Susceptibilities of genital mycoplasmas to the newer quinolones as determined by the agar dilution method

G. E. Kenny, T. M. Hooton, M. C. Roberts, F. D. Cartwright, J. Hoyt

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


The increasing resistance of genital mycoplasmas to tetracycline poses a problem because tetracycline is one of the few antimicrobial agents active against Mycoplasma hominis, Ureaplasma urealyticum, chlamydiae, gonococci, and other agents of genitourinary-tract disease. Since the quinolones are a promising group of antimicrobial agents, the suceptibilities of M. hominis and U. urealyticum to the newer 6-fluoroquinolones were determined by the agar dilution method. Ciprofloxacin, difloxacin, and ofloxacin had good activity against M. hominis, with the MIC for 50% of isolates tested (MIC50) being 1 μg/ml. Fleroxacin, lomefloxacin, pefloxacin, and rosoxacin had MIC50s of 2 μg/ml. Enoxacin, norfloxacin, and amifloxacin had MIC50s of 8 to 16 μg/ml, and cinoxacin and nalidixic acid were inactive (MIC50, ≥ 256 μg/ml). Overall the activities of 6-fluoroquinolones for ureaplasmas were similar to those for M. hominis, with MICs being the same or twofold greater. The most active 6-fluoroquinolones against ureaplasmas were difloxacin, ofloxacin, and pefloxacin, with MIC50s of 1 to 2 μg/ml. Ciprofloxacin was unusual in that the MIC50 for M. hominis was 1 μg/ml, whereas the MIC50 for ureaplasmas was 8 μg/ml. Since the MIC50s for the most active quinolones approximate achievable concentrations in blood and urine, quinolones have promise in treating mycoplasmal infections.

Original languageEnglish (US)
Pages (from-to)103-107
Number of pages5
JournalAntimicrobial agents and chemotherapy
Issue number1
StatePublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases


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