Chapter 7 Flashcards
Second only to pain management as the dental problem for which drugs are prescribed
Dental infections
Common dental infections include
Caries
Periodontal disease
Localized dental infections
Systemic infections
Dental infection progression
Gram positive cocci Mixed infection (gram + and gram -) Anerobic ( doesnt like oxygen - gram -)
Gram positive cocci
Streptococcus viridans
a-hemolytic streptococci
Mixed infection
Peptostreptococcus (peptococcus)
Bacteroides ( porphyromonas and prevotella)
Antibiotcs used in progression of infections
Penicillin/Amoxicillin
Macrolid (Erythomycin)
Clindamycin
Metronidazole
The factors that determine the likelihood of a microorganism causing an infection
Virulence
inoculum
immunologic response
Culturing
Growing the bacteria from a sample of infective exudate
Sensitivity testing
Exposing the organism to certain test antibiotics and determing whether the organism is sensitive or resistant
Indications for testing
Serious infection
Infection in a compromised patient
Infection that is not responding to treatment
Two types of resistance
Natural and acquired
Acquired resistance
Decrease in bacterial permeability
Production of bacterial enzymes
Alteration in target site
When prescribing antibiotics
Only when necessary
Only prescribe one unless two is absolutely necessary
Indications for antimicrobial agents
Therapeutic indications
Prophylactic indications
Disadvantages of antimicrobial agents
Superinfection Allergic reactions Drug interactions GI complaints Pregnancy Dose forms Cost
Drug interactions of antimicrobial agents
oral contraceptives and oral anticoagulants
Four major groups of penicillins
Penicillin G and V
Pennicillinase-resistant penicillians
Amoxicillin
Extended spectrum penicillins
Advantages of oral administration of penicillins
Convenience
Less likelihood of life threatening allergic reaction
Disadvantages of oral administration of penicillins
Blood levels rise more slowly
Blood levels are less predictable
Lack of patient compliance
Degraded by gastric acid
Pharmacokinetics of penicillins
Distributed throughout body except cerebrospinal fluid, bone and assesses
Crosses the placenta; appears in breast milk
Metabolized by hydrolysis in liver
Undergoes tubular secretion in kidneys
Bactericidal agent that attaches to penicillin-binding proteins on the bacterial cell membrane
Adverse reactions to penicillins
Toxicity Convulsions Renal damage Hemolytic damage Bone marrow depression Penicillinase resistance GI irritation Sterile absesses Thrombophlebitis
Allergy and hypersensitivity to penicillins
Anaphylatic reactions Rash Delayed serum sickness Oral lesions Interstital nephritis Hemolytic anemia Eosinophilia
Uses of penicillin
Treatment of dental infections
Effective against many aerobic and anerobic bacteria
Used for specific prophylactic indications
Amoxicillin
Ampicillins
Penicillinase-susceptible agents
Advantages of amoxicillin
Produces higher blood levels
Better absorbed
Requires less frequent dosing
Absorption is not impaired by food
Cephalosporins
Structually related to penicillins
Active against gram + and gram - organisms
True antibiotics
Adminstered orally, IV and IM
Pharmacokinetics of cephalosporins
Well absorbed orally
Excreted by glomerular filtrations and tubular secretion in the urine
Half-lives vary between 50 to 240 minutes
Inhibition of cell wall synthesis
Adverse reactions of cephalosporins
GI Nephtotoxicity Superinfection Local reaction Hemostasis and disulfiram-like reactions Allergy
Macrolides
Erythomycin
Clarithomycin
Azithomycin
Interferes with protein synthesis by inhibiting the enzyme peptide transferase at the P site of the 50S ribosomal subunit
Erythomycin
Erythomycin is not effective against many infections caused by
obligate anaerobes ( bacteroides species) involved in some dental infections
Adverse reactions of erythomycin
GI Cholestatic jaundice
May inhibit hepatic metabolism of some drugs
