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76 Cards in this Set
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define: antibiotic
p139 |
old: substances produced by microorganisms that supress growth of other organisms. new: now include purely synthetic agents
antimicrobial = antibiotic (and antifungal) |
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how are antibiotics selective in their toxicity?
p139 |
they expoloit bichem differences b/w humans and microorganisms. ie "magic bullet" (paul ulrich) drug - cell walls, microsomal subunits, DNA gyrase, membrane sterols
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what are some things that could be targeted by antibiotics?
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cell walls
different microsomal subunits DNA gyrase membrane sterols |
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what drugs inhibit cell wall synthesis?
p139 |
Penicillins and Cephalosporins - b/c they resemble D-alanyl-D-alanine (cross linking PGcans). compete for transpeptidase = lysis
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what drugs inhibit bacterial protein synthesis?
p140 |
Erythromycins and Clindamycin, bind the 50s ribosomal subunit. no translocation, no elongation. leads to bacteriostatic actions
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what drugs disrupt cytoplasmic membrane?
p140 |
NYSTATIN (and other antifungals) bind sterols in memB. Form Pores. more side effects b/c subtle differences b/w mammalian and bacterial cell memB's
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What drugs discrupt DNA synthesis?
p141 |
FLUOROQUINONES and METRONIDAZOLE. F's inhibit DNA gyrase combating "supercoiling" of DNA
host cells do not have DNA gyrase |
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difference b/w narrow and broad (extended) spectrum antibiotics?
p141 |
no specific definitions. when choosing antibiotic it's always to use one that is effective against the organisms causing the infection and has Narrowest spectrum possible
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get effective antibiotic concentration a site of action. (dose administered, route of administration, distribution of the drug, frequency of administration)
p141 |
dose - aim 4-8X the MIC (loading dose good dentally) Route - serious infections, IV used (IM also bypasses stomach acid) Distribution - b/c solubility some antibiotics distribute more readily to bone, abscesses, brain, etc
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how frequent administer antibiotics?
p142 |
controlled by biotransformation and excretion rates. determines the maintenance levels in blood, should be above MIC's.
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time dependent antibiotics
vs concentration dependent antibiotics p142 |
timing big b/c thie concentrations fall below MIC and effectiveness curtailed, inhibitors of cell wall, zb.
Conc. dependent posess postantibiotic effects, inhibit bacteria after below MICs ie. erytrhomycin / clindamycin |
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age/size of bacterial infection. most antibiotics work best on actively dividing cells. when is best time to administer?
p142 |
soon for max benefits. or it gets established and lotta cells, more beta-lactamase activity and bacteria become less susceptible to antibiotics (inoculum effect). especially in abscess
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T/F antibiotics, when used correctly can cure us.
p142 |
actually its our host defense mechanisms. antibiotics jus limit # of pathological organisms. [our defense down w/ pathological conditions and drugs]
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what drugs hinder cell growth, weakening host defense?
p142 |
drugs that hinder cell grown include corticosterioids, antineoplastic agents, etc
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what are the 2 types of bacterial resistance?
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Natural - existed before discovery of antibiotic. ie. gm - bacteria are not effected by pennicillin
acquired - occurs as consequence of antibiotic use and is result of selection for resistance organism. horizontal (transduction, transformation) vertical (duplications) |
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direct toxicities in antibiotics are seen why?
p143 |
adverse effects that are the result of innate ability of antibiotic directly modify cellular processes of the host. (often more for those that interfere with protein synthesis)
orally - local, but allergies exist, look at pennicillin, zb. skin rash to anaphylaxis |
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indirect toxicities in antibiotics are seen why?
p144 |
distrubance of hosts microflora that allows overgrowth of less susceptible bacteria or fungal leading to various problems . SUPERINFECTIONS ! broader spectrum = higher risk
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what is the most serious superinfection caused by dental antibiotics?
p144 |
pseudomemranous colitis. caused by toxins produced by overgrowin Clostridium difficile. destroy intestinal mucosa. bloody diarrhea = talk to dr.
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Pennicillin
- pharmacokinetics - indications p145 |
absorbed well orally, resists stomach acid. distributes poorly in brain. doesn't undergo metabolism, peed out.
