Dental Antibiotic Pharmacology Flashcards
(104 cards)
1
Q
what are the normal flora of the mouth
A
- viridans group streptococci
- other strep spps
- lactobacillus
- actinomyces spps
- preveotella spps
2
Q
what is the main gram negative in the mouth
A
prevotella spps
3
Q
describe gram positive organisms
A
- bulk of oral bacteria
- primarily cocci or irregular shape (pleomorphic)
- oxygen tolerance varies from facultative anaerobes to strict anaerobes
- cell wall has thick peptidoglycan layer
4
Q
are bacteria in the mouth more gram negative or gram positive
A
gram positive
5
Q
what are the 3 important genera of gram positive oral bacteria
A
- actinomyces
- lactobacillus
- streptococcus
6
Q
what type of bacteria is actinomyces and where is it found in the mouth
A
- facultative anaerobe
- periodontal pockets, dental plaques, on carious teeth
7
Q
what type of bacteria is lactobacillus and what does it do
A
-facultative anaerobe
- produce lactic acid, role in dentine caries rather than enamel caries
8
Q
what type of bacteria is streptococcus and what does it do in the mouth
A
- faculatative anaerobic cocci
- produce lactic acid some implicated in caries
9
Q
oral streptococci are referred to as:
A
viridians streptococci
10
Q
what does strep mutans do
A
- acidogenic (acid producing) and aciduric (acid tolerant) species
- highly associated with caries
- bacterial communities collected from dentin carious lesions contain notorious acidogenic and aciduric species including S mutans, Scardovia wiggsiae, parascardovia denticolens, and lactobacillus salivarius
11
Q
what does strep mitis and S sanuinis do
A
- first oral organisms detected in newborn infants
- commensals
- peroxigenic (produce hydrogen peroxide) inhibits the growth of S mutans and porphyromonas gingivalis and other oral pathogens
12
Q
describe gram negative organisms
A
- many gram negative bacteria found in the mouth, especially in established subgingival plaque
- range of oxygen tolerance but most important strict or facultative anaerobes
- some fermentative, produce acids which other organisms use acids as an energy source, others produce enzymes which break down tissue
- cell wall different to gram positive with a thin peptidoglycan layer, has B-lactamase which breaks down penicillin, also has LPS/endotoxin
13
Q
what are the gram negatives in the oral cavity and what are they associated with
A
- porphyromonas: P.gingivalis major periodontal pathogen
- prevotella: P. intermedia a periodontal pathogen
- fusobacterium: F. nucleatum periodontal pathogen
- actinobacillus/aggregatibacter: A.actinomycetemcomitans associated with aggressive periodontisis
- treponema: group important in acute periodontal conditions - ANUG
- neisseria
- veillonella
14
Q
what does bacteriostatic mean
A
arrests growth of organisms
15
Q
bacteriostatic must have:
A
active immune system
16
Q
what does bactericidal do
A
kill the organism
17
Q
what is the MOA of bactericidal antibiotics
A
- cell wall inhibitors: beta lactams, penicillins, cephalosporins
- inhibit DNA: fluoroquinolones, metronidazole
18
Q
which agents are better for patients with immunosuppression and severe disease
A
bactericidal
19
Q
what is the MOA of bacteriostatic ABs
A
- protein synthesis inhibitors: macrolides, clindamycin, doxycyline
20
Q
describe concentration dependent ABs
A
- higher peak concentration
- more extensive/faster kill-> greater killing
- maximize peak concentration (higher doses)
21
Q
what is the post antibiotic effect
A
bacterial suppression after antibiotic concentrations fall below MIC
22
Q
describe time dependent ABs
A
the more time above the MIC, more inhibition
- maximize duration of exposure above MIC
- concentrations need to be reinforced leading to more dosing
- more exposure -> more killing
23
Q
what ABs are concentration dependent
A
fluoroquinolones and metronidazole
24
Q
what are the the time dependent killing drugs
A
- No PAE: beta lactams
- Some PAE: clindamycin, azithromycin, tetracyclines
25
what is the usual dose range of cephalexin
250-1,000mg every 6 hours or 500mg every 12 hours
26
what type of drug is cephalexin, what is its half life and excretion
- time dependent: works best the longer concentrations stay above MIC
- half life: about 1 hour for adults
- excretion: urine 80-100% as unchanged drug in 6-8 hours
27
what does the excretion time of cephalexin suggest
4-6 hours of subtherapeutic blood concentrations with Q12 hour dosing
28
what is the cephalexin prescription for cellulitis
500mg 4 times daily
29
what is the cephalexin prescription for cystitis
500mg twice daily
30
what is the usual dosage range for amoxicillin for immediate release or extended release
