50’s Ribosomes Inhibitors ❖ Chloramphenicol - BACTERIOSTATIC ❖ Macrolide o Erythromycin - BACTERIOSTATIC OR CIDAL o Clindamycin - BACTERIOSTATIC OR CIDAL o Lincomycin
High dosage of tetracycline may lead to live and kidney damage and yellowing the teeth of children.
Chloramphenicol may cause temporary or permanent depression of bone marrow leading to aplastic anemia and leukemia (toxic side effect)
Aminoglycosides - Gentamicin, kanamycin, neomycin, streptomycin and tobramycin, they have cyclohexane ring and may cause deafness and loss of balance (toxic)
Chloramphenicol and erythromycin - bind to 23s rRNA on the 50s ribosomal unit.
Sulfonamides
inhibit Folic acid metabolism, high there
Trimethoprim
blocks tetrahydrofolate synthesis
Dapsone
interferes with F.A. synthesis.
Intrinsic resistance
Lack specific target site
Extrinisic resistance
Cannot bind to bacterial cell
TEST TUBE DILUTION/ BROTH DILUTION METHOD
Challenging the organisms of interest with antimicrobial agents in a broth.
Standard inoculum size of test tube dilution method / broth dilution method?
5 x 105 CFU/ml
Broth volume of Microdilution?0.05-0.1 ml
Macrodilution Broth volume: 10 ml or greater
The lowest conc. of the antibiotic without bacterial growth after 16 to 24 hours of incubation is the MIC.