2. Reminder
Terms and Concepts
1. 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.

3. Reminder
6. 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.

4. Terms
11. 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.

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:
Bactericidal
Bacteriostatic

7. Table 1 Summary of some common antibiotics
Beta-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)

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 which
confers resistance to most other antibiotics.

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;
• dry socket;

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.

11. Drainage is essential if there is
pus:
antibacterials will not remove
pus;

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.

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.

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.

15. • Amoxicillin is active orally (absorption
better than ampicillin).
• Not resistant to penicillinase.
• Contraindicated in penicillin
hypersensitivity
• 500 mg PO q6-8hr

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.

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 days

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 QID

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 q6-8hr

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 years

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.

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.

23. Antibacterial Teatrtment
Failure
• patient non-compliance
• local factors (e.g. foreign body);
• unusual type of infection;.

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.

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.

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.

28. • In immunocompromised
patients, antifungals are used for
prophylaxis,
• In immunocompromised patients
antifungals are increasingly
administrated systemically (azoles)

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.

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.

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.

32. • Amphotericin is close to Nystatin
characteristics
• Topically applied 10 to100 mg q6h

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 days

35. • herpes viruses are associated with most
oral viral infections,
• Also (papillomaviruses, and
enteroviruses).
• HIV and other viruses may also cause
orofacial lesions.

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.

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