Week 4 Antimicrobial Resistance

Question 1

According to the O’Neill AMR report, what are the major causes of death and the projected numbers for AMR-deaths? (IMPT)

Answer 1

• AMR (700,000 now, 10 mil by 2050)
• Cancer
• DM
• Diarrheal disease
• RTA
• Measles
• Cholera
• Tetanus

Question 2

What are the factors affecting population health, that are not due to Abx? (IMPT)

Answer 2

• Clean water, sanitation, hygiene, vaccines
• More work, health, nutrition, wealth
• Less poverty and crowding
• More peace and absence of conflict

Question 3

How can Abx resistance spread?

Answer 3

• Remain on meat in animals -> consumed and stay in human gut
• Fertiliser or water containing animal feces used to water food crops -> consumed and stay in human gut
• Spread within community

Question 4

How does AMR come about?

Answer 4

• Antibiotics changes the normal body flora
  ~ Kills susceptible bacteria and allows resistant bacteria to take over
• Overgrowth especially of candida and C difficile

Question 5

How is AMR a threat to patient safety? (IMPT)

Answer 5

• ^ morbidity and mortality
• ^ LOS
• ^ Delays the appropriate Abx
• Eventually causes untreatable infections

Question 6

According to the CDC, what germs are considered urgent threats?

Answer 6

• Acinetobacter (Carbapenem-resistant)
• Candida auris
• C difficile
• Enterobacteriaceae (Carbapenem-resistant)
• Neisseria gonorrhea

Question 7

According to the CDC, what germs are considered serious threats?

Answer 7

• Campylobacter (Drug-resistant)
• Candida (Drug-resistant)
• Enterobacteriaceae (ESBL-producing)
• VRE
• MDR Pseudomonas aeruginosa
• Salmonella (Drug-resistant)
• Shigella (Drug-resistant)
• MRSA
  -TB (Drug-resistant)
• Strep penumoniae (Drug-resistant)

Question 8

What is campylobacter associated with?

Answer 8

• Painful, bloody diarrhea
• Raw/undercooked poultry
• Cross-contamination of food

Question 9

What kind of antibiotics are associated with ^ penicillin resistance?

Answer 9

Beta-lactam antibiotics

Question 10

What is the empirical therapy for Strep pneumoniae meningitis?

Answer 10

• Ceftriaxone + vancomycin
• Unless lab report says bacteria is susceptible to penicillin

Question 11

Strep pneumonia RTI vs meningitis Abx

Answer 11

• Penicillins and ceftriaxone more reliable for RTI
• Does not penetrate BBB well so not well used for meningitis

Question 12

Vaccine for streptococcus pneumoniae?

Answer 12

• Pneumococcal conjugate vaccine (PCV)

Question 13

According to antibiograms, what drugs are recommended for Gram positive bacteria and what are not? (IMPT)

Answer 13

Recommended:
- Rifampicin
- Vancomycin
- Cotrimoxazole

Not:
- Cloxacillin (unless MSSA bacteria)

Question 14

According to antibiograms, what drugs are recommended for Gram negative bacteria and what are not? (IMPT)

Answer 14

Recommended:
- Ertapenem
- Meropenem
- Tazobactam
- Amikacin

Not:
- Ciprofloxacin
- Cotrimoxazole
- Cefuroxime

Question 15

What are some factors affecting choices for empirical therapy?

Answer 15

• Disease
• Type of cause
• Previous therapy
• Community-associated infections (CAI)
  ~ <48 hrs of admission
  ~ Bacteria is usually more susceptible
  ~ Often include px with multiple co-morbidities
• Hospital-associated infections (HAI)
  ~ >48 hrs
  ~ Bacteria generally more resistant
• Drug interactions
• Compliance
• Availability

Question 16

What bacteria are susceptibility tests not carried out on?

Answer 16

• Legionella pneumophilia
• Chlamydia trachomatis
• Treponema pallidum

Question 17

What lab tests are done to detect Abx resistance?

Answer 17

• Antimicrobial susceptibility test (AST)
• Minimum inhibitory concentration (MIC)
• Disc diffusion/ Kirby-Bauer method
• E test

Question 18

How is MIC test done?

Answer 18

• Gold standard testing
• Serial dilution method to find out the lowest concentration with no visible growth
• Cultured overnight

Question 19

How is E test for Abx resistance carried out?

Answer 19

• Strip with antibiotic gradient is put on a seeded plate to find out MIC

Question 20

How is automated incubation for MIC done?

Answer 20

• Seeded onto small wells
• Same day results but results are approximated MIC instead

Question 21

How is disc diffusion method done?

Answer 21

• Apply discs loaded with Abx and measure zones of inhibition where bacteria does not grow

Question 22

Why may therapy fail despite “sensitive” being shown on the results? (IMPT)

Answer 22

• Presence of abscess or foreign materials
• Inadequate dose or duration
• Development of resistance
• 2nd infection
• Wrong diagnosis due to contamination or mislabeled sample

Question 23

How to mitigate AMR?

Answer 23

• Infection control and prevention
• Education
• Ward level data
• Antimicrobial stewardship

Question 24

Antimicrobial stewardship?

Answer 24

• Optimizing the use of antimicrobial agents to improve patient outcomes while minimizing the development of antimicrobial resistance and reducing the overall societal impact of antimicrobial overuse and misuse
• Control availability
• Set guidelines and carry out audits
• Educate
• Improve diagnostics
• Prevent infections (hygiene, vaccination, line care)

Question 25

What are the common mechanisms of resistance?

Answer 25

• Inactivated antibiotic
• Altered target
• Decreased permeability
• Active efflux
• Bypass of target
• Overproduction of target

Question 26

What are the major resistance mechanisms of B-lactam Abx (penicillin, cephalosporins, carbapenems)? (IMPT)

Answer 26

• B-lactamase production
  ~ Enzyme which destroys the antibiotic
• Changes in the penicillin-binding proteins
  ~ Abx do not fit as well
  ~ Cell wall synthesis continues
• Porin loss in cell membrane
  ~ Abx cannot enter the cell

Question 27

What can be taken with B-lactams to counter AMR?

Answer 27

• B-lactamase inhibitors
• eg Co-amoxiclav (amoxicillin + clavulanic acid)