To investigate the therapeutic effects and safety of the combination of azithromycin (injection and granules) and montelukast sodium tablets on the treatment of Mycoplasma pneumoniae pneumonia (MPP) in children of different severity.

The children with MPP treated in our hospital were divided into control group and treatment group based on the treatment method. All children received intravenous infusion of azithromycin injection at a dose of 10 mg·kg^-1 qd for 5 days until body temperature returned to normal, followed by oral administration of azithromycin granules at the same dose for 3 days, then 4 days off, for a total course of 3 weeks. On this basis, the treatment group was additionally given montelukast sodium tablets, with a dose of 4 mg·d^-1 for children ≤5 years old, and 5 mg·d^-1 for children over 5 years old, for a total course of 3 weeks. According to the severity of MPP, patients were divided into mild MPP group and severe MPP group. After treatment, the clinical efficacy, NLRP3 inflammasome pathway-related indicators and small airway function indicators were compared between the two groups of children with different severity levels; multiple linear regression was used to analyze the correlation between NLRP3 inflammasome pathway-related indicators and small airway function; and generalized estimating equation (GEE) model was used to analyze the changes in NLRP3 inflammasome pathway-related indicators at different time points, in different groups, and with different severities.

This study included a total of 92 patients, with 46 cases in each group. Confounding factors were adjusted using propensity score matching (PSM), and after matching, 40 cases were included in each group, while 47 cases in mild MPP group and 33 cases in severe MPP group. The white blood cell count (WBC) in severe MPP and mild MPP groups were (10.82±1.59) and (10.06±1.47) ×10⁹·L^-1, C-reactive protein (CRP) were (19.45±8.94) and (8.67±4.08) mg·L^-1, interleukin-6 (IL-6) were (18.25±4.48) and (13.65±4.33) pg·mL^-1, and interleukin-10 (IL-10) were (6.70±1.89) and (5.26±1.35) pg·mL^-1. Comparisons of these indicators between subgroups showed statistically significant differences (all P<0.05). The effective treatment rates of children with mild MPP in treatment group and control group were 100.00% (22 cases/22 cases) and 88.00% (22 cases/25 cases), respectively; the effective treatment rates of children with severe MPP were 88.89% (16 cases/18 cases) and 60.00% (9 cases/15 cases), respectively. Comparisons between groups showed that these differences were statistically significant (all P<0.05). After treatment, the mild and severe MPP children in treatment group had NLRP3 mRNA levels of 0.89±0.11 and 1.11±0.10, apoptosis-associated speck-like protein (ASC) mRNA levels of 0.77±0.10 and 0.95±0.15, caspase-1 mRNA levels of 0.69±0.09 and 0.82±0.10; forced expiratory flow at 25% of the pulmonary volume (FEF25%) levels were (2.72±0.24) and (2.28±0.19) L·s^-1, forced expiratory flow at 50% (FEF50%) levels were (2.90±0.40) and (2.37±0.31) L·s^-1, forced expiratory flow at 75% (FEF75%) levels were (2.13±0.32) and (1.73±0.35) L·s^-1, all showing statistically significant differences (all P<0.05). Correlation analysis showed that in children with MPP, the NLRP3 inflammasome pathway-related indicators NLRP3, ASC and caspase-1 mRNA were all negatively correlated with small airway function indicators FEF25%, FEF50% and FEF75%, and the negative correlations were statistically significant (all P<0.001). GEE results indicated that the reduction in NLRP3 mRNA levels in treatment group was greater than that in control group. In mild MPP, the estimated values for treatment and control groups were -0.76 and -0.56, respectively; the reduction in ASC mRNA in treatment group was greater than in the control group, with estimated values of -0.56 and -0.26, respectively; the reduction in caspase-1 mRNA in treatment group was greater than in control group, with estimated values of -0.32 and -0.26, respectively, and all interaction terms were statistically significant (all P<0.05).

Azithromycin combined with montelukast sodium can significantly improve the clinical efficacy of children with different severity of MPP, reduce the excessive inflammatory response of children with different severity of MPP by targeting and inhibit the NLRP3 inflammasome pathway, and improve the function of the small airway, especially in children with mild disease.