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Pharmacology > Microbiology > Flashcards

Microbiology Flashcards

1
Q 
Penicillin G (IV and IM form)
Penicillin V (oral)
A

Prototype beta-lactam antibiotic (bactericidal)

Binds penicillin-binding protein (transpeptidase) -> blocks cross-linking of peptidoglycan -> activate autolytic enzymes

Use: gram + cocci (S. pneumo, S. pyogenes), gram + rods, actinomyces, gram negative coci and spirochetes (Neisseria, treponema, syphillis).

Tox: hypersensitivity, hemolytic anemia

Resistance: beta-lactamase cleaves beta-lactam ring

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2
Q

Nafcillin, Oxacillin, Diclocillin

A

Penicillinase-resistant penicillins

Bulky R group -> blocks access of Beta-lactamase to beta-lactam ring (same mechanism as penicillin)

Use: S. aureus (except MRSA - altered PBP target site)

Toxicity: hypersensitivity reaction, interstitial nephritis

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3
Q

Ampicillin, Amoxacillin

A

Aminopenicillins

Mechanism: same as penicillin; wider spectrum
Penicillinase sensitive. (combine with clavulanic acid)
Amox (higher bioavailability)

Use: HELPSS (H. flu, E.coli, Listeria, Proteus, Salmonella, Shigella)

Tox: Hypersensitivity, ampicillin rash, pseudomembranous colitis

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4
Q

Ticarcillin, Piperacillin

A

Antipseudomonals

Mechanism: same as penicillin, use with clavulanic acid

Use: pseudomonas and grap negative rods (bacteroides)

Toxicity: hypersensitivity reaction

Synergistic with aminoglycosides

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5
Q

Clavulanic Acid
Sulbactam
Tazobactam

A

Beta-lactamase inhibitors

Add to penicillin to protect from beta-lactamase destruction

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6
Q

Cephalosporins

A

Beta-lactam drugs, bactericidal
Less susceptible to penicillinase

Not covered: LAME
Listeria, Atypicals, MRSA, Enterococci
(MRSA is covered by ceftaroline)

Tox: hypersensitivity, vitamin K deficiency (blocks epoxide reductase), cross-reactivity with penicillin;
Increased nephrotoxicity of aminoglycosides

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7
Q

Cefazolin

Cephalexin

A

1st gen cephalosporins (beta-lactam drugs)

Use: PEcK
Proteus, E. coli, Klebsiella
Cefazolin: prevent S. aureus prior to surgery (wound infections)

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8
Q

Cefuroxime
Cefoxitin
Cefaclor

A

2nd gen cephalosporins

Use: HEN PEcKS
H. flu, Enterobacter aerogenes, Neisseria, Proteus, E. coli, Klebsiella, Serratia

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9
Q

Ceftriaxone

Cefotaxime

A

3rd gen cephalosporins

Use: serious gram negative infections resistant to beta-lactams

Ceftriaxone: neisseria meningitis and gonorrhea
Cefotaxime: pseudomonas

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10
Q

Cefepime

A

4th gen cephalosporin

Use: Pseudomonas and gram positive organisms

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11
Q

Aztreonam

A

Monobactam resistant to beta-lactamase
Binds to PBP3, synergistic with amino glycosides

Use: gram negative only (not for gram positives or anaerobes)
Penicillin-allergic patients; renal insufficiency who cannot tolerate aminoglycosides

Tox: no cross-allergenicity with penicillin; GI upset

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12
Q

Imipenem/Cilastatin

Meropenem

A

Beta-lactamase resistant carbapenem

Use: gram + cocci, gram - rods and anaerobes
Wide spectrum; life-threaning infections or other drugs failed

Tox: significant side effects - GI, skin rash, CNS toxicity (seizures) at high plasma level (less with meropenem)

Imipenem with Cilastatin to inhibit inactivation of drug in renal tubules by renal dehydropeptidase I

