Term | Definition |
Principles of controlling microbial growth | 1. Microorganisms have specific requirements
2. Certain structures and/or processes are essential
3. Any control strategy has to be tailored
4. Not all control methods are equally effective
5. Not all microorganisms are equally susceptible |
UV-rays sterilisation | 1. UV range: 50-400 nm wavelength
2. Absorbed by purine & pyramidine bases: forms pyramidine dimers
3. Doesn’t penetrate well: limited to surface sterilization
4. Uses: Sterilize some foods E.g., nuts and spices. |
Ionizing | Dislodges electrons from atoms Damages DNA and produces peroxides |
Disinfectants | 1. Quaternary ammonium compound
2. Halogens (iodine, chlorine)
3. Peroxides
4. Alcohols |
Function of antibiotics: Chloramphenicol, Streptomycin, Tetracyline, Macrolides. | Protein synthesis inhibition |
Antibiotics targeting protein synthesis inhibition | Chloramphenicol, Streptomycin, Tetracyline, Macrolides. |
Selective toxicity | Antibiotics that kill microbial cells but not the host's cells. |
Has stationary number of total cells and low number of viable cells | bactericidal compound |
bactericidal compound | Has stationary number of total cells and low number of viable cells |
Has a low total cell count and a low viable cell count | Bacteriolytic compound |
Key features of Antiseptics | 1. How effective it is depends on: antimicrobial activity and toxicity to living tissues.
2. ability to remove microbes before injection
3. ability to reduce numbers of microbes before cut or surgery |
Dilution test | ring dipped in colony --> ring washed with disinfectant --> ring washed with water --> ring put in nutrient broth --> effectiveness of disinfectant based on growth in broth. |
ring dipped in colony --> ring washed with disinfectant --> ring washed with water --> ring put in nutrient broth --> effectiveness of disinfectant based on growth in broth. | Dilution test |
Therapeutic antimicrobials | General term that is used to refer to natural and synthetic compounds with activity against microorganisms, that can be
used therapeutically. |
General term that is used to refer to natural and synthetic compounds with activity against microorganisms, that can be
used therapeutically. | Therapeutic antimicrobials |
Inhibitors of Reverse Transcriptase | Zidovudine (AZT) and Stavudine |
Mechanisms of Zidovudine (AZT) and Stavudine | NUCLEOSIDE ANALOG: Activated (phosphorylated) inside the infected cell and Inhibit the viral polymerase (reverse transcriptase) |
Inhbitors of petidigylcan syntehsis | Beta lactam antibiotics: Penicillin and Cephalosporins |
Mechanism of Beta lactam antibiotics: Penicillin and Cephalosporins | Blockage of synthesis of cross linkage in the peptidoglycan layers. Binds to the enzymes (transpeptidases) responsible for the cross-linking. |
Main targets for antibacterial action | 1. Protein synthesis
2. Metabolism
3. Cell wall
4. Cell membrane function
5. Nucleic acid synthesis |
Ergosterol | A steroid alcohol present in fungal cell membrane (responsible for stiffening the cell membrane) |