Lecture 1- Exam 1 Flashcards
Normal Flora of mouth: (5)
- Viridans group streptococci
- Other strep species
- Lactobacillus
- Actinomyces species
- Prevotella species
Most of the normal flora of the mouth are considered:
commensal organisms - they live in the mouth, help the mouth, and the mouth doesn’t mind them
Of the following normal flora of the mouth, which are gram positive? Which are gram negative?
- Viridans group streptococci
- Other strep species
- Lactobacillus
- Actinomyces species
- Prevotella species
Gram positive =
1. Viridans group streptococci
2. Other strep species
3. Lactobacillus
4. Actinomyces species
gram negative = prevotella
The main gram negative species we see in the mouth =
prevotella
What differentiates gram positive from gram negative bacteria?
cell wall
- Bulk of oral bacteria
- primarily cocci or irregular shaped (pleomorphic)
- oxygen tolerance varies from facultative anaerobes to strict anaerobes
- cell wall has THICK peptidoglycan layer
Gram positive oral bacteria
- facultative anaerobe
- periodontal pockets
- dental plaques
- carious teeth
- gram positive organism
Actinomyces
- facultative anaerobe
- produces lactic acid
- role in dentine carries rather than enamel caries
- gram positive organism
Lactobacillus
- facultative anaerobe
- cocci
- produces lactic acid
- some implicated in caries
- gram positive organism
Streptococcus
Why do we have more drugs available to gram positive bacteria?
our target site, the cell wall is more readily available to attack
If oxygen is present, this bacteria will readily utilize, however if oxygen is not available, they will still find the means to survive:
facultative anaerobes
Main strep species associated with caries:
strep mutans
What allows strep mutans to cause dental caries?
acetogenic (acid producing) & aciduric (acid tolerant)
The “bad” strep species of the oral cavity:
Strep Mutans
The “good” strep species of the oral cavity:
strep mitis & strep sanguinis
- acidogenic
- aciduric
- highly associated with caries
- notorious for dentin lesions
strep mutans
- first oral organisms detected in infants (primary colonizers)
- commensals
- peroxigenic (produce hydrogen peroxide)
Strep mitis & Strep sanguinis
Why are S. mitis and S. sanguinis considered “good” bacteria for the mouth?
They are peroxigenic (produce hydrogen peroxide), which inhibits the growth of S. mutans, and P. gingivalis, and other oral pathogens
Gram ____ bacteria have a higher resistance to antibiotics
gram negative
Many gram negative bacteria are found in the mouth but especially established in:
subgingival plaque
Describe the oxygen requirements for gram negative oral bacteria:
range of oxygen tolerance but most are strict or facultative anaerobes
Describe the cell wall in gram negative oral bacteria:
- thin peptidoglycan layer
- contains B-lactamase
- LPS/endotoxin
T/F: We see more of a systemic effect with gram negative bacteria in the mouth
True - due to LPS/endotoxin
List the gram negative bacteria found in the oral cavity:
- Porphyromonas
- Prevotella
- Fusobacterium
- Actinobacillus/Aggregatibacter
- Treponema
- Neisseria
- Veilonella
Gram negative bacteria that are periodontal pathogens:
- P. gingivalis (MAJOR)
- P. intermedia
- F. nucleatum
gram negative bacteria of the oral cavity associated with aggressive periodontitis:
A. actinomycetemcomitans
gram negative bacteria of the oral cavity that plays an important role in acute periodontal conditions (ANUG)
Treponema
T/F: PCNS and Amoxicillin are good drugs to use for initial gram positive infections:
true
Why are PCNS and amoxicillin less effective on gram negative bacteria?
because the beta lactamase produced by many of these bacteria
Drug that ARRESTS the growth of an organism:
Bacteriostatic
What must be present in order for a bacteriostatic drug to be effective?
must have active immune system
Drug that KILLS the organism:
Bactericidal
What type of patients would you AVOID using a bacteriostatic drug on?
patients without an immune system (neutropenic, meningitis, or endocarditis for example)
Type of drugs more commonly used when patients have poor immune system function?
Bactericidal
What are the two mechanisms of bactericidal drugs?
