TABLE 5.

Antibiotic susceptibility of P. aeruginosa MPAO1 and its mutant strains grown with or without spermidine

P. aeruginosa strain and growth conditionsMIC (μg/ml)a
Px-BCOLKANGENCIPNORTETEtBrACO
MPAO1 grown with
    MMP22160.2514825664
    MMP + spermidineb16166414168>512512
MPAO1 (oprH::Tc) grown with
    MMP48640.50.121>10025664
    MMP + spermidine163212820.54>100>512512
MPAO1 (phoP::Tc) grown with
    MMP22640.250.060.25>10025664
    MMP + spermidine2212810.120.5>100>512512
MPAO1 (phoQ::Tc) grown with
    MMP1632640.50.060.25>10025664
    MMP + spermidine≥128≥12812840.251>100>512512
MPAO1 (PA3552::Tc) grown with
    MMP22160.2514>10025664
    MMP + spermidine48641416>100>512512
  • a MIC measurements were repeated three times by the broth dilution method as described in Materials and Methods.

  • b A 20 mM concentration of spermidine was added to MMP containing 20 mM glucose as a carbon source. Px-B, polymyxin B; COL, colistin; KAN, kanamycin; GEN, gentamicin; CIP, ciprofloxacin; NOR, norfloxacin; TET, tetracycline; EtBr, ethidium bromide; ACO, acridine orange.