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2011-02-21 19:51:15
anti CD

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  1. what is a narrow spectrum antibiotic?
    covers only G+ve agents
  2. what is a broad spectrum antibiotic?
    covers G+ve and G-ve
  3. what do the broadest spectrum antibiotics cover?
    • G+ve
    • G-ve
    • anaerobes
  4. what is a bactericidal agent?
    • kills organism
    • eg penicillin
  5. what is a bacteriostatic agent?
    • stop replication
    • but organism still there, alive and dormant
    • then phagocytes comes to kill organism
  6. who should bacteriostatic agents NOT be used in?
    • 1. neutropenic patients
    • 2. site of infection where neutrophils cant get to
  7. what is MIC?
    • minimum amount of antibiotic (mg/l) available in the bloodstream
    • after a therapeutic dose
    • that will inhibit an organism
  8. why is MIC important?
    cant have an MIC that is unsafe - as even though it would kill the organism, it would also kill the patient. so need to know the MIC
  9. what is MBC?
    minimum bacterial concentration: lowest concentration needed to kill the bacteria
  10. what is generally higher, MIC or MBC?
  11. SE to kidney, liver, bone marrow?, children?, pregnancy?
    spectrum: MRSA? pseudomonas? anti anaerobic?
  12. name 3 intracellular organisms
    • chlamydia
    • Mycoplasma Tb
    • salmonella typhi (typhoid)
  13. what are 2 forms of resistance?
    • innate: eg if G+ve agent only, wont act on G-ve structures
    • acquired: acq genetic info that changes the organism so drug no longer active eg G+ve: B-lactamase (staphylococci), PBP (penicillin binding protein), G-ve: porins permeability, efflux.
  14. what SE assoc with sulphonamide?
    stephens johnsons syndrome
  15. what is the spectrum of penicillin V (oral)
    narrow spectrum: G+ve ONLY mainly streptococcal except also neisseria meningitis (not gonoccocal) which is G-ve
  16. what are the routes of penicillin?
    • penicillin V oral
    • Penicillin G iv (aka ben pen)
    • procaine penicllin im
  17. what are uses of penicillin V?
    penicillin V: oral - use for strep sore throat, prophylaxis in splenectomy pt.
  18. why is penicillin V use limited?
    • qds
    • poor absorption in stomach
    • poor tissue distribution
    • (but reaches in adequate concentration in hyperaemic tonsil
  19. what are uses of iv ben pen? and what do you need to remember with it?
    • remember if give high dose remember its got Na/K salt.
    • infective endocarditis against strep viridans,
    • cellulitis against GAS,
    • GBS in children,
    • meningococal meningitis,
    • pneumonia
  20. what are SE of B lactam?
  21. what is MOA of penicillin?
    inhibit cell wall synthesis
  22. what is penetration of penicillin?
    penetrates most tissue including inflamed meninges
  23. what are advantages of penicilins?
    • safe in children, pregnancy
    • not many kidney, liver or BM problems
    • cheap
  24. what is major problem of penicillin?
    cleaved by beta lactamase
  25. is there an im version of penicillin? what is it called and use?
    • procaine penicillin im
    • use: treponema palladium (syphilis)
  26. which penicillin is B lactamase stable therefore can be used for staph?
  27. what is the spectrum of fluclox?
    narrow: staph (some strep, but MIC to GAS is much higher than pen)
  28. what is route of fluclox?
    • iv: staph endocarditis, toxic shock, osteomyelitis, septic arthritis
    • oral: simple staph in community - abscess, folliculitis
  29. what are the 4 problem G+ve agents?
    • MRSA: res to flucloxacillin
    • Enterococci in general: e. faecium is resistant to amoxicillin
    • VRE: res to vancomycin
    • CNS: (in prosthesis and lines) most resistant to flucloxacilin
  30. which group of abx used for problem G+ve organism?
    • glycopeptides
    • vancomycin or teicoplanin
  31. what is the spectrum of glyocpeptides?
    narrow spectrum as only for problem G+ve agents
  32. what is the problem with glycopeptide?
    • iv only
    • penetration limited
    • vancomycin nephrotoxic so have to measure levels
    • expensive
    • resistance - VRE
  33. what is route of glycopeptide?
    iv only
  34. what is penetration of glycopeptide?
    • poor
    • none to CSF as large molecule
  35. why is vanc expensive?
    need to measure levels as nephrotox
  36. when use oral vancomycin?