- immediate release: oral 500mg to 1g every 8-12 hours
- XR: 775mg once daily
31
what is the amoxicillin prescription for periodontitis
oral- 500mg every 8 hours in combination with metronidazole for 7 to 14 days, used in addition to periodontal debridement
32
what is another acceptable dosage for amoxicillin
875mg po BID immediate release
33
what is the absorption of amoxicillin immediate and extended release
- immediate: rapid with or without food
- XR: rate of absorption is slower compared to immediate release formulations; food decreases the rate but not extent of absorption
34
what is the distribution of amoxicillin
- readily into the liver, lungs, prostate, muscle, middle ear effusions, maxillary sinus secretions, bone, gallbladder, bile and into ascitic and synovial fluids, poor CSF penetration
35
what is the protein binding of amoxicillin
20%
36
what is the half life elimination of amoxicillin
adults: immediate release: 61.3 minutes
- extended release: 90 minutees
37
what is the time to peak of amoxicillin
capsule, oral suspension: 1-2 hours; chewable tablet 1 hour; extended release: 3.1 hours
38
what is the excretion of amoxicillin
urine (60% as unchanged drug)
39
what are the downfalls of having an allergy to amoxicillin
- receive more vancomycin, clindamycin, and fluoroquinolones
- 63-158% higher cost of antibiotics
- increase length of hospitalization, average 0.59 more days
- increased drug resistant organisms
- 69% increased risk of MRSA infections
- 30.1% more VRE infections
- 26% increased risk of C. difficile infection
40
describe a side effect
- predictable, dose related, can affect anyone
41
what is an example of an overdose
hepatic failure (acetaminophen)
42
what is an example of a side effect
nephrotoxicity (with aminoglycosides); diarrhea (amoxicillin)
43
which is more common: an allergy or side effect
side effect
44
describe an allergy
- unpredictable (hypersensitivity reaction), not dose related, cannot affect anyone
- anaphylaxis or photoallergy
- antibody or T-cell stimulation
45
describe allergic-like or pseudo-allergic reactions and give examples
- resemble allergic reaction; NOT immune mediated
- vancomycin infusion reaction; morphine rash
46
what is the mechanism of the delayed onset benign cutaneous reaction
T-cell
47
what is the mechanism of acute onset benign cutaneous reaction
IgE
48
any non-SJS rash history to amoxicillin, re-exposed to amoxicillin ______ tolerate with no subsequent reactions
94-96%
49
what are the low risk penicillin allergy assessment symptoms
- non-hive rash
- itching
- hive rash
- diarrhea
- vomiting
- nausea
- runny nose
- cough
- family hx of allergy
50
what are the high risk symptoms for penicillin allergy
- lip/facial swelling
- difficulty breathing/wheezing
- skin peeling
- mouth blisters
- drop in BP
51
hives is _______ to avoid penicillin
not a reason
52
viral infections cause _____ of all cases of acute hives in children
more than 80%
53
what is the presentation of benign T-cell mediated cutaneous drug reactions
- delayed onset (greater than 6 hours after course begins)
- typically less pruritic than IgE mediated reactions
- each lesion lasts more than 24 hours
- fine desquamination with resolution over days to weeks
54
describe the presentation of IgE mediated cutaneous drug reactions
- onset minutes to hours into course
- significant pruritis
- raised off the skin
- each lesion lasts less than 24 hours
- fades without scarring
55
what is the presentation of severe T cell mediated or severe cutaneous reactions
- onset days to weeks into treatment course
- mucosal and/or organ involvement
- blistering and/or skin desquamination
- usually requires hospitalization
56
what are the low risk reaction symptoms and what is the action
- isolated reactions unlikely allergic (gastrointestinal symptoms, headaches)
- self limited rash
- remote (more than 10 years) non-severe reaction
- family history of Pcn allergy
- action: prescribe amoxicillin course or perform a direct amoxicillin challenge under observation
57
what are the medium risk symptoms and action
- reactions with IgE features but not anaphylaxis
-action: skin test plus amox challenge or graded challenge
58
what are the high risk symptoms and what is the action
- anaphylactic symptoms
- positive skin testing
- recurrent reactions
- reaction to multiple Beta lactam antibiotics
- action: skin test plus amoxicillin challenge
59
what is considered in the allergy assessment
- describe rxn: extent, where, itching, red, pain, duration, route administered
- timing of rxn: immediate (less than 4 hours), delayed (more than 24 hours)
- how long ago did rxn occur
- any treatment required?
