Antimicrobials

Question 1

What is the structure of beta lactam?

Answer 1

beta-lactam ring
looks like a house with a garage

Question 2

What is a common antibiotic used that has the beta-lactam structure?

Answer 2

phenoxymethyl penicillin (pen v)

Question 3

What are families of antimicrobials that have a beta-lactam ring?

Answer 3

penicilins
cephaloporins
carbapenems
monobactams

Question 4

What are types of penicillins and what are examples of each?

Answer 4

natural - pen V

aminopenicilin - amoxicilin

penicilinase resistant - flucloxacilin (meticilin)

extended spectrum - piperacilin

Question 5

How do the beta-lactams work?

Answer 5

by interfering with penicilin binding proteins (PBP) on bacteria which are responsible for cross-linked structure of peptidoglycan cell wall

Question 6

What did bacteria evolve to develop against beta-lactams?

Answer 6

enzymes called beta-lactamases

very common in gram negative bacteria (provotella and fusobacterium)

Question 7

What is a example of beta-lactamase inhibitor and how does is work?

Answer 7

block active site of bacteria beta-lactmase

clavulanic acid

Question 8

How do bacteria overcome beta-lactmase inhibitors?

Answer 8

produce lots and lots of beta-lactmase to overwhelm the inhibiors

Question 9

What is an esbl infection and how did it arise?

Answer 9

extended spectrum beta lactamase infection

from extended spectrum antibiotics that created a resistant extended spectrum beta lactamase

Question 10

How is a ESBL infection treated?

Answer 10

carbapenems

Question 11

What is the new class of beta-lactam antibiotics?

Answer 11

carbapenems

Question 12

What bacteria developed after carbapenems?

Answer 12

carbapenmase producing bacteria

Question 13

What is an example of a bacteria that produces carbapenemase?

Answer 13

carbapenemase producing enterobactericeae ( CPE)

rectal swab for screening

Question 14

What types of infection do CPE/CRE cause?

Answer 14

Pneumonia
UTI
Wound infections
Bacteraemia

Question 15

Why are CPE’s important to control?

Answer 15

1. They can be efficiently transmitted in healthcare facilities
2. Plasmids can transfer Resistance to other strains and species
3. Often the last resort for treating multidrug-resistant (MDR) infections.

Question 16

What do macrolides (erythromycin, clarithromycin) and lincosamides (clindmycin) inhibit?

Answer 16

inhibit 50S subunit of protein synthesis

Question 17

What do tetracyclines inhibit?

Answer 17

inhibit 30S sub unit of protein sythesis

Question 18

Wha does metronidazole inhibit and create?

Answer 18

inhibit nucleic acid synthesis or function

creates free radicals

Question 19

What kind of bacteria does metronidazole kill?

what are examples?

Answer 19

strict anaerobes
(anerobic streptococci, prevotella)

Question 20

What enzyme does metronidazole use?

Answer 20

pyruvate ferredoxin oxido reductase (PFOR)

Question 21

What type of ring is the chemical structure of metronidazole?

Answer 21

imidazole with nitro group

Question 22

What gene helps bateria bypass metronidazole and how does it work?

Answer 22

nim gene
adds two electrons and hydrogen metronidazole making it inactive

Question 23

What antibiotic is used most in dentistry?

Answer 23

metronidazole

Question 24

What did the governement change as first line antibiotic for dentoalveolar infections?

Answer 24

from amoxicillin to pen V

Question 25

What is the minimum inhibitory concentration?

Answer 25

minimum concentration of antibiotic required to inhibit the bacteria

Question 26

What is an example of an automated susceptibility testing system?

Answer 26

VITEK

Question 27

What is a breakpoint?

Answer 27

chosen concentration (mg/L) of an antibiotic which defines whether a species of bacteria is susceptible or resistant to the antibiotic

Question 28

What is clinical resistance?

Answer 28

when infection is highly unlikely to respond even to max does of antibiotic

Question 29

What are the areas of confounding variables found in clinical that affect resistance?

Answer 29

co-morbidities
pus collections
foreign bodies
biofilm
site of infection

Question 30

What is S in EUCAST defined as?

Answer 30

susceptible standard dosing regime
when there is a high likelihood of therapeutic success using a standard dosing regimen of the agent

Question 31

What is I in EUCAST defined as?

Answer 31

susceptible increased exposure
when there is a high likelihood of therapeutic success because exposure to the agent is increased by adjusting the dosing regimen or by it’s concentration at the site of infection

Question 32

What is R in EUCAST defined as?

Answer 32

high likelihood of therapeutic failure even when there is increased exposure (not just numbers, pus mode of administration etc)

Question 33

What are pharmacokinetics?

Answer 33

the absorption, distribution and elimination of drug
affected by physiological factors (site of injection)
drug factors (protein binding)

Question 34

What are pharmacodynamics?

Answer 34

relationship between concentration of drug and the antimicrobial efffect

Question 35

What is the killing effect of beta lactams dependent on?

Answer 35

time above the minimum inhibitory concentration (MIC)

Question 36

Which is better, Pen V or amoxicillin and why?

Answer 36

amoxicillin possesses the same spectrum as Pen V (against oral strep, anaerobes, and selected gram negative cocci)

plus

more active against gram negative cocci and members of the family enterobacteriaceae

Question 37

What is angiosus streptococci sensitive to?

Answer 37

both pen v and amoxicillin

Question 38

What do antimicrobial agents do to the ecological balance?

Answer 38

disturb the balance between the host and normal microflora

Question 39

Why is amoxicillin not used anymore?

Answer 39

amoxicillin has a broader spectrum of activity than peniciliin V, it has a greater impaact on selection of resistance in the host microflora

not needed