Lecture 2 Flashcards
Bactericidal or Bacteriostatis preferable?
Bactericidal
Antibiotic type that:
Relies less on host immune system
Takes effect more quickly
Maintains effect longer
Bactericidal
-Cidal or -Static for Prophylaxis?
Bactericidal
See post-antibiotic effects with -cidal or -static?
Post antibiotic effects seen with bacterioSTATIC drugs
The persistent suppression of bacterial growth after brief exposure to an antibiotic even in the absence of host defense mechanism
Post Antibiotic Effect - might be related to DNA alteration
Why are Z-Packs very good at treating Chronic Bronchitis?
Post-Antibiotic Effect! Azithromycin is a -static drug
Want Narrow or Broad Spectrum?
NARROW - kills only bacteria we want to kill- less super infection and alteration of normal flora; and often more effective
Penicilllin VK vs Amoxicillin: Broad of narrow?
Penicillin VK - narrow; Amoxicillin - broad
If MIC is high or half-life is long, how should you dose the antibiotic?
Give a Loading Dose!- 2-4x the therapeutic dose
Dosage is more critical for -static or -cidal?
More critical for -Static!!!
Minimum conc. of drug that will prevent visible growth of bacteria in culture after overnight incubation?
MIC
How long to take antibiotic?
Terminate antibiotic when sure patient is on the way to recovery based on clinical evidence
Adverse effects of antibiotics
Toxicity, Allergy, Super Infection
Allergy vs Toxicity
Toxicity is DOSE related
GI distress
Is a Toxicity of antibiotics
Antibiotics that most often cause Pseudomembranous Colitis
Cephalosporins, Ampicillin, Clindamycin
What bacteria causes P. Colitis?
C Difficile
Optimal Antibiotic
Pencillin
Characteristics of Optimal Antibiotic
Active against pathogens, reaches effective concentration, low toxicity Doesn't cause resisitance Desirable route Economical
About organisms involved in Orofacial infections
Oral bacteria are rarely the primary pathogens
And, generally several organisms, not just one
Type of antibiotic is the widest spectrum
Beta-Lactam Antibiotics
Penicillins, Cephalosporins, Carbapenems, monobactams, Carbacephems
Beta-Lactam Antibiotics
B-Lactamase resistant Penicillins
Oxacillin and Dicloxacillin
Mechanism of action of Penicillins
Disruption of cell wall synthesis - prevents cross linking in cell walls- which are only in humans, not bacteria
Good traits of Penicillin V
Stable in gastric pH so orally effective Low toxicity Narrow spectrum specific to oral microbes Cidal Inexpensive
Penicillin G
IV or IM Only!!
Formulated as Aqeous, procaine, or benzathine
Drug of Choice for Most Odontogenic Infections
Penicillin
Typical Dose for Penicillin
Load w/ 2 grams, then 500mg ever 6 hours
Indications for B-Lactamase Resistant Penicillins
Only for proven staphylococcal infections
AKA “Anti-Staph” penicillins
B-Lactamase Ressitant Penicillins - reasons we don’t use them
Less activity against oral bacteria,
expensive
Uses for Amoxicillin
Otitis Media, UTI SBE Prophylaxis NOT First line DOC for odontogenic NOT B-lactamase resistant
Extended spectrum Penicillins
Ampicillin - parenteral
Amoxicillin - oral
Use for strep, oral anaerobes, H. influenza, E. coli, salmonella, shigella, proteus
Best Antibiotic for Prophylaxis
Amoxicillin
Advantages of Amoxicillin over Penicillin for Prophylaxis
More predictable absorption- important since only taking once!
Longer half life than PCN
Higher plasma conc than PCN
NOT used for prophylaxis because it is broader spectrum though
What is NOT a reason to use Amoxicillin over Penicillin for prophylaxis?
