L17 Intro to antimicrobial chemotherapy

Question 1

Chemotherapy

Answer 1

the use of drugs that are selectively toxic to pathogens but innocuous to the host

Question 2

What to treat syphilis

Answer 2

Paul Ehrlich used Salvarsan (arsphenamine)

Question 3

antibacterials drugs

Answer 3

• aminoglycosides
• tetracyclines
• amphenicols
• penicillins
• macrolides
• cephalosporins

Question 4

Antifungals drugs

Answer 4

• azoles
• echinocandins
• polyenes
• allylamines

Question 5

Penicillins

Answer 5

antibiotics that got their name from the Penicillium mold

Question 6

cephalosporins on bacterial cell membrane

Answer 6

A large group of bactericidal antimicrobials that work via their beta-lactam rings. The beta-lactam rings bind to the penicillin-binding protein and inhibit its normal activity. Unable to synthesize a cell wall, the bacteria die.

Question 7

Antibacterial drugs that inhibit cell wall synthesis

Answer 7

Penicillins and Cephalosporins

Question 8

Antibacterial drugs that inhibit protein synthesis

Answer 8

aminoglycosides
tetracyclines
amphenicols
macrolides

Question 9

aminoglycosides

Answer 9

The aminoglycosides are antimicrobial drugs used alone or in combination with β-lactam antibiotics for the treatment of certain serious aerobic gram (−) infections. Broad spectrum

Inhibit protein synthesis

Question 10

tetracyclines as an antibacterial

Answer 10

Inhibit the 30S ribosomal subunit, hindering the binding of the aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex. When this process halts, a cell can no longer maintain proper functioning and will be unable to grow or further replicate.

Inhibits protein synthesis

Question 11

amphenicols

Answer 11

Class of antibiotics with a phenylpropanoid structure.

Inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit and affecting the activity of the peptidyltransferase enzyme

Question 12

macrolides

Answer 12

Ability to bind the bacterial 50S ribosomal subunit causing the termination of bacterial protein synthesis.

Question 13

Antifungal drugs that inhibit cell wall synthesis

Answer 13

Echinocandins

Question 14

Antifungal drugs that alter cell membrane integrity or permeability

Answer 14

polyenes
allylamines
azoles

Question 15

polyenes on fungal membrane

Answer 15

antifungal by virtue of binding to ergosterol, which is a prevalent steroid in the fungal cell wall, resulting in depolarization of the membrane leading to increased K+ and Na+ permeability and ultimately cell death.

Alter fungal membrane integritiy

Question 16

allylamines

Answer 16

interfering with the enzymes involved in the manufacture of ergosterol, a crucial component of the fungal cell membrane.

alter fungal membrane integrity and permeability

Question 17

Azoles

Answer 17

Work primarily by inhibiting the cytochrome P450-dependent enzyme lanosterol 14-alpha-demethylase.Enzyme is necessary for conversion of lanosterol to ergosterol, vital component of cellular membrane of fungi.

alter fungal membrane integrity and permeability

Question 18

Mechanisms of action of anti-HIV drugs

Answer 18

entry inhibitors
* reverse transcriptase inhibitors
* integrase inhibitors
-tegravir
* protease inhibitors
-navir

Question 19

Mode of action of anti-bacterial/fungal drugs

A drug can be -cidal or -static depending on the species

Answer 19

• -cidal - lethal to organism and kills microbes
• -static - slow down microbial growth by blocking replication

Question 20

Spectrum of action of anti-bacterial/fungal drugs

Answer 20

• broad spectrum - drugs are effective against a wide range of species
• narrow spectrum - drugs are effective against specific species

Question 21

Minimum inhibitory concentration (MIC)

Answer 21

The lowest concentration of a drug required to inhibit the visible growth of a microorganism

Question 22

Minimum bactericidal / fungicidal concentration

Answer 22

The lowest concentration of a drug required to kill a microorganism

Question 23

Antimicrobial resistance - a global issue

Answer 23

In the top ten health treats
* antimicrobial misuse and overuse (human health, agriculture)
* spread of drug-resistant microbes, e.g., poor infection prevention
* economic cost, e.g., prolonged hospital stays, disability and death

Question 24

Spread of drug resistance

Answer 24

• person → person (by bacteria)
• bacterium → bacterium (by plasmids)
• plasmid → plasmid by transposons
  many strains carry multiple resistance genes

Question 25

HIV - mutations and (multi)drug resistance proteins

Answer 25

* reverse transcriptase * protease * integrase * gp41

Question 26

(AST)

Answer 26

Antimicrobial susceptibility testing

Question 27

Antimicrobial susceptibility testing

Answer 27

* phenotypic or genotypic identification of microbe(s) * susceptibility and resistance of microbe isolates towards drugs * 2 standards and interpretation: EUCAST & CLSI

Question 28

phenotypic identification I, II & III

Answer 28

1. Disk Di ffusion 2. Gradient diffusion (Indicate MIC) 3. Broth microdilution (Determine MIC)

Question 29

phenotypic identification (I) - disk diffusion

Answer 29

collect samples (e.g., body fluids) for culture→ select colonies to prepare a suspension → inoculate onto an agar plate → incubation Zone of inhibition to see how its effectiveness.

Question 30

genotypic identification method

Answer 30

PCR

Question 31

Treatment and prevention of antibacterial drugs

Answer 31

* spectrum of action - broad spectrum drugs affect both harmful and beneficial species in the GI tract ▪ reduce competition between species / increase levels of resistance genes / reduce diversity * preoperative prophylaxis - ↓ risks of surgical site infection * toxicity

Question 32

Prevention of antifungal drugs

Answer 32

* spectrum of action * route of administration, e.g., oral / topical / intravenous * toxicity

Question 33

anti-HIV drugs

Answer 33

* combination therapy - single-pill, fixed-dose (e.g., Stribild) * potential drug-drug interactions * HIV prevention - PrEP (pre-exposure prophylaxis) / PEP (post-exposure prophylaxis)

Question 34

Broad spectrum

Answer 34

drugs are effective against a wide range of species

Question 35

Narrow spectrum

Answer 35

drugs are effective against specific species

Question 36

Mechanism of drug action

Answer 36

The process by which a drug produces a biological effect

Question 37

Big zone of inhibition means

Answer 37

More effective drug that inhibits growth of bacteria

Question 38

Antifungal susceptibility testing (AFST) colour detection

Answer 38

If alive colour if dead no colour

Question 39

32 well containing strip

Answer 39

another antifungal susceptibility test