CHAPTER 9: ANTIMICROBIALS IN PEDIA DENT

ppt + sas + notes

Antimicrobials

aka: antiinfectives

Are substances that kill or suppress the growth or multiplication of microorganisms, either bacteria, viruses, fungi or parasites.
-Naturally produced by microorganisms(yeast or fungi) and used to inhibit bacteria and sometimes protozoa

Classification of Antimicrobials

• Spectrum of Activity

  • Narrow-spectrum antibiotics

  • Extended-spectrum antibiotics

  • Broad-spectrum antibiotics

• Type of Action

  • Bacteriostatic Drugs

  • Bactericidal Drugs

• Categories of Antibiotic Use

  • Prophylactic

  • Empiric

  • Definitive

Narrow-spectrum antibiotics

Active against a single or limited group of microorganisms(e. g some gram-positive

organisms)

Extended-spectrum antibiotics

Effectiveagainst gram-positiveorganismsandasignificantnumberofgram-negative organisms

Broad-spectrum antibiotics

Act against a wide variety of species
Often initially prescribed to neutropenic or critically ill patients while awaiting the results of culture and sensitivity testing

alters normal flora, risking superinfection

Bacteriostatic Drugs

Limit the spread of the infection by halting bacterial growth and replication.

Effects on microorganisms are reversible

drugs under bactericidal

Penicillins

Cephalosporins

Carbapenems

monobactams

Fluroquinolones

Aminoglycosides

Vancomycin

Metronidazole

Bactericidal Drugs

Act independently of host immune defenses to cause cell death
Effects are irreversible, the microorganism will ultimately die following adequate drug exposure
Preferred for most infections including intraoral infections due to the fact that they act largely independent of host factors, which is an important consideration for rapidly progressing infections

drugs under bacteriostatic

Tetracyclines

Erythromycin

Clindamycin

Chloramphenicol

Sulfonamides

Macrolides (recent addition)

Trimethoprim

Prophylactic

Use of antimicrobials to prevent an infection

Previous bacterial endocarditis, uncontrolled diabetes, patients under immunosuppressive drug therapy, patients at high-risk for surgery

3 conditions:

• prior infection endocarditis

• pulmonary shunts

• blue baby syndrome

Empiric

Initial use of broad-spectrum antibiotic specially if the patient is seriously ill

Definitive

• Occurs following culture and susceptibility tests. After causative organism is identified,

  use an agent that is narrower in spectrum to target the specific pathogen.

transpeptidase

the enzyme in …

essential during cell wall synthesis

MOA of B-lactam antibiotics (bacteriacidal)

Inhibition of Cell Wall Synthesis

penicillins, cephalosporins, monobactams, amd carbapenems
Vancomycin

MOA of Clindamycin, Macrolides, Aminoglycosides, Tetracyclines (bacteriostatic)

Inhibition of Protein Synthesis

MOA of Fluroquinolones

Suppression of DNA Synthesis

MOA of antifungals

Alteration of Cell Membrane Permeability

Polyene antifungals → binds to sterols forming pores

Azole antifungals → inhibits fungal CYP450

Antibacterial Agents

Penicillins

Amoxicillin

Amoxicillin/Clavulanate(Co-amoxiclav)

Clindamycin

Metronidazole

Fluroquinolones

classification of penicillin

• natural penicillin

  • G → IV/IM (acid, unstable, taken w meals)

  • V → oral (acid stable, taken w/o meals)

• semi-synthetic penicillin

  • Penicillinase resistant penicillin:

    • Methicillin, Cloxacillin

  • Extended-spectrum penicillin:

    • Ampicillin → (taken on empty stomach)

    • Amoxicillin, Carbenicilin,Piperacilin

• B-lactamase Inhibitors

  • Clavulanic acid, Sulbactam

Penicillin

is generally the drug of choice assuming the patient does not have an allergy. Oral absorption of most penicillin is impaired by food and should be given 1 hour or 2 hours after meal. Exceptions to this rule are Penicillin VK and Amoxicillin.

Penicillin G

discovered by Alexander Fleming
- Given intramuscularly, Oral penicillin G is no longer used because it is subject to degradation in the presence of stomach acid

Penicillin V

and amoxicillin have chemical structures that enhance their stability in acidic environments and result in improved oral absorption. Penicillin V can be taken without regard to meals
-Administered orally and dosed at 6-hour interval
- historically, Drug of choice to treat mild to moderate dental infections in non-allergic patients

Amoxicillin

Replaced Pencillin VK as the drug of choice for the prevention of infective endocarditis by the American Heart Association because amoxicillin produces higher and longer sustained blood levels than Penicillin VK

Amoxicillin/Clavulanate(Co-amoxiclav)

Clavulanate helps amoxicillin to work better

used to eliminate beta lactamase enzyme produced by S. aerus

375mg or 625mg every 8hrs for 5 days

Clindamycin

A lincosamide antibiotic

-Both bacteriostatic and bactericidal
-Drug of choice for significant oral infections
-Patients allergic to penicillin can be given clindamycin -Available in 150 and 300 mg

contraindicated for px with clostridium difficile infection (CDI) as this will results to pseudomembranous colitis → managed with metronidazole

pedia note: the 75mg/mL suspension is notoriously unpalatable (horrible smell & taste)

