Does macrolide resistance play a role in the clinical outcome of patients with Mycoplasma pneumoniae infection?

BACKGROUND

A marked increase in Mycoplasma pneumoniae infections was observed across Europe in 2023, while data on resistance to macrolides, the recommended first-line therapy, remained limited. This study assessed the prevalence of macrolide-resistant M. pneumoniae (MRMP) and its impact on clinical outcomes.

METHODS

Patients diagnosed with M. pneumoniae infection by multiplex PCR between January 2024 and January 2025 were included. Macrolide-resistance mutations were retrospectively identified by PCR and Sanger sequencing of domain V of the 23S rRNA gene. Clinical characteristics, treatment without results on the macrolide-resistant genotype, and outcomes were analysed.

RESULTS

Among 373 PCR-positive cases (155 children, 218 adults), resistance genotype and outcome data were available for 179 patients. Overall MRMP prevalence was 21.2%, decreasing from 28.9% to 18.7% between study periods (p = 0.21). The most common mutation was A2063G (86.8%), followed by A2064G (10.5%) and A2064C (2.6%). The median time from symptom onset to diagnosis was 8 days, and 57.5% of patients were hospitalised. No significant differences were detected between MRMP and macrolide-susceptible M. pneumoniae (MSMP) infections in clinical characteristics, hospitalisation rates, or doxycycline use. Defervescence after macrolide therapy was numerically longer in MRMP than in MSMP infections, although the difference was not statistically significant (median 4 vs 2.5 days, p = 0.13).

CONCLUSIONS

MRMP was common but had limited impact on overall clinical outcomes, possibly reflecting the frequent doxycycline use. Macrolide resistance showed a non-significant trend towards delayed defervescence. Our findings suggest that doxycycline may represent a treatment option in complicated cases when susceptibility is unknown, but prospective studies are needed to determine its clinical effectiveness.