caa a22 4500 397593945 CHVBK 20180308164947.0 cr unu---uuuuu 161202e199609 xx s 000 0 eng 10.1093/jac/38.3.443 doi (NATIONALLICENCE)oxford-10.1093/jac/38.3.443 gyrA Mutations in high-level fluoroquinolone-resistant clinical isolates of Escherichia coli [Elektronische Daten] [S. Conrad, Jon. R. Saunders, M. Oethinger, K. Kaifel, G. Klotz, R. Marre, W. V. Kern] Double mutations in the quinolone resistance determining region of the gyrase A gene (gyrA) have recently been reported to be associated with high-level resistance to fluoroquinolones in clinical isolates of Escherichia coli. We examined the type and frequency of such mutations in a large number of clinical isolates that were obtained from ten different geographical locations and had been genotypically characterized by pulsed field gel electrophoresis (PFGE) of chromosomal DNA digests. Of 36 isolates with ofloxacin MICs ≥4 mg/L that represented at least 24 distinct genotypes, 35 had double mutations at amino acid codons 83 and 87 of gyrA, while two isolates with ofloxacin MICs of 0.5 and 4 mg/L, respectively, each had a single mutation at codon 83. Mutations at codon Ser-83 were uniform, resulting in substitution by Leu. The additional mutations at amino acid codon 87 in the 35 double-mutants were diverse, resulting in Asp-87 substitutions by residues Asn (23 isolates), Gly (7 isolates), Tyr (4 isolates), or His (1 isolate) without a discernable correlation with fluoroquinolone MICs or with phenotypic resistance to chemically unrelated antibacterial agents. Maximal differences between MICs of double-mutants with the same amino acid substitution were eight-fold. The changes of amino acid residues at codon Asp-87 differed between individual patient isolates with the same genotype (and similar MICs), suggesting that the amino acid codon 87 mutations (and possibly the development of high-level fluoroquinolone resistance) might have occurred after the transmission and sharing of a precursor strain carrying the Ser-83→ Leu mutation. © 1996 The British Society for Antimicrobial Chemotherapy Original articles nationallicence Conrad S. Departments of Virology aut Saunders Jon. R. Departments of Virology aut Oethinger M. Medical Microbiology and Hygiene aut Kaifel K. Medical Microbiology and Hygiene aut Klotz G. Departments of Virology aut Marre R. Medical Microbiology and Hygiene aut Kern W. V. Section of Infections Diseases and Clinical Immunology, University Hospital and Medical Center D-89070 Ulm, Germany aut Journal of Antimicrobial Chemotherapy Oxford University Press 38/3(1996-09), 443-456 0305-7453 38:3<443 1996 38 jac https://doi.org/10.1093/jac/38.3.443 text/html Onlinezugriff via DOI 1 other jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jac/38.3.443 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Conrad S. Departments of Virology aut NATIONALLICENCE 700 1- Saunders Jon. R. Departments of Virology aut NATIONALLICENCE 700 1- Oethinger M. Medical Microbiology and Hygiene aut NATIONALLICENCE 700 1- Kaifel K. Medical Microbiology and Hygiene aut NATIONALLICENCE 700 1- Klotz G. Departments of Virology aut NATIONALLICENCE 700 1- Marre R. Medical Microbiology and Hygiene aut NATIONALLICENCE 700 1- Kern W. V. Section of Infections Diseases and Clinical Immunology, University Hospital and Medical Center D-89070 Ulm, Germany aut NATIONALLICENCE 773 0- Journal of Antimicrobial Chemotherapy Oxford University Press 38/3(1996-09), 443-456 0305-7453 38:3<443 1996 38 jac Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford