For general dentists and dental students

1. Antibiotics Prescribing
For Dentistry
Dr. Hatem Abushiha
Resident doctor in oral surgery
Faculty of dentistry – Misurata University - Libya

2. ANTIBIOTICS

3. Definition :
Agents that used to treat bacterial infection
, either by killing or inhibiting growth of
bacteria .

4. Penicillin Discovered—by Accident :
n 1928 Alexander Fleming discovered penicillin
while he was investigating staphylococcus
a Penicillium mold spore had been accidentally
introduced into the medium—perhaps coming in
through a window, or more likely floating up a
stairwell from the lab below where various molds
were being cultured

5. What are the risks of using the
antibiotics ?

7. 1) Drug resistance :
Result as :
Prolonged treatment
Interrupted course
Inadequate dose
Abuse of drug

8. 2) Super infection :
Broad spectrum antibiotics or prolong using of
antibiotic disturb bacterial flora and leading to
microorganisms over growth for example :
Over growth of candida in oral cavity leading
candida infection

9. 3) Drug toxicity :
Chloramphenicol bone marrow
depression
Aminoglycoside nephrotoxicity
Tetracycline teeth discoloration
Streptomycin deafness

10. Clindamycin Mild diarrhea common
Metronidazole peripheral neuropathy may develop

11. 4) Allergy
Usually not dose dependent as :
Penicillin cause anaphylatic shock

12. What are benefits of antibiotic ?

13. 1) Prevent of infection
2) Prevent of spread of infection :

14. Classification of antibiotic :

15. based on their mode
of action
Bactericidal Bacteriostatic

16. Bactericidal Antibiotic : Capable of killing of
bacteria
Bacteriostatic Antibiotic : Capable of inhibiting the
growth or reproduction of bacteria.

17. Types of antibiotic
(based on therapeutic spectra )
Narrow spectrum Broad spectrum

18. Narrow spectrum antibiotic : kills bacteria of a
narrow range, For example, penicillin will kill
streptococci and oral anaerobic bacteria but will
have little effect on the staphylococci of the skin
and GIT bacteria.
Broad spectrum antibiotic : as amoxicillin-
clavulanate (Augmentin) are broad-spectrum
antibiotics, inhibiting not only streptococci and
oral anaerobes it has an effect on skin and GIT
bacteria

19. Pharmacodynamics
classification
Time
dependent
Concentration
dependent

20. Time-dependent antibiotics : exert bactericidal effect when
drug concentrations are maintained above the minimum
inhibitory concentration (MIC) , concentrations are
maintained at 2 to 4 times the MIC throughout the dosing
interval , higher concentrations do not result in greater kill
of organisms
Concentration-dependent antibiotics : achieve increasing
bacterial kill with increasing levels of drug , bactericidal
action continues for a period of time after the antibiotic level
falls below the MIC , concentrations of at least 10 times the
MIC are needed for optimal bactericidal effect

21. therapeutic
spectra
Pharmaco-
dynamic category
Antibacterial
action
Antibiotic
Narrow-
Spectrum
Time-dependentBactericidalPenicillin
Narrow-
Spectrum
Time-dependentBactericidalAmoxicillin
Broad-
Spectrum
Time-dependentBactericidalCefuroxime
Broad-
Spectrum
Time-dependentBacteriostaticTetracycline
Broad-
Spectrum
Time-dependentBacteriostaticAzithromycin
Narrow-
Spectrum
Time-dependentBacteriostaticClindamycin
Narrow-Concentration-dependentBactericidalMetronidazole

22. Mechanism Of Action Of Antibiotics :

24. Effective oral antibiotic for odontogenic
infection :
1) Penicillin
2) Erythromycin
3) Clindamycin
4) Tetracycline
5) Meterinadzole

25. What are Indications of antibiotic ?

26. 1) Therapeutic indication
2) Prophylaxis indication

27. 1) Therapeutic indication:

28. Indication of Antibiotic In Periodontology
cases :
1) Aggressive periodontitis
2) Chronic periodontitis (unclear)
3) Refractory periodontitis
4) Necrotizing ulcerative periodontitis
5) Necrotizing ulcerative gingivitis

29. Antibiotics are not recommended for :
1) Gingival diseases
2) Necrotizing ulcerative gingivitis
3) Chronic periodontitis
4) Periodontal abscess
Antibiotics In Periodontology :

30. Indication of Antibiotics In Endodontic
cases :
An antibiotic should be prescribed in when there
are :
1) systemic signs and symptoms of infection :
presence of a fever ,malaise, cellulitis ,unexplained
trismus and progressive swelling
2) progressive/persistent spread of infection

