Pharmacology
Module #4
Drug Control of
Infection
Chapter 7
Antiinfective Agents
Definitions. Anti- what?????

Antiinfective


Destroy infections
Antimicrobial

Antibacterial



Destroy or suppress
growth of bacteria


Chemical produced by
a microorganism that
can destroy or
suppress bacteria
Antifungal

Antibiotic

Destroy or suppress
growth of
microorganisms
Destroys fungi
Antiviral

Destroys viruses
Definitions cont.

Bactericidal


Ability to kill bacteria
Resistance

Bacteriostatic



Inhibit or retard
bacterial growth
Infection


Invasion of body by
pathogenic
microorganisms
Tissue reaction

Ability of bacteria to
resist effects of
antiinfective agents
Spectrum

Range of a drug’s
activity

Narrow or broad
More Definitions…

Superinfection


Synergism


Proliferation of microorganisms different from
those causing the original infection
2 antibiotics that when combined, produce
more effect than expected
Antagonism

2 antibiotics that when combined, produce
less effect than each agent alone
Synergism Vs. Antagonism
Synergism
 1+ 1= more than 2
 DO
 Example:





Bactericidal
Bactericidal
Note: addition of 2
bacteriostatic agent is
merely additive
1+1=2
DO
Antagonism
 1 + 1= less than 2
 DO NOT
 Example:


Bactericidal
Bacteriostatic
Dental Infection “Evolution”

Stage 1- gram +, aerobic microbes

Drug of choice Penicillin VK


Stage 2- also includes gram – anaerobes
(mixed infection)


If allergic- erythromycin or clindamycin
Pen VK or erythryomycin
Stage 3- predominantly anaerobes

Metronidazole or clindamycin
Antibiotics-To use or not to use??


Overuse of antibiotics is to blame for
resistant strains of bacteria
Incision and drainage is preferred method
of treatment for infection (no prescription
of antibacterial drugs)


normal immune system
localized infection
Video- YouTube Clip


Resistance
https://www.youtube.com/watch?v=AYvX8
tnCM9s
Culture and Sensitivity Testing

Culturing


Growing bacteria in a controlled environment
Sensitivity testing


Exposing bacteria to certain antiinfective
agents to determine sensitivity or resistance
Determines appropriate treatment of
infections
Antimicrobial Use in Dentistry

Conditions









ANUG
periodontal abscess
localized juvenile periodontitis
adult periodontitis
rapidly advancing periodontitis
abscess, pericoronitis
osteomyelitis
aerobes not sensitive to penicillin
anaerobes not sensitive to penicillin
Which antibiotic to prescribe?

ANUG:


Periodontal abscess:


Pen VK
Juvenile periodontitis:


Pen VK, Amoxicillin
Doxycycline, tetracycline
Adult periodontitis:

No drug treatment used
Which antibiotic to prescribe?

Rapidly advancing periodontitis:


Soft tissue oral infection:


Doxycycline, tetracycline, metronidazole
Pen VK, Amoxil
Osteomyelitis:

Pen VK, Amoxil
Which antibiotic to prescribe?

Aerobic mixed infection insensitive to
penicillin:


Amoxicillin with clavulanate
Anaerobic mixed infection insensitive to
penicillin:

Metronidazole, clindamycin
Dental Uses of Antibiotics

Therapeutic



Periodontal disease
Soft tissue infections
Prophylactic



Artificial heart valves
History of infective endocarditis
Total joint replacement
Updated Recommendations




American Heart Association website
American Dental Association website
Drug of choice is Amoxicillin
Alternatives:


Clindamycin
Azithromycin
Prophylactic Drug Regimens


1 hour before procedure
No allergy


Amoxicillin 2000 mg
Allergy to penicillins


Clindamycin 600 mg
Azithromycin 500 mg
National Board Question

The drug of choice for a person allergic
to penicillin for prophylaxis
premedication is
a.
b.
c.
d.
Erythromycin
Azithromycin
Ampicillin
Amoxicillin
Antibiotic Prophylaxis for Dental
Procedures

Recommended:



Procedures producing significant bleeding
Oral prophylaxis
Scaling and root planing
Antibiotic Prophylaxis for Dental
Procedures

Not necessary for:





Anesthetic injection through noninfected tissue
Taking impressions
Taking dental radiographs
Sealant placement
Fluoride treatments
Adverse Reactions

Superinfection


Potential overgrowth of an organism different
from the original infection cause
Resistant
More common with wide spectrum drugs
 More common if duration of use is long


Allergies

Hives to anaphylaxis

Penicillins and cephalosporins
Adverse Reactions cont.

