A case report of infective endocarditis caused by Mycoplasma pneumoniae in a child.

OBJECTIVE

This study aimed to investigate the clinical features and management strategies for infective endocarditis(IE) caused by Mycoplasma pneumoniae(M. pneumoniae) in children, in order to enhance understanding of this rare extrapulmonary complication of M. pneumoniae infection and provide clinical insights for its diagnosis and treatment.

METHODS

We retrospectively analyzed the clinical data and management process of a pediatric patient diagnosed with IE who was admitted to our hospital in September 2025.

RESULTS

A 9-year-old male patient was admitted with initial symptoms of fever and cough and was diagnosed with M. pneumoniae pneumonia. Subsequently, prompted by the detection of a faint blowing murmur on auscultation, transthoracic echocardiography was performed, which revealed a vegetation in the right ventricle. Empirical antibiotic treatment with doxycycline combined with vancomycin and ceftriaxone was initiated. M. pneumoniae was detected in two blood specimens using metagenomic next-generation sequencing (mNGS), while all three conventional blood cultures remained negative. Treatment was subsequently adjusted to doxycycline monotherapy. On hospital day 11, follow-up echocardiography examination showed resolution of the vegetative, with no evidence of thromboembolic events. After discharge, the patient continued oral doxycycline for a total treatment duration of 4 weeks. Follow-up revealed good recovery.

CONCLUSIONS

M. pneumoniae pneumonia in children may be complicated by IE. Antimicrobial agents should be guided by regional antimicrobial resistance patterns and resistance gene testing. The addition of anti-inflammatory and anticoagulant therapies should be considered when clinically indicated. mNGS is a valuable diagnostic tool for identifying pathogens in cases of blood culture-negative IE.