Mechanisms of Antibiotics Flashcards
how could infection control be established within the dental practise?
- disinfection of non-sterilisable surfaces and equipment
- heat sterilisation of all compatible equipment
- hand washing techniques + appropriate antiseptics
- appropriate barrier techniques (masks, gloves, eye protection)
what are disinfectants?
strong chemical agents that inhibit or kill microorganisms (used on non-biological surfaces)
what are antiseptics?
disinfecting agents with sufficiently low toxicity for host cells (can be used directly on skin, mucous membranes or wounds)
- no injection!
what are sterilants?
these kill both vegetative cells and spores when applied to materials for appropriate times and temperatures
what is the use of chemicals to destroy most pathogenic organisms on animate surfaces known as?
antisepsis
what properties does the ideal antiseptic have?
- toxicity to microorganisms but not to human cells
- cidal activity (kills microorganisms)
- long plasma half-life
- good tissue distribution
- low binding to plasma proteins
- no adverse reactions with other drugs
examples where antiseptics may be used?
- treatment of skin infections
- prevention of infections in cuts and wounds
- cleaning the skin area of surgery from microorganisms
what are the different classifications of antiseptics?**know
- antiseptics that denature proteins (cidal)
- antiseptics that cause osmotic disruption of the cell (cidal)
- those that interfere with specific metabolic processes (growth arrest/static)
what is the mechanism of action for cationic detergents?
interfere with plasma membranes permeability and cause leakage of enzyme, coenzyme and metabolites
examples of antiseptics that denature proteins and DNA bases (inhibiting the functionality of the cell)?
- phenols
- iodine
- alcohols
- aldehydes
what is the function of Iodophores?
used as either an antiseptic or disinfectant:
- kill vegetative bacteria, mycobacteria, fungi, lipid containing viruses
examples of alcohols that work as effective antiseptic and disinfectant agents?
- ethyl alcohol
- isopropyl alcohol
what is chlorohexidine?
an antiseptic (stays around for a long time)
what microbes is chlorohexidine most effective against?
- gram positive cocci
what is chlorohexidine least effective against?
- gram positive rods
- gram negative rods
how does chlorhexidibne act as an antiseptic?
strongly absorbs to bacterial membranes and causes leakage of small molecules and precipitation of cytoplasmic proteins
what is an example of an oxidising agent that is used as an antiseptic?
hydrogen peroxide (H2O2)
what % of hydrogen peroxide is sporicidal?
10-25%
what is potential dangerous for common users of antiseptics, disinfectants or sterilants?
- short term and long term toxicity
- general biocidal activity
- accumulate in the environment OR in the patients/caregivers body*
what are antibiotics?
naturally occurring antimicrobials
- metabolic products of bacteria and fungi
how are antibiotics destructive to organisms?
reduce competition for nutrients and space (dont kill microbes)
examples of bacteria antibiotics?
- streptomyces
- bacillus
examples of mould antibiotics?
- penicillium
- cephalosporium
what is the DEFINITION of an antibiotic?
an antibiotic is a chemical substance produced by one organism that is destructive to another
what are the two types of antibiotics?
- bacteriostatic (slows down organism)
- bacteriocidal (kills organism)
what are the cellular targets for antibiotics??*******know
- inhibition of cell wall synthesis
- injury to cell/plasma membrane
- inhibition of nucleic acid replication and transcription
- inhibition of protein synthesis
why is a long plasma half life an important trait for an ideal antimicrobial agent?
stays in the body for a while
what does misuse of antibiotics lead to?
antibiotic resistance
what are examples of misuse of antibiotics?
- using outdated or weakened antibiotics
- using antibiotics for the common cold and other inappropriate conditions
- failing to complete a course of antibiotics
what are some mechanisms of antibiotic resistance?
- blocking entry of antibiotic into cell
- inactivating enzymes
- efflux of antibiotic
- alteration of target molecule
what is antibiotic prophylaxis?
use of a drug to prevent imminent infection of a person at risk
