Lecture 1- Exam 1 Flashcards by Abagayle Moody

Normal Flora of mouth: (5)

Viridans group streptococci
Other strep species
Lactobacillus
Actinomyces species
Prevotella species

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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

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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

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The main gram negative species we see in the mouth =

prevotella

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What differentiates gram positive from gram negative bacteria?

cell wall

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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

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facultative anaerobe
periodontal pockets
dental plaques
carious teeth
gram positive organism

Actinomyces

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facultative anaerobe
produces lactic acid
role in dentine carries rather than enamel caries
gram positive organism

Lactobacillus

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facultative anaerobe
cocci
produces lactic acid
some implicated in caries
gram positive organism

Streptococcus

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Why do we have more drugs available to gram positive bacteria?

our target site, the cell wall is more readily available to attack

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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

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Main strep species associated with caries:

strep mutans

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What allows strep mutans to cause dental caries?

acetogenic (acid producing) & aciduric (acid tolerant)

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The “bad” strep species of the oral cavity:

Strep Mutans

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The “good” strep species of the oral cavity:

strep mitis & strep sanguinis

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acidogenic
aciduric
highly associated with caries
notorious for dentin lesions

strep mutans

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first oral organisms detected in infants (primary colonizers)
commensals
peroxigenic (produce hydrogen peroxide)

Strep mitis & Strep sanguinis

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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

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Gram ____ bacteria have a higher resistance to antibiotics

gram negative

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Many gram negative bacteria are found in the mouth but especially established in:

subgingival plaque

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Describe the oxygen requirements for gram negative oral bacteria:

range of oxygen tolerance but most are strict or facultative anaerobes

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Describe the cell wall in gram negative oral bacteria:

thin peptidoglycan layer
contains B-lactamase
LPS/endotoxin

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T/F: We see more of a systemic effect with gram negative bacteria in the mouth

True - due to LPS/endotoxin

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List the gram negative bacteria found in the oral cavity:

Porphyromonas
Prevotella
Fusobacterium
Actinobacillus/Aggregatibacter
Treponema
Neisseria
Veilonella

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Gram negative bacteria that are periodontal pathogens:

1. P. gingivalis (MAJOR) 2. P. intermedia 3. 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?

1. cell wall inhibitors 2. 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: 1. Usual dosage range: 2. Professors recommended dosing: 3. _____ depended drug 4. Categorized as a ____ 5. Half-life: 6. 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:

1. increased cost of antibiotics 2. 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:

1. Predictable (pharmacological action) 2. Dose related 3. Can affect ANYONE

Four characteristics of drug allergies:

1. Unpredictable (hypersensitivity rxn) 2. NOT dose related 3. Cannot affect 4. 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:

1. Vancomycin infusion reaction 2. 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

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:

1. Lip/facial swelling 2. Breathing difficulty/ wheezing 3. Skin peeling 4. Mouth blisters 5. 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

Is there cross-sensitivity between PCN and cephalosporin allergies

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

1. No 2. Yes

1. 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

1. No 2. Yes

1. 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

1. No 2. Yes

1. 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

1. no 2. yes

1. 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

1. yes 2. yes (certain cephs)

1. 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

1. yes 2. 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:

1. Limit spectrum of antibiotic therapy 2. Limit duration of antibiotic therapy 3. 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:

1. S. Boulardii 2. L. acidophillus + L. casei 3. L. acidophillus + L. delbrueckii + B. bifidum 4. L. acidophillus + L. delbrueckii + B. bifidum + S. salivarius

Who might we recommend the use of a probiotic?

1. Individuals 65+ yo 2. Recent hospitalization of nursing home 3. Weak immune system 4. Previous C. diff infection 5. 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:

1. Penicillin G 2. 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:

1. ampicillin 2. 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:

1. Efflux pumps 2. Beta-lactamases 3. 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:

1. What dose to use 2. Get weight to kg 3. Use recommended dose and kg to calculate patients specific dose 4. Divide total daily dose into Q12 or Q8 hrs (for amoxicillin) 5. 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