Antimicrobials

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Antimicrobials
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2010-10-30 12:38:13
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Antimicrobials
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  1. Definition:
    A single-celled or multicellular organism without chlorophyll that
    reproduces by spores and lives by absorbing nutrients from organic matter
    Fungus
  2. What are the two most important type of anti-fungals, and what do they target?
    Polene and Azole Drugs; target the fungal cell membrane
  3. Which type of fungus causes the most common mucocutaneous fungal infection in oral lesions?
    Candida Albicans
  4. Opportunistic mycoses tend to show up in certain patient populations such as the immunocompromised. What are the important organisms in this group (4)?
    Aspergillus, Candida, Cryptococcus, and Phycomycetes
  5. Definition:
    A crystalline steroid alcohol that provides stability to fungal membranes. The chief sterol in most fungal membranes
    Esterol
  6. What are the two important polyene anti-fungals? These are very lipophilic, and have a high affinity for ergosterol. Their mechanism of action is to remove ergosterol from fungal membranes, which causes leakage of cellular contents and death
    Nystatin and Amphotericin B
  7. What is the mechanism of action of Nystatin and Amphotericin B (polyene anti-fungals)?
    Act like detergents and remove ergosterol from fungal membranes, which causes leakage of cellular contents and death
  8. Which type of polyene anti-fungal is very effective for topical and oral Canaida infections?
    Nystatin
  9. Should Nystatin be given intravenously?
    No, NEVER
  10. Can Amphotericin B be given intravenously?
    Yes
  11. When is Amphotericin B used?
    Only for progressive, potentially life-threatening fungal infections
  12. Why should Amphotericin B only be used in life-threatening situations?
    Because it is severely nephrotoxic
  13. Should Amphotericin B be given with penicillin?
    No, because of its high nephrotoxicity
  14. Amphotericin B is considered the most toxic IV anti-infective on the market. What can be done to reduce its toxicity upon administration?
    Sodium loading with normal saline
  15. Azole drugs block the synthesis of ergosterol by inhibiting what molecule?
    lanosterol 14-alpha-demethylase
  16. Azole anti-fungals are typically well-tolerated. However, what serious adverse effect can be connected with these?
    Liver damage
  17. What is the cause of the liver damage that can potentially be associated with Azole anti-fungals?
    They inhibit fungal and some human forms of CYP450
  18. Which Azole has the lowest incidence of adverse side effects?
    Fluconazole
  19. What are the three uses of Fluconazole?
    • 1. Cryptococcal meningitis in AIDS pts
    • 2. Oropharyngeal and esophageal candidiasis
    • 3. Prophylaxis in HIV pts for mucosal candidiasis
  20. Which Azole has a broader spectrum of activity than fluconazole?
    Itraconazole
  21. What is a major adverse effect of Itraconazole?
    Serious hepatotoxicity
  22. Which azole is contraindicated for patients taking cisapride, dofetilide, ergot alkyloids, lovastatin, and simvastatin, because these drugs are metabolized by CYP3A4, an enzyme that this anti-fungal inhibits?
    Itraconazole
  23. Which azole has activity against Fusarium?
    Voriconazole
  24. What is a major adverse effect of Voriconazole?
    Visual disturbances (blurred vision, altered perception of color)
  25. Is Voriconazole safe for pregnant women?
    No
  26. Which azole has limited use because of a high incidence of side effects?
    Ketoconazole
  27. What is a major side effect of Ketoconazole?
    Gynecomastia and menstrual irregularities (can inhibit testosterone and estradiol synthesis)
  28. Which Azole is an excellent drug for oral candidiasis in AIDS patients?
    Clotrimazole
  29. What Azole is used for prophylaxis of invasive Aspergillus and disseminated candidiasis in severly immunocompromised hosts?
