Reminder Terms 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.
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.
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.
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: Bactericidal Bacteriostatic
Table 1 Summary of some common antibioticsBeta-lactams Broad-spectrum antibiotics*. Flucloxacillin and co-(penicillins, cephalospor amoxiclav are effective against some penicillin-ins) resistant organisms.Aminoglycosides Effective against gram negative bacteria e.g.(streptomycin, gentami Pseudomonas. Reserved for serious infections e.g.cin, 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)
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 infectionstrimoxazole, associated with HIV/AIDS. Trimethoprin istrimethoprin) 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 fromtissue samples.** Many bacteria produce an enzyme which destroys beta lactam antibiotics. In addition to this,MRSA (methicilin-resistant Staphylococcus aureus) produces an inactivating protein whichconfers resistance to most other antibiotics.
Indications for the use ofantibacterials(together with appropriate surgical drainage orother 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; • dry socket;
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.
Drainage is essential if there ispus:antibacterials will not removepus;
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.
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.
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.
• Amoxicillin is active orally (absorption better than ampicillin).• Not resistant to penicillinase.• Contraindicated in penicillin hypersensitivity• 500 mg PO q6-8hr
• 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.
• 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 days
• 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 QID
• 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 q6-8hr
• 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 years
• 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.
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.
Antibacterial Teatrtment Failure• patient non-compliance• local factors (e.g. foreign body);• unusual type of infection;.
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.
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.
• Candida Albicans• Local Factors• Systemic Factors• Antifungals are used to treat oral or oropharyngeal fungal infections but underlying predisposing factors should first be considered.
• In immunocompromised patients, antifungals are used for prophylaxis,• In immunocompromised patients antifungals are increasingly administrated systemically (azoles)
• 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.
• 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.
• 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.
• Amphotericin is close to Nystatin characteristics• Topically applied 10 to100 mg q6h
• 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 days
• herpes viruses are associated with most oral viral infections,• Also (papillomaviruses, and enteroviruses).• HIV and other viruses may also cause orofacial lesions.
• 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.
• 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