3. Hospital acquired infections Flashcards
What is the definition of a hospital acquired infection (HAIs)
An infection that patients get while receiving treatment for medical or surgical conditions
Why might HAIs become more of a problem in outpatient settings?
Often have limited capacity for infection control as compared to acute care setting
What are the 4 main risk factors of HAI?
Medical procedures and antibiotic uses
Organisational factors
Patient characteristics
Behaviour of healthcare staff
List some ways in which HAIs can be prevented
Increased compliance with and adoption of best practices of healthcare workers
Careful insertion, maintenance and prompt removal of catheters
Advance development of effective prevention tools
Explore new prevention approaches
What was the first antibiotic?
penicillin
What is a bacterial cell wall made of?
Lipid Bilayer membrane
Peptidoglycan (murein) matrix
What are the differences in cell walls between gram negative and gram positive bacteria?
Gram positive - Build thick peptidoglycan sheath around a single membrane
Gram negative - Build thin layer of peptidoglycan between two lipopolysaccharide membranes
What colour is Gram negative and Gram positive bacteria respectively?
Red/pink
Purple
If someone has an infection, what are their WBC count, CRP level and respiratory rate?
WBC count - High
CRP level - High
Respiratory rate - High
What are the components of a single molecule of peptidoglycan?
2 Sugars
Short chain of amino acids
Peptide bridge
How is the peptidoglycan matrix formed?
Peptidoglycan molecules bind to one another forming chains
These chains are crosslinked by the peptide bridges
How does Penicillin obstruct bacteria?
Peptidoglycan production prevented by penicillin so cell bursts due to osmotic pressue
What is D-alanyl-D-alanine carboxypeptidase transpeptidase also known as and what is its function?
Penicillin Binding Protein
Assists with peptidoglycan matrix assembling by creating crosslinks between chains
Describe the mechanism by which Penicillin prevents peptidoglycan production?
Penicillin’s Beta-Lactam ring binds to key serine on the Penicillin-Binding Protein’s active site
This inactivates enzyme & prevents formation of peptidoglycan matrix
How does altered target site antibiotic resistance work?
Acquisition of alternative gene or a gene that encodes a target-modifying enzyme
Alters structural conformation of protein that antibiotic targets
How does MRSA (strain of S. aureus) evade beta-lactam-containing antibiotics?
Expresses Penicillin-Binding Protein 2a with an altered active site that does not bind to the beta-lactam ring in these antibiotics
Explain how antibiotics can be inactivated?
Enzyme degradation or alteration rendering antibiotic ineffective
Inactivation can also be enzyme independent
How else can bacteria evade beta-lactam-containing antibiotics?
They can express a beta-lactamase enzyme which breaks beta-lactam of antibiotic, rendering the antibiotic useless
What is the name of a gene that is crucial in producing this beta-lactamase enzyme and what does the enzyme do?
NSM-1 → Production of New-Delhi metallo-beta-lactamase enzyme
This enzyme type can break down almost all known beta-lactamase drugs
What is a Beta-lactamase inhibitor?
Medication used to inhibit the activity of Beta-lactamases, allowing Beta-lactam antibiotics to work properly
Giving an example, how can antibiotics overcome bacteria that produce beta-lactamase?
Ampicillin & Clavulanic acid - Have beta-lactamase inhibitors, allowing antibiotic to inhibit Penicillin-Binding Protein freely
What is Co-amoxiclav?
Antibiotic consisting of both amoxicillin and clavulanic acid
What is meant by horizontal gene transfer?
Process in which organism transfers genetic material (plasmids) to another organism that isn’t offspring
What is meant by vertical gene transfer?
Transfer of genetic information including any genetic mutations from a parent to its offspring
- How can antibiotic resistance within one population of bacteria spread to another population?
Horizontal gene transfer from species with resistance to species without resistance
This involves transfer of plasmids
Vertical gene transfer of plasmids from one generation in species that previously did not have resistance, to the next generation
