TABLE 1.

Polyamine effects on antibiotic susceptibility of E. coli, S. enterica serovar Typhimurium, and S. aureus

AntibioticMIC (μg/ml)a for indicated strain and treatment
E. coliK-10E. coliK-12E. coli C921-61S. enterica serovar Typhimurium LT2S. aureus N315S. aureus Mu50S. aureus ATCC 35556
NoneSpNNoneSpNNoneSpNNoneSpNNoneSpNNoneSpNNoneSpN
Ampicillin80.542424112846422≤0.06
AmoxicillinNDNDNDNDNDNDNDND160.25160.51≤0.06
Azlocillin160.25162821641611610.50.12
Carbenicillin32216416281320.5≥51241≤0.06
CefoperazoneNDNDNDNDNDNDNDND40.5>1,0241610.25
CefotaximeNDNDNDNDNDNDNDND20.5≥1,02440.50.25
CeftazidimeNDNDNDNDNDNDNDND324512168≤0.06
CeftriaxoneNDNDNDNDNDNDNDND41>1,0241621
Cephaloridine80.542420.0150.0151≤0.06160.25≤0.06≤0.06
CephalothinNDNDNDNDNDNDNDND1≤0.066410.5≤0.06
CloxacillinNDNDNDNDNDNDNDND8≤0.06≥51210.12≤0.06
Oxacillin1,0246451212851212825612816≤0.0651210.12≤0.06
Penicillin G6426416328162320.12320.25≤0.06≤0.06
Piperacillin20.2520.520.540.5320.512820.50.12
Ticarcillin80.5824140.5320.25512410.25
Chloramphenicol161322422180.258280.25
Ciprofloxacin≤0.03≤0.03≤0.03≤0.03≤0.03≤0.03≤0.03≤0.0310.564320.250.25
Erythromycin648641664646432NDNDNDNDNDND
Fusidic acid>1,024641,0245121,0241,024>1,0241,024NDNDNDNDNDND
Kanamycin20.25414442NDNDNDNDNDND
Novobiocin>1,024512>1,0241,024512256>1,0241,024NDNDNDNDNDND
Polymyxin B0.50.250.250.250.50.50.50.5641612832644
Spectinomycin16116216163232NDNDNDNDNDND
Tetracycline80.58221220.12≤0.063240.12≤0.06
VancomycinNDNDNDNDNDNDNDND0.50.25≥4210.5
Spermineb1ND>16ND>16ND2ND4ND4ND4ND
  • a The MICs of antibiotics were determined in the absence (none) or presence of 1 mM spermine (SpN); only 0.5 mM of SpN was applied to E. coli K-10. ND, not determined.

  • b The MICs of spermine are expressed in mM.