infection prevention Flashcards
on what basis does infection prevention work on
memory from adaptive immunity
first exposure to Ag -> primary immune response develops -> proliferation of activated B and T cells into effector cells and some into memory T and B cells -> reexposure to same Ag -> activation of memory T and B cells -> generates secondary immune response with shorter lag time and heightened activity (aka more Ab produced)
what are the considerations when wanting to give live, attenuated vaccines
- avoid in pregnant women (no evidence of birth defects but may have fetal infection)
- avoid in infancy <1 yr (mother’s circulating Ab will neutralise so become less effective)
- avoid in severely immunocompromised
- avoid giving another live vaccine within 28d (circulating Ab can interfere with replication process and minimise response to vaccine)
- space 3-10m apart from administration of Ab containing products
what are examples of immunocompromised patients
hematologic/ solid organ malignancies, immunosuppressive meds, chemo tx, HIV with CD4 <200
what is herd immunity
protecting both vaccinated and unvaccinated individuals
percentage of population that needs to be vaccinated for herd immunity depends on how contagious the disease is
what is the childhood immunisation schedule
BCG (1, 0)
HepB (3, 0)
DTap (3, 1)
Tdap (0, 1)
IPV (3, 1)
Hib (3, 1)
PCV10/PCV13 (2, 1)
PPSV23 (1 or 2 if indicated, 0)
MMR (2, 0)
Varicella (2, 0)
HPV2/HPV4 (2, 0)
influenza (annual)
what is the adult immunisation schedule
HepB (all take 3 if not yet taken or not immune)
Tdap (all take 1 if pregnancy indicated)
PCV13 (1 if indicated, 1 if indicated, 1)
PPSV23 (1-2 doses depending on indication, 1-2 doses depending on indication, 1)
MMR (all take 2 if not yet taken or not immune)`
Varicella (all take 2 if not yet taken or not immune)
HPV2/HPV4 (all take 2 if not yet taken or not immune)
influenza (1 annually if indicated, 1 annually if indicated, 1)
what are the considerations for vaccine use
effectiveness
adverse effects
c/i and precautions
simultaneous administration and missed doses
what are uncommon and severe but rare adverse effects
uncommon: fever, hematoma
severe but rare: anaphylaxis, hypersensitivity
what happens if theres a missed dose
administer dose asap, usually do not need additional doses
what are the medical considerations before international travel
- risk assessment (medical history, prior travel experience, specific itinerary, activities, type of accommodation, traveler’s risk tolerance, financial challenges)
- standard in-office interventions (administration of immunisations, malaria chemoprophylaxis if at risk. traveler’s diarrhoea)
- focused education before the trip (vectorborne diseases if at risk, other travel related illnesses as applicable, medical kit and medical care abroad)
when does pre travel consultation happen
4-6w before departure
what are examples of other travel related illnesses
altitude illness, travelers’ thrombosis, motor vehicle injury, bloodborne and STI, swimming, water exposure and marine hazards, transportation associated illnesses, respiratory infections and TB, rabies and animal associated illness, skin conditions and wounds
what are the contents to cover regarding medical kit and medical care abroad
personal health kit, available medical facilities, evacuation insurance, supplemental health insurance
what are the necessary information for risk assessment during pre travel consultations
medical history, special conditions, immunisation history, prior travel experience, itinerary, timing, reason for travel, travel style, activities
what are the major routes of infection and examples of common vaccines used
- food or waterborne pathogens spread via fecal oral contamination -> cholera, hepA, typhoid, poliomyelitis
- insect vectorborne -> yellow fever, japanese encephalitis
- transcutaneous spread through bites and cuts -> tetanus, rabies
- respiratory spread -> influenza, MMR, varicella, BCG for TB, pneumococcus, meningococcus, diphtheria, haemophillus influenzae, pertussis
- blood and bodily fluids spread -> hepB, HPV
what are examples of vaccines and their type of vaccine and corresponding trip characteristics that suggests high risk
- cholera (live attenuated) -> poor sanitation and hygiene practices, humanitarian work
- Hep A (inactivated) -> poor sanitation and hygiene practices, adventurous eating habits, men who have sex with men