    C Diff (bowel)
  37. what is used to treat VRE?
    • oxazolidinones eg linezolid (only G+ve, oral and iv, excellent penetration skin and brain.
    • daptomycin ( lipopeptides)
  38. which 2 abx do u have to measure levels for?
    • vancomycin
    • gentamicin
    • as nephrotoxic
  39. what is spectrum of linezolid?
    only G+ve
  40. what is route of linezolid?
    oral and iv
  41. what is penetration of linezolid?
    • v gd skin, soft tissue
    • CSF
  42. what are the 3 important SE of linezolid?
    • suppression of BM: aplastic anaemia, thombocytopenia
    • peripheral neuropathy inc optic neuritis
    • cannot be given with MAOi
  43. what is the MOA of linezolid?
    acts on ribosome
  44. what are 2 uses of linezolid?
    • 1st line for VRE
    • 2nd line for MRSA
  45. what are broad spectrum penicillins good for?
    exponential gram -ve cover
  46. what was 1st broad spec pen?
  47. what is simplest, commonest G-ve infection you see in community?
    • UTI eg E coli
    • > 50% resistant to amoxicillin as have learnt to make beta lactamse (enterobetalactamase)
  48. what is MOA of trimethroprim?
    dihydrofolate reductase inhibitor
  49. what is Rx of UTI?
  50. what is Rx of UTI in pregnancy?
    amoxillin high dose
  51. what is use of amoxicillin?
    • UTI in pregnancy
    • not B lactamase stable (so cant use with staph)
    • don't use for sore throat empirically as EBV rash
  52. what is advantage of amoxicillin?
    • some G-ve activity
    • tds
    • better absorbed from stomach
    • oral
  53. if want to switch from iv ben pen to oral form, what use?? and why
    • use amoxicillin
    • not penicillin G as poor absorption and penetration and need it qds
  54. which 2 organisms is amoxicillin the DRUG OF CHOICE for?
    • enterococcal: but NOT e.faecium as its resis to amox!
    • listeria
  55. what is the main limitation of amoxicillin
  56. what is trade name for co-amoxiclav?
  57. what is advantage of co-amoxiclav?
    • beta lactamase stable
    • because the clavulanate binds to the beta lactamase produced by organism
    • releasing the amoxicillin
  58. could you use co-amoxiclav to treat a pure staph infection?
    • you could as beta lactamse inhibitor
    • but wouldn't because it is too broad a spectrum when you can hit the staph with a narrow spec eg fluclox
  59. what is spectrum of co-amoxiclav?
    • G+ve
    • G-ve
    • anti-anaerobic
  60. why is it bad to treat staph infection with co-amox?
    you are going to wipe out anaerobes so all the normal flora
  61. what are the main anaerobic antibiotics?
    • metronidazole
    • co-amoxiclav
    • piptazobactam
    • carbapenems
  62. when are you likely to get multiple org eg staph, anaerobes and G-ve infection?
    • aspiration pneumonia: mouth flora - streps and anaerobes
    • chronic osteomyelitis in diabetics
    • involve GI: diveriticulitis, appendicitis, tooth abscess,
    • severe sinusitis
  63. when in community are you likely to use co-amoxiclav?
    CAP secondary to chronic exacerbation of COPD where you need to cover strep and HAEMOPHILUS which is potent producer of beta lactamase
  64. what is scenario of use of co-amox?
    • sepsis without cause
    • need to cover broad spectrum
  65. which penicilins cover pseudomonas? route and spectrum?
    • piptazobactam = piperacillin & tazobactam
    • tazobactam: beta lactamase inhibitor
    • route: only iv
    • spectrum: staph, strep, anaerobic, G-ve, pseudomonas
  66. what are the problem G-ve organisms? why?
    • pseudomonas
    • klebsiella
    • enterobacter
    • proteus
    • serratia
    • acinetobacter
    • as multi drug resistance and ESBL
  67. what are ESBLs?
    extended spectrum beta lactamase?
  68. what can you NOT use for ESBL?
    • cephalosporin
    • beta lactam inhibitor combination may fail!
  69. what do you treat for ESBL producing organisms?
    carbapenems eg meropenem and ertapenem
  70. what is spectrum for carbapenems?
    very broad: G+ve, G-ve, anaerobic and pseudomonas
  71. what do carbapenems not do?
    problem causing G+ve (4 eg MRSA) so need glycopeptides for them
  72. what is route of carbapenems
    iv not oral
  73. what is problem with ertapenem?
    no anti pseudomonal activity
  74. why would u use ertapenem?
    if ESBL producing organism
  75. where do you normally get pseudomonas from?
    hospital acquired not community
  76. what is the spectrum for 1st gen cephalosporin?
    • some G+ve
    • minimal G-ve
  77. give an example of 1st generation cephalosporins
  78. what % of pen allergic are also cephalosporin allergic?
    10-12% so use with caution
  79. can you use cephalosporins for staph aureus?
    yes even though MIC is much higher than flucloxacillin
  80. what is the main use of 1st gen cephalosporin? why?
    • UTI in pregnancy where you cant give amoxicillin because its resistance or pt is allergic
    • they concentrate in urine well
  81. what is route of 1st gen cep?
  82. what is name of a 2nd gen cep?
  83. what is route of cefuroxime
    • iv
    • (oral has no better properties than 1st gen)
  84. what is spectrum of 2nd gen cep?
    broad spectrum so G+ve and G-ve
  85. what is use for iv cefuroxime?
    • serious UTI - cystitis, pyeloneph
    • strep pneumo pneumonia
    • COPD pt as want to cover haemophilus aswell which is G-ve
  86. what does cefuroxime NOT cover?
  87. how do you know when to use co-amoxiclav or 'cefuroxime and metronidazole'?
    • depends on hospital
    • hospital acquired infection - C-diff with cephalosporin treatment
  88. what have cephalosporins been assoc with?
    • C-difficile
    • enterococcal infections as they are resistant to cephalic
    • rise in ESBL producing organisms
  89. if you are treating infection above the diaphragm what do you want to add to cefuroxime?
    macrolide eg erythromicin or clarythromycin
  90. if you are treating infection below the diaphragm what do you want to add to cefuroxime?
    metronidazole (gut anaerobes)
  91. which cephalosporin is anti-pseudomonal?
    • ceftazidime
    • problem G-ve as long as not ESBL producers
    • prob G-ve: klebsiella, enterobacter, proteus etc
  92. name 3 3rd gen cephs?
    • ceftriaxone
    • ceftazidime
    • cefotaxime
  93. what is the spectrum of ceftriaxone?
    • G-ve: meningococcus, haemophilus
    • G+ve: pneumococcus
    • these covered are most likely cause of acute meningitis thats why treat empirically with ceftriaxone
  94. what is route of ceftriaxone?
  95. what is difference between cefotaxime and ceftriaxone?
    • ceftriaxone: slugging of bile in neonate and raised LFTs so use cefotaxime
    • cefotaxime: tds (ceftriaxone is od)
  96. what is cause of getting pseudomonas infection?
    hospital acquired eg ventilator associated pneumonia
  97. how to diagnose pen allergy?
    history: if anaphylactic avoid all beta lactam
  98. what is alternative to beta lactam?
  99. where do macrolides act?
    ribosome 50S
  100. name 3 types of macrolides
    • erythromycin
    • clarythromycin
    • azithromycin
  101. what is spectrum of macrolides?
    • narrow spectrum
    • G+ve
  102. are macrocodes bacteriostatic or cidal?
  103. what is erythromycin good for?
    • alternative to penicillins
    • staph and strep
    • where you can give it orally - out in community (not iv)
  104. why should erythromycin not be used iv?
  105. what is penetration of erythromycin like?
    no penetration to CSF
  106. what are macrocodes especially good for treating? give eg
    • atypical pneumonias eg
    • myocplasma pneumonia
    • chlamydia pneumonia
    • legionella pneumonia
  107. why cant you use penicillin to treat mycoplasma pneumonia?
    • because it doesn't have a cell wall and penicillons act by inhibiting cell wall!
    • need macrocodes which cause
  108. what is empirical Rx of pneumonia?
    beta lactam eg penicillin & macrolides (atypicals)
  109. what is advantage of macrolide for mycoplasma pneumonia and chlamydia pneumonia specifically and why?
    • they are intracellular organisms
    • macrocodes penetrate intracellularly very well
  110. what is the difference between erythromycin and clarythromycin?
    clary: iv and oral, better tolerated iv, marginally better spectrum as also covers haemophilus
  111. in community, which macrolide is better?
    clarythromycin: alternative for penicillin, good for atypicals, got some haemophilus activity.