31. Antibiotics are not recommended for healthy
patients with :
1) symptomatic pulpitis,
2) symptomatic apical periodontitis
3) draining sinus tract
4) localized swelling of endodontic origin
5) following endodontic surgery
Antibiotics In Endodontic :

32. Indication Of Antibiotic In Oral Surgery
cases :
1) Cellulitis
2) progressive swelling
3) Medically compromised patient
4) Severe pericoronitis
5) Osteomyelitis
6) Involvement of fascial spaces

33. Antibiotic In Oral Surgery :
Antibiotics are not recommended :
1) Dry socket
2) Mild pericoronitis
3) Minor vestibular abscess
4) Chronic localiezed abscess

34. 2) Prophylaxis indication:

35. 1) Prosthetic heart valves
2) history of rheumatic fever, Previous IE,
rheumatic heart disease
3) Patients with congenital heart disease
4) Dialysis patients – those with arteriovenous
shunts
5) Organ transplant patients

36. 6) Chemotherapy patients, including bone marrow
transplantation
7) Artificial joint patients
8) Poorly controlled diabetic patients
9) Radiation therapy patients, depending on
procedure
10) Down syndrome patients (many have cardiac
defects)
11) Immunosuppressed patients, depending on
treatment).

37. Principles of antibiotic choice :

38. 1) Identify of the pathogen
2) Spectrum
3) Tissue penetration
4) Antimicrobial safety
5) Patient factors
6) Pharmacokinetic
7) Cost

39. 1) Identify of the pathogen:
Most orofacial infections involve predictable organisms.
Clinicians should therefore have knowledge of the
microbiology of orofacial infections.

40. Anaerobic bacteriaAerobic & facultative
bacteria
PeptostreptococcusViridans streptococcus
ActinomycesStaphylococcus
EubacteriumCorynebacterium
LactobacillusEnterococcus
VeillonellaMicrococcus
FusobacteriumNeisseria
BacteroidesCampylobacter
SelenomonasPseudomonas
TreponemaMoraxella
AggregatibacterEnterobacter
LeptotrichiaHaemophilus

41. Aerobic 6 % of all odontogenic infections
Anaerobic bacteria alone are found in 44% of
odontogenic infections.
50% of odontogenic infections s caused by mixed
anaerobic and aerobic bacteria

42. Most likely etiological agent in relation
to most common oral infection :
In pericornitis : anaerobic alpha-hemolytic
streptococci
Amoxicillin proved to be highly effective
In aggressive periodontitis : Anaerobic
Aggregatibacter actinomycetemcomitans
doxycycline proved to be highly effective

43. Most likely etiological agent in relation
to most common oral infection :
In chronic periodontits : Anaerobic Fusobacterium
Micromonas micros
combination of amoxicillin and metronidazole is a reasonable
choice
 in periapical abscess : Anaerobic Fusobacterium
PenicillinVK is the antibiotic of choice

44. 2. Spectrum :
Narrow spectrum antibiotics better than broad
spectrum .

45. 3. Tissue penetration :
Ability of antibiotic to reach the site of infection and
Depending on
 properties of antibiotic is antibiotic lipid solubility
 presence of inflammation , in acute infection increase
micro vascularity while opposing in chronic state
 Adequacy of blood supply

46. Presence of abscess or foreign material make
antibiotic difficult to penetrate

47. 4) Antimicrobial safety :
Avoid antibiotic with serious effect , β-
lactam antibiotics, especially penicillins ,
are generally considered safe.
For patients allergic to penicillin, the best
choice is
clindamycin.
Clindamycin is a narrow-spectrum
antibiotic

48. 5) Patient factors :
The systemic use of antibiotics in pregnant
women involves an evaluation of risk versus
benefit.
Medically compromised patients need long time .

49. 6) Pharmacokinetic :
the level of drug absorption in the
gastrointestinal tract varies between individuals.
various factors can affect drug absorption

50. 7) Cost :
The cost of therapy may be an important factor in
determining the antibiotic regimen.

51. Principles of antibiotic treatment
regimen :

52. following factors should be considered:
1) Route of administration
2) Dose
3) Duration of therapy

53. 1) Route of administration:
Antibiotics are commonly administrated orally
because
 it is easy
 non-painful
 cost effective.
Antibiotics should be administrated parentral :
 in patients with trismus
 difficulty in swallowing.

54. 2) Dose :
Most infections can be managed with a standard
dosage of antibiotic.

55. 3) Duration :
. Once antibiotic therapy starts, the antibiotic
should be administrated for an adequate period
Antibiotic treatment is recommended for an
additional 2–3 days after clinical resolution of an
infection has occurred to avoid recurrence.

