Presentation 1 - Ex 7

EXERCISE 7 • To demonstrate the ability of different methods of physical and chemical control of microbial growth • To perform and understand the principle behind antibiosis, antimicrobial susceptibility and minimum inhibitory concentration • To test the effectiveness of handwashing in eliminating the growth of microbes

METHODS OF CONTROL • PHYSICAL – BOILING – RADIATION

• CHEMICAL – HAND WASHING

HANDWASHING AS A TOOL TO ELIMINATE MICROBES IS IT EFFECTIVE?

ANTIBIOSIS • HARMFUL INFLUENCE ELICITED BY ONE MICROORGANISM TO ANOTHER • PRODUCTION OF ANTIBIOTICS OR SIMILAR COMPOUNDS – BACTERIOCINS

ANTIMICROBIAL SUSCEPTIBILITY TESTING

MINIMUM INHIBITORY CONCENTRATION • CONCENTRATION OF THE ANTIMICROBIAL AGENT AT THE EDGE OF THE INHIBITION ZONE • LOWEST DOSE POSSIBLE TO INIHIBIT MICROBIAL GROWTH • TUBE DILUTION ASSAYS VS PLATE INHIBITION ASSAYS

RESISTANCE A MICROBE LOSES ITS SENSITIVITY TO A DRUG BY EXPRESSING GENES THAT STOP THE ACTION OF THE DRUG – SYNTHESIS OF ENZYMES THAT INACTIVATE THE DRUG • PENICILLINASE

– DECREASE IN CELL PERMEABILITY AND

– CHANGE IN THE NUMBER OF THE DRUG RECEPTOR SITES (MRSA) • STRUCURE OF KEY PROTEIN ALTERED (RIF/STREP) • ALTERATION OF THE 50S RIBOSOMAL BINDING (ERY/CLIND) • FUNGAL DRUGS DECREASE ERGOSTEROL PRODUCTION : PRINCIPAL DRUG RECEPTOR

– MODIFICATIONS OF AN ESSENTIAL METBOLIC PATHWAY • DORMANCY • L FORMS