Ch 85: Drugs That Weaken the Bacterial Cell Wall II: Cephalosporins, Carbapenems, Vancomycin, Telavancin, Aztreonam, and Fosfomycin

Question 1

The cephalosporins are beta-lactam drugs, but there are 3 exceptions. What are they?

Answer 1

Vancomycin, telavancin, and fosfomycin

p. 1025

Question 2

What are beta-lactamases?

Answer 2

Enzymes that cleave the beta-lactam ring, rendering the drug inactive.

(p. 1025)

Question 3

Which 5th generation cephalosporin has demonstrated activity against MRSA?

Answer 3

Ceftaroline (Teflaro)

p. 1025

Question 4

What is the only 4th generation cephalosporin?

Answer 4

cefepime (Maxipime)

p. 1026

Question 5

Cefepime is highly _________ to ____-__________, has a very _____ _____________ ________, and penetration to the ___ is ____.

Answer 5

Resistant to beta-lactamases
Broad antibacterial spectrum
CSF is good

(p. 1026)

Question 6

Practically all cephalosporins are eliminated by…

One notable exception is…

Answer 6

…the kidneys.
…ceftriaxone (Rocephin).

(p. 1027)

Question 7

Which two cephalosporins can cause bleeding tendencies?

By what mechanism do they do this?

Answer 7

Cefotetan and ceftriaxone
reduction of prothrombin levels through interference with vitamin K metabolism

(p. 1027)

Question 8

What serious immune-mediated reaction can be induced by cephalosporins?

Answer 8

hemolytic anemia

p. 1027

Question 9

Just as with penicillins, probenecid delays…

Answer 9

…renal excretion of some cephalosporins, prolonging their effects.

(p. 1027)

Question 10

What combination of drugs can form a potentially fatal precipitate?

Answer 10

ceftriaxone (Rocephin) and IV calcium

p. 1027

Question 11

What are the 2 prime rules of antimicrobial therapy?

Answer 11

Match the drug with the bug, and use a drug whose spectrum is no broader than required.

(p. 1028)

Question 12

What 4 carbapenems are available?

Answer 12

imipenem, meropenem, ertapenem, and doripenem

p. 1029

Question 13

Are any of the carbapenems active against MRSA?

Answer 13

No

p. 1029

Question 14

What interaction occurs between imipenem and valproate?

Answer 14

Imipenem can reduce blood levels of valproate.

p. 1030

Question 15

In general, how would you describe the class of carbapenems?

Answer 15

Carbapenems are beta-lactam antibiotics with a very broad antimicrobial spectrum.

(p. 1029)

Question 16

Resistant organisms have emerged when P. aeruginosa is treated with imipenem alone, so it should be…

Answer 16

…combined with another antipseudomonal drug when used against this microbe.

(p. 1030)

Question 17

What kind of microbe is Pseudomonas aeruginosa?

What should you know about it?

Answer 17

It’s an aerobic gram-negative rod
Most healthy people don’t get infected by this bug bc it has weak invasive abilities. In immunocompromised patients, it is a common cause of pneumonia.

(p. 81 of Clinical Microbiology Made Ridiculously Simple)

Question 18

What mnemonic should you remember for Pseudomonas aeruginosa?

Answer 18

C BE PSEUDO
(corneal infections, burns, endocarditis, pneumonia, sepsis, external malignant otitis media, UTI, diabetic osteomyelitis)

(p. 82 of Clinical Microbiology Made Ridiculously Simple)

Question 19

What kind of microbe is Clostridium difficile?

Answer 19

gram-positive, spore-forming, anaerobic bacillus

p. 1031

Question 20

What is virulence?

Answer 20

the ability of an organism to cause disease

Question 21

What is NAP1/BI/027?

Answer 21

A particularly virulent strain of C. diff.

p. 1031

Question 22

Intensive use of ________________, such as ____________ [_____] and ____________ [________], is believed responsible for the rapid spread of the NAP1/BI/027 strain.

Answer 22

fluoroquinolones,
Ciprofloxacin [Cipro] and levofloxacin [Levaquin]

(p. 1031)

Question 23

Vancomycin is active only against…

Answer 23

…gram-positive bacteria.

p. 1031

Question 24

What is the cause of red man syndrome associated with rapid infusion of vancomycin and what are possible symptoms?

Answer 24

They result from histamine release.
Flushing, rash, pruritus, urticaria, tachycardia, and hypotension.

(p. 1033)