60
what symptoms are not true allergies of penicillin and what do you give instead
- family history of penicillin allergy, GI symptoms, headache, yeast infection
- comfortable giving any penicillin
61
what symptoms are likely not a type 1 allergy and what do you give instead
- hive and non-hive rash reports (not SJS-like)
- may give amoxicillin, especially with distant history and non- immediate onset benign skin reactions
62
what is the risk of using amoxicillin
- no risk if the reaction is GI, headache, yeast infection, family history
- any non-SJS rash history to amoxicillin, re-exposed to amoxicillin 93-94% tolerate with no subsequent reactions
63
what oral antibiotic has the highest fatal, serious, and overall ADR rates
clindamycin
64
risk of clindamycin is ______ higher than amoxicillin
15 times higher
65
what has the lowest fatal, serious, and overall ADR rates
amoxicillin
66
outpatients with clindamycin antibiotic are ______ to develop C. difficile infection
5x more likely
67
when is the highest risk for c. difficile infection after clindamycin
first month after antibiotic exposure
68
risk for c.difficile infection remains elevated for how long
3 months after exposure
69
what can clindamycin cause
c. difficile infection
70
cross reactivity for cephalosporins with similar side chains is _____
higher
71
in cephalosporins without similar side chains to penicillin is considered _____ and ________
low risk and safe in patients with reported history or positive skin test
72
what are the cephalosporins that do not have similar side chains to penicillins
- oral: cefuroxime, cefdinir
- IV: cefazolin, ceftriaxone, cefepime
73
CDI is _____ in patients prescribed a PPI and antibiotic vs antibiotic alone
twice as high
74
exposure to PPI prior to initial CDI event _______ risk of recurrence
doubles
75
how can you prevent antibiotic issues
- limit spectrum
- limit duration
- limit combination
76
when would you consider recommending probiotics with the antibiotic
- 65 years and older
- recent hospitalization or nursing home
- weak immune system
- previous C. diff infection
- taking proton pump inhibitors
77
what are the history elements that favor low risk of penicillin hypersensitivity
- remote history of symptoms not suggestive of severe reaction more than 5-10 years ago
- delayed onset urticaria
- urticaria only, greater than 5-10 years ago
- self limited mild exanthem incompatible with allergy
- gastrointestinal symptoms only
- family history of penicillin allergy only
- avoidant from fear of allergy only
78
what percentage of penicillin allergy labels are acquired by age 3
75%
79
what are the consequences of a penicillin allergy label
- pressure prescribing of 2nd and 3rd line antimicrobials
- increased inappropriate antibiotic selection
- increased mortality risk during cancer and infection treatment
- delay the onset of appropriate antimicrobial therapy
- increase treatment failures/surgical infections
- associated increase in multidrug resistant infections
- longer lengths of stay
- higher healthcare costs
80
what are the best anti- infectives
beta lactams
81
what are the two main beta lactams
- penicillins
- cephalosporins
82
what are the penicillins that are beta lactams
- penicillin
- amoxicillin/ampicillin
- dicolxacillin
- peperacillin
83
what are the cephalosporins that are beta lactams
- cephalexin
- cefuroxime
- cefaclor
- cefprozil
- cefdinir
84
what is the beta lactam MOA
binds and inhibits penicillin binding protein
- block cell wall synthesis causing walls to leak
- lower cell death threshold
- includes penicillins, cephalosporins, carbapenems
85
all beta lactams are:
bactericidal
86
beta lactams are the ___used and effective antibiotics with_____
most used; least toxicitiy
87
side chains in beta lactams account for:
acid stability, absorption, spectrum, susceptibility to beta lactamases
88
how are beta lactams absorbed in pregnant women
cross placenta and distributed in breast milk
89
how are beta lactams eliminated
high renal excretion
90
which penicillins are inhibited by beta lactamases
penicillin G
- penicillin K
- ampicillin
amoxicillin
91
what are the resistance mechanisms to beta lactams
- efflux pumps
- beta lactamases
- RNA modifcation
92
what are the beta lactamase inhibitors
- calvulante (paired with amoxicillin)
- sulbactam (paired with amoxicillin)
- tazobactam (paired with piperacillin)
93
what is the MOA of beta lactamase inhibitors
- irreversibly bonds with beta lactamase
- ties up all beta lactamase
- allows the antibiotic to persist and extends activity to beta lactamase producing pathogens
94
beta lactamase inhibitors extends more coverage:
more gram negatives, anaerobes and staph
95
augmentin =
more gram negatives, anaerobes and staff
96
what is augmentin usually prescribed for with augmentin
dental infections with abscess or failed amoxicillin
97
what are b-lactams
- group of antibiotics
- have beta lactam ring as part of their structure
98
what is b-lactamase
- enzyme released by bacteria
- disables the bea-lactam ring thus the antibiotic is ineffective
99
what is beta lactamase inhibitor
- compound added to b-lactam antibiotic
- disables the beta lactamase thus antibiotic is effective again
100
what is the amoxicillin dose for adults and peds
- adult: 500mg PO Q8 hours
- pediatric: 20-40 mg/kg/day divided Q8 hours or 25-45 mg/kg/day divided Q12 hours
101
what is the dose for augmentin
adult:500mg PO Q8 hours or 875mg PO Q12 hours
- peds: 20-40 mg/kg/day divided by Q8 hours
or 25-45 mg/kg/day divided Q12 hours
102
is diarrhea associated more with augmentin, amoxicillin or penicillin
augmentin
103
what is the rate of diarrhea with augmentin
25%
104
