Journal of Microbiology

Research Support, Non-U.S. Gov't

Mutations in the GyrA Subunit of DNA Gyrase and the ParC Subunit of Topoisomerase IV in Clinical Strains of Fluoroquinolone-Resistant Shigella in Anhui, China: Li-Fen Hu , Jia-Bin Li , Ying Ye , Xu Li; J. Microbiol. 2007;45(2):168-170.; DOI: https://doi.org/2517 [pii]

Abstract: In this research 26 Shigella isolates were examined by PCR and direct nucleotide sequencing for genetic alterations in the quinolone-resistance determining regions (QRDRs). We tested for the presence of qnr genes by PCR in 91 strains, but no qnr genes were found. The results did show, however, some novel mutations at codon 83 of gyrA (Ser→Ile) and codon 64 of parC (Ala64→Cys, Ala64→Asp), which were related to fluroquinolone resistance.

Laboratory Developed fluoroquinolone Resistant Escherichia coli Has a new Missense Mutation in QRDR of PartC: Lee, Soon Deuk , Lee, Yeon Hee; J. Microbiol. 1998;36(2):106-110.

Abstract: The fluoroquinolone resistance mechanism of four laboratory developed fluorquinolone resistant strains of Escherichia coli was studied. Fluoroquinolone concentrations inside the resistant cells were similar to the concentrations in the susceptible cells. DNA sequencing of the quinolone resistance determining regions (QRDR) in gyrA and parC revealed the presence of Ser 83Leu and Asp87Gly mutations in GyrA, and Gly78Cys and Ser80Arh mutations in ParC of the ofloxacin, norfloxacin, and HK3140 resistant strains, while the ciprofloxacin resistant strain had Ser83Leu and Aasp87Tyr mutations in GyrA, and Gly78Cys and Ser80Ile mutations in ParC. A Gly78Cys substitution in ParC was newly detected in this work and seemed to be responsible for the extremely high MICs to fluroquinolones.

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