Clinical and laboratory profiles of refractory Mycoplasma pneumoniae pneumonia in children

• The purpose of this study was to explore the clinical and laboratory characterisitcs of children with refractory Mycoplasma pneumoniae pneumonia.
• The clinical relevance to refractory Mycoplasma pneumoniae pneumonia is still largely debated all over world. Excessive inflammation maybe play more important role in RMPP than macrolide resistance in China because of high prevalence of macrolide-resistant M. pneumonia.
• In present study, Mycoplasma pneumoniae load is closely correlated with neutrophils and disease severity. Inflammatory indicators such as TNF-α and INF-γ also contribute to the progression of refractory Mycoplasma pneumoniae pneumonia.
• In conclusion, both Mycoplasma pneumoniae load and excessive inflammation play a role in refractory Mycoplasma pneumoniae pneumonia.

SummaryObjectivesThe purpose of this study was to explore the clinical and laboratory characteristics of children with refractory Mycoplasma pneumoniae pneumonia (RMPP).MethodsSeventy-six children with RMPP and 26 children with non-refractory M. pneumoniae pneumonia (NRMPP), confirmed by both serology and fluorescent quantitation PCR in bronchoalveolar lavage fluid (BALF), were evaluated retrospectively.ResultsCompared to those with NRMPP, children with RMPP were older (66.6 ± 39.0 vs. 48.4 ± 35.4 months, p = 0.038) and had a longer duration of fever (12.7 ± 2.6 vs. 7.5 ± 1.8 days) and hospital stay (12.1 ± 3.2 vs. 7.4 ± 2.9 days). Children with RMPP presented neutrophil infiltration both in serum and BALF, as well as severe pulmonary lesions with pleural effusion. Children with RMPP had a significantly higher M. pneumoniae DNA load in BALF compared to NRMPP patients, and the M. pneumoniae load in BALF was significantly correlated with neutrophils and inversely correlated with macrophages for both the NRMPP and RMPP groups. The serum concentrations of tumor necrosis factor alpha (median 114.5 pg/ml, range 49.1–897.9 pg/ml) and interferon gamma (median 376.9 pg/ml, range 221.4–1997.6 pg/ml) were significantly higher in children with RMPP compared to children with NRMPP.ConclusionsThis study indicates that a direct microbe effect and the subsequent induced excessive host immune response contribute in part to the progression of RMPP.