Antimicrobial chemotherapy seminar Flashcards
Empiric
without microbiology result
directed therapy
based on microbiology
Primary prophylaxis examples
PEP eg HIV
anti-malarial
pre-operative
Secondary prophylaxis example
PJP in HIV
6 important patient characteristics
age renal function liver function pregnancy allergies immunocompromised
Some things to consider when choosing an antimicrobial
guidelines or individualised therapy bacteriocidal or bacteriostatic likely organism empirical therapy or results based single agent or combo potential adverse effects
Causative bacteria of soft tissue infection
strep pyogenes staph aureus strep group C or G E.coli pseudomonas aeruginosa clostridium
Causative bacteria of pneumonia
strep pneumonia H influenza staph aureus Moraxella catarrhalis mycoplasma pneumonia legionella pneumonia klebsiella pneumonia
bactericidal - example, action and example conditions
beta lactams
act on cell wall to kill the organism
meningitis, neutropenia and endocarditis
bacteriostatic - example and action
macrolides
inhibit protein synthesis and prevent colony growth
What is required in the use of bacteriostatic antimicrobials?
require the host immune system to mop up the residual infection
Some examples of conditions using combination therapy
HIV, TB, severe sepsis, mixed organisms eg faecal peritonitis
Advantages of single therapy
cheaper
fewer side effects
fewer drug interactions
Oral bio-availability
ratio of drug level when given orally compared to when given IV
When is the oral route given?
no vomiting
normal GI function
no shock
no organ dysfunction
When is IV route given?
severe or deep seated infection and when oral route is not reliable
2 types of allergic reactions and what happens
immediate hypersensitivity - anaphylactic shock
delayed hypersensitivity - maculopapular rash, erythema nodosum
most common antibiotics causing allergic reactions
penicillins and cephalosporins
Other adverse effects of antibiotics
c.diff infection, ototoxicity, optic neuropathy, thrush, nephrotoxic meds
What antimicrobial can cause megablastic anaemia?
co-trimoxazole
Antimicrobial stewardship
making the best use of our current anti-microbials
List people in the antimicrobial management team
IPC team antibiotic pharmacist infectious diseases acute medicine GP medical microbiology
Multifactorial cause of MRSA
lack of isolation facilities bed/staff shortages standard precautions antibiotic misuse poor hygiene, cleaning and disinfection readmission of MRSA carriers from community
What are all antivirals?
virustatic
What are viruses in terms of the host and why?
intracellular parasites
utilise host enzymes to replicate
Toxicity to host cell due to antivirals example
mitochondrial
What do most antivirals target?
intracellular stages with a greater effect being on viral replication than host cell function
nucleoside analogues action
inhibit nucleic acid synthesis
Some sites of antiviral drug action
receptor binding
cell entry
release
uncoating
prophylaxis - antiviral example
prevent infection
acyclovir for Herpes
pre emptive therapy + antiviral example
evidence of infection before symptoms
ribavirin for HCV
overt viral disease treatment
acyclovir and oseltamivir
suppressive therapy + antiviral example
keep viral replication below rate which causes tissue damage in asymptomatic infection patient eg ART
do anti virals eradicate virus from latent cells? consequence of this?
no
may need suppressive therapy after overt infection treatment
HSV manifestations
mucocutaneous, oral, genital, eye, skin
encephalitis
any site in immunocompromised
Aciclovir toxicity in uninfected cells and why
low - only active in herpes infected cell
Why only treat severe or life threatening cmv?
all drugs are significantly toxic
chronic hep B treatment
pegylated interferon alpha - subcut
nucleoside analogue
chronic hep c treatment
12-48 weeks
pegylated interferon alpha and ribavirin (oral)
and protease inhibitor
influenza treatment
oseltamivir and zanamivir
RSV treatment
ribavirin
phenotypic resistance
can virus grow in presence of compound?
genotypic resistance
sequence genome and identify resistance associated mutations
What to use in HSV and CMV resistance
foscarnet
4 reasons for IV to oral switch
swallow and tolerate fluids
temp 36-38
HR <100 for 12 hours
WCC 4-12 x10 (9)
5 reasons to not do an IV to oral switch
oral route compromised continuing sepsis special indication eg meningitis febrile neutropenia shock