1st choice in acute orofacial infections. >90% effective + narrowest spectrum (not recommended for IE chemoprophylaxis) |
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why not pennicillin?
p145 |
allergy, toxic, resistance
allergy -> 5-15% population. skin rxn, cross allergenicity w/ other penicillins (and beta lactam agents), misdagnosed often (if someone has flu, zb) get tested |
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toxic/resistant pennicillin?
p145 |
low incidence of superinfection (diarrhea), little direct toxicity,
Resistant - subject to cleavage by beta lacamase (via staph, zb), conferred via plamids. can make fat PBPs with low penn affinity. |
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amoxicillin AMOXIL
pharmacokinetics p146 |
orally well absorbed (better than ampicillin), acid stable, same distribution as pen VK, 60% less prtoein binding than pen VK, longer half life, tid (good compliance), enerohepatic cycling (some)
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when use amoxicillin?
p146 |
First choice for oral IE chemoprophylaxis, longer duration. possible substitute for pen VK if compliance is an issue
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adverse effects of Amoxicillin?
p146 Amox - developed as an extended spectrum penicillin, dental advantage questionable |
similar pattern of allergnicity as pen VK. greater incidence of superinfection than pen VK (b/c broader spectrum)
Note: suseptible to penicillinase |
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Amoxicillin + Clavulanate (Augmentin) wtc?
p147 |
clavulanate inhibits the action of penicillinase, this combination expands effectiveness of amoxicillin. use if penicillinase-producers suspected (if pen VK failed) use for medically compromised pt.
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Cephalexin (KEFLEX) cephalosporin antibiotic, first generation agent.
What's its pharmacokinetics? p147 |
absorbed well orally
like pen VK, little is metabolized, excreted via urine suseptible to beta-lactamase (cephalosprinase) |
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indications for Cephalenxin?
p147 |
3rd choice for acute orofacial infections. 3rd in IE chemoprophylaxis regimen in pen-allergic pts
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adverse effects of cephalexin?
p147 |
much less allergenic than pen VK
8% cross allergenicty with penn's. those immeiately sesnitive to penn, contraindicated! 1st dose in Office ( if penn allergic) superinfection possible broad spectrum - GI problems |
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ERYTHROMYCIN (E-Mycin) - microlide antibiotics.
what's the pharmacokinetics? p148 |
orally well absorbed. base susceptible to stomach acid, often enteric coating. well distributed. take on empty stomach (except sterate form). undergoes enterohepatic cycling (pood out)
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indications for Erythromycin?
p148 |
2nd choice for penn-allergic pt's, if tolerable. not routinely used in IE chemoprophylaxis
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Adverse effects of erythromycin?
p148 resistance develops rapidly to erythromycin (all routes) and bactriostatic for most common oral pathogens |
allergenicity much less than pen VK, BUT cholesostatic hepatitis can occur.
SPASMOGENIC - cramp and diarrhea. low superinfections (narrow spectrum). will inhibit p450 in liver (esp CYP3A4) basis for many drug interactions |
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Azithromycin & Clarithromycin - 2nd generation macrolides. why's this any better than erythromycin?
p149 |
less spasmogenicity, tollerated better and longer duration, qd, or bid dosing, better dosing
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Azithromycin VS. clarithromycin
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clarithromycin has broader spectrum, including anaerobic oral pathogens
clarithromycin cna be taken With meals Azithro mycin is associated with fewer drug interactions |
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CLINDAMYCIN (CLEOCIN): lincosamides
pharmacodynamics? p149 |
well absorbed orally
noted for ability to penetrate bone undergoes considerable enterhepatic cycling. |
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indications for CLINDAMYCIN?
p149 |
penn allergic pts with acute orofacial infections, especially bone infections
adjuct to penn whin unsuccessful, anaerobes or P-ase producers FIRST choice for IE chemoprophylaxis in penn allergic pts |
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adverse effects of Clindamycin?
