Antibiotics Flashcards
what is the definition of an antibiotic?
A substance produced either by micro-organisms or synthetically, which possesses the property of inhibiting the growth of, or of destroying other microorganisms
What are the 2 categories antibiotics are divided into?
bacteriostatic
bactericidal
What is the mode of action of a bacteriostatic agent?
Give examples of drugs
- prevent further growth or reproduction of micro-organisms in the host, leaving the body’s natural defence mechanisms to overcome the infection.
- examples: tetracycline, erythromycin, sulphonamides
What is the mode of action of a bactericidal agent?
Give examples of drugs
- not only inhibit the multiplication of the organisms but also kill bacteria even in the presence of pus.
- examples: penicillin, streptomycin, cephalosporins
What is the antibacterium spectrum?
term used to indicate the range of activity of a particular antibiotic
What does a broad spectrum antibiotic mean?
Give example
- An antibiotic that is effective against a large variety of bacteria.
- Example: tetracycline, this is effective against gram +ve and gram -ve as well as unknown pathogens
what does a narrow spectrum antibiotic mean?
Give example
- Effective against few types of bacteria
- Example: basic penicillin, only effective against gram +ve bacteria. Includes original penicillin: Penicillin G or Phenoxymethylpenicillin, also known as penicillin V.
What are the 2 uses of the antibiotics in dentistry?
1 - Therapeutic: for acute odontogenic (tooth) infections. For most dental infections/abcesses, except gingival and ANUG (acute necrotising ulcerative gingivitis)
2- Prophylaxis: Prevent infection prior to beginning treatment- usually for patients with cardiac problems
when should antibiotics NOT be used?
- inflammatory conditions (post-op oedema)
- fibrinolytic (blood-clotting) conditions (dry socket)
- non bacterial infections (viral/fungal)
What are the 4 main mode of action of antibacterial drugs?
Give examples of each
1 - interfere with cell wall synthesis: penicillin, cefalosporin, glycopeptide
2 - inhibit protein synthesis: erythromycin, tetracycline, clindamycin
3 - interfere with bacterial nucleic acid synthesis: metronidazole
4 - anti-metabolic action (inhibit cell metabolism): sulphonamides, trimethoprim
What are the 4 main types of antimicrobials in dentistry?
and what are their modes of action? (bacteriostatic/bactericidal)
1 - Penicillins: bactericidal
2 - Macrolides: bacteriostatic
3 - Tetracyline: bacteriostatic
4 - Metronidazole: bactericidal
What is Penicillin V?
MOA?
Use?
Dose?
- Oral penicillin, narrow spectrum, resists destruction by gastric juices
- bactericidal
- Used to treat acute infection
- adult dose: 250mg 4X daily, syrup available for children
What is Amoxicillin?
MOA?
Use?
Dose?
- Penicillin (derivative of ampicillin), broad spectrum, absorption not affected by food, drug of choice for prophylaxis
- Bactericidal
- used for oral infections.
- adult dose: 500mg 3X daily for 5 days, suspension available for children
- can be used prophylactically: 3g, 1 hour before invasive treatment
- can be used in conjunction with Metronidazole for aggressive perio: 500mg Amoxicillin and 400mg Metroidazole 3X every day for 7 days after RSD
What is Co-Amoxiclav?
MOA?
Use?
Dose?
-Penicillin mixture containing Amoxicilin and Clavulanic acid (betalactamase inhibitor)
-bactericidal
-used for for dental infection that is resisting penicillin
-250mg Amoxicillin and 125mg Clavulanic acid 3X daily, 7 days
severe dental infection: 500mg Amoxicillin and 125mg Clavulanic acid 3X daily, 7 days
What is Erythromycin?
MOA?
Use?
Dose?
- Macrolide drug
- Bacteriostatic
- 1st choice to use in Penicillin-sensitive patients. Active against gram +ve organisms. Can cause nausea/vomiting
- given orally
- Used for acute infections: 250mg 4X daily
- Used prophylaxis: 1.5g 2 hours before treatment followed by 500mg 4X daily for 24 hours
What is Clindamycin?
MOA?
Use?
Dose?
- not a true Macrolide drug, works in similar manner.
- Bacteriostatic
- Active against +ve cocci including Penicillin resistant cocci. Works well against anaerobes.
- Strong link to C. difficile.
- Used for dentoalveolar/salivary gland abscesses that haven’t responded to penicillin/metronidazole.