GI tract


Stomach pain, increased motility, diarrhea
Pseudeomembranous colitis


Helps to take with food
Pregnancy



Limited use- consult obstetrician
Pen VK/ erythromycin- OK
Tetracyclines- teratogenic
Drug Interactions

Oral contraceptives


May reduce effectiveness of birth control
Anticoagulants

May increase anticoagulant effect


More prone to bleeding/ hemorrhage
Other antibiotics

Antagonistic effect- decreases effect of both

Bacteriostatic and bactericidal
National Board Question

A two-year-old child has developed an
infection requiring an antibiotic. Which of
the following would be the least desirable
choice?
a.
b.
c.
d.
Erythromycin
Tetracycline
Cephaloxin
Ampicillin
Terms

Hypersensitivity




Most common drug - penicillin
Most common manifestation – rash
Cross-hypersensitivity with cephalosporins
Penicillinase


Bacteria produce this enzyme to break down penicillin
Adding clavulanic acid to amoxicillin (Augmentin)
prevents penicillinase from breaking it down.
Concepts

Mechanisms of action of antibiotics:




Spectrum


Inhibit cell wall synthesis
Inhibit protein synthesis
Make cell wall more permeable
Wide or narrow
Bacteriostatic or bactericidal
Classifying Anti-Infectives

Categorize by:

Spectrum or organism affected
Broad
 Narrow
 Fungus
 Virus




Bacteriostatic or bactericidal
Mechanism of action
See chart attached to objectives
Specific Antibiotics






Penicillins
Macrolides
Tetracyclines
Clindamycin
Metronidazole
Cephalosporins






Vancomycin
Aminoglycosides
Sulfonomides
Sulfamethoxazole/
trimethoprim
Antituberculosis
agents
Topicals
Penicillin

Mechanism of action



Spectrum


Inhibits cell wall synthesis
Bactericidal
Narrow
Resistance

Some bacteria produce penicillinase which
breaks down penicillin rendering it ineffective
Penicillinase-resistant Penicillins





Cloxacillin
Dicloxacillin
For infections that are penicillinaseproducing staphylococci only
More side effects
Not for people allergic to penicillin
Ampicillins





Examples: ampicillin, amoxicillin
(Augmentin, Amoxil, Trimox)
Not penicillinase resistant (Augmentin is)
Gram + cocci and enterococci
Better absorbed, requires less frequent
dosing, absorption not impaired by food
May cause allergic reactions
Macrolides


Examples: erythromycin, clarithromycin,
azithromycin
Mechanism of action



Inhibits protein synthesis
Bacteriostatic
Spectrum

Narrow
Macrolides cont.

Adverse reactions:



GI upset
Jaundice
Uses:


Patients allergic to penicillin
Effective against aerobes
Tetracyclines


Examples: tetracycline, doxycycline
Mechanism of action



Inhibits protein synthesis
Bacteriostatic
Spectrum


Wide
Aerobes and anaerobes
Adverse Effects of Tetracycline

GI


Nausea, vomiting, xerostomia, superinfectioncandiasis
Teeth and bones

Permanent tooth discoloration
Incorporated into tooth structure
 Do not give during pregnancy or children less than
9 years old


Enamel hypoplasia
Clindamycin

Mechanism of action



Spectrum


Inhibits protein synthesis
Bacteriostatic
Wide
Uses

Gram + and anaerobes
Clindamycin Adverse Effects

GI



Superinfection


Usual- nausea, vomiting, diarrhea, cramping
Severe- pseudomembranous colitis
(persistent diarrhea and passage of blood and
mucous) can be fatal
Candidiasis
Allergy
Metronidazole

Mechanism of action


Spectrum



Bacteriocidal
Anaerobes
Resistance is rare
Uses

Treatment of NUG
Metronidazole Drug Interactions

Alcohol


Causes headache, nausea, vomiting, cramps
Disulfiram= Antabuse reaction
Cephalosporins

