Microbiological Culture Sensitivity Test.

Microbiological Culture Sensitivity Test.Antibiotic Sensitivity Test ( AST )Akhil JosephPharm.D IVth Year.Reg.No: 13Q0402

According to the new ISO 20776-1 standard, which is valid all over the world, these terms are defined as follows:Susceptible (s):A bacterial strain is said to be susceptible to a given antibiotic when it is inhibited in vitro by a concentration of this drug that is associated with a high likelihood of therapeutic success.Intermediate (i):The sensitivity of a bacterial strain to a given antibiotic is said to be intermediate when it is inhibited in vitro by a concentration of this drug that is associated with an uncertain therapeutic effect.Resistant (r):A bacterial strain is said to be resistant to a given antibiotic when it is inhibited in vitro by a concentration of this drug that is associated with a high likelihood of therapeutic failure.

mg/Lmg/Lmg/Lmg/Lmg/Lmg/Lmg/Lmg/LAmpicillin0.250.512481632Ampicillin/sulbactam0.250.512481632Piperacillin/tazobactam0.5/21248163264Cefuroxime0.1250.250.5124816Cefotaxime0.1250.250.5124816Imipenem0.1250.250.5124816Gentamicin0.1250.250.5124816Doxycyclin0.1250.250.51248GCCotrimoxazole1248163264128Ciprofloxacin0.030.060.1250.250.5124Levofloxacin0.030.060.1250.250.5124Moxifloxacin0.030.060.1250.250.5124

Schematic representation of a microtitration plate for the determination of minimal inhibitory concentrations (MICs)

The results for a particular tested strain of E. coli.The MIC values for this strain and the sensitivity ratings that will be assigned to them henceforward by EUCAST (The European Committee on Antimicrobial Susceptibility Testing) , are:ampicillin= 4 mg/L (i);ampicillin/sulbactam= 1 mg/L (i);piperacilin/tazobactam= 2 mg/L (s);cefuroxime= 4 mg/L (i);cefotaxime= 0.125 mg/L (s);imipenem= 0.5 mg/L (s);gentamicin= 0.25 mg/L (s);doxycycline= 8 mg/L ();cotrimoxazole>128 mg/L (r);ciprofloxacin