Microbiology- Pharmacology Flashcards
How do Penicilin G IV, IM), V (PO) work?
bind penicillin-binding proteins (transpeptideases) and block PEP cross-linking of peptidoglycan in cell walls
AEs of Penicillin?
Hypersensitivity rxns, hemolytic anemia
Resistance to penicillin?
pencillinase in bacteria (B-lactamase)
What is the MOI of amoxicillin, ampicillin?
Same as penicillin but iwth wider spectrum (still penicillinase sensitive)- can combine with clavulinic acid to protect aginst B-lactamases
NOTE: Amoxicillin has greater bioavailabilty than ampicillin
What are the main uses of Amoxi/Ampicillin?
H. influenzae, H. pylori, E. Coli, Listeria, Proteus, Salmonella, and Shigella
AEs of amp/amoxicillin?
Hypersensitivity rxn, rash, pseudomembranous colitis
What is the MOI of dicloxacillin, nafcillin, oxacillin?
Same as penicllin, but narrow spectrum and penicillinase resistant because of a bulky R group blocks access of B-lactamase
What are the main clinical uses of dicloxacillin, nafcillin, oxacillin?
S. aurues (except MRSA- resistant due to altered penicillin-binding protein target site)
What are the AEs of dicloxacillin, nafcillin, oxacillin?
Hypersensitivity rxns, interstitial nephritis
What is the MOI of piperacillin and ticarcillin?
Same as penicillin, extended spectrum
What are the main uses of piperacillin and ticarcillin?
Pseudomonas spp. and gram neg rods; susceptible to penicillinase (use with a B-lactamase inhibitor)
What are the main B-lactamase inhibitors?
Clavulanic acid, sulbactum, taxobactam
How do cephalosporins work?
B-lactam drus that inhibit cell wall synthesis but are less susceptible to B-lactamases (bactericidal)
cephalosporins are ineffective against what bugs?
LAME
Listeria
Atypicals (Chlamydia, Mycoplasma)
MRSA (except ceftaroline)
Enterococci
What are the 1st gen cephalosporins?
Cefalozin and cephalexin
What are the uses of Cefalozin and cephalexin?
mostly gram pos cocci, Proteus, E. Coli, and Klebsiella
What are the 2nd gen cephalosporins?
Cefoxitin, Cefaclor, and Cefuroxime
What are the uses of Cefoxitin, Cefaclor, and Cefuroxime?
gram positive cocci, H. influenzae, Enterobacter, N. spp, Proteus, E. coli, and Klebsiella, Serratia
HEN PEcKS
What are the 3rd gen cephalosporins?
Ceftriaxone, Cefotaxime, and Ceftazidime
What are the uses of Ceftriaxone, Cefotaxime, and Ceftazidime?
severe gram neg infetions resistant to others (Ceftriaxone- meningitis, gonorrhea, disseminated Lyme disease; Ceftazidime-Pseudomonas)
What are the uses of 4th generation cephalosporins?
Cefepime- mainly gram neg organisms with icnreased activtiy against Pseudomonas
Main AEs of cephalosporins?
Hypersensivity rxns, autoimmune hemolytic anemia, disulfram-like rxns, vitK deficiency
cross reativity with penicillins
What are the carbapenems?
Imipenem, meropenem, Ertapenem, etc
How do carbapenems work?
Imipenem is a broad spectrum B-lactamase resistant carbapenem always given with cilastatin which is a renal dehydropeptidase I inhibitor
What are the Monobactams?
Aztreonam
How does Aztreonam work?
Less susceptible to B-lactamases; prevents peptidoglycan cross-linking by binding to penicillin-binding protein 3. Synergisitic with aminoglycosides (no cross-allergy with penicllins)
Uses of Aztreonam?
Gram neg rods only (no activity against gram pos or anaerobes)
good for penicillin allergic pts and those with renal insufficiency who cannot tolerate aminoglycosides
How does Vancomycin work?
Inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall percursors (bactericidal; not susceptible to B-lactamases)
What are the uses of Vancomycin?
Gram + bugs only - serious, multidrug resistant including MRSA, S. epi, sensitive Enterococcus spp. and C. difficile
AEs of Vancomycin?
Well tolerated but may cause nephro-, ototoxicity, thrombophlebitis, diffuse flushing (prevent with pretreamtnet with antihistamines)
How do antimicrobial protein synthesis inhibitors work?
Target the 30S or 50S subunits, leavin human 80S unaffected
What are the 30S inhibitors?
Aminoglycosides (bactericidal)
Tetracyclines (bacteriostatic)
What are the 50S inhibitors?
Chloramphenicol, Clindamycin (bacteriostatic)
Eryhtromycin (macrolides); bacteriostatic
Linezolid
Buy At 30, CCEl at 50
What are the Aminoglycosides?
Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin
How do Aminoglycosides work?
Bactericidal by binding to the 20S and causing mRNS misreading and blocking translocation
require O2 for uptake and therefore inneffective against anaerobes
What are the main uses of Aminoglycosides?
Severe gram neg rod infections. Synergistic with B-lactams
Neomycin for bowel surgery
AEs of Aminoglycosides?
nephrotoxicity, neuromuscular blockade, ototoxicity, teratogen
What are the tetracyclines?
tetracycline, Doxycycline, Minocycline
How do tetracyclines work?
Bacteriostatic by binding to the 30S and preventing attachment of the aminoacyl-tRNA (limited CNS penetration)
NOTE: Doxy is fecally eliminated and can be used in pts with renal failure. Also, dont taketetracyclines wth milk, antiacids, or iron containing preps because divalent cations inhibit its absorption
How does chloramphenicol work?
Blocks peptidyltransferase at 50S ribosomal subunit; bacteriostatic
What are the uses of Chloramphenicol?
Meningitis (H. influ, N, men., S. pneumo) and RMSF (Rickettsia rickettsii)
Limited use due to toxicities
What are the AEs of Chloramphenicol?
Anemia (dose dependent)
aplastic anemia (dose independent)
grey baby syndrome (in premature infants because they lack liver UDP-glucuronyl tranferase)
How does Clindamycin work?
Blocks translocation at the 50S subunit. Bacteriostatic
What are the uses of Clindamycin?
Anaerobic infections (e.g. Bacteriodes, Clostridium perfringens) in aspiration pneumonia, lung abscesses, and oral infections
Also effective against invasive GAS infections
Treats anaerobic infections above the diaphragm vs. metronidazole which treats below
What are the AEs of Clindamycin?
Pseudomembranous colitis, fever, diarrhea
How does Linezolid work?
Inhibits protein synthesis by binding to the 50S subunit and inhibiting formation of the initiation complex
What are the uses of Linezolid?
gram positive species including MRSA and VRE
What are the AEs of Linezolid?
Bone marrow suppression (especially thrombocytopenia), peripheral neuropathy, serotonin syndrome
What are the macrolides?
Azithromycin, clarithromycin, erythromycin
How do macrolides work?
Inhibit protein synthesis by blocking translocation; bind to the 23S rRNA of the 50S subunit;; Bacteriostatic
What are the AEs of Macrolides?
MACRO
GI motility issues
arrythmia caused by QT prolongation
Cholestatic hepatitis
Rash Eosinophilia
How does trimethoprim work?
Inhibits bacterial dihydrofolate reductase (bacteriostatic) (similar to pyrimethamine)
What are the uses of trimethoprim?
Used in combo with sulfonamides (trimethoprim-sulfamethoxazole), causing sequential blockade of folate synthesis- commonly used for UTIs
Shigella, Salmonella, Pneumocystitis jivroceii
toxoplasmosis prophylaxis
What are the AEs of trimethoprim?
Megaloblastic anemia
leukopenia
granulocytopenia
What are the sulfonamides?