    Posaconazole
  30. Which azole is active against Candida species that are resistant to other azoles?
    Posaconazole
  31. Which azole is active against Zygomycetes?
    Posaconazole
  32. What anti-fungal is typically reserved for nail and scalp infections that do not respond to topical therapies?
    Griseofulvin
  33. What anti-fungal is used only in combination with Amphotericin B to treat severe candida or cryptococcal infections (allows Amp B dose to be reduced)?
    Flucytosine
  34. What is a major side effect of Flucytosine?
    Very toxic to bone marrow and kidneys
  35. What class of anti-fungals inhibits 1,3-beta-D-glucan synthase (required for biosynthesis of polysaccharides used in fungal cell wall). This anti-fungal is safe to use in renally-impaired patients.
    Echinocandins
  36. What anti-fungal is excellent for life-threatening systemic fungal infections in patients that cannot tolerate Ampho B?
    Capsofungin
  37. Which anti-fungal does not have major effects on CYP450 system or drugs metabolized by it?
    Micafungin
  38. Which anti-fungal is widely held to be safe for use in pregnant women suffering from life-threatening fungal infections?
    Amphotericin B
  39. Definition:
    What are obligate intracellular parasites that depend on host cell enzymes for their propagation?
    Viruses
  40. What is the most common mechanism of action of anti-viral drugs?
    Inhibiting viral nucleic acid synthesis
  41. Incorporation of what terminates viral DNA or RNA replication?
    Antiviral Nucleoside Analogs
  42. Most current antiviral nucleoside analogs have modifications to which part of the molecule?
    Ribose
  43. What herpesvirus drug is a guanosine analog with an acyclic group replacing ribose? This is a prototypical anti-herpes drug
    Acyclovir
  44. What is a big problem with Acyclovir and why?
    Resistance, because viral enzymes mutate and no longer add initial phophate to the drug
  45. What are two alternative therapeutic options to Acyclovir?
    Foscarnet and Cidofovir
  46. Is Acyclovir FDA approved for use in pregnant women?
    No, but there are no birth defects associated with its use
  47. What medication is effective in near-term women with recurrent genital herpes to prevent spread of virus to newborn?
    Acyclovir
  48. What drugs are used for acyclovir-resistant HSV or VZV?
    Foscarnet and Cidofovir
  49. What is the drug of choice for CMV patients (life and sight-threatening). Can be used prophylactically in transplant patients
    Granciclovir
  50. Resistance to Granciclovir is associated with persistent infections. What can be used as an alternative treatment?
    Toscarnet and Cidotovir
  51. What drug has largely replaced IV and oral Ganciclovir for patients with CMV that is not life or sight threatening?
    Valganciclovir
  52. What drug is administered intravenously to delay progression of CMV retinitis in patients with AIDS, and is also effective against acyclovir-resistent HSV or VZV
    Cidofovir
  53. What is the causative agent of chicken pox and shingles?
    Varicella Zoster Virus (VZV)
  54. What is the live attenuated virus vaccine against chicken pox?
    Varivax
  55. What vaccine is used to prevent shingles?
    Zostavax
  56. What patient population is Zostavax indicated for?
    People over 60 years of age because they are immunocompetent
  57. What vaccine is contraindicated for immunocompromised patients and people with a history of anaphylactic shock to gelatin, neomycin, or other components of a vaccine?
    Zostavax
  58. What is the unique enzyme type encoded by HIV?
    Reverse Transcriptase (RT)
  59. What two factors measure the effectiveness of an HIV therapy?
    • 1. Viral RNA load
    • 2. CD4+ T-cell counts
  60. What is the mechanism of action of Nucleoside Reverse Transcriptase Inhibitors (NRTI) (Anti-HIV nucleoside analogs)?
    Inhibit RT -- Block transcription of viral RNA genome into DNA
  61. What are the adverse effects of the class of nucleoside reverse transcriptase inhibits (NRTIs), especially of Stavudine and Zidovudine (4)?
