Therapeutics in dentistry (antibiotics)


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Therapeutics in dentistry (antibiotics)

  1. 1. Therapeutics In DentistryAntimicrobials Iyad Abou Rabii DDS, OMFS, MRes, PhD
  2. 2. ReminderTerms and Concepts1. Antimicrobial or anti-infective-drugs used to prevent or treat infections caused by pathogenic (disease-producing) microorganisms. Include antibacterial, antiviral, and antifungal drugs.2. Antibacterial or antibiotic-usually refer only to drugs used in bacterial infections.3. Antiviral- drugs used to treat viral infections.4. Antifungal- drugs used to treat fungal infections.5. Antiparasitic- drugs used to treat parasite infections or infestations.Page  2
  3. 3. Reminder6. Broad Spectrum- antibacterial drugs that are effective against several groups of microorganisims.7. Narrow Spectrum- antibacterial drugs which are effective against only a few groups of microorganisms.8. Bacteriocidal- action of an antibacterial drug in that it kills microorganisms.9. Bacteriostatic- action of an antibacterial drug in that it inhibits growth of the microorganism.10. Superinfection- a new or secondary infection that occurs during antimicrobial therapy of a primary infection.Page  3
  4. 4. Terms11. Antibiotic combination therapy- use 2 or more drugs in combination to treat infections known or thought to be caused by multiple microorganisims, to get a synergistic effect, to prevent emergence of drug-resistance organisims, or to treat clients whose immune system is suppressed or client with bone marrow or organ transplant.Page  4
  5. 5. Antibacterial
  6. 6. Mechanism of Action: 1. Inhibition of Cell Wall Synthesis 2. Disruption of Cell Membrane 3. Inhibition of Protein Synthesis 4. Interference with Metabolic Processes NB: BactericidalPage  6 Bacteriostatic
  7. 7. Table 1 Summary of some common antibiotics Beta-lactams Broad-spectrum antibiotics*. Flucloxacillin and co- (penicillins, amoxiclav are effective against some penicillin- cephalosporins) resistant organisms. Aminoglycosides Effective against gram negative bacteria e.g. (streptomycin, Pseudomonas. Reserved for serious infections e.g. gentamicin, tobramycin) septicaemia, meningitis, hospital-acquired pneumonia. Glycopeptides Effective against Staphylococci resistant to other (vancomycin, drugs, including many strains of MRSA**. teicoplanin) Tetracyclines Broad-spectrum antibiotics (doxycycline, minocycline)Page  7
  8. 8. Macrolides Broad-spectrum antibiotics, prescribed if patient is (erythromycin) allergic to penicillins. Metronidazole Prescribed for surgical prophylaxis, bacterial vaginosis, pressure sores, leg ulcers. Quinolones Effective against gram negative bacteria, (ciprofloxacin) gonorrhoea, gastro-intestinal infections. Antitubercular drugs Reserved for treatment/ containment of (rifampicin, isoniazid, tuberculosis(TB). rifabutin, streptomycin) sulphonamides (co- Co-trimoxazole is reserved for serious infections trimoxazole, associated with HIV/AIDS. Trimethoprin is trimethoprin) prescribed for urinary tract infections. * Broad spectrum antibiotics are used when the infectious agent is unknown. Narrow spectrum antibiotics are prescribed when the micro-organisms have been identified from tissue samples. ** Many bacteria produce an enzyme which destroys beta lactam antibiotics. In addition to this, MRSA (methicilin-resistant Staphylococcus aureus) produces an inactivating protein whichPage  8 confers resistance to most other antibiotics.
  9. 9. Indications for the use of antibacterials (together with appropriate surgical drainage or other measures) – Cervical fascial space infections; – Osteomyelitis and osteoradionecrosis; – Odontogenic infections in ill, toxic or susceptible patients (e.g. immunocompromised); – Acute ulcerative gingivitis; – Some instances of: • pericoronitis; • dental abscess;Page  9 • dry socket;
  10. 10. Prophylactic use of Antibacterials – infective endocarditis ; – in cerebrospinal rhinorrhoea; – in compound facial or skull fractures; – in major oral and maxillofacial surgery (e.g. osteotomies or tumour resection); – In surgery in immunocompromised or debilitated patients, or following radiotherapy to the jaws.Page  10
  11. 11. Drainage is essential if there is pus: antibacterial will not remove pus;Page  11
  12. 12. Routes of administration  Oral preparations of antimicrobials are preferred in most instances.  Topical antibacterials, should usually be avoided, as they may produce sensitization and may cause the emergence of resistant strains.Page  12
  13. 13. Routes of administration  Parenteral administration of antibacterials may be indicated where: – no oral preparation is available; – high blood levels are required rapidly (e.g. serious infections); – the patient cannot or will not take oral medications (e.g. unconscious patient); – the patient is to have a GA within the following 4 h.Page  13
  14. 14. Which Antibacterial??  Anaerobes are implicated in many odontogenic infections, and these often respond to penicillins or metronidazole  Odontogenic infections are typically polymicrobial.  Most bacteria causing odontogenic infections are penicillin- sensitive. Oral phenoxymethyl penicillin is usually effective and is cheap.Page  14
