Microbiology

Question 1

Ampicillin/amoxicillin

Answer 1

HELPSS kill Enterococci (and normal pens)
H. Flu, E. Coli, Listeria, Proteus, Salmonella, Shigella, Enterococci
Hypersensitivity, Rash, Pseudomembranous colitis

Question 2

Penicillinase resistant penicillins

Answer 2

Oxacillin, Nafcillin, dicloxacillin
Narrow spectrum, use for staph
bulky R-group
Hypersensitivity, Interstitial nephritis

Question 3

First gen Cephalospirins

Answer 3

Cefazolin, Cefalexin
PEcK- Proteus, E. Coli, Klebsiella, GPC
Cafazolin before surg for staph

Question 4

Cephalospirins toxicities and what they don’t cover

Answer 4

Dont Cover LAME
Listeria, Atypicals (Chlamidia, mycoplasma), MRSA, Enterococci
Except, ceftaroline covers MRSA
Hypersensitivity, Vitamin K deficiency, increases nephrotoxicity of aminoglycosides

Question 5

Aztreonam

Answer 5

monobactam, B-lactamase resistant
Only covers aerobic GNRs
Binds PBP3
nontoxic
"pen allergic patient w/ renal insufficiency and can't tolerate aminoglycosides"

Question 6

Carbapenems

Answer 6

Imipenem, meropenem, ertapenem, doripenem
Imipenem needs cilistatin to block renal dehydropeptidase I.
meropenem has fewer seizures and stable to dehydropeptidase I
Wide spectrum but toxicity limits use
GI, Rash, CNS toxicity (seizures) at high plasma levels

Question 7

Vancomycin

Answer 7

Binds D-ala-D-ala
Only GPC (and oral for C. Diff)
Nephrotoxic, ototoxic, thromboembolic, red man syndrome if too fast
bacteria block by AA modification of peptidoglycan to D-ala-D-lac

Question 8

Aminoglycosides

Answer 8

GNATS- Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin
Inhibit formation of initiation complex and causes mRNA misreading
Binds 30s TIGHTLY, bacteriocidal
Requires O2 for uptake
Severe GNR infections, synergy w/ B-lactams
Neomycin for bowel surgery
TONN- Teratogenic, Ototoxic (esp w loop diuretics), nephrotoxic (esp w/ cephalosporins), Neuromuscular blockade
Bacterial transferase enzymes inactivate drug by acetylation, phosphorylation, or adenylation

Question 9

Tetracyclines

Answer 9

Tetracycline, doxycicline, minocycline
Bind 30s, prevent aminoacyl-tRNA attachment
limited CNS penetration, divalent cations block absorption in gut (milk, antacids, iron)
doxycicline pooped, okay for renal failure pts
Boriella Burgdorferi, Mycoplasma pneumonia, Rickettsia and chlamydia (accumulates intracellularly)
Discoloration of teeth, blocks bone growth, photosensitivity. No in pregnancy
Bacteria block by plasmid encoded transport pumps

Question 10

Macrolides

Answer 10

Azythromycin, erythromycin, clarithromycin
Binds 23s of 50s and blocks translocation
atypical pneumonia, chlamydia, GPC
MACROTA- Motility (GI), Arrhythmia (QT long), Cholestatic Hepatitis, Rash, eOsinophilia, Theophylline and Anticoagulant increases in blood
E and C- inhibit p450. A does not.
Bacteria block by methylating 23S rRNA binding site

Question 11

Chloramphenicol

Answer 11

Blocks peptidyltransferase at 50S subunit
Meningitis (H. Flu, N. Menin, S. Pneumo) and RMSF
Toxic but cheap so used in developing CNTRYs
Anemia (dose dependent), Aplastic anemia (dose independent), Grey Baby Syndrome (don’t have UDP-glucuronyl transferase)
Bacteria inactivate w/ plasmid encoded acetyltransferase

Question 12

Clindamycin

Answer 12

Blocks translocation at 50s
Anaerobic above diaphragm (oral, lung abcess)
Causes C. Diff

Question 13

Sulfonamides

Answer 13

Sulfadiazine, sulfisoxazole, sulfadiazine
Para-aminobenzoic acid antimetabilites inhibit dihydropteroate synthase (folate synthesis)
GP, GN, Nocardia, Chlamydia
Hypersensitivity, Hemolysis in G6PD deficient, Tubulointerstitial nephritis, photosensitivity, Kernicterus in infants, displace other drugs from albumin
Bacteria alter dihydropteroate synthase, PABA synthesis or block uptake

Question 14

Trimethoprim

Answer 14

Inhibits bacterial DHFR
Combine w/ sulfonamides
UTIs, Shigella, Salmonella, PCP and Toxo prophylaxis
Can cause megaloblastic anemia, leukopenia, glanulocytopenia

Question 15

Fluoroquinolones

Answer 15

-oxacin (fluoroq’s) and nalidixic acid (quinolone)
Inhibit DNA gyrase (topo II). Bacteriocidal
No NOT take w/ antacids
GNR of GI/GU, Neisseria
Can cause GI upset, superinfections, rashes, headache, Tendonitis and Tendon rupture, don’t give to kids/preg/old because cartilage damage
old and prednisone AND FQ- tendon rupture
Bacteria get chromosome encoded mutation in DNA gyrase, plasmid mediated resistance and efflux pumps