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13
Q

Vancomycin

A

Binds D-ala D-ala -> Inhibits cell wall peptidoglycan formation, bactericidal

Use: Gram positives only (serious multidrug-resistant organisms, MRSA, enterococci, Clostridium difficile), oral pseudomembranous colitis

Tox: Nephrotoxicity, Ototoxicity, Thrombophlebitis
Red Man Syndrome (Flushing) - decrease by giving histamine or slow infusion

Resistance: D-ala D-ala to D-ala D-lac

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14
Q 
Gentamicin
Neomycin
Amikacin
Tobramycin
Streptomycin
A

Aminoglycosides, bactericidal
Inhibit formation of initiation complex; cause misreading of mRNA and block translocation

Use: gram negative rods (neo for bowel surgery); synergistic with beta-lactam antibiotics
Require O2 for uptake (not useful for anaerobes)

Tox: Nephrotoxicity (with cephalosporins), Neuromuscular blockade, Ototoxicity (with loop diuretics), Teratogen

Resistance: transferase that inactivates drug by acetylation, phosphorylation, adenylation

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15
Q

Tetracycline
Doxycycline
Demeclocycline
Minocycline

A

Tetracyclines, bacteriostatic
Binds 30s subunit -> prevent attachment of aminoacyl-tRNA
Limited CNS penetration

Use: Accumulate intracellularly (Rickettsia, Chlamydia), Borrelia, M. pneum, acne

Tox: GI, discoloration of teeth, inhibits bone growth in children, photo toxicity

Resistance: decrease uptake into or increase efflux out of cell by plasmid-encoded transport pumps

Do not take with milk, antacids or iron-containing preparations (divalent cations inhibit absorption)

Doxycycline: renal failure patients (fecal eliminated)
Demeclocycline (ADH antagonist)

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16
Q

Azithromycin
Clarithromycin
Erythromycin

A

Macrolides, bacteriostatic
Bind to 23S rRNA of 50S ribosomal subunit -> inhibits translocation

Use: Atypical pneumonias (Mycoplasma, chlamydia, legionella), STDs (Chlamydia), gram positive cocci (patient allergic to penicillin)
Azithro: M. avium prophylaxis and treatment

Tox: MACRO
Motility issues, Arrhythmias from prolonged QT, acute Cholestatic hepatitis, Rash, eOsinophilia
p450 inhibit (increases theophylline, oral anticoagulants)

Resistance: methylation of 23S rRNA binding site

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17
Q

Chloramphenicol

A

Bacteriostatic; blocks peptidyltransferase at 50S

Use: meningitis (H. flu, Neisseria, S. pneumo); typhoid fever, salmonella

Tox: Anemia (dose dependent), Aplastic anemia (dose independent), Gray baby syndrome (lack of liver UDP-glucuronyl transferase)

Resistance: plasmid-encoded acetyltransferase that inactivates drug

Used in developing countries because of low cost

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18
Q

Clindamycin

A

Bacteriostatic, blocks peptide transfer at 50S

Use: Anaerobic infections (Bacteroides fragilis, Clostridium perfringens) in aspiration pneumonia/lung abscesses; anaerobes in oral infections (“above the diaphragm”)

Tox: Pseudomembranous colitis (C. diff overgrowth), fever, diarrhea

19
Q

Sulfamethoxazole
Sulfisoxazole
Sulfadiazine

A

Sulfonamides, bacteriostatic
PABA antimetabolites that inhibit dihydropteroate synthase

Use: Gram positive, negative, Nocardia, Chlamydia, UTI

Tox: hypersensitivity, photosensitivity, hemolytic anemia in G6PD, nephrotoxicity (tubulointerstitial nephritis), kernicterus, displaces warfarin from albumin

Resistance: altered bacterial dihydropteroate synthase; decrease uptake, increase PABA synthesis

