anti-bacterials

Question 1

what are two cefalosporins that have coverage against pseudomonas?

Answer 1

cetazidime (3rd gen)

cefepime (4th gen)

Question 2

what gram negatives are covered by ceftriaxone?

Answer 2

HENS PEcK

H. influenza
Enterobacter aerogenes
Neisseria
Serratia

Proteus mirabilis
E. Coli
Klebsiella pneumonia

Question 3

what type of antibiotic should not be combined with a loop diuretic due to the risk of ototoxicity?

Answer 3

aminoglycosides

gentamicin,
neomycin,
amikacin
tobramycin
streptomycin

remember “mean GNATS caNNOT kill anaerobes”

nephrotoxicity, neuromuscular blockade,
ototoxicity, teratogen

Question 4

what antibiotic causes grey baby syndrome?

Answer 4

chloramphenicol - especially in premature infants because they lack liver UDP-glucoronyl transferase

Question 5

what antibiotic is known for causing pseudomembranous colitis (C. diff) along with fever and diarrhea?

Answer 5

clindamycin - used for anaerobic aspiration infections such as bacteroids or clostridium perfringens

Question 6

what type of antibiotic causes discoloration of teeth and inhibition of bone growth in children?

Answer 6

tetracyclines

ALSO PHOTOSENSITIVITY!!!!

Question 7

what antibiotic cuases both dose dependent anemia and dose INDEPENDENT aplastic anemia as a potantial side effect?

Answer 7

chloramphenicol

Question 8

Does TMP-SMX have activity against pseudomonas?

Answer 8

NO

but DOC for pneumocystis jiroveci, toxoplasma gondii, nocardia

Question 9

what should be given to alcoholic with pneumonia?

Answer 9

clindamycin - covers bacteroides, prevotella, fusobacterium and peptospreptococcus - anaeobic oral flora

also covers strep pneumoniea

binds 50S ribosomal subunit thereby inhibiting protein sysnthesis

Question 10

what drugs act on the 50s ribosmal subunit?

Answer 10

chloramphenicol, clindamycin, linezolid and macrolides (e.g. azythromycin)

Question 11

where do macroles and clindamycin bind what is the mechanisms?

Answer 11

23S rRNA of the 50S subunit - block trranslocation of the ribosome on mRNA and inhibit protein synthesis

Question 12

what is the resistance to macrolides?

Answer 12

bacterial aquisition of genetic material encoding methylation of the 23S sRNA inhibits macrolide binding

Question 13

how is resistance to cephalosporins accomlished?

Answer 13

hydrolize the drug with cephalosporinases

Question 14

what is the mechanism of doxy/tetracycline?

Answer 14

bind to 30S, block aminoacryl-tRNA binding to the A site of on the ribosome and inhibit ELONGATION

Question 15

how is resistance to tetracyclines accomlished?

Answer 15

decreased uptake and increased transport out of the cell, chemical modification of the drug

Question 16

what is the mechanism for fluoroqinolones (e.g. moxifloxacin)?

Answer 16

inhibit DNA replication by binding to and stabilizing DNA-DNA gyrase (topo II) complex

Question 17

how is resistance to fluoroquinolones accomlished?

Answer 17

mutations that alter binding to DNA gyrase

Question 18

what is the mechanisms for vancomycin?

Answer 18

inhibit cell wall synthesis by binding to the D-alanyl-D-alanine bacterial cell wall

Question 19

how is resistance to vancomycin accomlished?

Answer 19

replacement of D-alanine with D-lactate

Question 20

what drug must travel through porin channels in bacterial out membrane and require and energy dependent mechanism to cross the bacterial inner membrane before binding to the 30S subunit?

Answer 20

aminoglycosides

Question 21

what is the mechanism of resistance for aminoglycosides?

Answer 21

decreased drug penetration or altered ribosomal binding sites

penecilins can increase aminoglycosides ability to penetrate in resistant bacteria

Question 22

what is the mechanism of resistance for trimethoprim or suylfamethoxazole?

Answer 22

decreased permeability, modified enzyme binding

Question 23

imipenem is given along with another drug. What is it and how does it work?

Answer 23

cilastatin

functions to prevent proximal renal tubular brush boarder hydrolysis of imipenem by dehydropeptidases (depeptidase) which prolongs imipenems antimicrobial effects in the URINE

Question 24

pt has a postive FTA-ABS result and is gen what two drugs? One is for the infection. What is the purpose and mechanism of the second drug?

Answer 24

Penicillin G and probenecid

FTA-ABS = fluorescent treponemal antibody absoption assay aka positive for syphalis

probenecid is given to prevent renal tubular secretion of penecillin. It works by inhibiting organic anion transper (OAT) in the renal proximal tubule

probenecid also blocks the urate transporter in the same cells, which decreases reabsoption of uric acid

Question 25

what tissue is tetracycline most likely to deposit in? Why?

Answer 25

Bone - forms stable compelexs with calcium

readily corsses placenta and can accumulate in fetal long bones => major reason for teratenicity

also accumulate in dentin of teeth causing yellow-grey staining and enamal hypoplasia