drugs used to treat bacterial infections

Question 1

beta-lactams contain 4 classes of abx

Answer 1

o Penicillins
o Cephalosporins
o Carbapenems
o Monobactams

Question 2

MOA beta-lactams

Answer 2

• Beta-lactams inhibit the biosynthesis of the bacterial cell wall, specifically the peptidoglycan structure
  o Beta-lactams bind to these penicillin binding proteins and this inhibits cell wall synthesis and leads to cell lysis

Question 3

penicillins are active againts:

Answer 3

Active against aerobic, gram + organisms
- Streptococcus
- Some Enterococcus strains
- Non-penicillinase-producing staphylococci

Question 4

beta-lactamases

Answer 4

a large group of enzymes w/ diverse ability to inactivate beta-lactams

Question 5

clinical use for penicillins

Answer 5

• URIs (Pharyngitis, Otitis media, and Sinusitis)
• Pneumonia
• STIs
• UTIs
• Wound infections

Other important indications:
* Endocarditis prophylaxis
* Eradication of H. pylori in gastritis and PUD
* Lyme disease

Question 6

pharmacodynamics of cephalosporins

Answer 6

Inhibit mucopeptide synthesis in the bacterial cell wall, making the bacterium osmotically unstable
* Inhibit PBPs involved in cross-linking peptidoglycans in the cell wall

Question 7

clinical use of cephalosporins

Answer 7

Active against many respiratory pathogens, including:
 Those that cause acute otitis media
 Sinusitis
 Group A streptococcal pharyngitis
 Pneumonia
 Chronic bronchitis

o Active against many pathogens that cause UTIs
o Ceftriaxone IM is the recommended treatment for gonorrhea
o Staphylococcal skin infections often respond to first generation cephalosporins such as cephalexin

Question 8

older group of fluroquinolones

Answer 8

Ciprofloxacin (Cipro)
Ofloxacin (Floxin)

Question 9

newer group of fluroquinolones

Answer 9

Levofloxacin (Levaquin)
Moxifloxacin (Avelox)
Delafloxacin (Baxdela)

Question 10

what is the newer group of fluroquinolones known as:

Answer 10

the respiratory fluroquinolones

Question 11

pharmacodynamics of fluroquinolones

Answer 11

• Fluroquinolones are bactericidal through interference with enzymes required for the synthesis and repair of bacterial DNA
• The fluorine molecule added to create the fluroquinolones provides increased potency against gram – organisms and broadens the spectrum to include gram + organisms as well
• Fluoroquinolones inhibit bacterial topoisomerase II (DNA gyrase) and topoisomerase IV

Question 12

what bacteria does fluroquinolones work against?

Answer 12

notable for their extensive gram negative activity:
- E. coli
- Klebsiella
- Enterobacter
- Campylobacter
- Salmonella
- Shigella
- Proteus
- Serratia
- Haemophilus
- N. gonorrheae
- N. meningitidis
- M. catahhalis

Question 13

boxed warning for fluroquinolones

Answer 13

risk of tendon rupture and tendonitis

Question 14

clinical use of fluroquinolones

Answer 14

used to treat a variety of infections but d/t resistance, are no longer considered 1st line treatments
* resp fluroquinolones are used for CAP

Question 15

pharmacodynamics of clindamycin

Answer 15

binds to the 50S subunit of the bacterial ribosome and suppresses protein synthesis

Question 16

clindamycin susceptible organisms

Answer 16

primarily gram positive organisms, but also effective against selected anaerboic pathogens
- Strep pyogenes
- Strep viridians
- S. aureus
- Corynebacterium diphtheria
- Corynebacterium acnes
AND
- Bacteroides
- Fusobacterium
- Actinomyces
- Peptocuccus
- Prevotella
- Clostridium perfringens
- Clostridium tetani

Question 17

clinical use for clindamycin

Answer 17

• used for 1st line therapy for serious infections treated parenterally in the hospital
• 1st line tx for MRSA
  tx of infectoins for those with PCN allergies
• drug resistant pneumococcal infections
• bacterial vaginalis

Question 18

macrolides and azalides

Answer 18

compounds characterized by a macrocyclic lactone ring with deoxy sugars attached

Question 19

macrolide drugs

Answer 19

• erythromycin
• clarithromycin (Biaxin)
• azithromycin (Zithromax)

Question 20

pharmacodynamics of macrolides

Answer 20

• reversibly binds to the P site of the 50S ribosomal subunit of susceptible organisms
• may inhibit RNA-dependent protein synthesis by stimulating the dissociation of peptidyl-tRNA from ribosomes
• these drugs are typically bacteriostatic depending on drug concentrations and the bacterial species tested

Question 21

organisms susceptible to macrolides

Answer 21

active against gram + organisms and some gram negative

Question 22

clinical use of macrolides

Answer 22

• CAP
• STIs
• H. pylori infections
• Endocarditis prophylaxis in those allergic to penicillins
• Off label uses for Lyme disease