Metronidazole

Active against protozoa in addition to anaerobic bacteria
-Drug of choice for the treatment of mild to moderate C.difficile colitis
-Can be combined with amoxicillin or cephalosporin for the treatment of periodontal disease -Inhibits alcohol-metabolizing enzymes, leading to an accumulation of acetaldehyde and the development of disulfiram-like adverse effects. Patients should not consume alcohol during metronidazole therapy and for at least 3 days after discontinuation.
-Available in 250 and 500 mg

often combined w amox

pedia note: very bitter, requires specialized compound benzoate salt kits to make taste for kids

Fluroquinolones

Bactericidal antibiotics with broad-spectrum activity for a variety of gram-positive, gram- negative and atypical organisms

pedia note: reserved only for multi-drug resistant pathogens with no safe alternative

historically avoided in pedia due to arthropathy / osteochondrosis seen in juvenile animal testing. causes phototoxicity (severe sunburn reactions to UV-A light)

Antifungal Agents

• Polyenes → poor effectiveness & high sucrose content

  • Nystatin

  • Amphotericin B

• Azole antifungals → severe drug interaction & QT prolongation risk

  • Clotrimazole

  • Miconazole, Fluconazole, Itraconazole

Nystatin

topical polyene antifungal
-considered as poor antifungal in activity
-only topical polyene for treatment of oral candidiasis

Amphotericin B

broad spectrum of action fungicidal. Mainstay for IV treatment of systemic antifunfal infections prior to development of the echinocandins, and broad-spectrum azoles.
-Called “amphoterrible” because it was noted for nephrotoxicity and infusion-related

reactions

Clotrimazole

(can be used for treatment of candidiasis)

macrolides

binds 50S ribosome

bactariostatic, long post-antibiotic effect allows for shorter, less frequent dosing regimens

drawback in dent → moderate coverage of streptococci but poor coverage of anaerobes

pedia note: high rate of dysgeusia (metallic taste - clarithromycing). high risk of drug-drug interactions. can prolong the QT interval (risk of torsades de pointes)

Antiherpetic Agents

Acyclovir

Valacyclovir

Acyclovir

10 times more potent against herpes viruses than against varicella-zoster virus and is approved for neonates

Valacyclovir

prodrug which is converted to acyclovir in vivo.
-FDA approved for children 12 years of age and older for treatment of herpes labialis

and 2 years of age and older for chickenpox.

effects of streptomycin

GI upset

effects of chloramphenicol

bone marrow suppression

aplastic anemia

gray baby syndrome

bacterial infections

periapical & periodontal abscess

cervicofacial cellulitis

NUG / NUP

periapical & periodontal abscess

pulpal necrosis / purulence or acute periodontal pocket infection

management: localized lesion with appropriate surgical drainage (I&D, extraction, endo) does not require antibiotic therapy

when to prescribe: only if systemic involvement is identifies (fever, lymphadenopathy) or px is immunocompromised develops cellulitis

cervicofacial cellulitis

diffuse, firm, warm, swelling

infection spreading into adjacent soft tissues

management: systemic antibiotics are definitively indicated alongside surgical I&D

H. influenzae type B is a risk in infant buccal cellulitis

NUG / NUP

management: primary tx is debridement and topical antiseptics

when to prescribe: prescribe / metronidazole only if fever and lymphadenopathy occur

Viral Infections

• Primary Herpetic Gingivostomatitis

• Secondary Herpetic Infections

  • Herpes Labialis

  • Herpes Zoster
    

Primary Herpetic Gingivostomatitis

most common acute viral infection affecting the oral mucosa
Caused by herpes simplex virus and transmission occurs through direct contact
-Most frequent sites of involvement include gingiva,tongue, palate, labial mucosa, buccal mucosa, tonsils, posterior pharynx.
-Heals within 7 to 10 days without scarring
-Management includes palliative care and may include systemic antiviral therapy when

indicated.

abrupt fever, malaise, red swollen mucosa with small vesicles that rupture into painful ulcers with pseudomembranes

pedia note: advise parents not to use otc benzocaine gels for pain in infants/young children due to the risk of methemoglobinemia

Herpes Labialis

-After the primary infection, virus remains latent in neural ganglion until reactivated. - -Predisposing factors for reinfection include illness, trauma, stress, UV light and immunosuppression.
-The most common sites of involvement include lips(herpes labilalis) and intraoral keratinized tissues such as hard palate, dorsal infection and attached gingiva

Herpes Zoster

-Varicella zoster virus causes the primary infection of chicken pox and presents as a recurrent infection in the form of herpes zoster(shingles).
-Recurrent infection usually presents in a unilateral distribution along the trigeminal nerve and extends to the midline.

Candidiasis/ Candidosis

a fungal infection

Most common intraoral superficial mycosis. -Most often caused by Candida albicans

white removable plaques with underlying erythema or red fissuring at commissures (angular cheilitis)

pedia note: infants with cleft lip/palate are highly susceptible due to breast milk/formula pooling in the cleft. caregivers must wipe the area with a moist cloth after feeding

practice question in sas

2 tests when administiring antibiotics

culture & serologic testing → identifies the specific pathogen

sensitivity testing → identifies the appropriate antibiotic

tests under sensitivity testing

rapid catalyst test → identifies the difference of staphy vs strepto

blood agar plate test → focuses on strepto

coagulates test → focuses on staphy

blood agar plate test

focuses on strepto:

if total lysis → B-hemolysis

if partial lysis → a-hemolysis

if no lysis → g-hemolysis

coagulates test

focuses on staphy:

positive → S. aerus (normal flora of the skin)

negative → S. epidermitis (most common in oral cavity & skin)

pharmacological rule

parts in a prescription writing

case study for the calculation flow

AHA endocarditis prophylaxis criteria