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Clinically useful families of beta- lactam compounds include penicillins , cephalosporins , monobactams carbapenems. The Action of Antimicrobial Drugs. The mechanism of action of penicillins and cephalosporins .
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Clinically useful families of beta-lactam compounds include • penicillins, • cephalosporins, • monobactams • carbapenems
The mechanism of action of penicillins and cephalosporins. β-Lactam antibiotics bind to and competitively inhibiting the transpeptidase enzyme that cross-links PG layers.
Pharmacokinetics • - Orally, IM or IV • - Absorption dependant on stability in acid and absorption to food • - Widely distributed in body fluids • - Lipid insoluble • - Do not cross blood-brain barrier • - Elimination via kidneys • - 90% tubular secretion • - Short plasma half-life • - Intermittent exposure advantageous
What are the side-effects of antibiotics? • Most common side-effects of antibiotics: • Diarrhoea • Feeling and being sick • Fungal infections of the mouth, digestive tract and vagina • Rare side-effects of antibiotics: • Formation of kidney stones (when taking sulphonamides) • Abnormal blood clotting (when taking some cephalosporins) • Sensitivity to sun (when taking tetracyclines) • Blood disorders (when taking trimethoprim) • Deafness (when taking erythromycin and the aminoglycosides)
Side Effects and Contraindications • - Hypersensitivity- rashes, fever • - GI disturbances • - Thrush • - Renal Impaired patients
Allergic reactions to antibiotics Some patients may develop an allergic reaction to antibiotics - especially penicillins. Side effects might include a rash, swelling of the tongue and face, and difficulty breathing. Reactions to antibiotics can be very serious, and sometimes fatal - they are called anaphylactic reactions.
Bacterial resistance: It is important to complete the whole course of the medication to prevent the infection from coming back. If you do not complete the course, there is a higher chance the bacteria may become resistant to future treatments - because the ones that survive when you did not complete the course have had some exposure to the antibiotic and may consequently have built up a resistance to it.
Antimicrobial Resistance • Relative or complete lack of effect of antimicrobial against a previously susceptible microbe
Antibiotic Resistance • A variety of mutations can lead to antibiotic resistance • Mechanisms of antibiotic resistance • Enzymatic destruction of drug • Prevention of penetration of drug • Alteration of drug's target site • Rapid ejection of the drug • Resistance genes are often on plasmids or transposons that can be transferred between bacteria.
Penicillin resistancevia penicillinase(βLactamase) Some penicillin resistant organisms produce Penicillinase which degrades penicillin.
Antiseptics • - Anti (against) Septic (putrefactive) • - “substance applied to living tissue to prevent sepsis” • - Disinfectant- “substance applied to non-living materials to prevent microbial growth”
History of Antiseptics • - 1867, Joseph Lister • Common antiseptics used during the last 150 years include alcohol, boric acid, hydrogen peroxide, iodine, carbolic acid and other phenol compounds, chlorohexadine, sodium chloride, sodium hypochlorite and calcium hypochlorite. • - Broad spectrum antimicrobials • - Multiple targets
Chemical structures and uses of biocides in antiseptics and disinfectants
Chemical structures and uses of biocides in antiseptics and disinfectants
Savlon • Manufactured by Novartis Consumer Health, UK
The active ingredients in Savlon cream • - Cholorohexidinegluconate - Cetrimide
Mechanism of Action • - Used topically • - Chlorohexidine- Bacteriocidal to Gram positive and Gram negative • - Membrane disrupting • - Cetrimide- cationic surfactant
Side Effects and Contraindications • - Localised sensitivity • - Incompatible with anionic substances • - Nausea/ Vomiting • - Depression of CNS • - No known contraindications