Antimicrobials- Purnuske

Question 1

What factors in presentation suggest it is bacterial pharyngitis?

Answer 1

Absence of cough
Age 3-14 years
Anterior cervical lymphadenopathy
Fever
Tonsillar erythema or exudates

Question 2

Is the positive rapid antigen detection test more specific or sensitive?

Answer 2

Specific! (>95%)

Sensitivity = 80%

Question 3

What color are gram + organisms on gram stain?

Answer 3

Purple!

Question 4

What color are gram - organisms on gram stain?

Answer 4

Pink!

Question 5

Describe the difference between treatments:
Prophylactic
Pre-emptive
Empiric
Definitive

Answer 5

Prophylactic: treating when there is risk, but no testing or symptoms

Pre-emptive: actively screening, treat if bug found, still asymptomatic

Empiric: SYMPTOMS! but don’t know what organisms is

Definitive: You know what’s up

Question 6

What is empiric therapy of choice for community acquired pneumonia in a previously healthy outpatient w/ no prior antibiotic use?

Answer 6

Macrolide (50s) = azithromycin, erythromycin, clarithromycin

Doxycycline (30s)

Question 7

What is empiric therapy of choice for community-acquired pneomnia in a patient with comorbities or previous antibiotic use?

Answer 7

Fluoroquinolone or high dose B-lactam + a macrolide

Question 8

What are the respiratory fluoroquinolones? MOA?

Answer 8

Gemifloxacin
Levofloxacin
Moxifloxacin

MOA = direct inhibitor of DNA replication by binding bacterial DNA topo II and IV

Question 9

Are fluoroquinolones bactericidal or bacteriostatic?

Answer 9

Bactericidial!

Question 10

What is the main mechanism of resistance for floroquinolones?

Answer 10

Mutations in topoisomerase

Active efflux of durg

Question 11

What is the spectrum for floroquinolones?

Answer 11

Gram +
Gram -
Atypical organisms like mycoplasma

Question 12

What would you use to treat mycoplasma pneumonia?

Answer 12

Doxycycline, Azithromycin

Question 13

What is the most likely mechanism for developing a multi-drug resistant infection?

Answer 13

Selection and replication of a colonizing organism that contained a PLASMID encoding SEVERAL resistance determinate genes

Question 14

MOA of Polymyxin E

Answer 14

Binds phosphatidylethanolamine in gram negative membrane to create holes in membrane

Question 15

Major side effect of polymyxin E?

Answer 15

Nephrotoxic!

Question 16

What drugs are used to treat MRSA?

Answer 16

Vancomycin and Linezolid

Question 17

MOA of vancomycin

Answer 17

Binds to D-ala-D-ala dipeptide and inhibits TRANSglycosylation reactions to prevent cell wall synthesis

**binds precursors!

Question 18

MOA of Linezolid

Answer 18

Inhibits protein synthesis by binding to 50S subunit and preventing formation of the initiation complex

Question 19

Why do you administer tazobactam with piperacillin?

Answer 19

Tazobactam is a B-lactamase inhibitor

Question 20

Why do you administer cilastatin with imipenem?

Answer 20

It protects the kidney by inhibiting the enzyme that makes toxic metabolites

Question 21

What is the treatment for a local fungal infection?

Answer 21

Itraconazole

Voriconazole

Question 22

What is the treatment for a systemic fungal infection?

Answer 22

Amphotericin B

Question 23

MOA of Amphotericin B?

Answer 23

Binds ergesterol (unique to fungi)

Forms membrane pores that allow leakage of electrolytes

Question 24

MOA of “azoles”

Answer 24

binds fungal P450 enzyme blocking production of the membrane protein ergosterol and causing the accumulation of Ianosterol

Question 25

What fungal infection is common east of the Mississippi River and Central America and cause an inflammatory lung disease?

Answer 25

Blastomycosis

Question 26

Can blastomycosis be transmitted person-to-person?

Answer 26

Nope!

Question 27

What fungal infection is associated with bird and bat droppings in the mississippi and ohio river valleys?

Answer 27

Histoplasma capsulatum

Question 28

What fungal infection found in the southwestern united states can causes pneumonia and meningitis?

Answer 28

Coccidioidmycosis

Question 29

Where do systemic fungal mycoses disseminate to?

Answer 29

Bones
Joints
CNS

Question 30

If there is CNS involvement during a fungal infection what should you treat with?

Answer 30

Amphotericin B and follow up with itraconazole

Question 31

What are the major adverse side effects of Amphotericin B?

Answer 31

Toxic because binds to cholesterol!

Decreases renal blood flow and can cause permanent BM destruction.

80% patients have nephrotoxicity

Question 32

What fungus primarily infects the lungs and causes a hypersensitivity with brown mucus plugs?

Answer 32

Aspergillus fumigatus causes allergic bronchopulmonary aspergillosis

Can causes systemic disease in immunocompromised

Question 33

What is the main mechanisms of resistance of the azoles?

Answer 33

• Altered cytochrome P450

- Upregulation of efflux pump transporters

Question 34

MOA of B-lactams?

Answer 34

Binds to transpeptidases and block cross-linking of peptidoglycan in cell wall

Question 35

MOA of doxycycline?

Answer 35

Binds to 30S and prevents attachment of aminoacyl-tRNA

Question 36

MOA of Macrolides?

Answer 36

Azithromycin
Clarithromucin
Erythromycin

Binds to 23s rRNA of 50S inhibiting translocation

Question 37

What is the main mechanism of resistance for macrolides?

Answer 37

Methylation of the 23S rRNA binding site prevents binding of drug.

Increased efflux also

Question 38

MOA of fluoroquinolones?

Answer 38

Gemifloxacin
Levofloxacin
Moxifloxacin

*Inhibits Topo II and Topo IV

Question 39

MOA of Oseltamivir, Zanamivir, Peramivir?

Answer 39

Oral prodrug activated by hepatic esterases

inhibits influenza (A & B) neuraminidase thus decreasing release of progeny virus

Question 40

When are the neuraminidase inhibitors most active?

Answer 40

48 hours after infection