L04 - General Principles of Treatment & Selection of Antimicrobial Regimens in Medical Practice Flashcards
Define the basic principles of antibiotic therapy
Administer antibiotics at a level high enough to inhibit/kill infecting organisms
Continue treatment until the host can complete curing/healing process
Drain infections of closed spaces
Know expected response
Be prepared to re-evaluate
In what two situations are antibiotics indicated?
Prophylaxis
Treatment
Define Prophylaxis
Use of antibiotics to prevent infection of a previously uninfected site (can be primary/secondary)
Define Treatment
Use of antibiotics to eliminate infection from an already infected site (req. clinical/microbiological diagnosis
Describe Microbiological Diagnosis
Organism defined AND antibiotic susceptibility predictable/lab confirmed
Describe Clinical Diagnosis
Empirical identification of organism (Best Guess)
What five factors should be considered regarding drug safety?
Known hypersenstivity/intolerance Impaired excretion Drug interactions Higher risk of toxicity Risk of antibiotic-associated diarrhoea
Define Bactericidal
An agent that kills bacteria
Define Bacteristatic
An agent that prevents growth of bacteria
In what situations are Bactericidal agents preferred?
Immunocompromised
Immunodeficient
Difficult sites
What possible steps should be taken 48h after starting treatment? (w/ cultures/clinical review)
If no evidence of infection STOP Switch from i.v. to oral Change antibiotics (narrow) Continue and review at 72h Start outpatient parenteral antibiotic therapy
Give six reasons to switch from i.v. to oral antibiotics
Reductions in hospital acquired bacteraemias Saves medical/nursing time Reduces discomfort/increases mobility Reduced cost Greater time control Reduced risk of ADR
Define COMS
The criteria for safe i.v. to oral switch:
Clinical improvement observed
Oral route not compromised
Markers normalising
Specific indication/deep seated infection
In what time scale to most infections respond?
5-7 (10) days depending on severity
Give three reasons for longer treatment lengths
Specific indicatoin
Deep seated infections
High risk infections
Define OPAT
Outpatient Paraenteral Antimicrobial Therapy
i.v. therapy at home (carries risks)
What three things make treating newborns difficult?
Increased risk of infection
Rapidly changing physiology
ADME subject to change
What affects drug absorption in newborns?
pH
Gut motility
Transit time
What affects drug distribution in newborns?
High ECF volume gives lower drug plasma concentrations
What affects drug metabolism in newborns?
Immature hepatic enzymes
Low G6PD concentrations
What affects drug excretion in newborns?
Renal immaturity
Leads to prolonged T1/2/raised Cmax
What are the five main infection risks in pregnancy?
URTI LRTI UTI Intrauterine infection Amnionitis
What five antibiotics are avoided in pregnancy and why?
Sulphonamides (Kernicterus)
Streptomycin (Ototoxicity)
Tetracyclines (Interfere w/ bone growth AND tooth discolouration)
Nitrofurantoin/Sulfonamides (Haemolysis)
Chloramphenicol (Cardiovascular collapse)
What antibiotic is contraindicated in breast feeding?
Metronidazole (1:1 serum:breast milk)
What five things make prescribing difficult in the elderly?
Organ/physiological function declining Often suffering from multiple diseases Often on multiple long-term medications Compliance compromised ADME compromised Need for written instructions
What affects drug absorption in the elderly?
pH alteration (by drug/disease) GI surgery
What affects drug distribution in the elderly?
Reduction in total body water (reduced Vd)
What affects drug metabolism in the elderly?
Hepatic involution
What affects drug excretion in the elderly?
Reduced GFR w/ age
Impaired renal blood flow
Give four examples of antibiotics unchanged in the elderly
Ciprofloxacin
Ceftriaoxone
Isoniazid
Rifampicin
Give four examples of antibiotics reduced in the elderly
Penicillins
Cephalosporins
Aminoglycosides
Vancomycin
What are the principles of prescribing in community medicine?
Empirical approach to treatment (syndrome based)
Minimising emergence of bacterial resistance
Safe, effective & economic use of antibiotics
