Development of macrolide resistance in Mycoplasma pneumoniae-infected Swedish patients treated with macrolides.

BACKGROUND

The proportion of Mycoplasma pneumoniae isolates carrying point mutations in the 23S region of the genome associated with macrolide resistance has increased. We evaluated the probability of developing M. pneumoniae macrolide resistance mutations during macrolide treatment.

METHODS

M. pneumoniae strains from initial and follow-up oropharyngeal samples from 38 Swedish patients were tested for 23S rRNA mutations by amplifying and pyrosequencing the gene target region. The duration of symptoms and of M. pneumoniae carriage were recorded in cases with and without the macrolide resistance mutation.

RESULTS

Macrolide resistance mutations were absent in all baseline strains. Twenty-two patients were prescribed macrolides; the longest M. pneumoniae carriage time in these patients was 7 months and the longest symptomatic period was 7.5 months. Macrolide resistance was detected after macrolide treatment in 1 patient (carriage time 3.5 months and symptomatic period 7.5 months).

CONCLUSIONS

M. pneumoniae may develop macrolide resistance during macrolide treatment. A long duration of M. pneumoniae carriage and symptoms is common in patients regardless of the presence of resistance.