Developmentofin-vitroSensitivityTestingforPathogenicBacteria

Abstract

Anewmethod developed for in vitrosusceptibility test in medicall aboratoriesconsistofmicrotubesorglovescontainingdehydratedtrypticsoyabroth,5%glucose,0.1%bromothymolblueandonetypeofantibiotics(ampicillin,tetracyclineandchloramphenicol)withcriticalconcentrationMIC(minimuminhibitoryconcentration)forsusceptibility.Standardqualitycontrolstrainsofbacterial(Escherichiacoli,StaphylococcusaureusandPseudomonasaeruginosa)suspensionwereadjustedto0.5McFarlandturbiditystandard(1×106cell/mL)wereusedininoculationthemediaandincubatedtwohoursat37°C.TheMICofampicillinagainstE.coli,S.aureus,andP.aeruginosawere4,32,and256µg/mLofthemediaforthebacteriarespectively,whiletheMICoftetracyclineagainstbacteriawere512,512and32µg/mLrespectively,theMICofchloramphenicolwere512,32and512µg/mL,respectively.Where,theresistantbacteriatotheantibioticscouldgrowandfermentglucosesugarproducingacolorchangeofthemediafrombluetoyellow,whilethesensitivebacteriadonotgroworshownochangeincolor.Ourstudyresultcomparedwithcommonusedantibioticdiskmethodobtainingsimilarresults.Thisdevelopedmethodcharacterizedbyfast(onlytwohours)andlesscostincomparisontoconventionaltechnique.Thenewmicrotubestripishighlystable(morethanoneyear)withmoresensitiveindetectionofvariablepathogenicbacteriaincludingstandardbacteriastrainscomparedwithconventionaltechnique.

Keywords

• medicallaboratoriestechnique
• Susceptibility
• MIC
• antibiotic