p149 |
low allergenicity and resitance development. Superinfections posssible. mostly pseudomembranous colitis (Bad rap)
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METRONIDAZOLE (Flagyl)
mechanism p150 |
reduced in cytoplasm by iron compounds, etc. generates nitro radical anion that attacks DNA
active only against obligate anaerobes |
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indicaions for METRONIDAZOLE
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adjunct with Pen VK when pen VK alone is not successful
refractory periodontal disease |
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TETRACYCLINE (Achromycin)
pharmacokinetics p150 |
absorption down by cations (Ca+, Fe, Mg, Al+) will precipitate
differential distribution to bone, skin fetus, teeth, enterohepatic cycling, inhibits GI organism |
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tetracycline indications
p150 |
refractory periodontal disease - after scaling and root planing, rarely used today.
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adverse effects of teteracycline
p150 |
discolors teeth causing enamel hypoplasia, contraindicated (prego). expiration date, b/c toxic breakdown, resistance fast, superinfection common (Broad specctrum, bacteriostatic)
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Doxycycline (Atridox, periostat), a tetracycline
indications? p151 |
refractory periodontal disease, adjunct to scaling and root planing.
limited clinical significance with extra expense and time required |
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Rationales for doxycycline ?
p151 |
ARIDOX - antibacterial activity directed to discrete area, limits systemic side effects.
PerioSTAT - systemic delivery of subantibiotic doses, inhibit inflammatory activity of PMNs w/in sulcus, limits toxicity, limits resistance development |
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Macrolide antibiotics have the ability to block cytochrome p450 nzymes (CYP3A4 zb) see high drug levels so contraindications with what drugs?
p151 |
"satin" anticholesterol agents (ZOCOR)
felodipine (PLENDIL) ergot alkaloids (CAFERGOT) sildenafil (VIAGRA) warfarin (COUMADIN) |
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why should someone be careful when drugs Digoxin (Lanoxin) and erythromcin are taken together?
p152 |
GI bacteria help regulate blood levels of digoxin by feeding off the drug when it enters intestines, lowers conc grad of digoxin.
erythromycin decreases these bacteria, increaseblood digoxin, a NTI drug |
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Methotrexate (RHEUMATREX) and penicillins: penn's are CONTRAINDICATED, why?
p152 |
penicillins interfere with the methotrexate metabolism which increase risk of renal toxicity of MTX
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contraceptives and antibiotics. break through pregnancy. 75% of all incidents involve what?
p152 |
rifampin, causes inducction of liver CYP450 system. no problem with other antibiotics. warn patients.
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t/f administration of an antibiotic prior to dental procedure can decrease risk of a posttreamtnet infection
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true
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Macrolide antibiotics have the ability to block cytochrome p450 nzymes (CYP3A4 zb) see high drug levels so contraindications with what drugs?
p151 |
"satin" anticholesterol agents (ZOCOR)
felodipine (PLENDIL) ergot alkaloids (CAFERGOT) sildenafil (VIAGRA) warfarin (COUMADIN) |
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why should someone be careful when drugs Digoxin (Lanoxin) and erythromcin are taken together?
p152 |
GI bacteria help regulate blood levels of digoxin by feeding off the drug when it enters intestines, lowers conc grad of digoxin.
erythromycin decreases these bacteria, increaseblood digoxin, a NTI drug |
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Methotrexate (RHEUMATREX) and penicillins: penn's are CONTRAINDICATED, why?
p152 |
penicillins interfere with the methotrexate metabolism which increase risk of renal toxicity of MTX
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contraceptives and antibiotics. break through pregnancy. 75% of all incidents involve what?
p152 |
rifampin, causes inducction of liver CYP450 system. no problem with other antibiotics. warn patients.
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t/f administration of an antibiotic prior to dental procedure can decrease risk of a posttreamtnet infection
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true
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rationale for antibiotic chemoprophlaxis, 2
p153 |
1. dental procedures cause transient bactermias, endocarditis is life threatening. aim is to us only when antibiotic risk will not exceed potential benefits.
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Cardiac conditions asoociated with IE include: prosthetic cardiac valve, previous infective endocarditis and what?
