Antibiotics Flashcards
What is penicillin? Its spectrum and mode of actions against bacteria
• Penicillin is a beta-lactam antibiotic
What is the spectrum of penicillin?
Spectrum: Gram-positive non-beta-lactamase producing gram-positive cocci, Enterococcus spp., non-penicillinase producing strains of Staphylococcus aureus, coagulase negative Staphylococcus aureus, Clostridium spp. (excluding C. difficile), Actinomyces spp.
What is penicillin’s mode of actions against bacteria?
• Bactericidal effect via inhibition of bacterial cell wall synthesis
o Inhibits formation of the peptidoglycan cross-links in the bacterial cell wall, by binding of the four-membered β-lactam ring of penicillin to the enzyme DD-transpeptidase
o Note that the bacterial enzymes that hydrolyze the peptidoglycan cross-links continue to function
o Cell wall is weakened, and osmotic pressure becomes increasingly uncompensated cell death
• Exerts bacterial autolytic effect by inhibition of certain penicillin binding proteins (PBPs) related to the activation of a bacterial autolytic process.
Ken:
- Beta-lactam ring binds to transpeptidases in bacteria to prevent cross-linking between peptide chains
- this disrupts cell wall synthesis
- Bacteria undergo osmotic burst
- Activation of a bacterial autolytic process by inhibition of certain penicillin binding proteins (PBPs)
What are the possible complications of penicillin? (2.5)
Diarrhea, rash, vomiting
Hematologic: anemia, thrombocytopenia, neutropenia, agranulocytosis
CNS: seizures
Renal: nephrotoxicity, interstitial nephritis
Hepatic: transient increases in transaminases
Other: Jarisch-Herxheimer Reaction (fever, chills, sweating, tachycardia, hyperventilation, flushing, and myalgia)
Name 2 commonly used antibiotics for periodontal conjunctive therapy (2) and name 3 periodontal pathogens (3)
Amoxicillin, metronidazole, doxycycline
Porphyromonas gingivalis; A. actinomycetemcomitans; Prevotella intermedia
Is antibiotic routinely given for uncomplicated extraction? Explain (2)
No – antibiotic resistance in the future
What are the most common antibiotics prescribed for periodontal therapy. (2marks)
Amoxicillin and Metronidazole (250-500mg t.i.d., 5-10 days)
What is the mechanism of metronidazole? (additional information)
A systemic trichomonacide and amebicide that disrupts bacterial and protozoal DNA, inhibiting nucleic acid synthesis.
Therapeutic Effect:
Produces bactericidal, antiprotozoal, amebicidal, and trichomonacidal effects.
Produces antiinflammatory and immunosuppressive effects when applied topically.
(additional info) Mechanism of clindamycin
A lincosamide antibiotic that reversibly binds to 50S ribosomal subunits and inhibits protein synthesis of the bacterial cell wall by binding to bacterial ribosomal receptor sites. Topically, it decreases fatty acid concentration on the skin.
Therapeutic Effect:
Bacteriostatic
Anti-acne.
Give 4 advantages with the use of systemic antibiotics with conjunction to periodontal therapy (4marks)
- More change in clinical attachment loss
- Greater effect on the deepest periodontal pockets
- Good for those with aggressive forms of the disease
- Lower incidence of suppuration
Give 3 disadvantages for the use of systemic antibiotics. (3 marks)
- Microbial antibiotic resistance
* Systemic effects of antibiotics such as a diarrhea, mild skin rash, loss of appetite
The patient wants to have antibiotics and ask you to prescribe. What will you do?
Inform patient about risks
What are the risks associated with antibiotic use?
- Risks associated with the use of antibiotics include nausea, vomiting, diarrhea and stomach cramps because of the disturbances of the gut microflora.
- A particular concern to the use of oral antibiotics is the development of Clostridium difficile infection. C. difficile was responsible for almost half a million infections and was associated with approximately 29,000 deaths in 2011 (1). Among the antibiotics prescribed for endodontic infections, clindamycin, amoxicillin, cephalosporins are commonly associated with C. difficile infection, whereas macrolides and metronidazole are less commonly so (2). Other side effects include the development of yeast infections in the mouth or vagina, again resulting from an imbalance in the body’s normal flora. Antibiotics can also cause allergic reactions ranging from rash, skin reactions, Stevens-Johnson syndrome to breathing difficulty and anaphylaxis.
What is the solution for the risks due to antibiotics use?
Solution: One strategy that may be useful is to educate the patient about the signs and symptoms of a spreading infection and give the patient a “stand-by” antibiotics prescription. The patient would only fill the prescription and call the prescriber’s office, if he/she perceives this type of infection to be occurring, prior to receiving definitive care.
Antibiotics are commonly used in dental practice. Write down 2 antibiotics that are commonly contraindicated in patients taking warfarin. (1)
Ciprofloxacin (Cipro), clarithromycin (Biaxin), erythromycin, metronidazole (Flagyl) or trimethoprim-sulfamethoxazole (Bactrim, Septra)