20
Q

Enoxacin
Nalidixic acid
Cirpofloxacin, Norfloxacin, Levofloxacin, Ofloxacin, Sparfloxacin, Moxifloxacin, Gatifloxacin

A

Fluoroquinolones, bactericidal
Inhibit DNA gyrase (topoisomerase II) and topoisomerase IV

Use: gram negative rods of urinary and GI (Pseudomonas), Neisseria, some gram positive

Tox: GI upset, tendon rupture (>60, taking prednisone), myalgias, skin rashes, headaches, prolonged QT intervals
Contraindicated in pregnancy (cartilage)

Must not take with antacids (Ca2+, Iron)

Resistance: chromosome-encoded DNA gyrase mutation, plasmid-mediated resistance, efflux pump

21
Q

Metronidazole

A

Bactericidal, antiprotozoal
Forms free radical toxic metabolites in bacterial cells that damage DNA

Use: GET GAP (“below the diaphragm”)
Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes, Pylori

Tox: disulfiram-like reaction with alcohol; headache, metallic taste

22
Q

Isoniazid (INH)

A

Activated by bacterial catalase-peroxidase KatG -> decrease synthesis of mycolic acid

Use: Mycobacterium tuberculosis (only solo prophylaxis)

Tox: Neurotoxicity, Hepatotoxicity, Lupus
Increase urinary excretion of Vitamin B6 (Pyridoxine can prevent neurotoxicity)
Slow acetylators more toxicity

Resistance: non-expression of catalase-peroxidase or INH binding site

23
Q

Rifampin

A

Inhibits DNA-dependent RNA polymerase

Use: Mycobacterium tuberculosis, leproxy (with dapsone), meningococcal and haemophilus type B prophylaxis

Tox: Revs up p450; orange body fluids (nonhazardous)
Rapid resistance if used alone

24
Q

Pyrazinamide

A

Converted to pyrazinoic acid -> acidify intracellular environment (in acidic pH of phagolysosomes where TB are engulfed by macrophages)

Use: mycobacterium tuberculosis

Tox: hyperuricemia, hepatotoxicity

25
Q

Ethambutol

A

Blocks arabinosyltransferase -> decrease carbohydrate polymerization of mycobacterium cell wall

Use: mycobacterium tuberculosis

Tox: optic neuropathy (red-green color blindness)

26
Q

Prophylaxis and Treatment for: M. avium

A

Prophylaxis: Azithromycin
Treatment: Azithromycin, rifampin, ethambutol, streptomycin, rifabutin

27
Q

Treatment for M. leprae

A

Tuberculoid: dapsone and rifampin
Lepromatous: dapsone, rifampin and clofazimine

28
Q

Antimicrobial prophylaxis

  1. Meningococcal infection
  2. Gonorrhea
  3. Syphilis
  4. Recurrent UTIs
  5. Endocarditis with surgical/dental procedures
  6. Pregnant women with group B strep
  7. Strep pharyngitis with prior rheumatic fever
  8. post surg infection with S. aureus
  9. Gonoccoal or chlamydial conjunctivitis
A
  1. Ciprofloxacin (rifampin in children)
  2. Ceftriaxone
  3. Benzathine Penicillin G
  4. TMP-SMX
  5. Penicillins
  6. Ampicillin
  7. Oral penicillin
  8. Cefazolin
  9. Erythromycin ointment
29
Q

HIV Prophylaxis
CD4 < 200
CD4 < 100
CD4 < 50

A

<50: Azithromycin (M. avium)

30
Q

Treatments for MRSA and VRE

A

MRSA: vancomycin
VRE: linezolid and streptogramins (quinupristin/dalfopristin)

31
Q

Amphotericin B

A

Binds ergosterol (unique to fungal) -> membrane pores that allow leakage of electrolytes

Use: serious systemic mycoses, cryptoccocus (amp B with flu cytosine), Blastomyces, Coccidioides, Histoplasma, Candida, Mucor; intrathecal for fungal meningitis

