis and Assessment of Disease Severity
There are over 120 species of mycoplasma, four of which are pathogenic to humans: MP, Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum. Most infections caused by MP, such as upper respiratory tract infections and bronchitis, are mild and do not require hospitalisation. Besides, most instances of MPP are atypical pneumonia, and the overall condition of the patient would be better than that of other bacterial pneumonias.

Professor Dong Jianping said that often, etiological information is difficult to obtain during initial diagnosis of community-acquired pneumonia in outpatient settings and emergency departments. In such situations, reliance is placed on the clinical experience of doctors, who integrate a combination of epidemiological knowledge and assessment of changes in clinical symptoms and radiological findings to accurately diagnose cases. For instance, in pneumonia-related cough symptoms, bacterial pneumonia often presents with characteristics including sticky, yellow, jelly-like phlegm, while MPP is characterised by dry cough.

Different types of pneumonia exhibit distinctive clinical characteristics. For example, fungal infections often occur in immunocompromised patients, such as the elderly, or patients with repeated medical visits and long-term use of antibiotics. Viral pneumonia often manifests as ground-glass opacity on imaging, and pleural effusion may be evident in severe cases. In the early stages of MPP, a “tree-in-bud sign” may appear. As the disease progresses, changes may occur, including the superposition of multiple lesions resulting in the appearance of ground-glass opacity. Professor Dong Jianping remarked, “Clinicians encounter a myriad of challenges and must adopt a holistic approach, considering epidemiology, imaging, and clinical manifestations. It is also a continual process of building up clinical expertise through experience.”

Severe Mycoplasma pneumoniae pneumonia (SMPP) can be associated with intrapulmonary and extrapulmonary complications. Intrapulmonary manifestations include shortness of breath, wheezing, dyspnoea, chest pain, haemoptysis, etc., while extrapulmonary manifestations include meningitis, myocarditis, etc. Severe cases tend to have a more significant impact on young children than on adults. Severe symptoms include persistent high fever, wheezing, shortness of breath, dyspnoea, chest pain, haemoptysis, and decreased blood oxygen (oxygen saturation ≤93%). On imaging, large areas of high-density consolidation or diffuse bronchiolitis may appear, and the lesions may progress rapidly.

Different Medication Approaches for Mycoplasma Pneumoniae Pneumonia Across Age Groups
Mycoplasma is the smallest microorganism that is capable of autonomous survival without a cell wall. Due to its structural features, MP are insensitive towards widely used clinical antibiotics such as cephalosporins, penicillins, carbapenems, and other β-lactam antibiotics, as well as other antibiotics that inhibit cell wall synthesis. As a result, treatment of MP infection necessitates the use of tetracyclines, quinolones, and macrolides.

It is crucial to consider patient conditions, potential adverse reactions, and contraindications to antibiotics. For instance, in managing children affected by MPP, tetracyclines pose the risk of negatively impacting the development of their teeth and bone tissue, while quinolones can affect chondrocyte development. Consequently, macrolides such as azithromycin and erythromycin are the preferred choice for treating mycoplasma infections in children. Azithromycin, apart from its anti-inflammatory properties, also exhibits immunomodulatory functions. Nevertheless, current research highlights a substantial resistance rate to macrolide drugs. For patients with severe or critical symptoms, more effective and safer treatments are imperative.

It is important to note that MP infection can occur at any age, but it tends to be more prevalent in children aged over 5.⁴ Given that this year marks a peak for MPP, there has been a rise in cases of SMPP in children, prompting a need to enhance the effectiveness of drugs. Consequently, doxycycline, minocycline, and quinolones can now be administered to children over 5 years old. MPP patients above 16 years old should encounter no issues with quinolones. As for adult patients, it is essential to consider other infection types based on epidemiological characteristics.

Professor Dong Jianping also pointed out that drug resistance is emerging as a major obstacle in the treatment of MPP. If a patient develops drug resistance, initial treatment carries a certain level of risk. In such cases, new quinolone drugs, such as the fourth-generation quinolone drug sitafloxacin, can be considered. It has antimicrobial activity against aerobic and anaerobic Gram-positive and Gram-negative bacteria, MP, and Chlamydia. This drug is also commonly used to treat urinary tract infections and community-acquired pneumonia.

The drug’s mechanism of action involves inhibiting the activity of DNA gyrase and topoisomerase IV, which is more effective than other quinolone drugs. It also has stronger inhibitory effect on the activity of quinolone-resistance–determining domain (QRDR) mutant enzymes. Furthermore, it has stronger antibacterial activity against other quinolone-resistant strains, providing coverage for a wider range of pathogenic bacteria, and can reduce the occurrence of bacterial resistance to a certain extent.⁵

Additionally, oral administration of sitafloxacin provides an optimised treatment option for urinary tract infections and respiratory tract infections. It helps reduce hospitalisation time, treatment costs, and the frequency of intravenous infusion. ⁶ It also relieves pressure on healthcare system, and provides additional benefits to patients.

Lastly, Professor Dong Jianping reminded us that MPP carries a risk of recurrence or reinfection. Isolation precautions, such as wearing a mask, are required when in contact with MPP patients. However, achieving this at home can be challenging. We can reduce the number of pathogenic bacteria per unit area by keeping windows open for ventilation in order to reduce the risk of infection. We must improve our immunity by developing a healthy lifestyle in order to facilitate the prevention of MPP during its peak year.

Summary
Autumn and winter are seasons when MP infections tend to surge. The incidence rate of MPP is gradually on the rise, but there is no need to panic. Adopting habits such as wearing a mask while traveling, avoiding gatherings, and cultivating healthy lifestyles can provide a certain level of protection. While most MPP patients recover well, it is crucial to not let our guard down. Vigilance, active prevention, and treatment are essential to safely navigate through MPP’s first peak year in this post-pandemic world.

References:

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