Antimicrobial Resistance

• How do cells acquire resistance?

  Transfer of resistance genes

  Mutation

  Selection due to antibiotics pressure

  Growth conditions - biofilms
• What is intrinsic resistance?

  Inherent resistance of a microorganism to a particular antimicrobial agent.

  The microorganism has never been susceptible to the drug.
• What has led to antimicrobial resistance?

  Increased use of antibiotics

  Prescriptions taken incorrectly

  Sold without medical supervision

  Prophylatic use before surgery

  Antibiotics used for viral infection

  Spread of resistat microbes in hospitals due to lack of hygiene

  Patients who do not complete course

  Antibiotics in animal feeds
• How can we manage antimicrobial resistance?

  Infection prevention & control

  Antimicrobials usage - aim for reduction, to reduce the risk of resistance
• What is antimicrobial stewardship?

  A set of coordinated strategies to improve the use of antimicrobial medications with the goal of enhancing patient health outcomes, reducing antimicrobial resistance, and decreasing unnecessary costs
• What is the function of a leader peptide?

  Terminate transcripts before the RNA polymerase reaches the first structural gene of the operon
• What are the 3 types of horizontal gene transfer>?

  Conjugation

  Transduction

  Transformation
• How does antibiotic resistance via conjugation occur?

  Genetic material is transferred via pili in the form of a plasmid

  Recipient bacteria use resistance genes to survive antibiotics
• How does antibiotic resistance via transduction occur?

  Virus that infects bacteria carries genetic material between bacteria & transfers resistance genes alongside its own viral DNA
• How does antibiotic resistance via transformation occur?

  Takes up free DNA from its own environment & incorporates resistance genes into its own DNA
• What are the different types of beta-lactamases?

  Narrow spectrum

  Extended spectrum

  Serine-carbapenemase

  Metallo beta-lactamses

  Cephalosporinases

  OXA-type enzymes
• In the absence of antibiotics, microorganisms can 'turn off' their resistance - due to resistant bacteria being often slower growing

  E.g. ermC in macrolide resistance

  
• What is the problem Carbapenem-resistant Acinetobacter baumannii?

  Gram negative rod

  Becoming a problem for immunocompromised neutropenic pts & those ventilate for extended periods

  Increasing numbers of isolates are found to be drug resistant

  Mortality rate up to 70%
• What is MRSA?

  Methicillin resistant staphylococcus aureus
• What is the problem with MRSA?

  Gram positive coccus (often seen in clusters)

  Leading causes of hospital-acquired infections

  Commonly associated with significant:

  • morbidity
  • mortality
  • length of stay
  • cost burden

  MRSA is resistant to all beta-lactams