56. Factor In Antibiotic Dosing :

57. 1) Renal insufficiency :
Initial and Maintenance Dosing in Renal Insufficiency.
The initial dose is unchanged, and the maintenance
dose/dosing interval are modified .
Alternative: Use antibiotic eliminated/inactivated by the
hepatic route in usual dose.
Doxycycline or clindamycin may preferred

58. 2) Hepatic Insufficiency :
Decrease total daily dose of hepatically-
eliminated antibiotic by 50% in presence of
clinically severe liver disease.
Alternative: Use antibiotic
eliminated/inactivated by the renal route in usual
dose.
Decrease dose of renally-eliminated antibiotic by
50% and
maintain the usual dosing interval.

59. Major Route of Elimination :
Hepatobiliary
Ceftriaxone
Doxycycline
Clindamycin
Metronidazole
Renal
Ciprofloxacin
 Tetracycline
 Most b-lactams
b-lactam/b-lactamase
inhibitors

60. Other Consideration In Antimicrobial
Therapy :

61. Bactericidal vs Bacteriostatic
Therapy
Intravenous vs Oral Switch
Therapy
Monotherapy vs Combination

62. Bactericidal vs. Bacteriostatic
Therapy
Bactericidal antibiotics preferred

63. Intravenous vs. Oral Switch
Therapy
switched to equivalent oral therapy after clinical
improvement (usually within 72 hours).
Advantages of early IV-to-PO switch programs :
reduced cost
less need for home IV therapy
 virtual elimination of IV line infections

64. Monotherapy vs. Combination
Therapy
If one can do don’t use two

65. DRUG INTERACTIONS :

66. Interaction with :
1) Anticoagulants
2) Oral contraceptives

67. 1) With Anticoagulants
Cephalosporin
 Erythromycin
 Metronidazole
Ampicillin
Amoxicillin
Increase bleeding tendency

68. 2) With Oral contraceptive
 Amoxicillin
 Ampicillin
 Tetracycline
 Erythromycin
Will affect the re-absorption of estrogen.

69. Metronidazole interaction :
with alcohol
disulfiram-like reaction which include nausea,
vomiting, flushing, dizziness, throbbing headache,
chest and abdominal discomfort.

70. Tetracyclines interaction :
with Antacids Lower serum levels of
tetracyclines
With Milk Reduced tetracycline absorption
With ACEIs Reduced serum levels of tetracyclines
(lisinopril, enalapril , …)

71. Doxycycline:
With Carbamazepine
Reduced doxycycline effect

72. Antibiotics & pregnancy :
All drugs should be avoided in pregnancy unless
potential benefit outweighs potential risks.
When necessary :
Azithromycin
Clindamycin
Metronidazole
Penicillins
Erythromycin

73. Antibiotics & breastfeeding :
Penicillins
Cephalosporins
Erythromycin

74. Antibiotics failure :

75. patient should be carefully monitored for
response to treatment and complications
Should be evaluate :
body temperature
trismus
 swelling,
 patient’s subjective feelings of improvement

76. Antibiotic Failure Causes :
Antibiotic Factors
• Inadequate
coverage/spectrum
• Inadequate
antibiotic blood tissue
levels
• Drug-drug
interactions
Unresponsive Infectious
Diseases
Viral or Fungal infections
Antibiotic Penetration
Problems
• Undrained abscess
• Foreign body-related
infection

77. Culture & Senstivity testing :
1) Rapid onset of severe infection and its rapid
spread
2) Postoperative Infection. if a patient had no
signs of infection when the original surgery
was done but returns 3 or 4 days later with an
infection
3) Infection that does not resolve as expected.
4) Recurrent Infection

78. CostRouteof administrationUsual intervalUsual doseAntibiotic
8 -20
LYD
Oral8 hr.500 mgAmoxicillin
19-90
LYD
Oral12 hr.1 gm.Augmentin
7—10
LYD
I.V12 hr.1 gm.Ceftriaxone
15-35
LYD
Oral12 hr.250 mgAzithromycin
20-40
LYD
Oral6 hr.150 mgClindamycin

79. CostRouteof administrationUsual intervalUsual doseAntibiotic
15-45
LYD
Oral6 hr.500 mgMetronidazole
10-150
LYD
Oral12 hr.500 mgCiprofloxacin
4-40
LYD
oral12 hr100 mgDoxycycline
10-30
LYD
Oral6 hr.250 mgTetracycline
15-45
LYD
Oral8 hr.500 mgMetronidazole

80. References :
1) Contemporary Of Oral And Maxillofacial Surgery
Textbooks
2) Oral And Maxillofacial Surgery By Lars Anderson ,
Karl-erik Kahnb, M. Anthony (Tony) Pogrel Textbooks
3) Scully’s Medical Problems In Dentistry Textbooks
4) Ingle’s Endodontics Textbooks
5) Antibiotic Essentials Textbooks
6) Carranza’s Clinical Periodontology

81. Thank you
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