- Hep B (recombinant) -> adventure travel, medical tourism, possibility of sexual contact at destination
- influenza (recombinant/ inactivated) -> mass gatherings, exposure to live poultry
- japanese encephalitis (inactivated) -> adventure travel in agricultural areas, open air accommodations, rural home stays
- MMR (live attenuated) -> antivaccine communities, mass gatherings, travel to one or more areas with current outbreaks
- meningococcal (conjugate, quadrivalent) -> mass gatherings, sub saharan africa
- poliovirus (inactivated)
- rabies (inactivated)
- Tdap (toxoid) -> activities that are injury prone, humanitarian aid
- yellow fever (live attenuated)
what are the considerations for immunisation for travelers
- review routine vaccinations
- choice of travel vaccines
- last minute travel
- giving more than 1 vaccine on same day
- minimum intervals between vaccines
- missed doses
what are the steps to take for last minute travel
advice for accelerated immunisation schedules, counselling on risk avoidance, drug prophylaxis if applicable and referrals to health services at their desitination
which mosquito breed is responsible for malaria transmission
anopheles
what bacteria species and which species is responsible for transmission of malaria
plasmodium (p. falciparum, p. malariae, p. ovale, p. vivax, p. knowlesi)
what are the clinical symptoms of malaria
fever, chills, sweat, N/V/D, headache, body ache and weakness, cough, abdominal pain, may progress to organ failure and sepsis without timely treatment
what are the modes of transmission of malaria
primarily through the bites of infected female anapheles but can also be transmitted through contaminated blood products, organ transplantation and vertical transmission from mother to fetus
what are the factors that increases risk of transmission of malaria
increase between dusk and dawn
decrease during colder season/ region
decrease in deserts
large urban areas usually free of transmission
decrease at high altitudes of at least 1500m above sea level
increase at end of or soon after rainy season
what are the three sub cycles in the plasmodium life cycle
- human liver (exo-erythrocytic cycle)
- human blood (erythrocytic cycle)
- mosquito (sporogenic cycle)
what occurs in each sub cycles in the plasmodium life cycle
- exo-erythrocytic cycle: grow and multiply in liver cell, p. vivax and p. ovale may be dormant ant take more than 4w or even up to a year
- erythrocytic cycle: grow and multiply in RBC, differentiation into sexual stages (gametocytes), clinical symptoms presented
- sporogenic cycle: mate, growth, multiply, release (ingests gametocytes)
what are the strategies for prevention of malaria
- awareness - of risk, possibility of delayed onset, main symptoms
- bite prevention - stay away from mosquitoes esp between dusk and dawn, use chemical or physical repellents
- chemoprophylaxis - adhere closely to antimalarial preventive medications when prescribed
- diagnosis - early recognition and seek treatment
- environments - avoid swamps and marshy areas esp late in evenings and at night
what are the drugs used for malaria chemoprophylaxis
- atovaquone and proguanil (malarone)
- chloroquine
- doxycycline
- mefloquine
what are the drugs that are likely to have resistance
chloroquine and mefloquine
what are the considerations when choosing antimalarial chemoprophylaxis
- travel itinerary
- traveler’s medical history (medical conditions, comorbs, medications)
- traveler’s preferences which may affect adherence
- travel departure date and duration
what are the different classifications of malaria risk and its corresponding type of prevention
- type A (very limited risk) - mosquito bite prevention only, do not need chemoprophylaxis
- type B (risk of non p. falciparum) - mosquito bite prevention with chemoprophylaxis
- type C (risk of p. falciparum) - mosquito bite prevention with chemoprophylaxis and note that chloroquinolone does not work
what is the dose, regimen, c/i, adr, ddi and special population of malarone
adult dose: 1 tablet (100mg atovaquone/ 150mg proguanil) daily with food or milky drinks (to increase absorption and decrease GI discomfort)
regimen: start 1-2d prior to departure, continue during, and for 7d after return (can reach suff conc quite fast and take for 7d after return to target parasites in liver phase)
c/i: hypersensitivity, renal impairment (<30)
adr: N/V/D, headache, stomach pain, dizziness