Question 23

Oxazolidinones

Answer 23

Linezolid (Zyvox) and tedizolid (Sivextro)

Question 24

pharmacodynamics for oxazolidinones

Answer 24

• Inhibit bacterial ribosomal protein synthesis, but unlike other antibiotics, they stop the first step in synthesis in which bacteria assemble ribosomes from their dissociated subunits
• Effective against aerobic gram-positive bacteria
• Linezolid retains activity against the most resistant forms of Enterococcus including VRE

Question 25

drug interactions for linezolid

Answer 25

MAOIs can lead to serotonin syndrome

Question 26

clinical use for oxazolidinones

Answer 26

MRSA PNA uncomplicated skin infections VRE infections

Question 27

uses for sulfonamides

Answer 27

- treatment for UTIs - alternative therapy options for drug-resistant - tx for specific infections in immunocompromised hosts (PNA in HIV pts)

Question 28

pharmacodynamics sulfonamides

Answer 28

Exert their bacteriostatic action by competitive inhibition of dihydrofolate synthetase, which is necessary for the conversion of para-aminobenzoic acid (PABA) to dihydrofolic acid - Inhibition of this pathway prevents folic acid synthesis Inhibit both gram positive and gram negative bacteria

Question 29

pharmacodynamics trimethoprim

Answer 29

- Inhibits bacterial dihydrofolic acid reductase - Inhibits synthesis of purines and DNA When given with a sulfonamide, it produces a sequential blocking in the metabolic sequence - Results in synergistic activity of both drugs Bactrim is the widely used combination * trimethoprim-sulfamethoxazole (TMP-SMZ)

Question 30

nitrofurantoin pharmacodynamics

Answer 30

a synthetic nitrofuran that is activated by bacteria to reactive intermediates that inactivate or alter bacterial ribosomes inhibits: - protein synthesis - aerobic energy metabolism - DNA and RNA synthesis - Cell wall synthesis

Question 31

why is nitrofurantoin's use limited to UTIs?

Answer 31

it concentrates in the urine

Question 32

fosfomycin pharmacodynamics

Answer 32

bactericidal antibiotic available only as an oral formulation for the treatment of UTIs

Question 33

clinical uses of Sulfonamides, Trimethoprim, Nitrofurantoin, and Fosfomycin

Answer 33

treat UTIs Bactrim is the only exception - tx of community acquired MRSA - used for prevention and treatment of PNA caused by Pneumocystis jirovecii in patients with HIV

Question 34

meds included in tetracycline class

Answer 34

- tetracycline - demeclocycline - doxycycline - minocycline

Question 35

pharmacodynamics of tetracyclines

Answer 35

Tetracyclines include a group of drugs with a common tetracycline nucleus structure and similar spectrum of activity - Inhibit protein synthesis by reversibly binding to the 30S subunit of the bacterial ribosome - Prevent the addition of amino acids to growing peptides - Also have anti-inflammatory properties - Have good activity against gram positive organisms - Effective against some gram negative organisms

Question 36

clinical use for tetracyclines

Answer 36

- sexually transmitted infections - acne - H. pylori Other less common infections including: - Primary drug of choice for ehrlichiosis and rickettsial infections is doxycycline - Rocky Mountain spotted fever - Typhus - Q fever - Trench fever caused by B. quintana - Minocycline is the primary drug of choice for Mycobacterium marinum (an infection associated w/ contamination by water from aquariums)

Question 37

glycopeptide drugs

Answer 37

- vancomycin - similarly structured lipoglycopeptides: dalbavancin (Dalvance) and oritavancin (Orbactiv)

Question 38

what are glycopeptides used for?

Answer 38

used for gram positive infections that are resistant to the first-line abx

Question 39

pharmacodynamics glycopeptides

Answer 39

Vanco is a tricyclic glycopeptide antibiotic that inhibits cell wall synthesis by binding firmly to the D-A1a-D-A1a terminus of nascent peptidoglycan pentapeptide Results in weakened cell wall susceptible to lysis

Question 40

glycopeptide adverse reactions

Answer 40

vancomycin infusion syndrome

Question 41

what occurs with vancomycin infusion syndrome?

Answer 41

- Includes potential severe hypotension - Flushing of the upper body - Urticaria - Pruritus - Rash

Question 42

clinical use for glycopeptides

Answer 42

PO - C. diff IV - specific dosing by serum drug concentrations

Question 43

what are the drugs that tx TB?

Answer 43

antimycobacterials

Question 44

first line TB meds

Answer 44

- isoniazid [INH] - rifampin [RIF, Rifadin, Rimactane] - ethambutol [EMB, Myambutol] - pyrazinamide [PZA]

Question 45

second line drugs used to tx TB

Answer 45

- para-aminosalicylic acid [PASA] - ethionamide [Trecator-SC] - capreomycin [Capastat] - cycloserine [Seromycin] - kanamycin [Kantrex] - levofloxacin [Levaquin] - moxifloxacin [Avelox] - streptomycin - bedaquiline [Sirturo]