Increase serum concentrations of some drugs > toxicity
Azithromycin and Clarithromycin
Inhibit RNA-dependant protein synthesis by binding to the 50S ribosomal subunit
Adverse reactions of Azithromycin
Elevate liver function tests
GI
Drug interactions
Adverse reactions of Clarithromycin
Produce metallic taste
GI
Drug interactions
Tetracyclines
Broad-spectrum antibiotics affection a wide range of microorganisms
First isolated from a strain of Streptomyces
Tetracyclines
Secreted in the saliva and breast milk
Tetracyclines
Stored in dentin and enamel of unerupted teeth
Tetracyclines
Where is tetracycline concentrated
Gingival crevicular fluid
All tetracyclines cross
the placenta and enter fetal circulation
Tetracycline (broad spectrum)
Effective against a wide variety of gram + and gram - bacteria
Adverse reactions of tetracyclines
GI
Diarrhea
Yellowish-brown discoloration of tongue
Candidiasis
Diarrhea with tetracycline
Staphylococcal enterocolitis
Intestinal candidiasis
Pseudomembranous colitis
Effects of teeth and bones with tetracycline
Produce permanent discoloration and enamel hypoplasia
Decrease in growth rate of bones
Minocycline can cause black pigmentation of mandibular and maxillary alveolar bone and the hard palate
Drug interactions of tetracycline
Drug enhancement
Increase effectiveness of oral coagulants
Uses for tetracycline
Chlamydial and rickettsia infections Treat acne COPD Travelers diarrhea Perio conditions
Clindamyciin (Cleocin)
Bacteriostatic
Effective primarily against gram + organisms and anaerobic Bacteroides species
Derived from lincomycin
Distribution of Clindamycin
Throughout most of the body tissues, including bone, but not the CSF
Crosses the placenta barrier
Adverse reactions of clindamycin
GI Glossitis and stomatitis Pseudomembranous colitis Superinfections by C. albicans Affect elements in blood Allergy Morbilliform
Uses of clindamycin
Infections caused by anaerobic organisms especially Bacteroides species
Some staphylococcal infections when the patient is allergic to pencillin
Metronidazole
An antiinfective agent with trichomonacidal, amebicidal, and bactericidal action
Also has antiinflammatory effects
Inhibits nucleic acid synthesis leading to death of the organism
Metronidazole
Adverse reactions of metronidazole
GI CNS Renal toxicity Transient neutropenia Oral effects
Oral effects of metronidazole
Dry mouth Unpleasant or metallic taste Altered taste of alcohol Glossitis Stomatitis Black hair tongue
Drug interactions of metronidazole
Can potentiate the effect of Warfarin
Phenobarbital and phenytoin can reduce plasma levels of metronicazole
Uses of metronidazole
Anaerobic spectrum
Treatment of trichomoniasis, giardiasis, amebiasis, and susceptible anaerobic bacterial infections
Treatment of peio infections EXCEPT against A. actinomycetemcomitans
Metronidazole
Stage 1 of dental infections
Gram + - acute abscesses
Penicillin V ( not allergic to penicillin)
Amoxicillin
Erythomycin (for pts allergic to penicllin)
Clindamycin (for pts allergic to penicillin)
Stage 2 of dental infections
Gram + organisms --> Penicillin or amoxicillin -->Erythomycin or clindamycin Anaerobes -->Clindamycin -->Metronidazole --> Penicillin V
Stage 3 of dental infection
Anaerobic
Most often incision and drainage are sufficient
If chronic infection persists or the pt is immunocompromised, use of antibiotic with anaerobic coverage is warranteed
Rationale for use of antiinfective agents in dentistry
Pt compliance Ineffective antibiotic Poor debridement Resistant organism Concentration did not reach site of infection Host defenses inadequate
Uses of sulfonamides
Chronic bronchitis
UTIs
Antituberculoni agent
Isoniazid
How to decide if patient needs antibiotic prophylaxis
Prevention of infective endocarditis Prosthetic joint prophylaxis Noncardiac medical conditions Prosthetic cardiac valve Previous infective endocarditis Congenital heart disease
