Table 2.

Susceptibilities of constructed mutants to various antimicrobial agents

Antimicrobial agentMIC (μg/ml)a
N107N148N108N150N127N128
Quinolones
 Nalidixic acid51222561322
 Piromidic acid>4,0968>4,09621284
 Pipemidic acid321640.5641
 Cinoxacin>2,04841284322
 Norfloxacin20.06160.01620.06
 Ofloxacin40.0680.01640.06
 Enoxacin20.0680.0340.06
 Ciprofloxacin0.250.00820.0020.50.008
 Tosufloxacin0.50.01620.00210.016
 Sparfloxacin10.03160.00820.03
Macrolides
 Erythromycin256644,096851264
 Oleandomycin>8,1922,048>8,19232>8,1922,048
 Spiramycin2,0485128,192644,096512
Tetracyclines
 Tetracycline641640.13321
 Chlortetracycline>2,048162,0484>2,04816
 Oxytetracycline161160.13161
Aminoglycosides
 Streptomycin2122561281
 Neomycin210.511281
 Kanamycin1616882568
 Gentamicin0.130.060.060.1380.06
 Amikacin0.250.130.130.25160.13
 Tobramycin0.130.060.130.1320.06
Others
 Lincomycin>4,096512>4,09664>4,096512
 Chloramphenicol5124256182
 Novobiocin4,09632256323232
 Polymyxin B111111
  • a N107 produced MexAB-OprM, N108 produced MexCD-OprJ, N127 produced MexXY-OprM, and N148, N150, and N128 were deficient in the three efflux systems.