3. Hospital acquired infections

Question 1

What is the definition of a hospital acquired infection (HAIs)

Answer 1

An infection that patients get while receiving treatment for medical or surgical conditions

Question 2

Why might HAIs become more of a problem in outpatient settings?

Answer 2

Often have limited capacity for infection control as compared to acute care setting

Question 3

What are the 4 main risk factors of HAI?

Answer 3

Medical procedures and antibiotic uses

Organisational factors

Patient characteristics

Behaviour of healthcare staff

Question 4

List some ways in which HAIs can be prevented

Answer 4

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

Question 5

What was the first antibiotic?

Answer 5

penicillin

Question 6

What is a bacterial cell wall made of?

Answer 6

Lipid Bilayer membrane

Peptidoglycan (murein) matrix

Question 7

What are the differences in cell walls between gram negative and gram positive bacteria?

Answer 7

Gram positive - Build thick peptidoglycan sheath around a single membrane

Gram negative - Build thin layer of peptidoglycan between two lipopolysaccharide membranes

Question 8

What colour is Gram negative and Gram positive bacteria respectively?

Answer 8

Red/pink

Purple

Question 9

If someone has an infection, what are their WBC count, CRP level and respiratory rate?

Answer 9

WBC count - High

CRP level - High

Respiratory rate - High

Question 10

What are the components of a single molecule of peptidoglycan?

Answer 10

2 Sugars

Short chain of amino acids

Peptide bridge

Question 11

How is the peptidoglycan matrix formed?

Answer 11

Peptidoglycan molecules bind to one another forming chains

These chains are crosslinked by the peptide bridges

Question 12

How does Penicillin obstruct bacteria?

Answer 12

Peptidoglycan production prevented by penicillin so cell bursts due to osmotic pressue

Question 13

What is D-alanyl-D-alanine carboxypeptidase transpeptidase also known as and what is its function?

Answer 13

Penicillin Binding Protein

Assists with peptidoglycan matrix assembling by creating crosslinks between chains

Question 14

Describe the mechanism by which Penicillin prevents peptidoglycan production?

Answer 14

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

Question 15

How does altered target site antibiotic resistance work?

Answer 15

Acquisition of alternative gene or a gene that encodes a target-modifying enzyme

Alters structural conformation of protein that antibiotic targets

Question 16

How does MRSA (strain of S. aureus) evade beta-lactam-containing antibiotics?

Answer 16

Expresses Penicillin-Binding Protein 2a with an altered active site that does not bind to the beta-lactam ring in these antibiotics

Question 17

Explain how antibiotics can be inactivated?

Answer 17

Enzyme degradation or alteration rendering antibiotic ineffective

Inactivation can also be enzyme independent

Question 18

How else can bacteria evade beta-lactam-containing antibiotics?

Answer 18

They can express a beta-lactamase enzyme which breaks beta-lactam of antibiotic, rendering the antibiotic useless

Question 19

What is the name of a gene that is crucial in producing this beta-lactamase enzyme and what does the enzyme do?

Answer 19

NSM-1 → Production of New-Delhi metallo-beta-lactamase enzyme

This enzyme type can break down almost all known beta-lactamase drugs

Question 20

What is a Beta-lactamase inhibitor?

Answer 20

Medication used to inhibit the activity of Beta-lactamases, allowing Beta-lactam antibiotics to work properly

Question 21

Giving an example, how can antibiotics overcome bacteria that produce beta-lactamase?

Answer 21

Ampicillin & Clavulanic acid - Have beta-lactamase inhibitors, allowing antibiotic to inhibit Penicillin-Binding Protein freely

Question 22

What is Co-amoxiclav?

Answer 22

Antibiotic consisting of both amoxicillin and clavulanic acid

Question 23

What is meant by horizontal gene transfer?

Answer 23

Process in which organism transfers genetic material (plasmids) to another organism that isn’t offspring

Question 24

What is meant by vertical gene transfer?

Answer 24

Transfer of genetic information including any genetic mutations from a parent to its offspring

Question 25

• How can antibiotic resistance within one population of bacteria spread to another population?

Answer 25

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