BACKGROUND AND OBJECTIVES: Recently a rapid decrease in the susceptibility of Neisseria gonorrhoeae isolates to fluoroquinolones has occurred and gonococcal fluoroquinolone resistance is now a significant problem in the treatment of gonorrhoea in Japan. Thus, in order to investigate the quinolone resistance mechanisms in clinical isolates of N gonorrhoeae we studied an alteration in the DNA gyrase subunit A (GyrA) which is well-known as a common mechanism of bacterial quinolone resistance. MATERIALS AND METHODS: Four clinical isolates of N gonorrhoeae resistant to norfloxacin and 5 strains susceptible to norfloxacin, including 2 clinical isolates and 3 WHO reference strains, were tested in this study. To identify mutations in the GyrA genes of gonococcal strains, polymerase chain reaction and direct DNA sequencing were performed. RESULTS: A single base change (serine codon TCC changed to phenylalanine codon TTC), which resulted in an amino acid change in GyrA at position 91, was identified in all 4 norfloxacin-resistant strains for which the MICs of norfloxacin ranged from 1.0 to 8.0 micrograms/ml, while no mutation within GyrA was detected in 5 norfloxacin-susceptible strains for which the MICs of norfloxacin ranged from 0.004 to 0.063 microgram/ml. CONCLUSIONS: The results from this study suggest that the serine-91 to phenylalanine substitution in GyrA is probably an essential mutation in fluoroquinolone resistance in clinical isolates of N gonorrhoeae.
BACKGROUND AND OBJECTIVES: Recently a rapid decrease in the susceptibility of Neisseria gonorrhoeae isolates to fluoroquinolones has occurred and gonococcal fluoroquinolone resistance is now a significant problem in the treatment of gonorrhoea in Japan. Thus, in order to investigate the quinolone resistance mechanisms in clinical isolates of N gonorrhoeae we studied an alteration in the DNA gyrase subunit A (GyrA) which is well-known as a common mechanism of bacterial quinolone resistance. MATERIALS AND METHODS: Four clinical isolates of N gonorrhoeae resistant to norfloxacin and 5 strains susceptible to norfloxacin, including 2 clinical isolates and 3 WHO reference strains, were tested in this study. To identify mutations in the GyrA genes of gonococcal strains, polymerase chain reaction and direct DNA sequencing were performed. RESULTS: A single base change (serine codon TCC changed to phenylalanine codon TTC), which resulted in an amino acid change in GyrA at position 91, was identified in all 4 norfloxacin-resistant strains for which the MICs of norfloxacin ranged from 1.0 to 8.0 micrograms/ml, while no mutation within GyrA was detected in 5 norfloxacin-susceptible strains for which the MICs of norfloxacin ranged from 0.004 to 0.063 microgram/ml. CONCLUSIONS: The results from this study suggest that the serine-91 to phenylalanine substitution in GyrA is probably an essential mutation in fluoroquinolone resistance in clinical isolates of N gonorrhoeae.
Authors: T E Clendennen; C S Hames; E S Kees; F C Price; W J Rueppel; A B Andrada; G E Espinosa; G Kabrerra; F S Wignall Journal: Antimicrob Agents Chemother Date: 1992-02 Impact factor: 5.191
Authors: H Yoshida; M Nakamura; M Bogaki; H Ito; T Kojima; H Hattori; S Nakamura Journal: Antimicrob Agents Chemother Date: 1993-04 Impact factor: 5.191
Authors: Jolinda de Korne-Elenbaas; Arno Pol; Jacqueline Vet; Mirjam Dierdorp; Alje P van Dam; Sylvia M Bruisten Journal: Sex Transm Dis Date: 2020-04 Impact factor: 2.830