    • 1. Potentially fatal lactic acidosis
    • 2. Peripheral lipoatrophy
    • 3. Central fat accumulation
    • 4. Hyperlipidemia
  62. What Anti-HIV Nucleoside Reverse Transcriptase Inhibitor (NRTI) is most highly associated with fatal lactic acidosis?
    Stavudine
  63. What type of anti-HIV drugs are metabolized by and inhibitors of P-450 enzymes (CYP3A4), and can therefore interfere with metabolism of other drugs?
    HIV Protease Inhibitors
  64. What is one adverse effect of HIV protease inhibitors?
    Fat redistribution (e.g., buffalo hump)
  65. What HIV protease inhibitor is good for use with pediatric patients?
    Indinavir
  66. What two drugs, given together, are the treatment of choice for treatment-naive patients (patients that have not had HIV for very long)?
    Lopinavir + Ritonavir
  67. What two drugs, give together, are the treatment of choice for patients that have had extensive treatment and drug resistant problems with HIV?
    Tipranavir + low dose Ritonavir
  68. What is the standard combination therapy for treatmend of HIV-positive patients?
    Highly Active Anti-Retroviral Therapy (HAART)
  69. What are the current recommendations for initial therapy in Highly Active Retroviral Therapy (HAART)?
    • 2 NRTIs + Efavirenz (NNRTI) or
    • 2 NRTIs + PI combination (Lopinavir/ Ritonavir)
  70. Prevention of perinatal HIV transmission:
    Transmission usually occurs during labor or delivery, and therapy is most effective if taken throughout pregnancy. The current recommendation is AZT + NRTI + PI (or Nevirapine). However, if a woman is not on therapy at onset of pregnancy, what is the current recommendation?
    Should wait until 10-12 weeks of gestation to begin therapy, and AZT administration to newborn for 6 weeks
  71. What agents are contraindicated in pregnant women when attempting prevention of perinatal HIV transmission?
    • Stavudine and Didanosine (fatal lactic acidosis)
    • Enfavirenz (teratogenic)
  72. What is the mechanism of action of Anti-Influenza Drugs?
    Block neuraminidase activity required for release of new virus particles from infected cells
  73. Anti-influenza drugs are effective against symptoms related to infection with which influenza types?
    Influenza A and B
  74. What is the most effective method of preventing infection of influenza?
    Annual immunization against Influenza A and B
  75. What patient population is Type I (inactivated, administered IM) Influenza Vaccine recommended for?
    • Children aged 6-59 months
    • Pregnant women in any trimester
    • People older than 50
  76. Which Influenza vaccine type should NOT be used in pregnant patients or the immunosuppressed? Indicated for patients 5-49 years of age
    Type 2--Live-attenuated, intranasal
  77. Patients that receive the type 2-- live-attenuated, intranasal influenza vaccine should avoid contact with what type of patietns for at least 7 days?
    Severly immunocompromised patients
  78. Currently, what are the best options for prophylaxis and early treatment of susceptible H5N1 strains of the Avian Flu?
    Oseltamivir and Zanamivir
  79. What antiviral drug blocks viral polymerases (DNA polymerization, RNA polymerization, and RT) by binding to the pyrophosphate site?
    Foscarnet
  80. What are the clinical uses of Foscarnet (3)?
    • 1. Acyclovir-resist HSV in AIDS patients
    • 2. Acyclovir-resist VZV
    • 3. CMV retinitis in immunosuppresssed patients (alternative to ganciclovir)
  81. Definition:
    Glycoproteins secreted by virally-infected cells
    Interferons
  82. What function do human interferons perform in Anti-hepatitis B and C drugs?
    Promote an antiviral state in unaffected cells
  83. What drug is used in combination with interferon alpha for treating chronic hepatitis C virus?
    Ribavarin
  84. What is a key characteristic of Ribavarin, making it important for women taking it to avoid getting pregnant for at least 6 months after its discontinued use?