Mechanism of action



Spectrum


Inhibits cell wall synthesis
Bactericidal
Wide
Uses


Infections resistant to penicillin
Gram – organisms
Vancomycin

Spectrum


Narrow
Uses

Non-dental

Eradicate bacteria in GI tract
Aminoglycosides

Spectrum


Wide
Adverse effects

Ototoxicity

Toxic to 8th cranial nerve- can lead to auditory and
vestibular (inner ear) disturbances
Sulfonamides

Mechanism of action


Spectrum


Wide
Uses


Interferes with folate metabolism
Non-dental, ear infections
Adverse effects

Renal crystallization- drink plenty of water
Sulfamethoxazole/ Trimethoprim

Combination antimicrobial drug


Bactrim
Uses

Ear infections in children
Antituberculosis Agents

Tuberculosis (TB)


Can be contracted in dental setting
Drugs used for treatment:
Isoniazid
 Rifampin
 Pyrainamide
 Ethambutol
NOTE: Used together b/c of resistance

Topical Antibiotics


Applied to the skin
Example: Neosporin

Neomycin, polymyxin, and bacitracin
Review of Mechanisms of Action

Bactericidal or bacteriostatic

Inhibit bacterial cell wall synthesis


Inhibit bacterial protein synthesis


bacteriostatic
Inhibit nucleic acid synthesis


bactericidal
RNA & DNA
Interfere with folate metabolism

anti-metabolites
Claire Cranberry



No
Allergy to penicillin
Classifications



candadiasis




tetracycline – antibiotic
Sudafed – alpha adrenergic agonist
tetracycline & sudafed both could be involved
nystatin or clotrimazole
clindamycin 600 mg (3 tabs) 1 h before appt.
NSAID?
Review

Which antibiotic causes damage to the 8th
cranial nerve?

aminoglycocides
Review

Which antibiotic causes
pseudomembranous colitits?


Clindamycin
Which antibiotic causes a disulfram-like
reaction?

metronidazole
Review

Name 4 broad spectrum antibacterial
agents.





Aminoglycocides
Cephalosporin
Clindamycin
Sulfonamides
Tetracycline
Review

Which antibiotic has a crosshypersensitivity with penicillin?

Cephalosporin
Matching- Method of action



Inhibit cell wall
synthesis
Inhibit protein
synthesis
Interfere with folate
metabolism






Tetracycline
Erythromycin
Penicillin
Cephalosporin
Sulfonamide
Amoxicillin
Chapter 8
Antifungal and Antiviral Agents
Antifungal Agents

Used to treat fungal infections

Example: candidiasis
Nystatin and Clotrimazole

Mechanism of action


Nystatin


Alteration of cell membrane permeability
Available as a suspension, lozenge, or cream
Clotrimazole

Available as a troche or cream
Nystatin and Clotrimazole

Directions for patient:

Suspension
Swish, swirl, spit or swallow 5 ml four x daily
 Should remain in mouth for 2 mins.


Troches/ lozenges
Dissolve in mouth slowly
 Take all of the medication

Amphotericin B

Uses


severe fungal infections- systemic
Adverse reactions

Hypokalemia, headache, chills, fever,
malaise, muscle and joint pain, gastric
complaints, nephrotoxicity
Antiviral Agents

Used to treat viral infections

Examples: HIV, herpes
Treatment of Herpes

Drugs


Adverse reactions


Acyclovir, docosanol, penciclovir
Burning skin, headache, dizziness, GI upset
Uses

Genital and oral herpetic lesions
Treatment of HIV

Nucleoside analogs



Zidovudine (AZT, ZDV)
Terminates the synthesis of viral DNA
Protease inhibitors


Indinavir
Prevent maturation of HIV-infected cells
Chapter 13
Oral Conditions and Their
Treatment
Herpes Simplex Labialis


AKA cold sore, fever blister
Antiviral agents



Acyclovir
Valacyclovir
Penicyclovir
Candidiasis

Antifungal agents


Nystatin suspension
Clotrimazole troches/ lozenges
Pericornitis/ Alveolar Osteitis

Treatment:






Rinsing with saline water
Debridement
Pack placement
Analgesics
Supportive therapy
If infection present, prescribe antibiotics