- Acute infection: 150mg 4X daily
- Prophylaxis: 600mg 1 hour before treatment
What are the 5 adverse reactions of antimicrobials?
1- superinfection 2- allergic reaction 3- drug interaction 4- GI complaints 5- harm to foetus during pregnancy
What is Doxycline?
MOA?
Use?
Dose?
- Tetracycline
- bacteriostatic, inhibits protein synthesis
- effectiv against gram -ve bacteria, including A.a (aggressive perio).
- used for aggressive periodontal disease alongside RSD
- 200mg orally for first day, then 100mg orally daily for 21 days during RSD treatment
Also admistered as Periostat (low dose and longer treatment adjunct to RSD and fine scaling)
-20mg, twice daily for 3 months
Also be used for recurrent aphthae (mouth ulcers).
-Dissolve contents of 100mg capsule in 10-15ml water and rinse around the mouth for 2-3 minutes as soon as the ulcer becomes apparent. Continue for 3 days.
What is Flagyl?
MOA?
Use?
Dose?
- Metronidazole
- bactericidal, narrow spectrum against obligate anaerobic bacteria but highly effective
- used to manage aggressive periodontitis and periodontal infection, particularly NUG
- Dose for NUG: 400mg for 3X daily for 3 days
- Dose for acute oral infection: 400mg 3X daily for 5 days
- Dose for severe infections: 500mg 3X daily for 5 days and taken alongside Amoxicillin
- Dose for aggressive periodontal disease: 400mg Metronidazole with 500mg Amoxicillin both taken 3X daily for 7 days. Starting on the final day of RSD.
Warning: do NOT give to pregnant patients/breastfeeding
do NOT take with alcohol
What 4 antifungal agents are used in dentistry?
1-Nystatin
2-Amphotericin
Azole Agents. 2 types:
3-Imidazole: Miconazole
4-Triazole: Fluconazole
what is Nystatin?
MOA?
Use?
Dose?
- antifungal agent
- active against fungal/yeast infections
- disrupts osmotic function of cell membrane and causes cell death. Not absorbed by mucous membranes, ideal for local effect in treatment of candida infections.
- Used for acute candida/denture stomatitis
- 1ml of 100,000 U/ml suspension swilled around mouth every 6 hours for 7 days
what is Amphotericin B?
MOA?
Use?
Dose?
- antifungal agent
- disrupts osmotic function of cel membrane. Must be used for some time after symptoms are resolved to ensure infection is cleared.
- used for acute pseudomembranous candidosis/ denture stomatitis
- 10mg lozenge dissolved in mouth every 6 hours for 10-15 days OR
- 1ml of SF suspension held against lesion every 6 hours for 14 days
what is Miconazole? MOA? Use? Dose? What warning is given with Miconazole?
-antifungal agent, of the Azole kind.
-suppresses the synthesis of ergosterol (interferes with fungal membrane function)
-used for chronic hyperplastic candidiasis, denture stomatitis, angular cheilitis
-25mg of oral gel held against lesion every 6 hours.
OR
-applied to surface on denture before insertion
OR
-for angular cheilitis use 25mg of oral gel in conjunction with hydrocortisone cream every 8 hours.
-avoid topical Miconazole in patients who are on Warfarin due to potential to for systemic absorption. IT POTENTIATES THE EFFECT OF WARFARIN = ↑ INR = ↑ BLEEDING
What is Fluconazole?
MOA?
Use?
Dose?
- antifungal agent, of the Azole kind
- has a long half life and can be administered as a single dose. Used widely with immunocompromised patients.
- used for severe candidal infections
- 50mg 1X daily for 7-14 days. (A higher dose for a longer duration is suitable if the patient is immunocompromised.)
How do antiviral agents affect viruses?
- immunostimulation of the host
- inhibition of viral nucleic acid synthesis
- inhibition of viral proteins
What is Aciclovir?
MOA?
Use?
Dose?
- antiviral agent
- becomes activated by viral enzymes and becomes a potent inhibitor of viral DNA synthesis –> inhibiting the virus from replicating
- used for primary herpetic gingivostomatitis (herpes virus)
- dose: 200mg 5X daily for 5 days
What other properties does tetracycline have?
- antibacterial properties.
- collagenase inhibition (stops breakdown of collagen)
- anti-inflammatory actions
- inhibition of bone resorption
- ability to promote the attachment of fibroblasts to root surfaces
