anti-microbials Flashcards
(24 cards)
what is included in infection control?
disinfection of non-sterilisable surfaces and equipment
heat sterilisation of all compatible equipment
handwashing techniques + appropriate antiseptics
combined with barrier techniques: masks, gloves and eye protection
what are disinfectants?
strong chemical agents that inhibit or kill microorganisms
what are antiseptics?
disinfecting agents with sufficiently low toxicity for host cells
-can be used directly on skin, mucous membranes, or wounds
what are sterilants?
kill both vegetative cells and spores when applied to materials for appropriate times and temperatures
what is antisepsis?
use of chemicals to destroy most pathogenic organisms on animate surfaces
what properties are important for antiseptics and disinfectants?
toxicity to microorganisms but not to human cells
degree of selectivity depending on contacted tissues
what are uses of antiseptics?
treatment of skin conditions
prevention of infections in cuts and wounds
cleaning the skin area of surgery from microorganisms
prophylaxis and treatment of infections in mucosal areas such as mouth, nose, vagina that are open to environment
as a scrub for surgeons and the medical personnel
what are the classifications of antiseptics?
those that denature proteins (cidal)
those that cause osmotic disruption of the cell (cidal)
those that interfere with specific metabolic processes (growth arrest/static)
what is the mechanism of action of phenols, iodine, alcohols, aldehydes and metallic compounds?
denature proteins and DNA bases
what is the mechanism of action of cationic detergents?
interfere w/ plasma membrane permeability and cause leakage of enzyme, coenzyme and metabolites
what is the mechanism of action of oxidizing compounds?
oxidize functional molecules in the microorganisms
what are iodophores?
oxidize -SH groups of proteins and enzymes to produce S-S bonds and disrupt structure and function of these
either antiseptic/disinfectant
kill vegetative bacteria, mycobacteria, fungi, lipid containing viruses
what are alcohols?
ethyl alcohol (70%) and isopropyl alcohol
antiseptic/disinfectant
reduce bacterial numbers 90% on skin
rapidly kill vegetative bacteria, fungi and inactive lipophilic viruses
denature proteins and disturb the membrane permeability of bacteria
limited antibacterial spectrum
what is chlorhexidine?
antiseptic
most effective agains gram+ cocci
less gram- and + rods
spore germination inhibited
strongly adsorbs to bacterial membranes and causes leakage of small molecules and precipitation of cytoplasmic proteins
resistant to inhibition by blood/organic material
what are oxidising agents?
H2O2 antiseptic
concentrations potentially useful for antisepsis are against vegetative bacteria, higher conc. sporicidal
disinfection of respirators, acrylic resin implants, plastic eating utensils, soft contacts, cartons for milk/juice
10-25%
what is the danger of antiseptic, disinfectant and sterilant to users
short term/long term toxicity
general biocidal activity
accumulate in environment/body
what are antibiotics?
a chemical substance produced by one organism that is destructive to another
naturally occurring antimicrobials
-metabolic products of bacteria and fungi
-reduce competition for nutrients and space
what are the types of antibiotic?
bacteriostatic
bacteriocidal
what are the cellular targets of antibiotics?
cell wall
cell membrane
nucleic acid
protein synthesis
what properties does the ideal antimicrobial agent have?
selective toxicity against microbial target minimal toxicity to host cidal activity long plasma half-life good tissue distribution low binding to plasma proteins oral and parenteral preparations no adverse interactions with other drugs
what is the mechanism of action for antibiotics?
cross linking of cell wall prevented
what contributes to antibiotic resistance?
misuse
what is included in misuse of antibiotics?
using outdated or weakened antibiotics
using antibiotics for the common cold & other inappropriate conditions
using antibiotics in animal feed
failing to complete the prescribed regimen
using someone else’s leftover prescription
what are the resistance mechanisms for antibiotics?
blocking entry
inactivating enzymes
alteration of target molecule
efflux of antibiotic