ddi: incompatible with rifampicin, metoclopramide, efavirenz
special population: cannot take in pregnant and breastfeeding if child <5kg
what are the reasons to take malarone
- good for last min travelers (can take 1-2d prior)
- some prefer daily meds
- good for shorter trips as only need take 7d after returning
- very well tolerated, side effects uncommon
- pediatric tablets available and may be more convenient
what are the reasons not to take malarone
- cannot be used by pregnant or breast feeding if children <5kg
- cannot be taken by severe renal impairment
- more expensive
- some dont want to take everyday
what is the dose, regimen, c/i, adr, ddi and special population for chloroquine
adult dose: 300mg base/ 500mg salt weekly in a single dose with or after meals
regimen: start 1-2w prior, continue during, continue for 4w after return
c/i: hypersensitivity, regions with chloroquine resistance, caution for exacerbate psoriasis, seizure disorders, myasthenia gravis, auditory damage, liver impairment, g6pd
adr: N/V, skin rash or itch
ddi: caution with QT prolongation strong cyp3a4 inhibitors like voriconazole and clarithromycin
special population: can be used by pregnant and breastfeeding
what are the reasons to take chloroquine
- some prefer to take weekly medication
- good choice for long trips as only once weekly
- some already taking chronically for rheumatologic conditions
- safe in all trimesters of pregnancy
what are the reasons not to take chloroquine
- some may not prefer weekly medication
- short trip, need take for 4w after return
- may exacerbate psoriasis
- cannot be for use in resistant areas
- not for last min travelers as need 1-2w prior
what is the dose, regimen, c/i, adr, ddi and special population for doxycycline
dose: 100mg daily with or without food, swallow with full glass of water and maintain upright for at least 30mins after
regimen: start 1-2d prior, continue during, continue for 4w after
c/i: not for use by children <8yr, pregnant, breastfeeding, caution in GI discomfort and photosensitivity
adr: N/V, GI discomfort, sunburn, vagina candidiasis
ddi: decrease bioavailability in presence of multivalent ions
special population: not for use in children <8yr, pregnant, breastfeeding
what are the reasons to take doxycycline
- some prefer to take medications daily
- good for last min travelers
- least expensive
- some already taking chronically for prevention of acne
- can also prevent additional infections like rickettsiae and leptospirosis
what are the reasons not to take doxycycline
- cannot be used by children <8yr, pregnant
- some do not prefer daily meds
- for short trips will not want for 4w after return
- women prone to getting vaginal yeast infections may prefer a different meds
- persons planning on considerable sun exposure
- concerned about potential upset stomach
which group of people prefer to take doxycycline
hikers, campers, wading and swimming in fresh water
what is the dose, regimen, c/i, adr, ddi and special population for mefloquine
dose: 100mg weekly in one dose after meals
regimen: start at least 1w (preferred 2-3w) before, continue during, continue 4w after
c/i: hypersensitivity, regions with resistance, patients with history of psychiatric or convulsive disorders, history of cardiac conduction abnormalities
adr: GI discomfort, dizziness, headache, fatigue, insomnia, vivid dreams, neuropsychiatric disorder
ddi: ketoconazole
special population: can be used by patients >5kg, pregnant, breastfeeding
what are the reasons to take mefloquine
- prefer once weekly
- good choice for long trips
- can be used during pregnancy
what are the reasons not to take mefloquine
- cannot be used for certain psychiatric conditions
- cannot be used in resistant areas
- cannot be used in seizure disorders
- not recc for patients with cardiac abnormalities
- not for last min travelers
- might not prefer weekly meds
- not for short trips
what are the bite prevention techniques
- avoid exposure by staying indoors, especially dusk to dawn
- wear clothing that exposes as little skin as possible
- wear light coloured clothing
- sleep under permethrin-impregnated bed net
- sleep in sealed, aircon room or screened windows with fan
- insect repellent (efficacy and duration of protection vary among products and among species, higher conc of active ingredient provide longer duration of protection regardless of active ingredient)
