pharmacology module #4 drug control of infection

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