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

Abstract

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.

Keywords: 23S rRNA gene; Genotype; Macrolide resistance; Mycoplasma pneumoniae; p1 gene.