  15. 15.  Amoxicillin is active orally (absorption better than ampicillin).  Not resistant to penicillinase.  Contraindicated in penicillin hypersensitivity  500 mg PO q6-8hrPage  15
  16. 16.  Augmentin is a mixture of amoxicillin and potassium clavulanate – inhibits some penicillinases and therefore is active against most Staph. aureus; – inhibits some lactamases and is therefore active against some Gram-negative and penicillin-resistant bacteria • Contraindicated in penicillin hypersensitivity.Page  16
  17. 17.  Metronidazole may be preferred as an alternative to a penicillin if the patient is allergic, or has had penicillin with the previous month (resistant bacteria).  Suppositories are effective. Contraindicated in pregnancy.  500 mg PO, q6-8hr  with meals.  Use only for 7 daysPage  17
  18. 18.  Erythromycin is an alternative for penicillin-resistant infections where a Beta-lactamase producing organism is involved. However, many organisms are now resistant to erythromycin or rapidly develop resistance and its use should therefore be limited to short courses.  250-500 mg PO QIDPage  18
  19. 19.  Clindamycin is no more effective than penicillins against anaerobes  Should not be used for routine treatment of odontogenic infections.  Serious side-effects, mainly antibiotic-associated colitis. So limited use.  Clindamycin is used for prophylaxis of endocarditis in patients allergic to penicillin  150-450 mg PO q6-8hrPage  19
  20. 20.  Tetracyclines have a broad antibacterial spectrum, but of the many preparations there is little to choose between them.  Use of Tetracyclines may predispose to candidiasis.  Useful in Acute ulcerative gingivitis.  100 mg PO BID  Contraindicated in pregnancy and children up to at least 7 yearsPage  20
  21. 21.  Cephalosporins are broad-spectrum, expensive antibiotics with few absolute indications for their use in dentistry,  Gentamicin is reserved for use in pregnancy and myasthenia gravis. Reduce dose in renal disease, 5 mg/kg daily.Page  21
  22. 22. Which Antibacterial??  Pus (as much as possible) should be sent for culture and sensitivities, but antimicrobials should be started immediately following sampling, if they are indicated.Page  22
  23. 23. Antibacterial Teatrtment Failure patient non-compliance local factors (e.g. foreign body); unusual type of infection;.Page  23
  24. 24. Antibacterial Teatrtment Failure inadequacy of drainage of pus; inappropriateness of the drug or dose; antimicrobial insensitivities of micro-organism (staphylococci are now frequently resistant to penicillin and some show multiple.Page  24
  25. 25. Antibacterial Teatrtment Failure impaired host defences (unusual and opportunistic infections are increasingly identified, particularly in the immunocompromised patient); non-infective cause for the condition! In serious or unusual cases of infection, consult the clinical microbiologist.Page  25
  26. 26. Antifungal
  27. 27.  Candida Albicans  Local Factors  Systemic Factors  Antifungals are used to treat oral or oropharyngeal fungal infections but underlying predisposing factors should first be considered.Page  27
  28. 28.  In immunocompromised patients, antifungals are used for prophylaxis,  In immunocompromised patients antifungals are increasingly administrated systemically (azoles)Page  28
  29. 29.  Antifungal resistance is now a significant problem to immunocompromised persons, especially those with a severe immune defect, who may show Candida species resistant to fluconazole and, sometimes, to other azoles.Page  29
  30. 30.  Antifungal resistance may sometimes be overcome by using higher drug doses, or changing the agent  Antifungals should be continued for at least 1 week following resolution of clinical manifestations.Page  30
  31. 31.  Nystatin is not active orally, very active ative topically.  Pastilles taste better than lozenge. • Dose qid – 500 000 unit loz-enge, – 100 000 unit pastille or – 100 000 unit per mL of suspension.Page  31
  32. 32.  Amphotericin is close to Nystatin characteristics Topically applied 10 to100 mg q6hPage  32
  33. 33.  Miconazole is active topically and orally.  Also has antibacterial activity.  Interacts with terfenadine cisapride, astemizole and warfarin.  Avoid in pregnancy, porphyria  Dose – 250 mg tablet q6h – 25 mg/ml gel (Daktarin®) used as 5 mL q6h for 14 daysPage  33
  34. 34. Antiviral
  35. 35.  herpes viruses are associated with most oral viral infections,  Also (papillomaviruses, and enteroviruses).  HIV and other viruses may also cause orofacial lesions.Page  35
  36. 36.  Management of viral infections is predominantly supportive, as, at present, there are few antiviral agents of proven efficacy.  Most antivirals will achieve maximum benefit if given early in the disease.Page  36
  37. 37.  Systemic aciclovir should be used with caution in pregnancy and renal disease. Aciclovir may cause liver enzymes, and urea, rashes and CNS effects.  Famciclovir should also be used with caution in pregnancy and renal disease. Famciclovir may cause headache and nausea.  Topical Forms (cream) are preferred in oral medicine – 5 application by days – 5-10 daysPage  37
  38. 38. Page  38