Gentamicin asabactericidal agentinvirological tissue cultures

SYNOPSISForuseinvirological tissue culture work,gentamicin ismore convenient thanpenicillin + streptomycin. Itisbactericidal fora wider rangeoforganisms, may beusedatonly half the concentration needed forpenicillin andstreptomycin, doesnotapparently interfere withgrowth oftissue cultures andviruses, remains active at37°C., and,mostremarkable ofall, itisstable at autoclave temperatures andsocanbeputinto mediabefore sterilization, thuslessening thenumber ofadditions tothesterilized medium. Gentamicin isnow inroutine use inthis laboratory. Withtheantibiotics currently employed invirology itispossible toeliminate mostbacteria, natural flora orcontaminants, inspecimens cultured to isolate viruses andintissues processed forculturing viruses. However, thespecimens andtissues often contain bacteria resistant tothese antibiotics. This difficulty is, tosomeextent, overcome byusing a mixture ofantibiotics, forexample, penicillin + streptomycin, andsometimes alsopolymyxin or neomycin. Someofthese arenotheat-stable andso mustbeaddedaseptically after sterilization ofthe mainmedium;somelosetheir potency during incubation at37°C.Itwouldtherefore beadvantageous tohaveanantibiotic withawideenough rangeofactivity tobeusedalone, andheat-stable so that itcould beincorporated inthemediumbefore sterilization andwouldmaintain itspotency at incubation temperatures. Theproperties ofgentamicin suggested thatitmight meetthese requirements. Gentamicin isa broad-spectrum antibiotic, related chemically tothestreptomycin group, active against Gram-positive andGram-negative bacteria andhaving aremarkable degree ofefficacy against Proteus andPseudomonas species, butnotactive against fungi (Rosselet, Marquez, Meseck, Murawski,Hamdan,Joyner, Schmidt, Migliore, and Herzog, 1963; Barber andWaterworth, 1966). Itis stable overa widerangeoftemperature, which permits autoclaving (Taplin, 1965). However, it seemedwisetoinvestigate whether gentamicin's knownbactericidal action wasaffected bytheuseof acomplex mediumassolvent andbythepHchange fromtissue metabolism, whether ithadanyeffect on tissue cultures andonvirus particles, andhowit performed inroutine use.