  112. what is azithromycin used for?
    • gum clinic: STI eg chlamydia
    • typhoid as intracellular
  113. what is adv of azithromycin?
    • very long half life
    • huge intracellular concentration
  114. what type of organism is clindamycin?
  115. what is spectrum of clindamycin?
    • staph and strep ie G+ve
    • anaerobic
    • (but no G-ve cover)
  116. what is advantage of clindamycin and therefore its use?
    • acts on ribosome switch off toxin making material in cell
    • so good for toxic infections: TSS, necrotising fasciitis
  117. what is clindamycin the alternative to fluclox for?
    • orthopaedic infection
    • penetrates bone and joint v well
  118. what do you combine fluclox for orthopaedic infections?
    fusidic acid
  119. what are uses of clindamycin?
    • 1. aspiration pneumonia: as has strep and anaerobic cover
    • 2. toxin assoc conditions eg TSS, necrotising fasciitis
    • 3. penetration into bone and joint
    • 4. abscesses
  120. route of clindamycin?
    oral and iv
  121. disadvantage of clindamycin?
    assoc with C-diff diarrhoea
  122. what give if patient had pseudomonal or pyelonephritis if allergic to penicillin?
    quinolone - ciprofloxacin
  123. for bone and joint infections what is first line? (remember combo)
    • flucloxacillin
    • fusidic acid
  124. if pen allergic what give for pseudomonas?
  125. what is eg of quinolone?
  126. what is spectrum of quinolone?
    • broad
    • staph but NOT STREP
    • all G-ve including pseudomonas
    • not anti-anaerobic so if treating gut infection add metronidazole
  127. what is the only non-beta lactam anti-pseudomonal?
    ciprofloxacin (quinolone)
  128. what is the penetration of cipro?
    • v gd penetration intracell
    • adequate brain penetration
  129. what are 2 main problems with cipro?
    • widespread resistance
    • C-diff recently
  130. is cipro liscenced for everyone?
    not liscenced in pregnancy and not yet in children
  131. which group of children get lots of pseudomonal lung infections?
    • cystic fibrosis
    • so use cipro off licence - document risk v benefit
  132. what is drug of choice for food poisoning?
    ciprofloxacin - salmonella
  133. what is ciprofloxacin very good for and why?
    • food poisening
    • epididymitis
    • orchitis
    • prostatitis
    • cystitis
    • concentrates very well into that tissue
  134. when should you NOT give cipro?
    • strep infection
    • skin, soft tissue
    • pneumonia
    • sore thraoat
  135. what is special about cipro and its anti-pseudomonal activity?
    • its the only oral anti-pseudomonal
    • only one for pen allergic
  136. what are the newer quinolones called? and advantage?
    • levofloxacin
    • moxifloxacin
    • have activity against PNEUMOCOCCAL
  137. what is site of action of quinolones?
    • DNA gyrase- not cell wall acting
    • so single agent to treat pneumonia
  138. what is disadv of newer quinolones?
    not anti-pseudomonal
  139. what is spectrum of aminoglycosides?
    • broad spectrum
    • G+ve: staph NOT strep
    • G-ve: potent, including pseudomonas
  140. route of gentamicin?
    only iv
  141. SE of gentamicin?
    • nephrotoxicty oto
    • measure levels
  142. where in body will gent act best?
    • 100% water soluble - so not lipid soluble so wont cross BBB, no penetration into cells or tissue
    • if remove O2 it will not work
    • so only a bacteraemia agent - blood
    • not lung consolidation as no oxygen
    • not for cellulitis!
    • but can be used as an adjunct
  143. when would you add gentamicin?
    if suspect septicaemia - rigors
  144. what is gent an adjunct for?
    • IE: anti-microbial synergy against strep and staph
    • beta lactam creates leaky cell wall and gentamicin enters and acts on ribosome
  145. what are the 2 types of resistance?
    • innate
    • acquired
  146. what are the 3 steps required for resistance?
    • 1. genetic modification: mutation/acquire DNA or plasmid/loss of DNA
    • 2. selection pressure
    • 3. add antibiotic - selective advantage
  147. name 4 methods of resistance?
    • 1. B lactamase production
    • 2. efflux pumps
    • 3. target site alteration eg PBP or ribosomal binding site
    • 4. impermeability: porins loss in G-ve
    • 5. bypass ie even though the antibiotic blocks one enzyme, the organism will make another enzyme
  148. why are porins only related to G-ve organisms?