Question 16

Metronidazole

Answer 16

Forms free radical toxic metabolites in bacteria that damage DNA
Bacteriocidal, antiprotozoal
GET GAP on the metro
Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes, Pylori
Disulfram-like rxn w/ alchohol, metallic taste
Anaerobic infections BELOW diaphragm

Question 17

Isoniazid

Answer 17

Decreases synthesis of mycolic acid
Bacterial catalase-peroxidate (KatG) needs to convert INH to active metabolite
TB- only solo agent used
Check fast v. slow acetylators
Neurotoxicity (give B6), hepatotoxic, lupus

Question 18

Rifamycins

Answer 18

Rifampin, Rifabutin
Inhibits DNA dependent RNA Polymerase
Delays dapsone resistance in Leprosy
prophylaxis for meningicoccus
prophylaxis in child contacts of H. Flu
4 R's 
RNA polymerase inhib
Ramps up p450
Red/orange body fluids
Rapid resistance if alone
RifAMPin ramps up p450 (use rifabutin in HIV)

Question 19

Pyrazinamide

Answer 19

Acidify phagolysosomes via conversion to pyrazinoic acid (TB phagocytized by macrophages)
hyperuricemia, hepatotoxicity

Question 20

Ethambutol

Answer 20

Blocks arabinosyltransferase (decrease cell wall carbohydrate polymerization)
optic neuropathy (R-G color blind) (reversible but check vision periodically)

Question 21

Amphototericin B

Answer 21

Binds ergosterol (fungi), forms pores
use in serious systemic mycoses, intrathecally for fungal meningitis
fever/chills, nephrotoxic (give Mg and K and hydrate), arrhythmias, anemia.
Lyposomal amphototericin less toxic and potent

Question 22

Nystatin

Answer 22

Pores like amphototericin

Really toxic, not absorbed, topical and swish/swallow for candida

Question 23

Azoles

Answer 23

Inhibits fungal ergosterol synthesis by inhibiting p450 that converts lanosterol to ergosterol
Use for local and less serious
fluconazole- supress cryptococcal men in HIV
Itraconazole for blast, cocc, histo
clotrim and micon for topical
Ketoconazole inhibits testoterone synthesis
p450 inhibitor

Question 24

Flucytosine

Answer 24

Inhibits DNA/RNA synthesis (cytosine deaminase converts to 5-FU)
systemic infection w/ Amphototericin B
Causes bone marrow supression

Question 25

Echinocandins

Answer 25

Caspofungin, micafungin, anidulafungin
Inhibits cell wall synthesis by blocking synthesis of B-glucan
Use in invasive asperigillosis
can cause GI upset and flushing (histamine release)

Question 26

Terbinafine

Answer 26

Inhibits fungal enzyme squalene epoxidase
sermatophytoses (especially onychomycosis)
GI, H/A, Hepatotoxicity, taste disturbance

Question 27

Griseofulvin

Answer 27

Interferes w/ microtubule function, disrupts mitosis
Deposits in keratin-containing tissues
oral treatment of superficial treatments (dermatophysis)
teratogenic, carcinogenic, increase p450 and warfarin metabolism

Question 28

Chloroquine

Answer 28

Blocks detoxification of heme into hemozoin- heme accumulates and is toxic to plasmodia
treat plasmodia other than P. falciparum
resistance by efflux pump
retinopathy and pruritis (in dark skinned)

Question 29

Neuraminidase inhibitors

Answer 29

Oseltamivir and zanamivir
blocks release of progeny virus
Influenza A and B if in first 24 hours

Question 30

Ribavirin

Answer 30

Inhibits synthesis of guanine analogs by competitively inhibiting inosine monophosphate dehydrogenase
use in RSV and chronic Hepatitis c
causes hemolytic anemia, severe teratogen

Question 31

Acyclovir, famciclovir, valacyclovir

Answer 31

Monophosphorylated by HSV/VZV thymidine kinase only in infected cells (few adverse effects)
guanosine analog, preferentially inhibits viral DNA polymerase
weak against EBV, nothing against CMV
use for herpes lesions and encephalitis
no effect on latent HSV/VZV
For zoster, use famciclovir
can cause obstructive crystalline nephropathy and ARF without hydration
Bacteria mutate thymidine kinase

Question 32

Gancyclovir

Answer 32

5’ monophosphate formed by CMV viral kinase
guanosine analog, preferentially inhibits viral DNA polymerase
Causes leukopenia, anemia, neutropenia, thrombocytopenia (more so than acyclovir
Bacteria mutate DNA polymerase or lack viral kinase

Question 33

Foscarnet

Answer 33

Viral DNA polymerase inhibitor- binds pyrophosphate binding site
Doesn’t need activation by viral kinase
CMV retinitis or HSV resistant to acyclovir
causes nephrotoxicity
Bacteria mutate DNA polymerase

Question 34

Cidofovir

Answer 34

Preferentially inhibits viral DNA polymerase
Doesn’t need activation by viral kinase
CMV retinitis or HSV resistant to acyclovir
Long half life
nephrotoxic (give probenecid and IV saline)

Question 35

Interferons

Answer 35

INF-a chronic HBV, HCV, Kaposi, hairy cell leukemia, condyloma acuminatum, RCC, malignant melanoma

INF-b MS

INF-y Chronic granulomatous disease

neutropenia and myopathy