C.1. General considerations of antimicrobial therapy. Disinfectants and antiseptics Flashcards
what does antimicrobial therapy do?
kills or inhibits the growth of microorganisms (bacteria, viruses, fungi, protozoans)
what are the characteristics of antibiotic therapy?
- directed against the cause of the disease
- antimicrobial activity + sufficiently high concentration at the site of infection
- microbes respond to the Ab
- permanent interference with the environment
- the most effective and least toxic drug has to be used
give 5 consideration in antibiotic choice and therapy
- spectrum of action
- site of infection (degree of penetration)
- pharmacodynamics and pharmacokinetic properties
- dosage
- adverse effects
- presence of renal or hepatic failure
- drug interactions
- cost
what are the types of antimicrobial therapy?
- empiric therapy
- definitive therapy
- prophylactic therapy
what is empiric therapy?
treatment is given based on clinical presentation and experience. broad-spectrum antimicrobial agents
what is definitive therapy?
based on microbiological results and/or sensitivity tests. narrow antibiotic spectrum.
what is prophylactic therapy?
administration of antimicrobial agent for preventing infection prior to clinical presentation.
classified as either pre-exposure prophylaxis or post-exposure prophylaxis
what do bacteriostatic agents do?
inhibit the growth of microorganisms
what do bacteriocidal agents do?
kill microorganisms within a short period of time.
what is the minimum inhibitory concentration (MIC)?
the lowest concentration that inhibits the growth of the organism.
what is the minimum bactericide concentration (MBC)?
the lowest concentration that kills 99.9% of the organisms
why are immunocompromised patients given bactericidal agents rather than bacteriostatic?
cause their host immunity cannot achieve the final elimination of the weakened organisms.
what is a concentration-dependent antibacterial activity?
killing action increases proportionally above the MIC. Requires high-dose administration, once daily.
ex. Aminoglycosides
what is a time-dependent antibacterial activity?
killing action continues as long as the drug serum concentration is maintained 40-60% above the MIC.
Requires continuous administration or multiple doses daily.
example for Ab with synergistic effect?
aminoglycosides +cell wall active agent
sulfonamide +trimethoprim
beta lactam+ beta-lactamse
when do we use an extended antimicrobial spectrum Ab?
polymicrobial infections
when is Ab given in combination to prevent the development of resistance?
Tuberculosis
what is disinfection?
removal of actively dividing microorganisms. only reduce the number of potential pathogens
what is sterilization?
complete elimination of all viable microorganisms.
what is Asepsis?
state of being free from disease-causing microorganisms
what is Antisepsis?
the process whereby the risk of medical infection is reduced
what is a disinfectant compound?
compound that is used to kill microorganisms in an inanimate environment
what is an antiseptic compound?
compound that is used to inhibit bacterial growth both in-vitro and in contact with the surfaces of living tissues
what effective Alcohol skin disinfectants do we have?
Ethanol 70%
Isopropanol 70-90%
what is more effective- ethanol or isopropanol?
isopropanol
but more toxic
what are the effects of Alcohol as disinfectants?
denature microbial proteins (bactericidal effect)
removal of lipids from skin surfaces
what is Povidone-iodine?
halogen
when is Povidone-iodine (iodophor) used?
as a pre-operative skin antiseptic
what is Hydrogen peroxide (H₂O₂)?
an Oxidizing agent
what is Hydrogen peroxide used for?
mouth wash, for cleansing wounds, and for disinfection of contact lenses.
what are the advantage and disadvantages of alcohol?
adv: no material damage
dis: inflammable
what are the advantages of oxidizing agents?
wide spectrum, bactericidal, virucidal and fungicidal
what does H₂O₂ do?
release of molecular oxygen is antimicrobial
list chlorinated phenols
chlorhexidine
phenol
cresol
when do we use chlorinated phenols (chlorhexidine)?
in-hospital scrub routines to cleanse skin sites
not to be used during middle ear procedures (severe ototoxicity)
what do chlorinated phenols do?
they strongly adsorb to bacterial membranes, causing leakage of small molecules
active against gram + cocci and mycobacteria, variable activity against fungi and viruses.
what are Octenidin dihydrochloride & invert soaps?
cationic surfactant
what are invert soaps?
class of synthetic detergents in which the surface-active part of the molecule is the cation
what is Octenidin dihydrochloride active against and what is it used for?
active against gram + and gram - bacteria
used as antiseptic prior to medical procedures, including on neonates
when is mercury used as a disinfectant?
on the skin, good antifungal effect
which disinfectants have the widest spectrum?
Aldehydes–> Formaldehyde.
what are the advantage and disadvantages of aldehydes?
adv: bactericidal, sporicidal, virucidal, fungicidal
dis: very irritable
what are the characteristics of an ideal disinfectant?
- effective at ↑ dilution
- it does not damage tissues
- odorless
- stable
- water-soluble
what is Spaulding’s classification?
classification of medical equipment/devices and required level or processing
division of Spaulding’s classification
critical
semi-critical
noncritical