    Can stay in RBCs for months
  85. What drug is both teratogenic and embryotoxic for pregnant women, and so potent that pregnant women should avoid contact with anyone using it, and women should refrain from becoming pregnant for 6 months after its discontinued use?
    Ribavarin
  86. What is a key treatment for Human Papilloma Virus (HPV)?
    Gardasil
  87. Should Gardasil be used by pregnant women?
    No
  88. Definition:
    Gastroenteritis with fever, V, D, and dehydration
    Rotavirus
  89. Which type of bacteria have a single cell membrane and a thick peptidoglycan layer?
    Gram-Positive Bacteria
  90. Which type of bacteria have a thin peptidoglycan layer enclosed within a dual membrane system?
    Gram-Negative Bacteria
  91. Which type of antibiotics inhibit transpeptidase?
    Penicillin (beta-lactam)
  92. Definition:
    An adverse environment, signal, or condition that the bacterium must overcome in order to live, replicate, and grow in the environment
    Selective Pressure
  93. Definition:
    An organsim that can overcome selective pressure better than most others has a....
    Selective advantage
  94. Definition:
    A mechanism of bacterial genetic exchange that involves the transfer of "naked" DNA
    Transformation
  95. Definition:
    A mechanism of genetic exchange that involves transfer requiring cell-to-cell contact
    Conjugation
  96. Definition:
    A mechanism of genetic exchange that involves transfer mediated by a bacteriophage
    Transduction
  97. Major groups of helminths (3)?
    • Cestodes (tapeworms)
    • Trematodes (flukes)
    • Nematodes (round worms)
  98. What is the underlying principle of antimicrobial therapy? There are three ways to achieve this:
    1. Target a process vital and unique to the invading organism
    2. Use a toxic drug that can only be activated by the invading organism
    3. Selective uptake of a toxic compound by the invading organism
    Selective Toxicity
  99. What is the treatment goal with drugs against antimicrobials (in regard to MIC)?
    To maintain circulating concentrations of the drug above the MIC, because bugs can recover if dip below the minimum inhibitory concentration
  100. What is the most common adverse effect to antibiotics?
    Miscellaneous GI effects
  101. How can antibiotics cause an overgrowth of non-susceptible organisms?
    By disturbing the normal flora
  102. True or False:
    Antiseptics and Germicides are for external use only
    True
  103. What is the most important class of antibacterial cell wall synthesis inhibitors?
    Beta-lactam antibiotics
  104. What is the most common adverse effect of beta-lactam antibiotics?
    • Allergic reactions to the drug
    • Non-allergic toxicity of note: CNS problems (lethargy, confusion, seizures)

    **Allergic reactions most common problem
  105. What is the mechanism of action of beta-lactam antibiotics?
    Inhibit cell wall synthesis by convalently binding to enzymes (a.k.a. PBPs) in the bacterial cell membrane that function in the building and remodeling of the bacterial cell wall
  106. Beta-lactam antibiotics are most active against?
    Growing Bacteria
  107. True or False:
    The beta-lactam ring must be intact for it to be effective
    True
  108. What is the most common mechanism of resistance to beta-lactam antibiotics?
    The production of beta-lactamases--microbial enzymes that hydrolyze the beta-lactam ring, rendering the antibiotic ineffective
  109. How are penicillins most commonly excreted?
    In urine as unchanged drug
  110. What is the antibiotic of choice for many organisms, especially Gram positive bacteria?
    Penicillin
  111. How is the G form of penicillin administered?
    Penicillin G is given by injection because of erractic oral absorption
  112. What infection is resistant to beta-lactam penicillins, as well as most other antibiotics, and is a growing problem in hospital settings and in the community at large?
    MRSA
  113. Extended spectrum antibiotics, such as Ampicillin and Amoxicillin, are active against which bacteria?
    Gram positive and negative
  114. What are two clinical uses for Amoxicillin?
    • Acute otitis media/sinusitis
    • Lower respiratory infections
  115. What broader spectrum penicillin has the best activity against pseudomonas and is often combined with aminoglycoside?