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CHD (congenital heart disease) 1. unrepaired cyanotic CHD (palliative shunts/ conduits), 2. completely repaired congenital heart defect with prosthetic material or device w/in 6 mo. 3. repaired CHD prosthetic, 4. cardiac transplantation who have valvulopathy
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when are procedures where endocarditis prophylaxis is recomended for high risk pts vs NOT recommended
p154 |
Yes: procedure manipulates gingival tissue or periapical region of teeth or perforation of oral mucosa
no: local anesthetic in infected tissue, placing appliance, placing brackets, taking radiographs, adjusting appliances, shedding 1' teeth, or bleeding from trauma to the lips or oral mucosa |
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specific regimens, see p 155
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see p 155, ties it together well
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what if pt is already taking antibiotics?
p 156 |
us antibiotic that targets differnt mechanism of action, reducing cross-resistance
if on pen, then use clindamycin zb |
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what if pt has unexpected bleeding?
p156 |
stop treatment, go back to typical regiment
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what if pt has multiple day treatments?
p156 |
use typical acute maintenance dose of antibiotic between treatments and use the typical prophylatic dose 30-60 min before the next days procedure
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what patients are at potential increased risk of hematogenous total joint infections, HIGH risk?
p156 |
those with inflammatory arthropathies, rheumatoid arthritis, systemic lupus erythematosus, or disease/drug/radiation-induced immunosuppression
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what patients are at potential increased risk of hematogenous total joint infections, MODERATE risk?
p156 |
insulin-dependent diabetic (type I), first 2 yrs following joint placement, previous prosthetic joint infection, malnourishment and hemophilia
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hematogenous prosthetic total joint infection.
prophylaxis (antibiotic) may be indicated because of risk of bacteremia when? p157 |
same as cadidates for endocarditis prophylaxis
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when is prosthetic joint antibiotic prophylaxis considered?
p157 |
used to prefent infection of total knee and hip prosthesis SHOULD be considered if pt is a high risk pt, used if procedure = high incidence of bacteremia
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when may prosthetic joint antibiotic prophylaxis considered?
p157 |
if pt is a moderate RISK pt and you are performing a procedure that is associated with High Incidence of Bacteremia
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consultation: pt presents w/ prophylaxis recommendationcontrary to JADA guidelins, a consultation with the physician is suggested. purpose of mtg?
p157 |
determine if there are any unusual circumstances that would lead physician to suggest a regimen that deviates for the guidelines, if not, follow guidelines not ithe physicians recommendations
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p 158 specific drug regimens:
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see p 158
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pt has acute orofacial infection. day 1: incise and drain, collect specimen for testing later and Rx?
p159 |
penicillin V (Pen-VEE K); 1000mg loading dose; 500mg Q6H "for 5 days"
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pt has acute orofacial infection. day 2: call pt, if not improved (fever, pain swelling, malaise) and Rx?
p159 p159 |
metronidazole (FLAGYL) 250mg Q6H "for 5 days" to be taken along with the Pen-Vee K
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pt has acute orofacial infection. day 3: if not improved, switch antibiotics and Rx?
p159 |
clindamycin (CLEOCIN) 300mg loading dose; 150 mg Q6H "for 5 days", send speciment o labe for sensitivty testing
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pt has acute orofacial infection. day 4: if not improved?
p159 |
if not improved, send to hospital dental service
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__________ would be a rational subsitution for Pen VEE K for the initial antibiotic. broader spectrum makes it a bit more effective against orofacial pathogens, more help for the host defense mechanism. p159
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augmentin
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for penicillin-allergic patients, what would be the 1st drug of choice?
p159 |
Clindamycin (cleocin), 150mg Q6H "for 5 days"
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what is the "backup drug" if Clindamycin doesn't work (and pt is penicillin allergic)
p159 |
Clarithromycin (BIAXIN) 1000mg loading dose; 500mg Q12H "for 5 days"
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duration of antibiotic treatment, t/f should not be a ritual! rarely should exceed 5 days t/f not need to be taken for all 5 days, discourage what?
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t/t/t
discourage indiscriminat use of antibiotics ot decrease resistance development |
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how long take antibiotics after systems subside?
p160 |
2 days after
also, if source of infection is eliminated, an orofacial infection should not "rebound" once the systoms of infection have subsided |