micro lecture 17 Flashcards
what is the goal of antimicrobial therapy?
achieve maximum eradication of the causative organisms from the site of infection
to clinically reduce: deaths > complications > resistance > duration
what are the Principles of antibiotic prescribing
Know when to say ‘No’ Seek source control Investigate judiciously Cherish your normal flora The need to be right Right drug, right dose, right duration
concerning Catheter bacteruria how do you Treat the patient, not the result
50% urinary catheters colonised by day 10
Abx are unlikely to eradicate if catheter remains
Treatment will select out resistant organisms which will colonise the catheter
If the patient is not symptomatic, don’t send a urine and don’t treat (except pregnancy)
concerning chronic wounds how do you Treat the patient, not the result
Chronic wounds (e.g. leg ulcer)
Open wounds are like agar plates, bugs will grow!
Treat only if the patient is symptomatic
how do you find evidence of infection form clinical assessment clinically?
General signs/symptoms of infection
Peripheral / local
Systemic
Vital signs
Demographic considerations
Age, sex, occupation, pets
Pre-existing medical problems
Anatomical location – working diagnosis
Most likely pathogens will be known
Therefore can predict most suitable drug
from local pathogen knowledge
Route of administration to get it there
Topical, Oral, Injection, Inhalation
Previous results (grown something before ?) Recent antibiotics (use something else)
how do you find evidence of infection from the laboratory?
tests
Haematology
Biochemistry
Microbiology
Confirmation of pathogen – identification
Microscopy, then indicative testing
Local epidemiological knowledge of
bug-drug susceptibility patterns
Selection of antimicrobial chemotherapy
Breakpoints: likely efficacy
MIC determination – more accurate but still “one colony”
what are the three ways to find evidence of infection?
clinical assessment: e.g. physical examination
from the laboratory
imaging: e.g. x-ray
what is the full meaning of MICs?
Minimum inhibitory concentrations
what are the three uses of MICs?
MICs have three uses
comparing likely effectiveness of antibiotics
observing trends of increasing MICs over time
predicting clinical efficacy in combination with pharmacodynamics
how is MIC determined?
Quantitative techniques
Chemically defined media
Governed by regularly updated guidelines
what are the quantitative techniques used to determine MIC?
Disk diffusion
Broth and agar dilution
E-tests
Other automated methods
what are the regularly updated guidelines
used to determine MIC?
what country for each one?
BSAC (UK),
EUCAST (EU),
CLSI (USA)
who makes the guidelines used to determine MIC for the UK?
British Society for Antimicrobial Chemotherapy. (BSAC)
MIC Interpretive Criteria = ____________________
BREAKPOINTS
what are are break points used to determine?
These are intended to predict CLINICAL efficacy