    Piperacillin
  116. Penicillin Pharmocokinetics:
    What are the typical absorption qualities of penicillins?
    • Decreased by food (except Amoxicillin)
    • Take 1 hr before or 2 hrs after a meal
  117. Penicillin Pharmacokinetics:
    What is a concern with the excretion method of penicillins?
    Have rapid excretion in urine --> Patients with renal insufficiency can have high levels of penicillin build up and cause seizures
  118. Allergic reactions are classified as immediate, accelerated, or delayed. Which is most common with penicillins, and what are some common symptoms seen?
    • Delayed---days to weeks post exposure
    • See skin rashes, pruritis, urticaria
  119. What is "ampicillin rash"?
    A non-allergic skin rash seen in patients with infectious mononucleosis and lymphatic leukemia

    Can also happen with amoxicillin
  120. What are three qualities describing beta-lactamase inhibitors?
    • Poor antimicrobial effects
    • Irreversibly inhibit bacterial lactamases
    • Used only in combination with penicillins
  121. What is one notable use for beta-lactamase inhibitors?
    Mixed aerobic and anaerobic infections such as intra-abdominal infections
  122. Cephalosporins are similar to penicillins in what three ways?
    • Chemically
    • Mechanism of action
    • Toxicity profile
  123. What first generation cephalosporin has good tissue penetration and is often used for surgical prophylaxis (cardiac, thoracic, vascular, craniotomy, orthopedic, head and neck, C-section, etc.)?
    Cefazolin (parenteral)
  124. What second generation cephalosporin is widely used for prophylaxis during abdominal surgery due to activity against anaerobes?
    Cefoxitin
  125. Third and Fourth Generation Cephalosporins tend to do what better than the first two generations?
    Cross into CSF better
  126. Are cephalosporins safe to give to patients that have previously exprienced anaphylactic shock from penicillin?
    No
  127. Is cross reactivity of most 2nd, 3rd, and 4th generation cephalosporins with penicillins high or low?
    Low (2005 study showed it to be below 1%)
  128. What are two toxicities associated with Cephalosporins?
    • CNS excitation from high doses
    • Bleeding abnormalities and alcohol intolerance especially associated with NMTT side chain-- inhibits clotting factors
  129. Ceftriaxone (3rd gen used for gonorrheae and meningitis) should not be mixed with IV solutions containing what ion? Why is this contraindicated?
    • Calcium
    • Causes:
    • Fatalities in neonates
    • Contraindicated for all ages
    • Do not co-admin in same or different infusion lines or sites within 48 hours of each other
  130. Imipenem is metabolized by what renal enzyme?
    Dehydropeptidase
  131. What can be done to block the metabolism and nephrotoxicity of imipenem?
    Co-administer it with Cilistatin
  132. What is the drug of choice for enterobacterial infections (nosocomial pathogens responsible for range of infections: lower resp tract, skin, soft tissue, UTI, ophthalmic, etc.)?
    Carbapenems
  133. What drug has a low degree of cross allergenicity with other beta-lactam antibiotics due to the beta-lactam ring not being fused to a second ring?
    Aztreonam
  134. Which drug (and drug class) has a narrow spectrum, and is effective for Gram (-) bacilli only (e.g., Pseudomonas aeruginosa)?
    Aztreonam (Monobactams)
  135. Summary of Beta-lactams (no actual question!)
    --High degree of selective toxicity
    --Most bacteria will respond to beta-lactams
    *resistance most commonly due to inactivation of beta-lactamases
    --High incidence of allergic reactions
    *cross allergic reactions can occur (~5%)
    --Primarily renal excretion
    --CNS symptoms occur at high levels
    *Carbapenemas most problematic
  136. When are other inhibitors of cell wall synthesis useful (Vancomycin, Bacitracin, Fosfomycin, etc.)?
    Useful against Beta-lactamase-producing microbes because do not contain beta-lactam rings
