L07 - Chemoprophylaxis Flashcards
Define Chemoprophylaxis - Give an example
The use of an antimicrobial drug to prevent an infection - Use of antimalarials to prevent malaria in travellers
What six factors should be present when considering prophylaxis?
Significant and predictable risk of infection Serious consequences of infection Period of higher risk is known Microbial causes are predictable Antimicrobial sensitivity is predictable Cheap and safe antimicrobials available
Give five examples of potential disadvantages of chemoprophylaxis
Cost ADRs Disturbance of the normal human flora Colonisation with antibiotic-resistant bacteria Selection of antibiotic resistance
What strain of Malaria is potentially fatal?
Falciparum malaria
What groups are particularly at risk of Malaria?
Pregnant women
Splenectomy patients
Describe the three most common regimens for Malaria chemoprophylaxis
Chlorouqine +/- Proguanil
Mefloquine
Doxycycline + Atovaquone (Malarone = Proguanil + Ataovaquone)
How long must malaria prophylaxis be maintained?
Continued for 4 weeks after leaving malarious area (1 wk for Malarone)
What antibiotics are given as chemoprophylaxis for invasive Group A Strep infections?
Oral penicillin (Erthyromycin or Azithromycin)
How many cases of group A strep are required in a household for chemoprophylaxis?
2 or more cases in 30 days
Describe Group B Strep infections
Part of normal vaginal flora
Can cause neonatal meningitis/septicaemia
Particular risk for pre-term, low birth weight infants
Describe chemoprophylaxis for Group B strep
Penicillin/Clindamycin given during labour to high risk pregnancies:
Pre-term labour
Prolonged membrane rupture
History of group B strep in prev pregnancy
Known carrier of group B strep
What is Rheumatic fever?
The immunological response to infection with Streptococcus pyogenes
Describe the chemoprophylaxis for Rheumatic fever
Penicillin prophylaxis (Sulfadiazine) 250mg bd until >16 y/o
What is the most common cause of meningitis?
Viral infection
What is the major bacterial cause of meningitis/meningococcal disease?
Meningococcal meningitis (Septicaemia) Invasive infection by Neisseria meningitidis
Describe the vaccination program for meningitis
Conjugated vaccine vs. serogroup C (infants)
Men B (infants)
ACWY (14-18 y/o and travel)
What is the chemoprophylaxis regimen for bacterial meningitis/meningococcal disease?
Chemoprophylaxis for close contacts (+/- immunisation)
Rifampicin 600mg p.o. b.d. for 2 days (ADR w/ pill and contact lenses)
Ciprofloxacin 500mg p.o. stat
Ceftriaxone IM for pregnancy
What is Hib meningitis?
Haemophilus influenzae capsular type B
Cause of meningitis <4
What is the relevant chemoprophylaxis for Hib?
Rifampicin 600mg p.o. o.d. for 4 days (for all household contacts)
What three groups are at risk of recurrent UTIs?
Children <5
Pregnant women
Females
What is the major risk of recurrent UTIs?
Risk of repeated kidney damage
What three antibiotics can be given as chemoprophylaxis for UTIs?
Trimethoprim
Nitrofurantoin
Cephalexin
What is the most common problem with splenectomised patients?
Severe overwhelming infections
Capsulated bacteria (strep. p, meningococci, hib)
Malaria
What chemoprophylaxis is appropriate for splenectomy patients?
Penicillin (to prevent pneumococcal infections)
Give six examples of immunosuppression
Primary IDS HIV Malignancy of immune system Cancer chemotherapy Drugs (steroids, azathoprine, cyclophosphamide) Organ transplants
What drug can be given as chemoprophylaxis after HIV infection?
Co-trimoxazole (to prevent PCP following 1st infection or when CD4 <200)
What is the chemoprophylaxis for neutropenia?
Ciprofloxacin (to prevent Gram-ve infections)
What is the chemoprophylaxis for Bone Marrow Transplant?
Ciprofloxacin + Aciclovir + Fluconazole
What three actions are appropriate following trauma/bites?
Surgical debridement (+/- delayed closure) Antibiotic prophylaxis (co-amoxiclav, metronidazole, doxycycline) Tetanus booster (+/- tetatnus Ig)
Is antibiotic prophylaxis appropriate for endocarditis?
No (generally)
In what four ways can surgical operations be described?
Clean
Clean w/ implant (req. prophylaxis)
Contaminated (req. prophylaxis)
Dirty (req. treatment)
Describe the five most common UK surgical chemoprophylaxis regimens
Appendectomy (Metronidazole)
Elective colorectal surgery (Coamoxiclav/Cefuroxime+Metronidazole/Genatmicin+Metronidazole)
Breast implant (Coamoxiclav)
Cardiac surgery (Cefuroxime/Glycopeptide)
Orthopaedic implants (Cefradine+Cefuroxime)
What are the three most common faults with surgical antibiotic prophylaxis?
Used for clean operations
Given for too long (max 24h)
Given w/o regard for prev. treatment
Describe the chemoprophylaxis regimen for Influenza A
Ideally <48 hours of exposure
Oseltamivir/Zanamivir
Who are the at risk groups for Influenza A?
>65 y/o Pregnant women Chronic resp/cardiac/renal/liver/neurological disease Immunosuppresive disease Diabetes
When should post-exposure prophylaxis for HIV be considered?
Penetrating needlestick injuries
Blood splashes to mucous membranes/non-intact skin
Sexual contact (rape)
When source is known/suspected to be HIV+ve
Describe Post Exposure Prophylaxis for HIV
Ideally given <1h (offered up to 2 wks after exposure)
Combination of anti-retrovirals (AZT/DDI + Protease Inhibitors)
Taken for 4 wks
