Failure of polymyxin B nonapeptide to augment bactericidal activities of novobiocin, rifampin, and of defibrinated human blood against Serratia marcescens.
Polymyxin B (PB) and polymyxin B nonapeptide (PBNP), when combined with rifampin or novobiocin, but not vancomycin, yielded additive inhibitory effects against test strains of Serratia marcescens of three varieties: those that produced cocarde growths around PB disks (coc+); those that grew adjacent to PB disks (coc-, 6); and those that yielded clear inhibition zones around PB disks (coc-, clear). However, time kill curve experiments disclosed that only the combination of rifampin + PB exerted a potent bactericidal effect against coc+ strains of S. marcescens; rifampin + PBNP and novobiocin + PB or PBNP merely effected transient decreases of colony counts. Assays involving 50% (v/v) of fresh defibrinated human blood + PB or PBNP revealed that only PB clearly augmented the antibacterial activity of blood against coc+, and less so against coc- test strains of S. marcescens.
Traub
W H
WH
Institut für Medizinische Mikrobiologie und Hygiene, Universität des Saarlandes, Homburg a.d. Saar, FRG.
Kohl
K H
KH
Spohr
M
M
Bauer
D
D
D001770:Blood Bactericidal Activity / Q000187:drug effects*; D004357:Drug Synergism; D006801:Humans; D008826:Microbial Sensitivity Tests; D009675:Novobiocin / Q000494:pharmacology*; D011112:Polymyxin B / Q000031:analogs & derivatives / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D012293:Rifampin / Q000494:pharmacology*; D012706:Serratia marcescens / Q000187:drug effects*
D011113:Polymyxins; D009675:Novobiocin; C038934:polymyxin B nonapeptide; D011112:Polymyxin B; D012293:Rifampin