L13 - Prophylaxis Flashcards
What ‘soils’ can act as reservoirs of pathogens?
bodily fluids
dust
Definition of cleaning?
process in which substantial amount of any material that is not part of an item is removed
Definition of disinfection?
any process in which the potential of an item to cause infection is removed by reducing the number of microorganisms present
Definition of Sterilisation?
process used to render an object free from ALL living organisms?
desirable properties of chemical disinfectants?
wide spec of microbicidal activity
rapid action
not be inactivated by (in)organic matter
non-corrosive
not irritant
cheap
What disinfectants do be normally used in environments?
chlorine-based disinfectants
sodium hypochlorite, chlorine dioxide
What disinfectants do we normally used in kitchens and near patients?
Quaternary ammonium compounds (QACs)
What bacteria an used QACs as a carbon source?
pseudomonas
How do chlorine-based disinfectants work?
disrupt membrane
How do QACs work?
membrane damage
What are 2 problems with disinfection?
re-contamination of surfaces can be RAPID
Poor education/cost cutting = cleaners spread pathogens through hospital
Why do repeat used medical instruments pose a problem?
they have to be cleaned and reused
some cannot be autoclaved
How are medical instruments sterilised?
washer disinfectors
equipment packaged and autoclaved
check for prion contamination
What pathogens sometimes are not killed by autoclave?
Bovine spongiform encephalopathy - C, J, D
What are 4 alternatives to autoclaving?
Ethylene oxide
Glutaraldehye
Peracetic acid
Ionising radiation
how does ethylene oxide work?
alkylation of protein/DNA/RNA
How does Glutaraldehyde work?
crosslinking of macromolecules
How does peracetic acid work?
oxidation
How does ionising radiation work?
ROS production - dsDNA breaks, carbonylation of proteins, peroxidation of lipids
What are CRE?
carbapenem-resistant eneterbacteriaceae
What are duodenoscopes prone to contaminated by?
UPPER GI organisms
How does air filtration help prevent infection during surgery?
pass through HEPA
removes 99.97% of all particles >0.3um
What are the 3 ways a HEPA filter stops particles
INTERCEPTION - adhere to surface of fiber
IMPACT - do not move fast enough, disintegrate
DIFFUSION - changes movement within HEPA filter - creating increase for impact and interception
What 2 areas are disinfected before surgery?
skin in surgical field
hands/arms of surgeon
What 2 chemicals used for antisepsis?
Iodophor
Chlorhexadine
Definition of anti-septic?
a chemical disinfection compatible with use on skin
Mode of action of Iodophor?
inactivation of proteins by binding to thiols - denature
Mode of action of Chlorhexadine?
disrupt membrane integrity
What alcohol is used in hand gel?
isopropanol
benefits of alcohol gel vs. handwashing?
less time
accessible location
don’t dry hands (moisturisers contaminated)
not sporocidal
What is antibiotic prophylaxis?
use of antibiotics before, during or after a diagnostic, therapeutic or surgical procedure to PREVENT infection
Which surgeries require antibiotic prophylaxis?
S.aureus colonised (10-40%)
GI, respiratory UT surgeries
open wounds
fracture bones (debridement)
acute inflammation/pus areas
Is bone infection easy to clear?
NO - VERY DIFFICULT TO TREAT
How are patients tested for S.aureus carrier?
Swab
plate onto selective indicator mediu (MSA, CHROMagar)
How are patients carrying S. aureus decolonised?
Mupirocin
Post-exposure prophylaxis?
use antimicrobial chemotherapy to prevent disease arising in individuals that have been exposed to pathogen
Why is organ transplant prophylaxis needed?
stops body rejecting transplanted organ/tissue
How are burn wounds prevented from infection?
remove necrotic tissue
apply dressing containing antimicrobial (silver)
Why are nano-silver compounds now used?
silver nitrate was painful
What is immunisation?
treatment to produce immunity to a disease - typically by inoculation
What is passive immunisation?
antibody containing preparations
PASSIVE IMMUNITY
receive serum containing antibodies
SHORT TERM PROPHYLAXIS
What is active immunisation?
antigen containing preparations
ACTIVE IMMUNITY
patient produces antibodies
LONG TERM PROPHYLAXIS
