Molecular features and antimicrobial susceptibility of Mycoplasma pneumoniae isolates from paediatric inpatients in Weihai, China: Characteristics of M. pneumoniae In Weihai.

OBJECTIVES

We analysed the molecular features and antimicrobial susceptibility of Mycoplasma pneumoniae isolates from Weihai, China, in 2019.

METHODS

Pharyngeal swabs of 160 paediatric patients with pneumonia-related symptoms were collected and were subjected to culture and subsequent characteristic analysis. The characteristics of M. pneumoniae isolates were analysed by real-time PCR and genotyping. Antimicrobial susceptibility testing was performed against four antibiotics. All isolates were amplified for analysis of macrolide (ML) resistance mutations in domain V of the 23S rRNA gene and were genotyped using multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) and 'AGT' VNTR detection in the p1 gene.

RESULTS

The M. pneumoniae nucleic acid and culture-positive rate of 160 specimens were 88.1% (141/160) and 51.3% (82/160), respectively. Almost all isolates were ML-resistant (81/82). Point mutation at position 2063 in 23S rRNA was identified in all ML-resistant isolates. The ML resistance rate of M. pneumoniae genotype 2 isolates was 97.6% (41/42). MLVA types 4/5/7/2 and 4/5/7/3 belonged to genotype 1, while type 3/5/6/2 belonged to genotype 2. The numbers of 'AGT' VNTR in the p1 gene from all isolates was in the range of 5-15.

CONCLUSION

This is the first report that the two genotypes of M. pneumoniae were present in a relatively equivalent ratio, with genotype 2 slightly predominant, in paediatric patients in Weihai in 2019, and the overall ML resistance rate was close to 100%. The minimum inhibitory concentration (MIC) of erythromycin in M. pneumoniae with ML resistance mutation A2063T in Weihai was higher than previously reported.