Micro 13 - Cephalosporins

Question 1

What happens as we increase in generation of cephalosporin?

Answer 1

There is an increase in G(-) coverage but decrease G(+) slightly as well.

Question 2

What are the two big 1st generation cephalosporins and what do they cover?

Answer 2

Cefazolin and Cephalexin. They cover G(+) cocci but some G(-) as well.[PEcK] Proteus mirabilis, E.coli, Klebsiella.

Question 3

What are the clinical uses of 1st generation of cephalosporins?

Answer 3

UTIs, URIs (sometimes), can be used for prophylaxis for viridans strep endocarditis (before dental procedures in patients with mechanical valves But amoxicillin is used first line).

Question 4

What are the four big 2nd generation cephalosporins and what do they cover?

Answer 4

Cefoxitin, Cefaclor, Cefuroxime, Cefprozil. [HENS PEcK]: Haemophilus influenzae, Enterobacter, Neisseria, Serratia marcescens, Proteus mirabilis, E.coli, Klebsiella. Although Neisseria is on the list, we don’t use it for gonorrhea anymore due to increased resistance.

Question 5

What are the four big 3rd generation cephalosporins and what do they cover?

Answer 5

Ceftriaxone, Cefotaxime, Ceftazidime, Cefdinir. For serious G(-) infection. [HENS PEcKS]: Haemophilus influenzae, Enterobacter, Neisseria, Serratia, Proteus mirabilis, E.coli, Klebsiella, Streptococcus pneumoniae.

Question 6

Which of the 3rd generation cephalosporins has the longest half life and how is it given?

Answer 6

Ceftriaxone. Given IV or IM once or twice daily. Treatment of choice for Neisseria gonorrhoeae.

Question 7

How is Ceftriazone excreted? How do we use this to our advantage?

Answer 7

Excreted in bile, so it is great for patients that have renal failure.

Question 8

What is a good 3rd generation cephalosporin that covers Pseudomonas infection?

Answer 8

Ceftazidime.

Question 9

What is Cefdinir used for?

Answer 9

Resistant cases of otitis media.

Question 10

What is the one big 4th generation cephalosporin and what is it used for?

Answer 10

Cefepime. It is a broad spectrum (breaks the rule of decreasing G(+) coverage) and is very good against pseudomonas.

Question 11

Lewis Note: what generation does each cephalosporin belong to? Ceftazidime, cefepime, cephalexin, Cefuroxime, Cefotaxime, Cefaclor, Cefazolin, Cefdinir, Cefoxitin, Ceftriaxone.

Answer 11

1st: Cephalexin, Cefazolin. 2nd: Cefuroxime, Cefaclor, Cefprozil, Cefoxitin. 3rd: Ceftazidime, Cefotaxime, Cefdinir, Ceftriazone. 4th: Cefepime.

Question 12

What are the bacterias that cephalosporins are NOT very good at covering?

Question 13

To which other class of antibiotics can cephalosporins have a cross-reactivity to?

Answer 13

There is 5-10% cross-reactivity with penicillins.

Question 14

To which other class of antibiotics can cephalosporins have an increase nephrotoxicity?

Answer 14

Only if used with aminoglycosides (gentamicin).

Question 15

Which generation of cephalosporin would you use for UTI prevention?

Answer 15

1st or 2nd generation.

Question 16

Which generation of cephalosporin would you use for Serratia UTI?

Answer 16

2nd Generation.

Question 17

Which generation of cephalosporin would you use for N.meningitidis?

Answer 17

3rd generation.

Question 18

Which generation of cephalosporin would you use for Pseudomonas?

Answer 18

3rd (Ceftazidine) or 4th generation (cefepime).

Question 19

Which generation of cephalosporin would you use for Otitis media due to nontypable H.influenzae?

Answer 19

2nd generation.

Question 20

What side effect would you be concerned about if a patient is receiving both ceftriazone and gentamicin?

Answer 20

Nephrotoxicity.

Question 21

What 1st generation drug is used for surgical prophylaxis, especially in orthopedic surgeries?

Answer 21

Cefazolin.

Question 22

What is the mechanism of action of cephalosporins?

Answer 22

They are bacteriocidal beta-lactams that inhibit cell wall synthesis. Unlike penicillins, they are less susceptible to penicillinases.