New-generation tetracyclines for severe macrolide-resistant Mycoplasma pneumoniae pneumonia in children: a retrospective analysis.

Background: Macrolide-resistant Mycoplasma pneumoniae (MRMP) strains are increasingly prevalent, leading to a rise in severe Mycoplasma pneumoniae pneumonia incidence annually, which poses a significant threat to children's health. This study aimed to compare the effectiveness and safety of oral minocycline and doxycycline for the treatment of severe MRMP pneumonia in children.

Methods: This retrospective analysis included children treated for severe MRMP pneumonia at the Pediatric Department of Tongji Hospital, Shanghai, China, between September 2023 and January 2024 using minocycline and doxycycline. The patients were divided into four groups according to treatment: oral doxycycline alone (DOX group), oral minocycline alone (MIN group), oral doxycycline with intravenous glucocorticoids (DOXG group), and oral minocycline with intravenous glucocorticoids (MING group). Student's t-test, Mann-Whitney U test, and χ² or Fisher's exact tests were used for group comparisons.

Results: A total of 165 patients were included in this study: 84 received minocycline, and 81 received doxycycline. The DOX group had higher fever resolution rates within 24, 48, and 72 h compared to the MIN group (63.2% vs. 31.8%, 79.0% vs. 63.6%, and 100% vs. 90.9%, respectively; all p < 0.05). The DOXG group showed higher fever resolution rates within 24 and 48 h than the MING group (92.3% vs. 83.4%, 100% vs. 92.7%, all p > 0.05). There were no statistically significant differences in time to imaging improvement, cough improvement, and disappearance of wet rales between groups, regardless of glucocorticoid combination. The longer the duration of fever prior to tetracycline therapy, the greater the likelihood of hypoxemia (p = 0.039) and a greater than two-fold elevation in the D-dimer level (p = 0.004).Univariate binary logistic regression model analysis revealed that CRP and erythrocyte sedimentation rate at disease onset were associated with defervescence within 24 h after treatment with tetracyclines alone (p = 0.020, p = 0.027), with erythrocyte sedimentation rate also influencing defervescence within 48 h (p = 0.022).

Conclusion: Doxycycline treatment resulted in a higher rate of defervescence than minocycline. Prompt treatment reduced the probability of pleural effusion, hypoxemia, pulmonary atelectasis, and D-dimer levels > 2 times the reference value.