    G-ve have thick outer membrane: LPS which is hydrophilic so they evolved to get porins for things to get through and also antibiotics could get through! but when loss them the antibiotics cant get through
  149. what mechanism of resistance does MRSA use?
    PBP2a: unable to bind B-lactam abx
  150. name 5 ways to reduce resistance?
    • 1. narrow spectrum antibiotic to reduce the potential selection pressure on other organisms
    • 2. culture before use broad spectrum antibiotics then target the antibiotic to the organism once know the organism = DE-ESCALATION
    • 3. multiple drugs of different MOA = COMBINATION THERAPY
    • 4. reserve new abx
    • 5. prescribe when necessary
    • 6. stop antibiotic early when you know its not the right organism as the longer the bacteria is exposed to a selection pressure, more resistance!
    • 7. dose: short sharp dose. cipro acquires resistance in stepwise mutations
  151. how do you stop infection spreading?
    infection control
  152. name 4 iv Rx for MRSA
    • vancomycin
    • teicoplanin
    • gentamicin
    • chloramphenicol
  153. name 4 oral Rx for MRSA
    • rifampicin
    • tetracycline eg doxycycline
    • fusidic acid
    • trimethorpim
  154. what are the 3 last ditch Rx for MRSA? and routes
    • 1. linezolid: iv and oral
    • 2. daptomycin: iv only
    • 3. tigecycline
  155. which type of MRSA infection can you not use daptomycin and why?
    MRSA pneumonia as it is inactivated by surfactant
  156. what are the SE of linezolid?
    • irreversible: neuropathy, inc optic neuropathy
    • reversible: BM suppression
  157. what is MOA of glycopeptides?
    inhibit cell wall synthesis by steric hindrance ie as they are bulky they can physically stop the molecules coming together to make the cell wall.
  158. what is the disadvantage of glycopeptides?
    • they are big molecules
    • so don't penetrate tissue well
    • stay in blood (so good to Rx MRSA bacteraemia)
  159. what is the disadvantage of vancomycin?
    need to measure levels - which is useful for MRSA bacteraemia as want to know how much is getting to the organism
  160. what is the major SE of fusidic acid?
    very hepatotoxic
  161. if there is a deep seated pneumonia or osteomyelitis MRSA, what is Rx?
    • combination
    • vanco/teic + oral drug eg rifampicin (as oral has better absorption)
  162. when is the most likely scenario to use doxycycline in MRSA infection?
    mild MRSA infection eg cellulitis
  163. which agent is used for prosthesis infected by MRSA?
    rifampicin as penetrates biofilms well
  164. when is the only use vancomycin orally?
    c diff diarrhoea (2nd line after metronidazole) as it stays in gut where we want it to act
  165. what is Rx for a man due for operation but has MRSA in nose?
    • need to decolonize. treat at home
    • 5 days MUPIROCIN up nose
    • chlorhexidine shampoo
    • mouthwash
    • side room
    • adjust surgical prophylaxis to cover MRSA
  166. what does ESBL stand for?
    extended spectrum beta lactamases
  167. what makes an organism ESBL?
    if it is able to hydrolyse 3rd generation cephalosporins and penicillins
  168. which organisms commonly have ESBL?
    enterobacteriacaea eg E Coli, Klebsiella
  169. what is Rx for systemic ESBL infection?
    • 1. carbapenems
    • 2. amikacin (aminoglycoside) - sometimes
    • 3. colistin
    • 4. tigecycline (tetracycline)
  170. what are SE of colistin?
    • fits
    • renal failure
  171. which carbapenem would you use for ESBL, why?
    • ertapenem as it does not have pseudomonal activity
    • don't want to use meropenem as you increase the selection pressure and get resistance of mero to pseudomonas as it is everywhere in environment
  172. how Rx local ESBL infection? eg UTI
    • nitrofurantoin
    • fosfomycin
  173. which abx use for ESBL UTI in pregnancy?
  174. if a pregnancy patient is pen allergic and has a simple UTI, what is Rx?
    1st gen ceph
  175. if a pregnant woman is pen allergic and has a complex UTI, what is Rx?
  176. which 2 classes of abx act on 30s ribosome?
    • aminoglycosides
    • tetracycline
  177. which 3 class of abx act on 50s?
    • macrolides
    • chloramphenicol
    • clindamycin - lincosamides