- cell wall inhibitors
- DNA inhibitors
List some examples of bactericidal drugs that are cell wall inhibitors:
- beta lactams
- PCNS
- Cephalosporins
List some examples of bactericidal drugs that are DNA inhibitors:
- Fluoroquinolones
- Metronidazole
How do bacteriostatic agents work?
protein synthesis inhibitors
List some examples of bacteriostatic agents that work via protein sytnthesis inhibitors:
- Macrolides
- Clindamycin
- Doxycycline
Drugs that work better the higher the peak concentration gets above the minimum inhibitory concentration
Concentration dependent
MIC:
minimum inhibtory concentration- (of a drug necessary to inhibit the growth of an organism)
How do we typically dose concentration dependent drugs?
Give HIGH dose with extended intervals between doses
Concentration dependent drugs often have a ____ that is fairly long
PAE (post-antibiotic effect)
PAE
post-antibiotic effect (bacterial suppression after antibiotic concentrations fall below MIC)
Type of drug that is dependent on the amount of TIME rather than concentration above the MIC
Time dependent drug
How do we dose time-dependent drugs?
Due to no PAE, we have to dose them more frequently throughout the day (in order to keep the concentrations above the MIC)
Higher concentration —> greater killing
Concentration dependent
Give some examples of concentration dependent drugs:
Fluoroquinolones (dosed 1x daily) & Metronidazole (dosed 2x daily)
- Concentrations need to be reinforced , leading to more dosing
- More exposure –> more killing
Time-dependent drugs
Give some examples of time-dependent drugs:
Beta lactams (NO PAE)
Clindamycin (some PAE)
Azithromycin (some PAE)
tetracyclines (some PAE)
Fill in the following information for Cephalexin:
- Usual dosage range:
- Professors recommended dosing:
- _____ depended drug
- Categorized as a ____
- Half-life:
- Excretion:
1) 250mg-1000mg Q 6hrs OR 500mg Q 12hrs
2) 500mg Q6hrs
3) Time-dependent
4) Beta-lactam
5) Approximately 1 hr
6) 80-100% as unchanged drug in 6-8hrs
Patients who have a PCN allergy receive more:
- Vancomycin
- Clindamycin
- Fluoroquinolones
What are two aspects that are “increased” due to PCN allergies:
- increased cost of antibiotics
- increased length of hospitalization
When someone has a PCN allergy, and other drugs are prescribed in place of, we see increased drug resistant organisms including:
- 69% increased risk of MRSA infections
- 30.1% more VRE infections
- 26% increased risk of C. diff infection
Looking at statistics, _____ in 10 patients report a PCN allergy
1: 10
What percentage of people DO NOT have a PCN allergy?
99%
Less than 1:1000 PCN allergies results in:
anaphylaxis
Three characteristics of side effects:
- Predictable (pharmacological action)
- Dose related
- Can affect ANYONE
Four characteristics of drug allergies:
- Unpredictable (hypersensitivity rxn)
- NOT dose related
- Cannot affect
- Antibody or T-cell stimulation
Resembles allergic reactions but are not immune-mediated:
allergic-like or pseudo allergic reaction
Give two examples of pseudo-allergic rxns:
- Vancomycin infusion reaction
- Morphine rash
Antibody responsible for anaphylaxis:
IgE
If a patients response to a drug is rash, when you give them that drug again, their response will be:
rash
T/F: There is a genetic component to allergies
false- NO genetic component
Less than ___% of all reported PCN allergies result in anaphylaxis
1%
Rash characterized by skin breakdown/ falling off
SJS
What are some high risk signs of PCN allergy indicating likely an IgE or T-cell response:
- Lip/facial swelling
- Breathing difficulty/ wheezing
- Skin peeling
- Mouth blisters
- Drop in BP
T/F: Hives is a reason to avoid PCN
False
Most common cause of hives?
