Antibiotics Part 1

Question 1

What is the drug of choice for strep pharyngitis?

Answer 1

Penicillin V

Question 2

What is the drug of choice for syphilis?

Answer 2

Penicillin V

Question 3

What is the drug of choice for acute otitis media?

Answer 3

Amoxicillin

Question 4

What is the drug of choice for meningitis?

Answer 4

Ceftriaxone + Vancomycin

Question 5

What is the drug of choice for N. gonorrhea?

Answer 5

IM Ceftriaxone

Question 6

What is the drug of choice for HCA-MRSA?

Answer 6

Vancomycin

Question 7

Mechanism of Action for Vancomycin

Answer 7

Inhibits bacterial cell wall synthesis at earlier step than Beta lactams

Question 8

Spectrum of Activity for Vancomycin

Answer 8

G+ : very active against; 
Staph, 
MRSA (HCA) and MRSE- DOC for both
Strep (including all strep pneumoniae)
Enterococcus

G-: No coverage

Question 9

Vancomycin Resistant Strains

Answer 9

Vancomycin Resistant S. aureus

Vancomycin Resistant Enterococcus

Question 10

Common uses of Vancomycin

Answer 10

Serious infections caused my HCA-MRSA (DOC), MRSE, and Enterococci (good option if penicillin allergic)
Serious infections caused by S. aureus, Enterococcus, or Strep in pts tolerant of Beta lactams
Clostridium dificile colitis (po) because Vanco will stay in the GI tract
Endocarditis prophylaxis

Question 11

Adverse effects of Vancomycin

Answer 11

Nephrotoxicity
Ototoxicity
Red neck/man syndrome

Question 12

Vancomycin Monitoring

Answer 12

Obtain peak/trough levels around 4th dose

Recommended trough levels: 10-15 micrograms/ml

Question 13

Mechanism of Action for Carbapenems

Answer 13

Binds to PBPs and interferes with cell wall synthesis

Question 14

Spectrum of Activity for Carbapenems

Answer 14

G +: Staph and Strep
G -: Good activity including Pseudomonas
Anaerobes: Good activity except C. diff

Question 15

Mechanism of Bacterial Resistance fro Carbapenems (Imipenem specifically)

Answer 15

Generally stable in the prescence of most types of Beta lactamases
Pseudomonas has shown altered permeability to imipenem
Antagonism has been seen when Imipenem is used with other Beta lactams d/t increased Beta lactamase production

Question 16

Common Uses of Carbapenems

Answer 16

Serious nosocomial infections
Serious polymicrobial infections 
Nosocomial intra-abdominal infections
Pseudomonas infection
Febrile neutropenia

Question 17

Adverse Effects of Carbapenems

Answer 17

Allergy: rash, anaphylaxis (cross sensitivity with Beta lactam anaphylaxis
Seizures: (Imipenem primarily) Generally occurs in pts predisposed to seizures; DO NOT use in meningitis
GI problems

Question 18

Common uses of Ertapenem…the other Carbapenem

Answer 18

Intra-abdominal infections
Skin and skin structure infections
UTI, pylonephritis

Question 19

Spectrum of Activity for Ertapenem

Answer 19

Similar to Imipenem BUT no pseudomonas, MRSA, or Enterococcus coverage

Question 20

Mechanism of Action for Monobactams

Answer 20

Binds to PBPs and therefore inhibits cell wall formation

Question 21

Spectrum of Activity for Monobactams

Answer 21

Considered a G - specialist; good against G- anaerobes including Pseudomonas

Question 22

Common Uses for Monobactams

Answer 22

G- sepsis
UTI
G- osteomyelitis
G- pneumonia
Intra-abdominal infections
CF (inhaled)

Question 23

Adverse Effects of Monobactams

Answer 23

Rash, N/V/D, rare cross sensitivity to PCNs and cephalosporins reported

Question 24

Mechanism of action for Penicillins

Answer 24

inhibit bacterial cell wall synthesis by inhibiting the transpeptidase rxn that cross links the peptidoglycan component of the cell wall

Question 25

Penicillin classification

Answer 25

Beta-lactam abx

Question 26

Mechanism of bacterial resistance to penicillins:

Answer 26

B-lactamase enzymes, reduced affinity of PBP for the abx, and decreased entry of the drugs into bacteria through outer membrane porins – in some bacteria it is a combination of these effects.

Question 27

Describe the host factors that should be considered when selecting antibiotic therapy.

Answer 27

• drug allergies (not all allergies are the same; if patient is allergic to one drug in a class, then he/she is allergic to all the rest in the class)
• age (tetracycline is not be used for children less than 8 YOA)
• pregnancy
• renal and hepatic function (reduced function implies the need to reduce dosage to avoid toxicity)
• site of infection (a higher dose may be needed for the blood brain barrier or male prostate)
• concomitant drug therapy
• underlying disease states

Question 28

Describe the drug factors that should be considered when selecting antibiotic therapy.

Answer 28

• antimicrobial activity (bactericidal, bacteriostatic) -antimicrobial spectrum of activity (narrow, extended, broad, MIC, microbial sensitivity, antibiotic resistance [decreased permeability, drug efflux, drug inactivation, altered target])
• pharmacokinetics & pharmacodynamics (MIC, CDKR, PAE]
• tissue penetration (need adequate antibiotic concentration as site of infection)
• adverse effects
• cost
• convenience