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Antibiotic Use In Dentistry
Kevin Nakagaki, D.D.S.
Director, Hospital Dental Clinic
University of Minnesota
Writing Prescriptions
Rx: Drug Name (can be generic) Unit Dose
(ex: Pen V-K 500 mg, Elixer, Sol’n)
Disp: # of pills, milliliters (ml)
Sig: Directions for use. q24h (daily), q12h, q8h, q6h, q4h,
prn pain, till gone
Refills__
Signature
DEA #
General Rules
 Write Legibly!!
 Remember your audience (Generally non-docs)
this will improve compliance.
 Preferable to order specific hourly dosage time
(q12h vs. bid, q8h vs. tid, etc.)
 Sig: Specify # of pills to take each dose
 Prescribe an endpoint. (prn pain, till gone)
Barry Brainfart Dental Clinic 666 Bite Me Ln
Crossbyte Falls, MN Ph: 555-YOU-HURT
Pt. Name:

Rx:

Disp:

Sig:
Refill____
Address:
DOB:
Date:
Barry Brainfart, DDS
DEA:______________________
Antibiotic Strategies
 Cardinal Rules: 1) Use the right drug.
2) Use the right dose. 3) Use the correct
dosing schedule. 4) Correct duration.
 Hard and Fast—Especially early. Why?
 Use a loading dose to rapidly achieve
therapeutic blood levels.
 Avoid combinations of bacteriostatic and
bacteriocidal drugs.
Considerations
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Gram Positive?
Gram Negative?
Mixed Infection?
Anaerobes?
Discussion: Antibiotic Choice
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Narrow Spectrum?
Extended/Broad Spectrum?
Designer Antibiotics?
Anaerobes? Consider if the infection is
present > 3days or if no improvement.
Narrow Spectrum Antibiotics
 Specific for the pathogen.
 Fewer disturbances of non-pathogenic
bacteria.
 Fewer side effects.
 Rapid response for sensitive organisms.
 Ex: Pen VK, Pen G, Erythromycin
Broad Spectrum Antibiotics
 Affects both Gram + and Gram – bacteria,
better for mixed infections.
 May give up some effectiveness for Gram +
to gain effectiveness for Gram -.
 Examples: Amoxicillin, Ampicillin
Common Pathogens
Necrotic pulp and apical abscesses
Obligate anaerobic bacteria
Gram negative rods
Prevotella & porphyomonas spp.
Fusobacterium spp.
Campylobacter rectus
Gram positive rods
Eubacterium spp.
Actinomycetes spp.
Gram positive cocci
Peptostreptococcus spp.
Facultative anaerobic bacteria
Gram positive cocci
Strep and Entercoccus spp.
Common Pathogens
 Periodontal Diseases
Gingivitis
Fuso, strep, & actinomycetes
Adult peritonitis
Bacteroides, porphyomonas,
peptostreptococcus & prevotella
Acute necrotizing ulcerative gingivitis
Spirochetes, prevotella, fuso
Localized juvenile periodontitis
Actinobacillus
Common Pathogens
 Fungal Infections
Candida spp.
Mucorales spp.
Let’s Talk About Resistance
 Three main types
– Chromosome mediated
 Spontaneous mutations
 Non-major form of drug resistance
 Rarely lead to complete resistance
– Plasmid mediated (conjugation)

