Antimicrobials II

Question 1

all cephalosporins are inactive against what organisms

Answer 1

MACELL
Mycoplasma
Actinobacter
Chlamydia
Enterococci
Listeria
Legionella

Question 2

explain the activity of the generations of cephalosporin

Answer 2

• going from 1st to 3rd: activity against gram pos diminishes and activity against gram neg increases
• 4th: activity against gram pos (like 1ST) and active against all gram neg bacilli
• 5th: same as 3rd gen but has activity against MRSA

Question 3

what are the first generation cephalosporin

Answer 3

Cefazolin (parenteral)

Cephalexin (oral)

Question 4

organisms that first generation cephalosporin are active against (name them)

Answer 4

cefazolin and cephalexin

PEcK
Gram pos cocci
Proteus
E. coli
Klebsiella

Question 5

major use of cefazolin

Answer 5

surgery prophylaxis (especially preventing staph aureus infections) due to its long half life

Question 6

what are the second generation cephalosporin

Answer 6

AAOO
Cefaclor
Cefamandole
Cefotetan
Cefoxitin

Question 7

what are second generation cephalosporins used for (name them)

Answer 7

cefoxitin, cefaclor, cefotetan cefamandole

sinus, ear, and resp infections caused by H. influenza, M. catarrhalis, bacterioides fragillis

Question 8

what are the third generation cephalosporins

Answer 8

Cefoperazone
Cefotaxime
Ceftazidime
Ceftriaxone
Cefixime

Question 9

what are third generation cephalosporins used for (name them)

Answer 9

cefoperazone, cefotaxime, ceftazidime, ceftriaxone, cefixime

against gram neg bacteria that are resistant against beta lactams and they can penetrate BBB

Question 10

ceftriaxone is drug of choice for what condition

Answer 10

PALM

Penicillin resistant gonorrhea
Ampicillin resistant H. influenza meningitis
Lyme disease
prophylaxis for Meningitis in exposed individuals like pregnant women

Question 11

drugs in third generation cephalosporin are usually reserved for what conditions (name them)

Answer 11

cefoperazone, cefotaxime, ceftazidime, ceftriaxone, cefixime

reserved for serious infections with exception to gonorrhea and acute otitis media

Question 12

Cefotetan, Cefoperazone, Cefomandole all contain what as part of their molecular structure and the importance

Answer 12

N-methylthiotetrazole side chain which competitively inhibits Vitamin K action increasing PT –> increased bleeding

side chain also has disulfiram like reaction to alcohol

Question 13

what is the fourth generation cephalosporin and is it used for

Answer 13

Cefepime

more resistant to beta lactamases produced by gram negative

activity against both gram pos (like 1st gen) and against gram neg

Question 14

what is the fifth generation cephalosporin and mechanism

Answer 14

Ceftaroline

bind to penicillin binding protein 2a (PBP-2a) produced by MRSA

Question 15

which cephalosporin are available for oral use

Answer 15

Cephalexin
Cefaclor
Cefixime

Question 16

which cephalosporin causes the BBB easily hence probably suitable for treatment of meningitis

Answer 16

Ceftriaxone

Question 17

adverse effects of cephalosporins

Answer 17

DDT HAPeNS
Diarrhea
Disulfarim like reactions because of NMTT
Thrombophlebitis

Hypoprothrombinemia because of NMTT
Allergy (hypersensitivity)
Pain
Nephrotoxicity and Neurotoxicity (ceftriaxone cross BBB and causes kernicterus in fetus)
Superinfections - secondary infections

Question 18

what are the carbapenems

Answer 18

Imipenem
Meropenem

low susceptibility to beta lactamases

Question 19

carbapenems are drug of choice for what (name them)

Answer 19

imipenem and meropenem

enterobacter infections and extended spectrum beta lactamase producing gram negatives

Question 20

what drug must imipenem be given with and why

Answer 20

imipenem must be given with Cilastatin, a dihydropeptidase inhibitor (with imipenem, the kill is LASTIN’ with ciLASTIN)

imipenem is rapidly inactivated by renal dihydropeptidase I to form a nephrotoxic metabolite so it is given with cilastatin, a dihydropeptidase inhibitor, which increases half life of imipenem and inhibits formation of the nephrotoxic metabolite

Question 21

adverse effects of carbapenems (name them)

Answer 21

imipenem and meropenem

GI distress (nausea, vomiting, diarrhea)
CNS toxicity (seizures)

Question 22

what is the monobactam

Answer 22

Aztreonam

Question 23

monobactam has activity against what microorganisms (name it)

Answer 23

Aztreonam

activity against aerobic gram neg rods (including those with beta lactamases) includes Pseudomonas

no activity against gram pos or anaerobes

Question 24

adverse effect of monobactam (name it)

Answer 24

aztreonam

rashes and elevated aminotransferases
thromophlebitis and pain at injection site

if inhaled, cough