what are examples of insect repellents
- DEET
- picaridin
- oil of lemon eucalyptus
- IR3535
- 2-undecanone
what are examples of insect repellents
- DEET
- picaridin
- oil of lemon eucalyptus
- IR3535
- 2-undecanone
what are examples of insect repellents
- DEET
- picaridin
- oil of lemon eucalyptus
- IR3535
- 2-undecanone
at what conc and for how long does DEET give protection for
20-50% gives 6-12h
what are the precautions to take when using insect repellent
- apply only to exposed skin or clothing as directed, do not apply to skin covered by clothing
- never use on cuts, wounds and irritated skin
- do not spray directly onto face, spray on hands first then apply to face, do not apply to eyes or mouth, apply sparingly around ears
- apply just enough to cover skin or clothing
- children should not handle repellents
- wash hands after application to avoid accidental exposure to eyes or ingestion
- after returning indoors, wash repellent-treated skin with soap and water/ bathe, wash clothing before wearing again
what are other advices when treating malaria
- interventions to prevent malaria are not 100% effective but can be effective when used properly
- if symptoms occur, seek immediate medical attention
- malaria is always serious and may be deadly, travelers who become ill with fever or flu like illness either while traveling in malaria risk area or after returning home for up to 1 year should seek immediate medical attention and tell physician medical history
- if high risk should carry full course of malaria medicine with them
- exclusion from blood donation 4m after return
what is meant by surgical abx prophylaxis (SAP)
administration of abx just prior to clean and clean-contaminated surgeries to prevent post operative surgical site infections (SSI)
what are the characteristics of an optimal SAP
- effective against the pathogens most likely to contaminate the surgical site
- given in an appropriate dose and at a time that achieves highest tissue conc upon skin incision
- safe
- administered for the shortest effective period to minimise adverse effect, development of antimicrobial resistance and costs
what are the indications for SAP
- clean surgery where prosthesis or implant will be inserted or when SSI would pose catastrophic risk
- clean contaminated surgery
- contaminated surgery where abx will be used for treatment and not for SAP
what is the choice of abx for MRSA risk
vancomycin prophylaxis for known MRSA colonisation or recent MRSA infection, consider adding cefazolin
what abx should patients with penicillin allergy not receive
beta lactams
what is the timing for administration of SAP
within 30-60mins before surgical incision, antibiotic should be infused completely prior to incision
fluoroquinolones and vancomycin require longer infusion time so give 1hr prior
what are the considerations for redosing
considerations: duration of procedure exceeds two half lives of drug or if there is excessive intraoperative blood loss (>1500ml) or extensive burns
how long should duration of SAP be for
not more than 24h
what are the non SAP procedures to prevent SSI
- do not remove hair at operative site unless presence of hair will interfere with operation, do not use razors -> if removal of hair necessary, remove hair outside operating room using clippers or a depilatory agent
- control blood glucose during immediate postoperative period (<equal 180mg/dL aka 10mmol/L)
- maintain normothermia (temp >equal 35.5decG) during perioperative period
- optimise tissue oxygenation by administering supplemental oxygen during and immediately following surgical procedures involving mechanical ventilation
- use alcohol containing preoperative skin preparatory agents if no c/i exists
- use impervious plastic wound protectors for GI and biliary tract surgery
- use a checklist based on WHO checklist to ensure compliance with best practices to improve surgical patient safety
- perform surveillance for SSIs
- provide ongoing feedback of SSI rates to surgical and perioperative personnel and leadership
what are the commonly used abx for SAP with its corresponding adult dose and re-dosing interval
- cefazolin 2g every 4h
- ceftriaxone 2g every 12h
- metronidazole 500mg every 8-12h
- clindamycin 600-900mg every 4-6h
- vancomycin 15-20mg/kg every 8-12h
- gentamicin 3-5mg/kg NA
- amoxicillin-clavulanic acid 1.2g every 4h
- ciprofloxacin 400mg IV/ 500mg PO every 8-12h
- aztreonam 2g every 4h