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VERY important from clinical standpoint
Mostly gram negs
Mediate resistance to multiple drugs
High transfer rate from cell to cell
– Transposon (transduction and transformation)
 Phage mediated
 Clinically important for Gram +
Antibiotic Choices
ß-Lactams
 Natural penicillins
– Pen VK and Pen G
 MOA: Inhibit cell wall synthesis
 Dose: 250-500 mg qid x 7-10 days
 Contraindications:
– Allergies
– Poor renal fxn
 Adverse events: GI upset
 Drug interactions: oral contraceptives
 Pregnancy category B
ß-Lactams
 Natural penicillins
– Pen VK and Pen G
 Bactericidal
 Allergic reaction: rare (4 per 100,000)
 Spectrum:
– Strep, staph, enterococcus, neiseria, treponema, listeria
 Resistance:
– Mostly staph (>80%)
ß-Lactams
 Amino-penicillins
– Amoxicillin, ampicillin
 MOA: Inhibit cell wall synthesis
 Dose: 250-500 mg q 8 h x 7-10 days
 Contraindications:
– Allergies
– Poor renal fxn
 Adverse events: GI upset
 Drug interactions: oral contraceptives
 Amoxicillin and clavulanic acid (Augmentin)
ß-Lactams
 Amino-penicillins
– Amoxicillin, ampicillin
 Bactericidal
 “ampicillin” rash (4-10%)
 Spectrum:
– Strep, staph, enterococcus, neiseria, treponema, listeria,
E. coli, proteus, H. Flu, shigella, salmonella
 Resistance:
– Entero, citro, serratia, proteus vulagris, provedincia,
morganella, pseudomonas aeriginosa, acinetobacter
Cephalosporins
 Cephalexin (Keflex)
– MOA: Inhibit cell wall synthesis
– Dose: 250-1000mg q 6 h x 7-10 days
– Contraindications:
 Allergies
 Poor renal fxn
– Adverse events: mild GI
– Drug interactions: probenecid
– Pregnancy category B
Cephalosporins
 Cephalexin (Keflex)
– Bactericidal
– Spectrum:
 Gram +
– Resistance:
 Methicillin resistant gram +
– Low cross sensitivity with PCN
Lincosamides
 Clindamycin (Cleocin)
– MOA: binds to the 50S ribosomal subunit and inhibits
protein synthesis
– Dose: 100-450mg q 6 h x 7-10 days
– Precautions:
 Poor hepatic fxn
– Adverse events: GI upset, pseudomembraneous
colitis
– Drug interactions: neuromuscular blocking agents
– Pregnancy category B
Lincosamides
 Clindamycin
– Bactericidal or static depending on
concentration
– Spectrum:
 Gram +, anaerobes, parasites
– Resistance
 Enteroccocus
*Clostridium diff. pseudomembranous colitis!!
Macrolides
 Azithromycin (Zithromax), clarithromycin (Biaxin)
– MOA: bind to the 23S rRNA in the 50S subunit ribosome
– Dose: 250-500 mg/day x 5-10 days
– Precautions :
 Poor hepatic fxn
– Adverse effects: GI
– Drug interactions: Cytochrome P-450 (Remember
Seldane?)
– Pregnancy category B
Macrolides
 Azithromycin, clarithromycin
– Bactericidal
– Spectrum:
 Gram +, gram -, anaerobes
– Resistance:
 B. fragilis, and strep pneumo
Tetracyclines
 Doxycycline (Vibramycin)
– MOA: inhibit protein synthesis by preventing aminoacyl
transfer RNA from entering the acceptor sites on the
ribosome
– Dose: 100mg qd-bid x 7-14 days
– Contraindications:
 Food
 pregnancy
– Adverse events: GI
– Drug interactions: anti-epileptics
– Pregnancy category D
Tetracyclines
 Doxycycline
– Bacteriostatic
– Spectrum:
 Broad, Gram +, -, anaerobes, aerobes, and
spirochetes
– Resistance:
 Widespread, cross resistance
– PHOTO SENSITIVITY!!!
Nitroimidazoles
 Metronidazole (Flagyl)
– MOA: reduced intermediate interacts and
breaks the bacterial or parasitic DNA
– Dose: 250-1000 mg q 6-8 h x 7-10 days
– Precautions : poor hepatic fxn
– Adverse events: HA, N/V/D
– Drug interactions: EtOH, warfarin, Li+
– Pregnancy category D
Nitroimidazoles
 Metronidazole
– Bactericidal
– Spectrum:
 Gram - anaerobes
– Resistance:
 Rare, H. Pylori?
– Unpleasant metallic taste
Fluoroquinolones
 Ciprofloxacin (Cipro)
– MOA: Inhibition of DNA gyrase, and Topo II
– Dose: 250-500 mg qd x 7-10 days
– Contraindications: <18 yrs old, pregnancy
– Adverse events: spontaneous tendon rupture
– Drug interactions: probenacid, warfarin
– Pregnancy category C
Fluoroquinolones
 Ciprofloxacin
– Bactericidal
– Spectrum:
 Very broad except B. frag
– Resistance:
 MRSA, MRSE
Antifungals
 Nystatin
– MOA: inhibit cell wall synthesis
– Dose: 5 ml swish and swallow q 4 h x 10-14 d
– GI upset
– Drug interactions: minor
– Pregnancy category C
Antifungals
 Clotrimazole (Mycelex), ketoconazole
(Nizoral), fluconazole (Diflucan)
– MOA: inhibit cell wall synthesis
– Dose: 200-800 mg qd x up to 12 months
– GI upset
– Drug interactions: major p-450 enzyme inhibitor,
interactions with many drugs
– Pregnancy category C
ADA/AAOS Advisory
Statement
July 1997
AAOS Statement
Antibiotic prophylaxis is NOT
recommended for dental patients
with plates, pins, or screws, nor is
it routinely recommended for
MOST dental patients with TOTAL
JOINT REPLACEMENTS.
AAOS recommendations
 Prophylaxis recommended
– Total joint replacement within the last two years
AND:
 Compromised immune system OR
 Type 1 DM OR
 Previous prosthetic joint infections OR
 Malnourishment OR
 Hemophilia
AAOS recommendations
 Prophylaxis antibiotic recommendations
– Same as AHA OR
– No specific regimen recommended
– Keflex is often the first drug of choice
Legal Considerations
 The dentist may not be aware of the
patient’s medical condition.
 Physician may not be aware of the advisory
statements or of the dental procedure to be
performed.
 Vicarious Liability: “The devil made me do it”
 “I forgot to take my antibiotic.”
 Documentation.
Legal Considerations
 I forgot my antibiotics!
 Animal studies have shown antibiotics are
effective up to 2 hours after the procedure.
 Differentiate between prophylaxis vs.
treatment of an early infection.
 Take into consideration patient’s risk factors.
 Legal twists.
In Summary….
Principles of Antibiotic Therapy
 Therapeutic effectiveness
– Clinical indications
 Pharmcodynamics, pharmacokinetics
– Age and extent of infection
Patient factors
 Age, allergies, compliance, pregnancy risk
 Patient function
– Renal, hepatic, immunosuppresion, route
applicability
 Cost
– Brand name, length of course, alternatives?
Cost
Drug Name
Cost of Therapy $ (~10 Days) Generic if Available
Pen VK
6.81
Amoxicillin
8.41
Ampicillin
12.45
Cephalexin
15.65
Clindamycin
38.45
Azithromycin
41.52
Clarithromycin
74.45
Augmentin
76.82
Doxycycline
5.15
Metronidazole
9.65
Ciprofloxacin
76.65
Nystatin
9.86
Clotrimazole
97.05
Ketoconazole
30.69
Fluconazole
116.25
Dental Infection
Acute—Rapid growth
< 3 days
Chronic > 3 days
Pen VK 500mg q6h or
Amox 500mg q8h or
Cephalosporin
Think Anaerobes
Add Metronidazole 250-500mg
To PCN, Amox, or Ceph
Allergic to PCN
Clindamycin 300mg q8h
Clindamycin 300mg q8h or
Cephalosporin (check allergic Rxn) or
Azith or Clarithromycin