Characterization of Mutations in DNA Gyrase and Topoisomerase IV in Field Strains and In Vitro Selected Quinolone-Resistant Mycoplasma hyorhinis Mutants

• Published in: Antibiotics (Basel) Vol. 11; no. 4; p. 494
• Main Authors: Li, Jun, Wei, Yanna, Wang, Jia, Li, Yao, Shao, Guoqing, Feng, Zhixin, Xiong, Qiyan
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 07.04.2022; MDPI
• Subjects: Amino acids; Antibiotics; Antimicrobial agents; antimicrobial resistance; Arthritis; Bacterial infections; Ciprofloxacin; DNA topoisomerase; DNA topoisomerase IV; Fluoroquinolones; in vitro; Infections; Molecular modelling; Mutants; Mutation; Mycoplasma; Polyserositis; QRDRs; selection; Swine; Europe; fluoroquinolones; selection; antimicrobial resistance; in vitro; QRDRs
• ISSN: 2079-6382; 2079-6382
• DOI: 10.3390/antibiotics11040494

is ubiquitous in swine, and it is a common pathogen of swine that causes polyserositis, arthritis, and maybe pneumonia. Fluoroquinolones are effective antimicrobials used for the treatment of mycoplasmal infection. However, a decrease in fluoroquinolones susceptibility in mycoplasma was observed. The molecular mechanisms have been studied in many mycoplasma species, while the mechanism in is still unknown. This study aimed to illustrate the in vitro development of fluoroquinolone resistance in and unveil the resistance mechanisms in both in vitro selected mutants and field strains. Seven ciprofloxacin-sensitive isolates were chosen to induce the fluoroquinolone resistance in vitro, and the point mutations in the quinolone resistance-determining regions (QRDRs) were characterized. The substitutions first occurred in ParC, resulting in a 2- to 8-fold increase in resistance, followed by additional mutations in GyrA and/or ParE to achieve a 32-fold increase. The mutations occurred in hot spots of QRDRs, and they were diverse and variable, including five in ParC (Ser80Phe, Ser80Tyr, Phe80Tyr, Glu84Gly, and Glu84Lys), four in GyrA (Ala83Val, Ser84Pro, Asp87Tyr, and Asp87Asn) and one in ParE (Glu470Lys). Target mutations in field strains were observed in the ParC (Ser80Phe, Ser81Pro, and Glu84Gln) of isolates with MIC = 2 μg/mL. This study characterized the point mutations in the QRDRs of and could be useful for the rapid detection of fluoroquinolone resistance in field isolates.