Antibacterials

Question 1

What is the primary objective of antibiotic therapy?

Answer 1

Understand the principles of antibiotic therapy and how they work in the body

Question 2

Define ‘bactericidal’.

Answer 2

Drugs that are directly lethal to bacteria at clinically achievable concentrations

Question 3

Define ‘bacteriostatic’.

Answer 3

Drugs that can slow bacterial growth but do not cause cell death

Question 4

What are the two main types of prokaryotes?

Answer 4

Bacteria and Archaea

Question 5

What is necrotizing fasciitis commonly known as?

Answer 5

Flesh-eating disease

Question 6

What is the average size of prokaryotic cells compared to red blood cells?

Answer 6

1-5 μm compared to 7.5 μm for RBCs

Question 7

What is the difference between infection and colonization?

Answer 7

Infection involves invasion and multiplication of organisms; colonization does not usually harm the host

Question 8

List the shapes of bacteria.

Answer 8

• Cocci (circular) * Bacilli (rod-like) * Staphylococci (clumps) * Streptococci (chains)

Question 9

What is a Gram-positive cell wall characterized by?

Answer 9

Thick peptidoglycan layer that traps Gram stain, making cells appear purple

Question 10

What is a Gram-negative cell wall characterized by?

Answer 10

Thin peptidoglycan layer and an outer membrane, with less Gram stain being trapped

Question 11

What are ‘narrow-spectrum’ antibacterials?

Answer 11

Antibacterials that are selective against one class of bacteria

Question 12

What are ‘broad-spectrum’ antibacterials?

Answer 12

Antibacterials that are effective against both Gram-positive and Gram-negative bacteria

Question 13

What is a superinfection?

Answer 13

New microbes take over when antibacterials kill normal flora

Question 14

What are opportunistic infections?

Answer 14

Infections that occur in immunocompromised patients that would not normally harm an immunocompetent person

Question 15

True or False: The immune system plays a critical role in controlling bacterial infections.

Answer 15

True

Question 16

Name one mechanism of action for antibacterial drugs.

Answer 16

• Disruption of critical metabolic reactions * Interference with cell wall synthesis * Interference with protein synthesis * Interference with DNA replication

Question 17

What are sulfonamides known for?

Answer 17

One of the first groups of antibacterials, broad spectrum, and bacteriostatic

Question 18

What are the contraindicated conditions for sulfonamides?

Answer 18

• Known allergy * Pregnancy (1st trimester) * Infants less than 2 months of age

Question 19

What are β-lactam antibacterials used for?

Answer 19

Inhibit cell wall enzyme responsible for peptidoglycan synthesis and are bactericidal

Question 20

List the four groups of β-lactam antibacterials.

Answer 20

• Penicillins * Cephalosporins * Monobactams * Carbapenems

Question 21

What is the mechanism of action for penicillins?

Answer 21

Enter bacteria, bind to penicillin-binding proteins, disrupt cell wall synthesis, causing bacteria cells to rupture

Question 22

What are the adverse effects of penicillins?

Answer 22

• GI problems * Allergic reactions * Skin rashes * Subcutaneous edema

Question 23

What is the purpose of β-lactamase inhibitors?

Answer 23

Used in combination with penicillins to inhibit enzymes that destroy penicillins

Question 24

What are cephalosporins derived from?

Answer 24

Semisynthetic derivatives from a Cephalosporium fungus

Question 25

List the generations of cephalosporins.

Answer 25

* First Generation * Second Generation * Third Generation * Fourth Generation * Fifth Generation

Question 26

What is the primary use for carbapenems?

Answer 26

Reserved for severe, complicated body cavity and connective tissue infections

Question 27

What is the only monobactam approved in Canada?

Answer 27

Aztreonam

Question 28

What is the mechanism of action for macrolides?

Answer 28

Inhibits protein synthesis by binding to ribosomes

Question 29

List examples of macrolides.

Answer 29

* Erythromycin * Azithromycin * Clarithromycin

Question 30

What are macrolides?

Answer 30

A class of antibiotics used for respiratory, skin, and soft tissue infections ## Footnote Includes azithromycin and clarithromycin

Question 31

What infections are macrolides commonly used to treat?

Answer 31

Respiratory infections, skin infections, soft tissue infections, Strep infections, spirochetal infections, gonorrhea, chlamydia, and mycoplasma ## Footnote Also used for opportunistic infections in HIV/AIDS patients

Question 32

What are the adverse effects of macrolides?

Answer 32

GI disturbances, nausea, vomiting, diarrhea, provoke cardiac dysrhythmia (long Q-T) ## Footnote Azithromycin and clarithromycin have fewer drug-drug interactions

Question 33

What is the mechanism of action of tetracyclines?

Answer 33

Inhibit protein synthesis, bacteriostatic ## Footnote Broad-spectrum antibiotics

Question 34

List the tetracyclines.

Answer 34

* Tetracycline * Doxycycline * Minocycline * Demeclocycline

Question 35

What are the indications for tetracyclines?

Answer 35

Gram-negative and Gram-positive infections, mycoplasma, rickettsia, chlamydia, syphilis, and protozoa ## Footnote They can bind to metal ions, affecting absorption

Question 36

What should tetracyclines not be used in?

Answer 36

Children less than 8 years old, pregnancy, and breastfeeding ## Footnote Can cause discoloration of teeth and retard fetal development

Question 37

What are the adverse effects of tetracyclines?

Answer 37

GI disturbances, photosensitivity, superinfection, diarrhea, pseudomembranous colitis ## Footnote Must be timed with bacteriocidal antibiotics to avoid antagonistic effects

Question 38

What are aminoglycosides?

Answer 38

Natural and semisynthetic antibiotics produced from Streptomyces, bactericidal ## Footnote Effective against gram-negative bacteria

Question 39

List some aminoglycosides.

Answer 39

* Gentamicin * Neomycin * Streptomycin * Tobramycin * Amikacin

Question 40

What is the main use of aminoglycosides?

Answer 40

Active against gram-negative bacteria, often used in combination with other antibacterials for synergistic effect ## Footnote Poorly absorbed through the GI tract

Question 41

What are the serious toxic effects of aminoglycosides?

Answer 41

* Ototoxicity * Nephrotoxicity

Question 42

What are the indications for quinolones?

Answer 42

Urinary tract infections, lower respiratory tract infections, bone and joint infections, infectious diarrhea, skin infections, sexually transmitted diseases, anthrax ## Footnote Bactericidal and broad-spectrum

Question 43

What are common adverse effects of quinolones?

Answer 43

GI disturbances, skin rashes, headache, dizziness ## Footnote Oral absorption can be reduced by antacids and certain minerals

Question 44

What is the mechanism of action of vancomycin?

Answer 44

Inhibits cell wall synthesis, bactericidal ## Footnote Targets a different protein than B-lactams

Question 45

What is vancomycin primarily used to treat?

Answer 45

MRSA and other Gram-positive infections ## Footnote Also used orally for pseudomembranous colitis

Question 46

What are the adverse effects of vancomycin?

Answer 46

* Flushing syndrome * Ototoxicity * Nephrotoxicity * Fever and chills * Phlebitis

Question 47

True or False: Aminoglycosides can be given orally to treat systemic infections.

Answer 47

False ## Footnote They are poorly absorbed through the GI tract and are typically given parenterally

Question 48

Fill in the blank: Tetracyclines can form insoluble complexes with _______.

Answer 48

[metal ions] ## Footnote This affects their absorption