Sulfamethoxazole (SMX), Sulfisoxazole, Sulfadiazine
What is the MOI of sulfonamides?
Inhibit folate synthesis- PABA antimetabolites inhibit dihydropteroate synthase
What are the AEs of sulfonamides?
hypersensitivity rxns, hemolysis if G6PD deicient, nephrotoxicity, photosensitivity, kernicterus in infants
What are the Fluoroquinolones?
Ciprofloxacin, -floxacins
What is the MOI of Fluoroquinolones?
Inhibit prokaryotic enzymes topoisomerase II (DNA gyrase) and IV. Bactericidal (dont take with antacids)
What are the AEs of Fluoroquinolones?
GI upset, skin rashes, HA, dizziness
Leg cramps and myaglaias
Contraindicated in pregnant women, nursing mothers, and children less than 18 yo due to possible cartilage damage.
tendonitis/tendon rupture
QT prolongation
How does Daptomycin work?
Lipopetide that disrupts cell membranes of gram-positive cocci (good for S. aureus skin infctions, endocarditis, VRE)
NOTE: Dont use for pneumonia (inactivated by surfactant)
What are the AEs of Daptomycin?
Myopathy, rhabdomyolysis
How does Metronidazole work?
Forms toxic free radical metabolites in the bacterial cell that damage DNA. Bactericidal
What are the AEs of Metronidazole?
Disulfram-like rxn (severe flushing, tachycardia, hypotension), metallic state
What is the prophylaxis of Mycobacterium TB?
Isoniazid
What is the prophylaxis of Mycobacterium avium?
Azthromycin or rifabutin
How is M. avium tx?
More drug resistant than M. tb. tx with azitrho or clarithromycin + ethambutol (can add rifabutin or ciprofloxacin)
Mycobacterium cell wall

What are the rifamycins?
Rifampin, rifabutin
How do rifamycins work?
Inhibit DNA-depedent RNA polymerase
Major uses of rifamycins?
M. tb; delay reisstance to dapsone when used for leprosy
Used for meningococcal prophylaxis and chemoprophylaxis in contract of childrens with H. influenzae type B
AEs of rifamycins?
Minor hepatotocixity and DDIs (induce CYP450)
orange body fluids (nonhazardous side effect)
Rifabutin favored over rifampin in pts with HIV infection due to less cyp activation
What are the 4 R’s of Rifampin?
RNA polymerase inhibitor
Ramps up CYPs
Red/orange body fluids
Rapid resistance if used alone
How does Isoniazid work?
Decreased synthesis of mycolic acids
NOTE: Bacterial catalase-peroxidase (encoded by katG) needed to convert INH to activate metabolites
AEs of Isoniazid?
neurotoxicity, hepatotoxicity
Pyridoxine (VitB6) can prevent neurotoxicity
How does pyrazinamide work?
Mehcanism uncertain but it is a prodrug that is converted to the active compound pyrazinoic acid
AEs of pyrazinamide?
Hyperuricemia and hepatotoxicity
How does ethambutol work?
Decreased carbohydrtae metabolism of mycobacterium cell walls by blocking arabinosyltransferase
AEs of ethambutol?
Optic neuropathy (red-green color blindness)
What is the preferred prophylaxis for AIDs pts with CD4 less than 200 cells/mm3?
TMP-SMX (protect against pneumocystis jivroceii)
What is the preferred prophylaxis for AIDs pts with CD4 less than 100 cells/mm3?
TMP-SMX
What is the preferred prophylaxis for AIDs pts with CD4 less than 50 cells/mm3?
Azithromycin or claitromycin (protect against mycobacterium avium)
How should MRSA be tx?
Vanco, daptomycin, linezolid, tigecycline ceftaroline
How should VRE be tx?
Linezolid or tigecycline
How should Mmulti-drug resistant P. aeruginosa or multidrug resistant Acinetobacter baumannii be tx?
polymyxins B and E (colistin)