Amox is broader spectrum
Extended Spectrum Penicillins
NOT indicated for oral bacteria or head and neck infections
Carbenicillin, Ticarcillin, Piperacillin
B-Lactamase action
Cleaves the B-Lactam ring
How to combat B-Lactamase
Add R chains or by competitive inhibition
The three B-Lactam Inhibitors
Clavulonic Acid
Sulbactam
Tazobactam
Augmentin
Amoxicillin + Clavulonic Acid
Improved staph and H. flu coverage
Indications for Augmentin
Otitis
Sinus infections not caused by a tooth
Bite wounds
UTI
Unasyn
Ampicillin + Sulbactam
Parenteral
Penicillins- Adverse effects
Allergy- 2% of people allergic
Antagonistic with -static drugs
Decreased excretion in very young and very old
DOC for odontogenic infection
Penicillin V
Which antibiotic is limited to prophylaxis in dentistry
Amoxicillin because better absorption, but negatively has broader spectrum
Which antibiotic reserved for more serious infection
PCN G
If significant anaerobic component, may need…
B-lactamase inhibitor or metronidazole
Bites, non-odontogenic sinusititis, and otitis require…
Augmentin or other B-lactamase inhibitors
Cephalosporins
Four generations, we only use the FIRST GEN
Cephalosporins Pharmacology
-Cidal - cell wall inhibition B-lactam configuration Low toxicity broad spectrum expensive Don't have as good post-antibiotic effect
Cephalosporins very good against
Streptococcus and Oral Anaerobes
Cephalosporins Indications
Community acquired Staph infection
Surgical wound prophylaxis
Odontogenic infection in PCN allergic pt
1-10% of PCN allergic patients also allergic to
Cephalosporins
Avoid if have Cephalosporin allergy
PCN
If have PCN allergy avoid
Cephalosporin if PCN allergy is severe
IF its mild, Cephalosporin probably okay
Macrolides: Mech
Irreversibly bind 50s ribosomal unit - STATIC
- Inhibit RNA dependent protein synthesis
What antibiotics should immunocompromised people not take
-static!!
Clarithromycin - when to use in relation to other antibiotics
For if pt allergic to PCN and gets GI problems from clindamycin
Clarithromycin: traits
Similar to erythromycin but less resistance, better H. Influenza coverage, less GI distress, expensive
Clarithromycin Indications
Sinus infection
Mild/moderate odontogenic infection in PCN allergic pts w/ GI sensitive
Pneumonia or bronchitis
Can use for prophylaxis too
Azithromycin - when to use
Should be reserved for URI
Azithromycin traits
Similar to Clarithromycin but better against strep and g-anarobes
Don’t need to time with meals
Less GI distress
Expensive
Marcolides (-mycins) Adverse Effects
GI distress (worst with Erythromycin) Ototoxicity Cholestatic jaundice with Erythrmycin Long QT interval/Torsade de Pointes Increased activity of Digitalis Potentiation of oral anticoagulants like Warfarin Adverse reaction with statins - myopathy
Lincosamides
Clindamycin is the only one we use
Clindamycin: Mech
Binds 50s ribosome leading to inhibition of protein synthesis –> -static!
2nd line Antibiotic
Clindamycin
Clindamycin indications
Chronic recurrent infection
Osteomyelitis
Odontogenic infection in immunocompromised pt w/ severe PCN allergy
Disulfuram Effect seen with what Antibiotics
Metronidazole - make you nauseated with alcohol
Metronidazole
-cidal - disrupts DNA synthesis Mild toxicity Inexpensive Disrupts Anaerobic bacteria \+ penicilln for severe infections Effective bone penetration
Metronidazole Indications
Chronic anaerobic infection
In combo w/ PCN or cephalo for serious odontogenic infections
Tetracyclines
Inhibit 30s ribosome –> -static
Broad spectrum
High resistance
Inexpensive
Tetracyclines
good for resistant bacteria H.bactor related gastric and peptic ulcers For topical therapy Dry socket prevenetion NO indication for odontogenic infection
Problems w/ tetracycline
Stain teeth permanently
Photosensitivity to sun
