Lecture 10 - chemoprophylaxis Flashcards
Define chemoprophylaxis
The use of an antimicrobial drug to prevent infection
When should chemoprophylaxis be considered?
- significant risk of infection with serious consequences
- cause of infection and Abx sensitivity predictable
- cheap and safe Abx available
Name some disadvantages of chemoprophylaxis
- Disturb normal human flora
- Side effects and drug interactions
- Can cause colonisation with more Abx resistant bacteria
- Cost
When is prophylaxis for malaria particuarly neccessary
pregnancy and patients with a splenectomy
When is group B strep infection common
during labour as part of vaginal flora. particular risk for pre-term babies or low birth weight infants
When is prophylaxis necessary for Group B strep
pre term labour, ruptured membranes, history of infection in previous pregnancies, or mother known to be carrying
When is prophylaxis for Group A invasive strep necessary
if either mother or baby develops infection in neonatal period must use prophylaxis on the other AND for all household if 2 or more cases in 30 days
What is rheumatic fever?
Immunological response to infection with strep pyogenes (Gr A Strep) - 2-3 weeks after initial saw throat you get carditis and heart valve damage, joint inflammation, rashes and chorea
Why is long periods of penicillin prophylaxis routine in rheumatic fever?
penicillin resistance has never been reports in a Group A strep
What happens if individuals are prone to repeated rheumatic fever attacks?
progressive valvular heart damage
Which meningitis strains are immunised against
Meningococcal group C is nationally immunised. Quadrivalent vaccines against ACWY are also available
Men B is also recently available but not national programme
Who receives prophylaxis after a case of meningococcal meningitis?
kissing contacts, mouth to mouth resus, same house (e.g. in halls if few cases whole halls vaccinated)
What is Hib and what can it cause?
haemophilus influenzae can cause meningitis, mainly in the under 4’s
Who is vaccinated in cases of Hib
ALL household contacts if the house contains a child under 4 who is unvaccinated
What does prophylaxis against TB achieve
eradication of the dormant disease before the active form becomes apaprent
Which cases would receive a TB vaccination
children under 16 who are found to be TB positive:
- on new immigrant screens
- school BCG programe
- contact tracing of an index case
and neonates under 2 who are in close contact with a smear positive case
adults with recent Tb seroconversion
threats of MDR TB
What is diphtheria? where is it usually found?
1) infection with corynebacterium duptheriae - causes severe saw throat, bacteria releases toxins causing complications to heart and CNS
2) eastern europe, asia, africa - risk to travellers
When is diphtheria vaccines given?
after one case - to prevent a second. given to non-immune close contacts. immunised just get booster
What is pertussis?
persistant paroxysmal cough (whooping cough) serious in young children
Who receives prophylaxis against pertussis?
close contacts of cases - immunity from vaccinations aren’t long term
Which groups are prone to recurrent UTIs?
pregnant women, children under 5, some adults (females)
Possible consequence of recurrent UTIs?
chronic pyeloneopritis
What is a risk of giving a patient prophylaxis for recurrent UTIs
patient will still get the odd breakthrough with strains showing resistance to the prophylactic. can cause more multi drug resistant UTIs but overall number of episodes will be lower so will balance out
what infections are splenectomised patients at a higher risk of?
strep pneumonia, meningococci, Hib (immunisation important)
What happens if individuals are prone to repeated rheumatic fever attacks?
progressive valvular heart damage
Which meningitis strains are immunised against
Meningococcal group C is nationally immunised. Quadrivalent vaccines against ACWY are also available
Men B is also recently available but not national programme
Who receives prophylaxis after a case of meningococcal meningitis?
kissing contacts, mouth to mouth resus, same house (e.g. in halls if few cases whole halls vaccinated)
What is Hib and what can it cause?
haemophilus influenzae can cause meningitis, mainly in the under 4’s
Who is vaccinated in cases of Hib
ALL household contacts if the house contains a child under 4 who is unvaccinated
What does vaccination against TB achieve
eradication of the dormant disease before the active form becomes apaprent
Which cases would receive a TB vaccination
children under 16 who are found to be TB positive:
- on new immigrant screens
- school BCG programe
- contact tracing of an index case
and neonates under 2 who are in close contact with a smear positive case
adults with recent Tb seroconversion
threats of MDR TB
What is diphtheria? where is it usually found?
1) infection with corynebacterium duptheriae - causes severe saw throat, bacteria releases toxins causing complications to heart and CNS
2) eastern europe, asia, africa - risk to travellers
When is diphtheria vaccines given?
after one case - to prevent a second. given to non-immune close contacts. immunised just get booster
When is post exposure prophylaxis used in HIV
needlestick injuries, blood splashes tomucous membranes and sexual contact when source is known to have HIV
Who gets immunised against pertussis?
close contacts of cases - immunity from vaccinations aren’t long term
Which groups are prone to recurrent UTIs?
pregnant women, children under 5, some adults (females)
Possible consequence of recurrent UTIs?
chronic pyeloneopritis
What is a risk of giving a patient prophylaxis for recurrent UTIs
patient will still get the odd breakthrough with strains showing resistance to the prophylactic. can cause more multi drug resistant UTIs but overall number of episodes will be lower so will balance out
what infections are splenectomised patients at a higher risk of?
- strep pneumonia, meningococci, Hib
- animal bites and malaria
Why is penicillin prophylaxis used in splenectomy patients? Why is there an issue with compliance?
When is the highest risk of infection with splenectomy?
1- to prevent pneumococcal infections.
2- as they have to take it every day for every
3- first two years following infection
Give some examples of immunosuppression?
immune deficiency, HIV, chemo. steroids, BMT or organ transplant
what are immunosuppressed patients susceptible to that health patients aren’t?
opportunistic pathogens
What prophylaxis is used for endocarditis
used to use prophylaxis following dental surgery and surgical procedures in high risk patients to prevent bacteria infecting the heart valves however currently discontinued by NICE
which patients are viewed to be high risk of endocarditis?
prosthetic heart valves, previous endocarditis or CHD
Describe these surgical operation classifications:
1) Clean
2) Clean with implant
3) Contaminated
4) Dirty
1) doesn’t enter body cavity with bugs (e.g. bowel)
2) foreign body added (PRO)
3) enters site that cant be sterilized e.g. bowel (PRO)
3) infection already present prophylaxis not used as full therapeutic treatment should be used
Give two occasions where surgery prophylaxis should be reconsidered
if patient is at risk of carrying MRSA
if patient has recently been prescribed same antibiotics (bowel flora would be altered therefore ABx not as effective)
When is prophylaxis to influenza offered?
to un-immunised when its circulating in the community. ideally within 48h of exposure
who is at high risk of influenza A
over 65, chronic disease, pregnancy
maximum time for surgery prophylaxis?
24h
