Antibiotics

Question 1

Penicillin G, V: MOA, clinical use, toxicity, resistance

Answer 1

1. Binds PBP, blocks crosslinking, activates autolytic enzymes
2. Gram +ve, Syphillis, N meningitidis
3. Hypersensitivity, hemolytic anemia
4. Penicillinase

Question 2

Amoxycillin, ampicillin: MOA, clinical use, toxicity, resistance

Answer 2

1. Same as penicillin, wider spectrum
2. Extended spectrum-> HHELPSS kill enterococci (h infl, H pylori, e coli, l monoC, salmonella, shigella
3. Hypersensitivity, rash, pseudoM colitis
4. Penicillinase

Question 3

Dicloxacillin, flucloxacillin: MOA, clinical use, toxicity,

Answer 3

1. Same as penicillin, narrow
2. Staph aureus (not MRSA)
3. HypersenS, interstitial nephritis

Question 4

Piperacillin, ticarcillin: MOA, clinical use, toxicity, resistance

Answer 4

1. Same as penicillin
2. Pseudomonas, gram -ve rods
3. Hyeprsensitivity

Question 5

Cephalosporins generations 1-5

Answer 5

1. Inhibits cel wall synthesis
2. Organisms not covered->Listeria, Atypicals (Chlamydia, mycoplasma), MRSA, Entercocci (LAME)
3. Clinical use:
   a. 1st: cephazolin, cephalexin-> Proteus mirabilis, E. coli, Klebsiella (PEcK)
   b. 2nd-> cefoxitin-> H. Influenza, Enterobacter, Neisseria, Proteus, E coli, Klebsiella, Serratia (HEN PEcKS)
   c. 3rd: ceftriaxone (meningitis, gonorrhea, Lyme), cefotaxime, ceftazidime-> serious gram negative organism
   d. 4th: cefepime->gram negative
   e. 5th: borad gram +ve and gram negative
4. HyperS, AI hemolytic, disulfuram, vit K deficiency, cross reactivity with penicillin, +nephrotoxicity

Question 6

Imipenem, meropenem: MOA, clinical use, toxicity, resistance

Answer 6

1. Imipenem + cisplatin
2. Gram +ve cocci, gram -ve rod and anaerobes. Significant side effects limit use to life threatening
3. GI distress, skin rash, CNS toxicity

Question 7

Vancomycin: MOA, clinical use, toxicity, resistance

Answer 7

1. Inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion. Bacteriacidal
2. Gram positive->serious, multidrug resistant-> MRSA, S epidermidis, Enterococcus, C difficile
3. Nephrotoxic, ototoxic, thrombophlebitis, red man syndrome

Question 8

Aminoglycosides->gentamicin: MOA, clinical use, toxicity, resistance

Answer 8

1. Irriversible inhibition of 30S->misreading mRNA. Blokcs translocation. Needs oxygen
2. Severe gram negative rods, synergistic w/ beta lactams
3. Nephrotoxcity, NM blockade, ototoxicity (w/ diuretics+_, teratogen

Question 9

Tetracycline->doxycyclin: MOA, clinical use, toxicity, resistance

Answer 9

1. Binds 30S, inhibits tRNA binding. Limited CNS penetration. Do not use with milk, antacids or iron containing
2. M pneumonia, Rickettsia, Chlamydia, acne
3. GI distress, teeth discolouration, inhibits bone growth in children, photosensitivity, contraI in pregnancy

Question 10

Chloramphenicol: MOA, clinical use, toxicity, resistance

Answer 10

1. Blocks translocation at 50S
2. H influenza, N menigitidis, S pneumonia, RMSF
3. Anemia, aplastic anemia, gray baby syndrome

Question 11

Clindamicin: MOA, clinical use, toxicity, resistance

Answer 11

1. Blocks translocation 50S

2. Anaerobes->bacteroides, C perfringes, aspiration pneumonia, lung abscesses, oral infections, invasive GAS

Question 12

Macrolides->azithromycin, clarithromycin, erythromycin: MOA, clinical use, toxicity, resistance

Answer 12

1. Blocks translocaation at 50S
2. Atypical pneumonias, STIs, gram +ve cocci, B pertussis
3. MACRO: motility issues (GI), Arrythmia prolonged QT, Cholestatic hepatitis, Rash, eosinophilia, inhibition of p450

Question 13

Trimethoprim and sulfamethoxazole: MOA, clinical use, toxicity, resistance

Answer 13

1. Dihydrofolate inhibitor and dihydropteroate inhibitor via anti-metabolites
2. Combination with sulfamethoxazole: UTIs, Shigella, salmonella, PJP prophylaxis, toxoplasmosis prophylaxis
3. Megaloblastic anemia, leukopenia, granulocytopneia
   TMP= treats marrow poorly

Question 14

Fluroquinolones->ciprofloxacin: MOA, clinical use, toxicity, resistance

Answer 14

1. Inhibits DNA gyrase. Bacteriocidal, do not take with antacids.
2. Gram negative rods of UTI, GIT
   3, GI upset, skin rash, HA. Not for pregnant, not for nursing, prolong QT

Question 15

Metronidazole: MOA, clinical use, toxicity, resistance

Answer 15

1. Toxic free metabolite
2. GET GAP: Giardia, entameba, trichomonas, Gardnerella, anaerobes, H pylori
3. Disulfuram reaction with alcohol