Antimicrobial Chemotherapy, Diseases, Yr 3, Wk 1 Flashcards
Principles of Prescribing: 1. Indications for antimicrobials:
Give the 2 types of therapy and describe them:
Therapy:
-Empiric: without microbiology results
-Directed: based on microbiology results
Name the 2 types of Prophylaxis and describe them:
Prophylaxis:
Primary:
-Anti-malarial; immunosuppressed patients
- pre-operative surgical
- post-exposure e.g. HIV, meningitis
Secondary:
-to prevent a second episode e.g. PJP
(An antibiotic can be used in 2 ways : therapy – to treat: empiric- clinical hunch but no microbiology to support that
Primary prophylaxis e.g. when a family member gets meningitis, the rest of the family are given antibiotics to prevent them from developing it)
PoP: What are the different types of Diagnosis of Infection:
- Clinical
- Laboratory
- None (no treatment)
(PoP = principles of prescribing)
PoP: Name some severity assessments:
? Sepsis (qSOFA: syst BP <100, altered mental, RR >22)
? Septic shock (need for vasopressors, lactate >2)
(qSOFA= quick sofa assessment)
PoP: List some patient characteristics:
- age
- renal function
- liver function
- immunocompromised
- pregnancy
- known allergies
PoP: List some things you need to consider when selecting an antimicrobial:
- Guideline or “individualised” therapy
- ? likely organism(s)
- empirical therapy or result-based therapy
- bactericidal vs. bacteriostatic drug
- single agent or combination
- potential adverse effects
What should antibiotic selection be based on?
Antibiotic selection should be based on the known (or likely) causative organism(s)
(Picture showing triangle with bacteria, disease, antibiotics(s) )
What are some causative bacteria in soft tissue infections
- Streptococcus pyogenes
- SA
- Streptococcus group C or G
- E. coli
- Pseudomonas aeruginosa
- Clostridium species
(Bottom 3 are gram negative bacteria- more common in diabetes)
What are some causative bacteria in pneumonia?
- Streptococcus pneumonia (commonest)
- Haemophilus influenzae
- Staphylococcus aureus
- Klebsiella pneumonia
- Moraxella catarrhalis
- Mycoplasma pneumonia
- Legionella pneumonia
- Chlamydia pneumonia
Bactericidal vs. Bacteriostatic:
-Discuss Cidal
(kill the bacteria = cidal)
(inhibit the proliferation of the bacteria = static)
Cidal:
- e.g. beta-lactams
- act on cell wall
- kill organisms
- indications include neutropenia, meningitis and endocarditis
(cidal- wall falls apart and kills the organism)
Discuss Static:
- e.g. macrolides
- inhibit protein synthesis
- prevent colony growth
- require host immune system to “mop up” residual infection
- useful in toxin-mediated illness
Give reasons why single therapy should be used as opposed to combination therapy?
Single:
-Simpler
- Fewer side effects
- Fewer drug interactions
Give reasons why combination therapy should be used as opposed to combination therapy?
Combination:
-HIV and TB
- severe sepsis (febrile neutropenia)
- mixed organisms (faecal peritonitis)
(one agent or combination of agents)
PoP: Give some things to consider when doing REGIMEN SELECTION:
- Route of administration
- Dose
- Adverse effects (side effects/toxicity)
- Duration
- Intravenous to oral SWITCH therapy
- Inpatient or Outpatient therapy (outpatient parenteral antimicrobial therapy (OPAT)
- Therapeutic drug monitoring
When should the oral route of drug administration be given?
- If not vomiting
- Normal GI function
- No shock
- No organ dysfunction
(Wherever possible, the drug should be given orally)
When should the IV route of drug administration be given?
- For severe or deep-seated infection
- And when oral route is not reliable
Describe oral bio-availability:
-Ratio of drug level when given orally compared with level when given IV
(Varies widely:
- Flucloxacillin 50-70%
- Linezolid 100%)
(Oral bioavailability (F%) is the fraction of an oral administered drug that reaches systemic circulation. After intravenous administration, a drug is directly and fully available in the bloodstream and can be distributed via systemic circulation to the point where a pharmacological effect takes place.)
(Adverse effects) Give 2 types of Allergic Reactions:
- Immediate Hypersensitivity: anaphylactic shock
- Delayed Hypersensitivity: rash, drug fever, serum sickness, erythema nodosum, Stevens-Johnson syndrome
Mostly with penicillins and cephalosporins
(-Anaphylactic shock`; swollen lips, swollen tongue, wheeze; uncommon
-Delayed: day 3 or 4 when using penicillin)
Give name of a type of rash you can get (picture of the back with a big pink rash) from a drug reaction:
Maculopapular drug rash
Give some GI system related adverse effects of drugs:
- nausea
- vomiting
- diarrhoea
- Clostridium difficile infection
When can Candida (thrush) occur?
when using broad spectrum penicillins, cephalosporins
When can liver adverse effects occur?
- All drugs, particularly tetracyclines, TB drugs
- More likely if pre-existing liver disease
When can renal adverse effects occur?
- When taking gentamicin, vancomycin
- More likely if pre-existing renal disease or nephrotoxic meds
(Gentamicin- aminoglycoside (gram –ve infectons treatment) and vancomycin (glyocpeptide and used for treatment of gram positive infections such as staph aureus) these 2 drugs are from different families
Nephrotoxic drugs; NSAIDS)
Give some Neurological adverse effects:
- Otoxicity- gentamicin, vancomycin
- Optic neuropathy- ethambutol (TB)
- Convulsions, Encephalopathy- penicillins, cephalosporin
- Peripheral neuropathy- isoniazid (TB), metronidazole
