Use of a naturally occurring codon bias for identifying topoisomerase mutations in ciprofloxacin resistant <i>Escherichia coli</i> using PCR and future prospects with other bacterial genera: A pilot study

Abstract

We developed a novel PCR method aimed at identifying and amplifying native codon sequences of mutation-prone amino acids in DNA gyrase implicated in quinolone resistance using a naturally occurring codon bias in E. coli DNA gyrase A.

A study of the correlation between phenotypic antimicrobial susceptibility testing methods and the associated genotypes determined by whole genome sequencing for a collection of Escherichia coli of bovine origin

“…In E. coli, gyrA mutations usually occur at serine-83, which is substituted by leucine or tryptophan and causes high resistance to quinolones. However, the replacement of serine by alanine causes a lower resistance level (Ruiz, 2003;Krishnan et al, 2012). In our study, the gyrA_S83A gene resulted in a strain which was phenotypically susceptible to ciprofloxacin and marbofloxacin and intermediately resistant to nalidixic acid (Figure 7), therefore confirming the findings of previous studies.…”

Evaluation of Resistance to Ciprofloxacin and Identification of Mutations in Topoisomerase Genes in Escherichia coli and Klebsiella pneumonia Isolated from Pediatric Urinary Tract Infections

“…Most mutations have been detected in the limited region of QRDR that codes the amino acids 67 to 106. The most common mutations in the gyrA gene occur in the nucleotides 248 and 260, which cause changes in the amino acids of ser83 and Asp87; and the most common mutations in the parC gene are in the nucleotides 238 and 250, which cause changes in the amino acids of ser80 and Glu84 (8)(9)(10). In position 83 of the gyrA gene, the amino acid serine is usually replaced by leucine, followed by ser83val and ser83Ala; these alterations increase the Minimum Inhibitory Concentrations (MIC) value of ciprofloxacin.…”

The Mutations of Topoisomerase Genes and Their Effect on Resistance to Fluoroquinolones in Extended-Spectrum β-Lactamase-Producing Escherichia coli

“…In E. coli, gyrA mutations usually occur at serine-83, which is substituted by leucine or tryptophan and causes high resistance to quinolones. However, the replacement of serine by alanine causes a lower resistance level (8,13). Another common mutation is the substitution of aspartate-87 by asparagine and/or valine (13).…”

“…However, the replacement of serine by alanine causes a lower resistance level (8,13). Another common mutation is the substitution of aspartate-87 by asparagine and/or valine (13). Mutations in parC usually occur at 78, 80 and 84 positions, with the replacement of glycine by aspartate, serine by arginine, or isoleucine and glycine by aspartate, respectively (14).…”