Antimicrobial Susceptibility Profiles and Genetic Characteristics of Mycoplasma pneumoniae in Shanghai, China, from 2017 to 2019

Na Wang,1,2,* Hong Zhang,3,* Yihua Yin,4,* Xiaogang Xu,1 Li Xiao,5 Yang Liu1 1Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, 200040, People’s Republic of China; 2Department of Medical Oncology, Shanghai Cancer Center, Fudan University, Shanghai, 200032, People’s Republic of China; 3Department of Clinical Laboratory, Shanghai Children’s Hospital, Shanghai Jiaotong University, Shanghai, 200062, People’s Republic of China; 4Department of Gynecology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, People’s Republic of China; 5Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, USA*These authors contributed equally to this workCorrespondence: Yang Liu, Institute of Antibiotics, Huashan Hospital, Fudan University, 12 Urumqi Middle Road, Shanghai, 200040, People’s Republic of China, Tel +86-21-52888197, Email liuyang@fudan.edu.cn Li Xiao, Department of Medicine, University of Alabama at Birmingham, 1720 2nd Ave South, SHEL 206, Birmingham, AL, 35294, USA, Tel +1-205-996-1378, Email lixiao@uabmc.eduObjective: The current study investigated the recent genetic characteristics and antimicrobial susceptibility profiles of Mycoplasma pneumoniae (M. pneumoniae) in Shanghai, becoming a clinical reference for treating M. pneumoniae infection in Shanghai.Methods: Clinical strains were isolated from nasopharyngeal aspirates of the pediatric patients in Shanghai from 2017 to 2019. Nine antimicrobial agents of three antimicrobial classes macrolides, fluoroquinolones and tetracyclines, against M. pneumoniae isolates were investigated using the broth microdilution method. The mechanism of macrolide resistance was analyzed by evaluating the sequences of the 23S rRNA gene and the ribosomal protein genes L4 and L22. Molecular genotyping was undergone to classify the P1 subtypes and the multi-locus variable-number tandem-repeat analysis (MLVA) types.Results: A total of 72 isolates were resistant to macrolides (MICs > 64 mg/L for erythromycin) based on the A2063G mutation in the 23S rRNA gene. These strains were susceptible to tetracyclines and fluoroquinolones. P1 type 1 (166/182, 91.2%) and MLVA type 4-5-7-2 (165/182, 90.7%) were the dominant subtypes. MLVA type was associated with the P1 subtypes. The distribution of the P1 subtypes and MLVA types did not change over time. The macrolide-resistant rate in P1 type 2 and MLVA type 3-5-6-2 strains were increased during the three-year study. The 5-loci MLVA typing scheme revealed the clonal expansion of MLVA type 3-4-5-7-2 strains which are macrolide-resistant in 2019.Conclusion: Macrolide resistance in M. pneumoniae in Shanghai is very high and is evolving among certain subtypes. Cautions should be taken for the possible clonal spreading of macrolide-resistant genotypes within this populated region.Keywords: Mycoplasma pneumoniae, molecular genotyping, macrolide resistance, resistant mechanism