2 - Antimicrobials II

Question 1

All drugs that inhibit protein synthesis are ________

Answer 1

Bacteriostatic

Question 2

What is the MOA of Tetracyclines?

Answer 2

Suppress bacterial growth by inhibiting protein synthesis

Question 3

Why don’t tetracyclines alter mammalian protein synthesis?

Answer 3

They require an energy-dependent transport system to enter the cell, which mammalian cells (thankfully) do not have

Question 4

In what disease are tetracyclines first line drugs?

Answer 4

Rickettsial disease (Rocky mountain fever, typhus)

Chlamydia

Cholera

Mycoplasmic Pneumonia

H Pylori

Lyme Disease

Anthrax

Question 5

Two tetracyclines are used for periodontal disease:

Answer 5

Doxycycline

Minocycline

Question 6

Tetracyclines should not be administered with:

Answer 6

Tetracycline = NO 2+ cations

No milk products, calcium supplements, iron supplements, mag laxatives, antacids

Question 7

How do tetracyclines effect teeth in utero?

After birth?

Answer 7

In utero: cause staining of deciduous teeth, but not permanent teeth

4-8 years: stains permanent teeth

In other words, it only stains teeth that are actively developing

Question 8

What happens if tetracyclines are taken with metal ions?

Answer 8

They chelate in the gut and aren’t absorbed

Question 9

If a patient taking a tetracycline develops diarrhea, what should you suspect?

Answer 9

C. Diff. It’s a big cause of superinfections

Question 10

As a rule, which patients should never receive tetracyclines?

Answer 10

Pregnant and Postpartum women

causes liver damage

Question 11

What does clindamycin carry a black box warning for?

Answer 11

C. Diff

Question 12

Aminoglycosides are used primarily against:

Answer 12

gram negative bacteria

Question 13

What is the MOA of aminoglycosides?

Answer 13

Disrupt protein synthesis by binding to bacterial ribosomes

AND (more importantly) causes production of abnormal proteins

Question 14

Are aminoglycosides polar?

Answer 14

Yes! Highly polar!

They cannot readily cross membranes, so they aren’t absorbed well from the GI tract, they don’t enter the spinal fluid, and they’re rapidly excreted by the kidneys

Question 15

Most of the killing action of aminoglycosides is due to:

Answer 15

The production of abnormal proteins caused by binding to ribosomes, in addition to inhibition of protein synthesis

They lodge in the cell wall, weakening it and causing it to leak

Question 16

Complete blockade of protein synthesis causes _______

Answer 16

bacteriostasis

IT IS NOT BACTERIOCIDAL

Question 17

Aminoglycosides cannot kill:

Answer 17

Anaerobes

Transport of aminoglycosides across the cell membrane is oxygen dependent

Question 18

The principle use of aminoglycosides is:

Answer 18

treatment of serious infections due to aerobic gram-negative bacilli

Pseudomonas

E. Coli

Klebsiella

Serrata

Question 19

Which aminoglycoside is sometimes used for gram positive cocci?

Answer 19

Gentamicin, in combination with Vanc or a beta lactam ABX

Question 20

Aminoglycosides can be absorbed ______ and _____

Answer 20

topically

Parenterally

Question 21

Aminoglycosides have a black box warning for:

Answer 21

ototoxicity (IRREVERSIBLE)

Nephrotoxicity

Neuromuscular Blockade

Question 22

What kind of drugs should never be given with aminoglycosides?

Answer 22

Drugs that hurt the eyes or kidneys

Question 23

What’s more important to monitor in patients taking aminoglycosides: peak or trough?

Answer 23

A high trough is what causes nephrotoxicity and ototoxicity

Question 24

Of all the aminoglycosides, Amikacin has two outstanding features:

Answer 24

1. Has the broadest spectrum
2. Is the least vulnerable to inactivation by bacterial enzymes

Question 25

Sulfonamides are primarily used to treat:

Answer 25

UTIs

Question 26

Sulfonamides are bacterio\_\_\_\_\_

Answer 26

static

Question 27

What is the MOA of sulfonamides?

Answer 27

Inhibit folate synthesis by mimicking PABA Bacteria are unable to synthesize DNA/RNA and proteins

Question 28

Why don't sulfonamides harm mammalian cells?

Answer 28

Because they acquire folate nutritionally They don't synthesize it

Question 29

Should sulfonamides be given during pregnancy?

Answer 29

Ideally not. They cross the placenta VERY easily and can cause toxicity in newborns, including kernicterus

Question 30

There is one subset of people who absolutely cannot take sulfonamides

Answer 30

G6PD deficiency. Can cause hemolysis Most common among blacks and people of Mediterranean origin

Question 31

Why do sulfonamides cause kernicterus?

Answer 31

They bind with the same protein as bilirubin, kicking the bilirubin in to the blood stream. Since the BBB is poorly developed, it enters the brain and accumulates

Question 32

How do sulfonamides impact the kidneys?

Answer 32

Tend to crystallize in the kidneys, so have to be taken with LOTS of water to ensure dilution

Question 33

What is the mechanism of Trimethoprim?

Answer 33

Similar to Sulfonamides, just effects folate synthesis in a different part of the synthesis chain

Question 34

Patients taking trimethoprim should educated about early signs of: Why?

Answer 34

blood dyscrasias! (sore throat, fever, pallor) People with an unknown folic acid deficiency can sometimes develop megaloblastic anemia, thrombocytopenia, neutropenia Folate = Anemia

Question 35

When Trimethoprim/Sulfamethoxazole are combined, what are they used to treat?

Answer 35

Most UTIs Also otitis media, bronchitis, whooping couhg

Question 36

The common name for Trimethoprim/Sulfamethoxazole is:

Answer 36

Bactrim!

Question 37

There are two urinary tract antiseptics:

Answer 37

Nitrofurantoin Methenamine

Question 38

What is the MOA of nitrofurantoin?

Answer 38

MACROBID Prodrug that Injures bacteria by damaging DNA after undergoing enzymatic transformation It's selective because only bacterial cells have the converting enzyme

Question 39

Why is Macrobid ideal for UTIs?

Answer 39

It becomes concentrated almost entirely in the urine and is active against common UTI pathogens

Question 40

In which population of women should Nitrofurantoin and Methenamine be avoided?

Answer 40

In pregnant women They should always be treated according to a complicated UTI regimen

Question 41

What is the MOA of methenamine?

Answer 41

prodrug that breaks down into ammonia and formaldehyde in acidic environments Denatures bacterial proteins

Question 42

In order for methenamine to work, the urine must be at a pH of at most:

Answer 42

5.5 or lower

Question 43

Which drug should methenamine not be combined with?

Answer 43

Sulfonamides Sulfonamides and formaldehyde form an insoluble complex that can cause crystalluria