Supplement Mg and K because of altered renal tubule permeability

Tox: fevers/chills, hypotension, nephrotoxicity, arrhythmias, anemia, IV phlebitis

Hydration reduces nephrotoxicity (liposomal reduces toxicity)

32
Q

Nystatin

A

Same as amphotericin B; topical form because too toxic for systemic

Use: oral candidiasis (swish and swallow); topical for diaper rash or vaginal candidiasis

33
Q 
Fluconazole
Ketoconazole
Clotrimazole
Miconazole
Itraconazole
Voriconazole
A

Inhibit p450 lanosterol -> ergosterol (inhibit sterol synthesis)

Use: local and less serious systemic mycoses
Fluconazole: chronic suppression of crypto (AIDS) and candidiasis
Itraconazole: Blasto, Coccidio, Histo
Clotrimazole, miconazole: topical

Tox: p450 inhibitor; testosterone synthesis inhibition (gynecomastia with ketoconazole)

34
Q

Flucytosine

A

Converted to 5-FU by cytosine deaminase -> inhibits DNA and RNA biosynthesis

Use: systemic fungal infections (meningitis by crypto with amp B)

Tox: bone marrow suppression

35
Q

Caspofungin

Micafungin

A

Inhibits synthesis of beta-glucan -> inhibits cell wall synthesis

Use: invasive aspergillosis, candida

Tox: GI upset, flushing (histamine release)

36
Q

Terbinafine

Naftifine

A

Inhibit squalene epoxide (lanosterol synthesis)

Use: dermatophytoses (onychomycosis)

Tox: abnoraml LFT, visual disturbances

37
Q

Griseofulvin

A

Interferes microtubule function -> disrupt mitosis
Deposits in keratin-containing tissues (nails)

Use: oral treatment of superficial infections; dermatophytes (tinea, ringworm)

Tox: teratogenic, carcinogenic, confusion, headaches, P-450 induction (warfarin metabolism)

38
Q

Treatments for:

1) toxoplasmosis
2) trypanosoma brucei
3) t. cruzi
4) leishmaniasis
5) Schistosomas/flukes

A

1) pyramethamine
2) suramin and melarsoprol
3) nifurtimox
4) sodium stibogluconate
5) praziquantel

39
Q

Chloroquine

A

Blocks detox of heme into hemozoin -> heme accumulates and is toxic to plasmodia

Use: plasmodium except for falciparum (resistance from membrane pump decreasing intracellular concentration)

Tox: retinopathy

40
Q

Treatment for P. falciparum

A

Artemether/lumifantrine
Atovaquoune/proguanil

Life-threatening: IV quininidine (quinine) or artisunate

41
Q

Zanamivir

Oseltamivir

A

Inhibit influenza neuraminidase -> decrease release of progeny virus

Use: tx and prevention of influenza A and B

42
Q

Ribavirin

A

Competitively inhibits IMP dehydrogenase -> inhibits synthesis of guanine nucleotides

Use: RSV, chronic hep C

Tox: hemolytic anemia, severe teratogen

43
Q

Acyclovir
Valacyclovir (oral)
Famcyclovir

A

Monophosphorylated by HSV/VZV thymidine kinase -> inhibits viral DNA polymerase by chain termination (guanosine analog)

Use: HSV and VZV (weak EBV); no CMV
HSV-induced mucocutaneous/genital lesions/encephalitis; prophylaxis in immunocompromized
Famcyclovir: herpes zoster

Resistance: mutated viral thymidine kinase

44
Q

Ganciclovir

Valganciclovir (oral)

A

5’-monophosphate formed by CMV viral kinase (guanosine analog) -> inhibits viral DNA polymerase

Use: CMV (immunocompromised)

Tox: leukopenia, neutropenia, thrombocytopenia, renal toxicity

Resistance: mutated cmv dna polymerase or lack of viral kinase

Pharmacology (8 decks)

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