Antiinfectives Flashcards
what are high level chrmical sterilants
destroy all microorganisms
aldehydes, hypochlorites, peroxygenes
what are low level disinfectants
destroy most bacteria, some viruses and fungi
excludes TB, some viruses, fungi, bacterial spores, prions
what are some intermediate-level disinfectants
destroy all bacteria, most viruses and fungi
excludes some viruses, bacterial spores and prions; like alcohols, phenolics, iodine
what are antisepsis disinfectants
work on living tissues
decrease wound infections/normal skin flora prior to surgery
decrease spread of infection by hand cleansing
what are the properties of 4% chlorhexidine gluconate antiseptic
high activity in immediate, persistent, residual disinfectants
what are the properties of alcohol and chlorhexidine antiseptic
high activity in immediate, persistent and residual disinfectants
what factors affect choice of chemical agent
higher bioburden required higher concentrations and longer expsore times
biofilms are more resistant to disinfectants
what is transient bacteria
gram negative
like e.coli
what is resident bacteria
gram positive
staph.a
what effect does organic matter have on sterilisation
can reduce antimicrobial capacity
what effect do divalent cations have on sterilisation
reduced activity and stabalise cell walls, block disinfectant adsorption sites
what effect does dilution have on sterilisation
higher conc of disinfectant increases efficacy and reduces exposure time, but dilution does not affect killing capacity of all disinfectants in the same way
what is the suspension test
dilutions of disinfectant added to standardised bacterial suspension in water and albumin at set temp
at specific time interval, sample removed, disinfectant neutralised, determines viable count
what validation does the suspension test give
know viable count of innoculum, experimental conditions validation, neutraliser toxicity validation, disinfectant neutralisation validation
what qualatative test estimates bacteriostasis
minimum inhibitory concentration
estimation of bacteriostasis
how are minimum inhibitory concentrations tested
double dilutions of test agent prepared, innoculated with test organism, incubate overnight, score for growth, MIC is lowest conc with no growth
what is the disc susceptability test
agar spread with test organism, filter paper disc impregnates with known conc test agent placed on plate, zone of growth inhibition indicates antimicrobial activity, measure, compare to standards
how to evaluate antiseptics with time kill
for each microorganism and antimicrobial; dilute each test agent, innoculate with test organism, at designated time intervals remove sample/neutralise antimicrobial and determine viable count
what classes of agent are used as disinfectants
organic acids and esters, aliphatic alcohols, aldehydes, biguanides, halogens, hydrogen peroxide and peracetic acid, phenolics, surface acting agents
what are the advantages of using aliphatic alcohols
broad antimicrobial activity- active against bacteria including fungi, rapid kill, water soluble, relatively non-toxic, no residues
what are the disadvantages of using aliphatic alcohols
non sporicidal, isopropranolol not virucidal, poor penetration of organic matter, high dilution coefficient, flammable
what are examples of aliphatic alcohols
ethanol, isopropanol
what are examples of aldehydes
glutaraldehyde, formaldehyde
what are advantages of aldehydes
broad spectrum, sporicidal, rapid kill, not affected by organic matter
what are disadvantages of aldehydes
unstable, activity lowered by polymerisation, toxic
what is an example of biguanides
chlorhexidine
what are advantages of biguanides
good bacterial activity, non toxic
what are disadvantages of biguanides
not active against mycobacteria or viruses, not sporicidal or virucidal, not very soluble in water, activity decreased by anionic compounds
what are some examples of halogens
Cl2
active against bacteria, fungi, viruses and spores
irritant
what are some advantages of hypochlorites
readily available, cheap/compatible, broad spectrum, rapid kill
what are some disadvantages of hypochlorites
corrosive, irritant, inactivated by organic matter, unstable
what are advantages of using iodine
broad spectrum, rapid kill, less affected by pH/temp/organic matter compared to Cl2 compounds
what are some disadvantages of using iodine
stains skin and fabric, irritant
what are idophores
allow slow release of I2 from a complex
what are some examples of iodophores
povidone-iodine
what are some advantages of peroxygen compounds
powerful antimicrobials and sporicides, active in presence of organic matter
what are some disadvantages of peroxygen compounds
unstable in sunlight, irritant, corrosive
what are some advantages of phenolics
good antimicrobial activity, poor sporicide, cheap
what are some disadvantages of phenolics
activity decreased by dilution, some are harmful/toxic, some have strong odour, some corrosive
what are examples of substituted phenols
phenolic tar acids, cresols, xylenols, ethyl phenols
what are some advantages of substituted phenols
broad spectrum, rapid kill, cheap, not affected by organic matter
what are some disadvantages of substituted phenols
not sporicidal, leave residues
what are cationic surface-active agents
quaternary ammonium compounds
what are advantages of cationic surface agents
water soluble, most effective, stable, non-toxic, non-corrosive, broad spectrum, active at low conc
what are some disadvantages of cationic surface active agents
not sporicidal, activity decreased by organic matter
what are examples of drugs with narrow therapeutic window
theophylline, digoxin, lithium, amoniglycosides, antiepileptic drugs
what does TDM stand for
therapeutic drug monitoring
what is TDM
intervention that improves pt response and decreases adverse reactions, intervention to optimise clinical outcome and manage pt condition with measured drug conc
what are some commonly monitored drugs
anticonvulsants (primidone, valoprate), antiarrythmias (digoxin, lidocaine), antiasthmatics (theophylline), immunosuppressives (cyclosporin), antidepressants (lithium, TCAs), antineoplasics (methotrexate), abx (aminoglycides, glycopeptides)
what is the ideal therapeutic level for gentamicin
5-10microns/mL
what are some reasons for TDM
narrow therapeutic range, assessment of adherance to medication, suspected toxicity, lack of response, unpredictable dose, no clear endpoint to observable therapeutic success, C-at steady state, assess therapy following change in dosing regime, change in pt state, drug interaction, toxicity and disease symptoms are similar
what are the physiochemical properties of gentamicin
very water soluble, poorly lipid soluble, poor oral absorption
what is the primary phase of aminoglycoside action
rapid, drug conc dependent action
what is the secondary phase of aminoglycoside action
slow, independentt of drug conc, postantibiotic effect is prolonged, surviving bacteria may not be able to metabolise for up to 8hours after extracellular aminoglycoside has been washed away
exposure of surviving bacteria to second dose of amoniglycoside before they have recovered from the first impairs bactericidal effect of second dose
what are the risks of using gentamicin
nephro and ototoxicity can occur after accumulation in tissues
important to ensure that preak drug concs are high enough but also that values sufficiently low to avoid accumulation
how does gentamicin work
active transport into cells of the inner ear and renal proximal tubule
kidneys are the major site of drug deposition
what is gentamicin toxicity related to
the duration of the treatment
how to reduce nephrotoxicity of gentamicin
once daily administration; saturable uptake into renal cortex