  137. What are the adverse effects of Vancomycin (3)?
    • Causes tissue necrosis if given IM
    • Must be given by slow infusion
    • Nephrotoxic and is excreted from the kidney (must monitor kidney function)
  138. What is the main use for Vancomycin?
    • MRSA
    • *bacterias resistant to safer drugs
  139. What are some notable clinical uses of Vanco?
    • Sepsis, endocarditis, severe skin and soft tissue infection caused by MRSA
    • Taken orally for antibiotic-associated colitis (if resistant to metronidazole)
  140. What cell wall synthesis inhibitor is used topically for surface lesions of skin, in wounds, and on mucous membranes?
    Bacitracin
  141. What cell wall synthesis inhibitor is taken orally and used for urinary tract infections in a single dose; safe for pregnant women?
    Fosfomycin
  142. Most inhibitors of bacterial protein synthesis are considered to be what, with the important exception of Aminoglycosides?
    Bacteriostatic
  143. What type of elimination do macroglides engage in?
    Hepatic
  144. Do macroglides enter the CSF?
    No. They are well distributed throughout the body but do not enter CSF well (even if meninges are inflamed)
  145. What drug has a similar spectrum of activity to pen G and is often used in patients with penicillin allergy?
    Erythromycin
  146. True or False:
    Cross resistance is complete between Erythromycin and other macroslides
    True
  147. What is the best absorbed oral form of Erythromycin?
    Estolate Salt
  148. What is an adverse effect of Erythromycin?
    Acute cholestatic hepatitis (fever, jaundice, impaired liver function)--believed to be an allergic reaction
  149. What is a notable clinical use of Erythromycin?
    Penicillin allergic patients with staph, strep, or pneumococci infection
  150. What are 4 advantages of Clarithromycin over Erythromycin?
    • Relatively more potent
    • Acid stable
    • Better absorbed, less GI upset
    • Longer half-life--BID dosing vs QID for erythromycin
  151. What macrolide has a long half-life (~3 days) --> QD dosing; is not metabolized --> does not affect metabolism of other drugs in liver; and has very low plasma levels
    Azithromycin
  152. What drug is highly effective against anaerobic pathogens, including Bacteroides fragilis, and has excellent penetration into bone.
    Clindamycin
  153. What is a concern with Clindamycin?
    Antibiotic-associated colitis caused by an overgrowth of C. diff --> requires immediate treatment with metronidazole or vancomycin
  154. What is a notable clinical use of Clindamycin?
    Severe anaerobic infections (Bacteroides)
  155. What is one of the few antibiotics effective against Salmonella--treats Typhoid fever, and is effective against anaerobes?
    Chloramphenicol
  156. Chloramphenicol gets excellent penetration into....?
    CSF, ocular and joint fluids
  157. Use of Chloramphenicol is limited due to what serious toxicity?
    Aplastic anemia due to stem cell damage (RBC, WBC, and platelets)
  158. What antibiotics are primarily used for bacteria resistant to older drugs (MRSA, Vanco-resistant E. Faecium)
    Streptogramins
  159. What is Streptogramin primarily indicated for?
    Infections from vancomycin-resistant strains of E. faecium
  160. What antibiotic is reserved for treatment of infections caused by multiple drug resistant, Gram (+) bacteria?
    Oxazolidinones
  161. What antibiotic class form insoluble complexes with cations found in antacids, multivitamins, and dairy products?
    Tetracyclines
  162. Where are tetracyclines distributed, and what are they primarily used for based on this?
    • High concentrations in skin and saliva;
    • Used for dermatological and dental
  163. What is the tetracycline of choice for renally impaired patients?
    Doxycycline
  164. What is an adverse effect of Tetracyclines that makes them contraindicated for pregnant women and children under 8?
    Damage developing teeth and bone
  165. When is renal toxicity primarily seen in patients taking Tetracyclines, and what should be done as a preventive measure?
