Diagnosis and treatment of severe mycoplasma and refractory mycoplasma pneumonia
I. Diagnosis of severe mycoplasma pneumonia.
On the basis of the general clinical manifestations of mycoplasma pneumonia (high fever, intractable violent cough, few pulmonary signs), severe mycoplasma pneumonia can be diagnosed if one of the following manifestations is present: (1) necrotizing pneumonia manifestations; (2) large lobar solid lung changes with moderate to large pleural effusion; (3) affecting respiratory function or combined with other systemic dysfunction; (4) combined occlusive bronchitis; (5) combined systemic inflammatory response syndrome. (6) rapid onset, heavy symptoms, solid lung lobes, and poor response to single macrolide antibiotic therapy.
Definition of refractory mycoplasma pneumoniae pneumonia (RMPP).
There is no exact definition of RMPP.
The definition of RMPP proposed by Japanese scholars: children with macrolide antibiotics applied for 1 week or more still exhibit fever and clinical symptoms and imaging manifestations continue to worsen.
Domestic scholars have reached a consensus that: (1) macrolide antibiotics are not effective (the child’s condition does not improve after about 1 week of regular application of macrolide antibiotics); (2) the child has a combination of extra-pulmonary multisystem complications, and the condition is severe (extra-pulmonary multisystem damage in addition to severe pulmonary lesions); (3) the course of the disease is long (usually >3-4 weeks), or even prolonged, and a significant proportion of them are severe mycoplasma pneumonia.
Third, the causes of mycoplasma pneumoniae infection difficult to treat:
1, the pathogenesis of Mycoplasma pneumoniae pneumonia cellular immune response is a very important factor, in which a variety of cytokines such as TNF-α, IFN-β, IL-4, IL-6, IL-8, etc. are involved. These cytokines can aggravate the occurrence and development of the disease and cause further damage to the organism.
2, drug resistance of mycoplasma. The mechanism of drug resistance includes gene mutation, the presence of macrolide exclusion gene (mef).
3, mixed infection factors.
IV. Laboratory tests for MP infection.
1, MP-Ab-IgM: confirm the diagnosis of acute MP infection: double serum (2 weeks apart) antibody titer in the recovery period rose 4-fold or fell to 1/4 of the original or MP-IgM antibody titer continued >1:160; MP-Ab- IgG test can be used for retrospective diagnosis, no early diagnostic value.
2, MP isolation culture is the most reliable method to diagnose MP infection, but the domestic positive rate is low.
3, PCR technique has high specificity and certain sensitivity, and the diagnosis can be confirmed within 1-2 days of onset, and simultaneous testing with MP-Ab-IgM can improve the positive detection rate.
V. Treatment of severe mycoplasma and RMPP.
1. Combined application of antibiotics.
① Because of the high blood concentration of erythromycin and the high tissue concentration of new macrolide antibiotics (such as azithromycin), the efficacy of erythromycin may be better than azithromycin when there is mycoplasmaemia; ② Macrolides combined with rifampin act on different stages of protein synthesis and have a synergistic antibacterial effect on MP; ③ If mixed infection factors are considered, the addition of antibacterial, antiviral and antifungal in the combined anti-infection drug treatment.
2. Immunotherapy of RMPP.
① Glucocorticoids: can block the role of inflammatory mediators in the process of immune response. It can be applied when RMPP has pulmonary atelectasis, interstitial fibrosis, bronchiectasis or extra-pulmonary complications.
② Intravenous immunoglobulin (IVIG): can be tried in children with severe MP infection, extra-pulmonary complications or when there are contraindications to the use of glucocorticoids.
3. Application of fiberoptic bronchoscopy: Children with RMPP are prone to mucus plug blocking the bronchi, leading to pulmonary atelectasis. Alveolar lavage using fiberoptic bronchoscopy to remove mucus plug is beneficial to pulmonary reopening and improve prognosis.