viral infections
T/F: Common rash and itching likely do not represent true IgE allergy and therefore , DO NOT require avoidance of PCN
True
Helps distinguish a side effect rash from an allergic reaction:
time of onset
T/F: If a rash appears within one hour of initial dose of drug, it is much more likely for that to be a sign of a true allergic reaction
true
- Delayed onset ( 6+ hours after drug course begins)
- Typically less prurititic
- Lesions lasting more than 24 hours
- Fine desquamation with resolution over days to weeks
Benign T-Cell mediated (NOT A TRUE ALLERGIC RXN)
- Onset minutes to hours after drug given
- Significant puritis
- Raised off the skin
- Each lesion lasting less than 24 hours
- Fades without scarring
IgE mediated (true allergic rxn)
- Onset days to weeks into treatment course
- Mucosal and/or organ involvement
- Blistering and/or desquamation
- Usually requires hospitalization
Severe T-cell mediated or Severe cutaneous
T/F: PCN true IgE reaction is rare
True
Are the following indicators a patient may truly have a PCN allergy?
- fam history of PCN allergy
- GI symptoms
- Headache
- yeast infection
NO
Is there cross-sensitivity between PCN and cephalosporin allergies
no
PCN and Cephalosporins both contain:
Beta-lactam rings
T/F: The allergy to PCN is related to the beta-lactam ring
FALSE (its due to the r-side chain)
Although there is little cross-sensitivity with PCN and cephalosporins rxns, the most common cephalosporins rxns when a patient is allergic to PCN occur with:
Cephalosporins with a similar R side chain to PCNs (1st & 2nd generation cepaholsporins)
1 . Do you need to avoid amoxicillin? 2. Can you use a cephalosporin given the following situation?
Drug: PCN
Rxn: Rash
Timing: Unsure of onset
How long ago: 20+ years ago
Treatment: None
- No
- Yes
- Do you need to avoid amoxicillin? 2. Can you use a cephalosporin given the following situation?
Drug: PCN
Rxn: unknown
Timing: unsure
How long ago: 30+ years ago
Treatment: none
- No
- Yes
- Do you need to avoid amoxicillin? 2. Can you use a cephalosporin given the following situation?
Drug: Amoxicillin
Rxn: Rash
Timing: 2 days
How long ago: 5 years
Treatment: none
- No
- Yes
- Do you need to avoid amoxicillin? 2. Can you use a cephalosporin given the following situation?
Drug: Augmentin
Rxn: Rash/ itching
Timing: 4 days
How long ago: 12 years
Treatment: none
- no
- yes
- Do you need to avoid amoxicillin? 2. Can you use a cephalosporin given the following situation?
Drug: IV PCN
Rxn: Difficulty breathing
Timing: hours
How long ago: 50+ years
Treatment: Hospital
- yes
- yes (certain cephs)
- Do you need to avoid amoxicillin? 2. Can you use a cephalosporin given the following situation?
Drug: Ampicillin
Rxn: Skin ulcerations
Timing: 1-2 days
How long ago: 15-20 years
Treatment: Hospital
- yes
- yes (certain cephs)
The deadliest antibiotic you can prescribe:
Clindamycin
What is the main risk associated with the dangers of Clindamycin:
C. difficile infection (25-fold increased risk)
Once c-diff is contracted, one in five people will get it again.
one in three people who get recurrent c-diff will:
die within 6 months
Most significant risk factor for C-diff infection:
antibiotics
the highest risk for c-diff is ___ after antibiotic exposure
first month
To reduce the risk of c-diff, a dentist should prescribe _____ antibiotics as opposed to ___. As well as using a ___ duration.
one; two
shorter
Patients taking ____ are twice as likely to contract C-diff due to antibiotic use
PPI
List the components to C-diff prevention through antibiotic stewardship:
- Limit spectrum of antibiotic therapy
- Limit duration of antibiotic therapy
- Limit combination antibiotic therapy
you’ve an antibiotic script to the patient with the following. How can you help to prevent c-diff:
- 65+ yo
- recent hospitalization or nursing home
- weak immune system (HIV/AIDS, cancer, or on immunosuppressive)
- previous c-diff infection
- taking PPI
prescribe probiotic
Probiotics reccomended for adults and children on antibiotic treatment:
- S. Boulardii
- L. acidophillus + L. casei
- L. acidophillus + L. delbrueckii + B. bifidum
- L. acidophillus + L. delbrueckii + B. bifidum + S. salivarius
Who might we recommend the use of a probiotic?