    Usually associated with taking expired Tets; advise patients to throw out outdated Tets
  166. Which is the drug of choice among the Tetracyclines?
    Doxycycline
  167. What are Tetracyclines primarily indicated for?
    STDs (gonorrhea, syphilis, chlamydia)
  168. What is a newly developed Tetracycline indicated for complicated skin and intra-abdominal infections; works well for many organisms that are Tet-resistant but also CANNOT be give to pregnant women or children under 8?
    Tigecycline
  169. What is the mechanism of action of Aminoglycosides?
    Bacteriocidal
  170. Which antibiotic type work synergistically with beta-lactam antibiotics--this combination is frequently used to treat severe infections?
    Aminoglycosides
  171. True or False:
    Aminoglycosides can be mixed in the same injection solution as beta-lactams
    False--they chemically inactivate one another
  172. Which class of Aminoglycosides is the most widely used aminoglycoside, is used to treat Gram (-) infections, and if often used synergistically with beta-lactams to treat severe infections (sepsis, pneumonia) resistant to other antibiotics often found in immunocompromised patients?
    Gentamicin
  173. Which Aminoglycoside is especially active against Pseudomonas aeruginosa?
    Tobramycin
  174. Which class of antibiotics inhibit DNA gyrase and are highly active against Gram (-) bacteria?
    Quinolones
  175. What antibiotic is a 2nd generation fluoroquinolone, has excellent Gram (-) activity, and is the most effective quinolone for P. aeruginosa?
    Ciprofloxacin
  176. What antibiotic is a generation 4 fluoroquinolone and is effective against anaerobes?
    Moxifloxacin
  177. Fluoroquinolones are all orally effective, but have drug interactions with what type of ions?
    Di- and tri-valent cations (antacids, multivitamins)
  178. What is the distribution of Fluoroquinolones?
    Penetrate well into prostrate and bone
  179. What are the adverse effects of Fluoroquinolones? Who are they contraindicated for?
    • Adverse effects on cartilage development (permanent in animals, not known in humans)
    • Contraindicated for pregnancy
    • Not recommended for children under 18
  180. What is an adverse side effect of Fluoquinolones, seen especially with norfloxacin? And what is the recommendation to counteract this side effect?
    • Crystalluria
    • Drink copious amounts of water
  181. What are some notable clinical uses of Fluoroquinolones (4)?
    • Most Gram (-) organisms
    • Excellent Pseudomonas activity
    • Prostatitis
    • Soft tissue, bone, joint, intra-abdominal and respiratory infections (except norfloxacin bc of poor absorption from gut)
  182. What is the most common treatment use for Rifamycins?
    Mycobacterial diseases, and primarily for treatment of TB
  183. True or False:
    Rifamycins are not used alone
    True, because resistance develops readily
  184. What antibiotic is effective against anaerobic bacteria (Bacteroides and Clostridium), antibiotic-associated enterocolitis, and is the drug of choice for E. histolytica infections?
    Metronidazole
  185. When are inhibitors of cell membrane function primarily used, and why (these include Daptomycin, Colistin)?
    Last resort drugs bc most are too toxic for routine use
  186. What inhibitor of cell membrane function is effective against Gram (+) organisms that are resistant to other drugs (MRSA, etc), and is used for skin and soft tissue infections?
    Daptomycin
  187. What is the mechanism of action of "sulfa" drugs?
    Compete with para-aminobenzoic acid (PABA) for the enzyme Dihydropteroate synthase
  188. Are sulfa drugs broad or narrow spectrum antibiotics?
    Broad Spectrum
  189. True or False:
    Most sulfa drugs are highly protein bound in serum (i.e. not active when protein bound) --> can displace other protein-bound drugs and proteins and limits renal elimination of sulfanomides
