Pharmacology
Module #4
Drug Control of Infection
Chapter 7
Antiinfective Agents
Definitions. Anti- what?????
Antiinfective Destroy infections
Antibacterial Destroy or suppress
growth of bacteria Antibiotic
Chemical produced by a microorganism that can destroy or suppress bacteria
Antimicrobial Destroy or suppress
growth of microorganisms
Antifungal Destroys fungi
Antiviral Destroys viruses
Definitions cont.
Bactericidal Ability to kill bacteria
Bacteriostatic Inhibit or retard
bacterial growth Infection
Invasion of body by pathogenic microorganisms
Tissue reaction
Resistance Ability of bacteria to
resist effects of antiinfective agents
Spectrum Range of a drug’s
activity Narrow or broad
More Definitions…
Superinfection Proliferation of microorganisms different from
those causing the original infection Synergism
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
If allergic- erythromycin or clindamycin
Stage 2- also includes gram – anaerobes (mixed infection) 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=AYvX8t
nCM9s
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: Pen VK, Amoxicillin
Periodontal abscess: Pen VK
Juvenile periodontitis: Doxycycline, tetracycline
Adult periodontitis: No drug treatment used
Which antibiotic to prescribe?
Rapidly advancing periodontitis: Doxycycline, tetracycline, metronidazole
Soft tissue oral infection: 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. Erythromycin
b. Azithromycin
c. Ampicillin
d. 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. Erythromycin
b. Tetracycline
c. Cephaloxin
d. 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: Inhibit cell wall synthesis Inhibit protein synthesis Make cell wall more permeable
Spectrum 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 Inhibits cell wall synthesis Bactericidal
Spectrum Narrow
Resistance Some bacteria produce penicillinase which
breaks down penicillin rendering it ineffective
Penicillinase-resistant Penicillins
Cloxacillin Dicloxacillin For infections that are penicillinase-
producing 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, superinfection-
candiasis 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 Inhibits protein synthesis Bacteriostatic
Spectrum Wide
Uses Gram + and anaerobes
Clindamycin Adverse Effects
GI Usual- nausea, vomiting, diarrhea, cramping Severe- pseudomembranous colitis
(persistent diarrhea and passage of blood and mucous) can be fatal
Superinfection Candidiasis
Allergy
Metronidazole
Mechanism of action Bacteriocidal
Spectrum Anaerobes Resistance is rare
Uses Treatment of NUG
Metronidazole Drug Interactions
Alcohol Causes headache, nausea, vomiting, cramps Disulfiram= Antabuse reaction
Cephalosporins
Mechanism of action Inhibits cell wall synthesis Bactericidal
Spectrum 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 Interferes with folate metabolism
Spectrum Wide
Uses 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
bactericidal Inhibit bacterial protein synthesis
bacteriostatic Inhibit nucleic acid synthesis
RNA & DNA Interfere with folate metabolism
anti-metabolites
Claire Cranberry
No Allergy to penicillin Classifications
tetracycline – antibiotic Sudafed – alpha adrenergic agonist
candadiasis 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 cross-hypersensitivity 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 Alteration of cell membrane permeability
Nystatin 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 Acyclovir, docosanol, penciclovir
Adverse reactions 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