Macrolide Susceptibility and Molecular Characteristics of Bordetella Pertussis

Abstract ObjectiveTo compare the macrolide resistance and molecular characteristics of clinical isolated Bordetella pertussis, and explore the relationship between the macrolide-resistance and genotypes. MethodsErythromycin、azithromycin and clarithromycin susceptibility of clinical isolates during 2018-2020 was determined by E-test. The A2047G of the 23S rRNA genes was sequenced for drug-resistance mutation. Multilocus antigen sequence typing (MAST)、Multiple Locus Variable-number tandem repeat Analysis (MLVA) and Pulsed field gel electrophoresis (PFGE) methods were employed to do molecular typing for the strains. Results58 strains were isolated in this study, 46 of them were macrolide-resistant and 12 sensitive. All macrolide-resistant strains carried a genetic mutation at the A2047G site, genotype was prn1/ptxP1/ptxA1/fim3-1/fim2-1, the MLVA types were identified as MT195、MT55 and MT104, PFGE profiles were classified into BPSR23 and BpFINR9 types. However, no mutations were found in all macrolide-sensitive strains whose genotypes were (prn9 or prn2)/ptxP1/ptxA1/fim3-1/fim2-1 and MT27, and PFGE classified other profiles. ConclusionsThe clinical isolated Bordetella pertussis has serious resistance to erythromycin and began to spread to other macrolides. There were differences between macrolide-resistant and -sensitive Bordetella pertussis in genotypes. The acquisition of macrolide resistance may be associated with change of specific molecular types.