    True
  190. What is the most serious complication of Sulfonamides?
    Crystalluria
  191. What are some methods to prevent crystalluria in patients taking Sulfonamides (3)?
    • High fluid intake
    • Alkalinization of the urine (to make sulfas more soluble)--use sodium bicarbonate
    • Using mixtures of sulfa drugs in which each drug dose is lower than what would be taken individually
  192. Sulfonamides are contraindicated in pregnant women because of possible....?
    Kernicterus possible in neonates (displacement of bilirubin from albumin)
  193. What is a severe allergic reaction associated with Sulfa drugs?
    • Stevens-Johnson Syndrome--> (rare, skin and mucous membrane eruptions-->detachment of epidermis-->potentially fatal)
    • **epidermis sloughs off
  194. What inhibits dihydrofolate reductase?
    Trimethoprim
  195. What is the most common bacterial cause of UTIs, estimated to cause ~80% of cases?
    E. coli
  196. What urinary antiseptic is contraindicated for patients with glucose-6-phosphate dehydrogenase deficiency, because it causes hymolytic anemia and peripheral neuropathy in these patients?
    Nitrofurantoin
  197. Which antibiotic inhibits pyruvyl transferase (cell wall synthesis enzyme), has a single dose (3 g for adults) cure for uncomplicated UTIs, and is safe for use in pregnant patients?
    Fosfomycin
  198. What is the treatment plan for mycobacterial tuberculosis (very general)?
    Long-term treatment with combinations of drugs
  199. What combination of drugs, given for 9 months, can cure most susceptible TB?
    Isoniazid (INH) and Rifampin
  200. What is the drug of choice for prophylaxis and treatment of active and latent infections of TB; it inhibits mycolic acid biosynthesis (cell wall)
    Isoniazid (INH)
  201. What is given with Isoniazid (INH) to prevent the neuritis (in adults) and convulsions (in kids) usually associated with its administration?
    Pyridoxine (Vit B6)--> INH depletes B6
  202. What is a major adverse effect of Isoniazid?
    INH-induced hepatitis--> most frequent major toxicity (1% of pts); can be fatal-->must discontinue use immediately
  203. What is the most widely used drug in combination with Isoniazid or other first line agents for treatment of TB?
    Rifampin
  204. What are the adverse effects of Rifampin (3)?
    • Induces liver P450 enzymes--> inhibits effectiveness of oral contraceptives
    • Red-orange coloration of urine, tears, body fluids
    • Hepatoxic--> cholestatic jaundice and hepatitis
  205. What other rifamycins are recommended in place of Rifampin for AIDS pts taking protease inhibitors or NNRTIs (2)?
    • Rifabutin
    • Rifapentine
  206. What drug inhibits cell wall synthesis by blocking arabinosyl transferase? Adverse effects associated with this drug include Retrobulbar neuritis (loss of visual acuity, red-green color blindness-->vision checks recommended periodically) and is therefore contraindicated for children too young to permit assessment of red-green color blindness?
    Ethambutol
  207. What drug is highly effective in comination with INH and rifampin for short term (6 month) regimens, but has liver toxicity as an adverse effect (1-5% of pts) so much monitor pt liver function with its use?
    Pyrazinamide
  208. In combination chemotherapy for TB, what is the initial 'standard' 4 drug regimen?
    • Isoniazid
    • Rifampin
    • Pyrazinamide
    • Ethambutol
  209. When are second-line ant-TB drugs used?
    Reserved for use following the emergence of resistance to first-line agents
  210. When is the second-line anti-TB drug Streptomycin sulfate used?
    When an injectable drug is needed
  211. Is INH used to treat other mycobacterial diseases?
    No, only used for TB
  212. What is the drug of choice for Leprosy? What is the dosing regimen? What other drug can be used?
    • Dapsone
    • Once a week dosing
    • Rifampin
  213. What is the most prominent and important use of antibiotic prophylaxis--use of drugs to prevent infections?
    Bacterial Endocarditis
  214. When were new guidelines issued for prophylactic use of antibiotics in dentistry to prevent bacterial endocarditis?
    Summer of 2007

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