- Individuals 65+ yo
- Recent hospitalization of nursing home
- Weak immune system
- Previous C. diff infection
- Anyone taking PPI
____% of PCN allergies labels are acquired before the age 3.
75%
_____ are the best anti-infectives
Beta-lactams
(extremely powerful, extremely effective, extremely safe)
B-Lactam mechanism of action:
Binds & inhibits Penicillin Binding Protein (PBP)
Binds to PCN binding proteins (PBP); blocks cell wall synthesis causing the walls to leak; lower cell death threshold
Beta-lactams
T/F: ALL betal lactase are bactericidal
True!
Most used & effective antibiotics with least toxicity:
beta lactams
What accounts for the differences in beta lactams? (Such as acid stability, absorption, spectrum, susceptibility to beta-lactamases)
Side chains
T/F: Beta lactams cannot cross the placenta and are not distributed into breast milk
False- THEY ARE placenta crossing and distributed in breast milk
Natural PCNs include:
- Penicillin G
- Penicillin VK
Natural Peniccilins mechanism of action is predominately active agains:
strep species
Natural Penicillins are ineffective against:
gram negative species
Extended spectrum penicillins are also referred to as:
aminopenicillins
Aminopenicillins include:
- ampicillin
- amoxicillin
What is the benefit of the amino group on aminopenicillins?
They are able to penetrate the gram negative cell wall
All PCNS (amino & natural) are inhibited by:
beta-lactamases
Enzymes that break down beta lactams:
beta-lactamases
Resistance mechanisms utilized by bacteria to avoid antibiotics:
- Efflux pumps
- Beta-lactamases
- RNA modification
What is the reason behind adding Calulanate with Amoxicillin?
Clavulanate is a beta-lactamase inhibitor
Clavulanate + Amoxicillin =
augmentin
What does Augmentin work against (clavulanate + Amoxicillin)
more gram negatives, anaerobes & staph
If you have a dental infection with an abscess that has failed amoxicillin, what is a suitable option?
Augmentin
When an abscess is present in the mouth, we should start to think:
gram negative anaerobes
Abscesses on the outside of the body =
Abscesses on the inside of the body =
MRSA
gram negative anaerobes
Group of antibiotics that have a B-lactam ring as part of the structure:
B-lactams
Enzyme released by bacteria that disables the B-lactam ring thus the antibiotic is ineffective:
B-lactamase
Compound added to a B-lactam antibiotic that disables the B-lactamase thus the antibiotic is effective again:
B-lactamase inhibitor
A major side effect with augmentin:
diarrhea
List the steps needed in order to calculate prescriptions:
- What dose to use
- Get weight to kg
- Use recommended dose and kg to calculate patients specific dose
- Divide total daily dose into Q12 or Q8 hrs (for amoxicillin)
- Determine strength of suspension
Which of the following antibiotics will effectively and consistently inhibit/kill Streptococcus species?
a- Penicillin (Pen VK)
b- Amoxicillin (Amoxil)
c- Amoxicillin/clavulanate (Augmentin)
All of the above
Which of the following antibiotics consistently retains the ability to inhibit/kill streptococcus species and oral gram-negative bacteria?
a- Penicillin (Pen VK)
b- Amoxicillin (Amoxil)
c- Amoxicillin/clavulanate (Augmentin)
Amoxicillin/clavulanate (Augmentin)
Which of the following antibiotics consistently retains the ability to inhibit/kill streptococcus species and oral gram-negative bacteria, and Bacteriodes (anaerobes)?
a- Penicillin (Pen VK)
b- Amoxicillin (Amoxil)
c- Amoxicillin/clavulanate (Augmentin)
Augmentin
Which antibiotic is NOT a beta-lactam
a- Penicillin (Pen VK)
b- Amoxicillin (Amoxil)
c- Amoxicillin/ Clavulanate (augmentin)
d- Azithromycin (Zithromax)
d- Azithromycin
Which of the following antibiotics carries the highest risk for diarrhea?
a- PCN (pen vk)
b- Amoxicillin (amoxil)
c- Amoxicillin/Clavulanate (augmentin)
Augmentin