Antibiotics: types, indications, doses for each condition
Definitions
Antimicrobial
an agent that kills microorganisms or stops their growth
Antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria
Antiseptic
An agent which slows down the growth of bacteria, but doesn’t kill them
Mechanisms of action
Drugs that inhibit cell wall synthesis
Penicillins, cephalosporins and vancomycin.
o Their actions are bactericidal
Drugs that inhibit protein synthesis
Aminoglycosides, tetracyclines, chloramphenicol, macrolides and fusidic acid.
Drugs that inhibit bacterial DNA synthesis and degrade existing bacterial DNA
Metronidazole
Indications
Bacterial infections
Antibiotics are only appropriate for oral infections where there is evidence of spreading infection (cellulitis,
lymph node involvement, swelling) or systemic involvement (fever, malaise).
o Temperatures <36C or >38C are indicative of systemic involvement.
Usually antibiotics are used in combination with local measures
Acute periodontal conditions (Necrotising periodontal diseases, pericoronitis, abscesses)
o NUG - associated with anaerobic fuso-spirochaetal bacteria and is more common in patients who
smoke, the immuno-suppressed and those with poor oral hygiene
o Pericoronitis – associated with anaerobic bacteria
o This agrees with the clinical use of antibiotics, because antibiotics tends to be used to manage acute
infections where there is systemic involvement or persistent swelling despite local treatment.
o Especially if there is lymphadenopathy and increased temperature
Periodontitis
o Antimicrobials are used for susceptible patients and grade C periodontal disease as an adjunct to
mechanical therapy
RSD can be used to disrupt the biofilm so that antibiotics will be effective
o Systemic antibiotics are effective for periodontal treatment because they are present in high
concentrations in the GCF, thus can act in the desired area
o Systemic antibiotics are used to achieve better clinical outcomes
Osteomyelitis
Sinusitis
o where there are persistent symptoms and/or purulent discharge lasting at least seven days or where
symptoms are severe
Prophylaxis for dental treatment
Osteoradionecrosis prevention
Patients who are medically compromised to prevent infective endocarditis
o Only some groups apply
Contra-indications
, Antibiotics: types, indications, doses for each condition
Chronic infections
Pulpitis
Prevention of dry socket
Allergy
Do not prescribe amoxicillin to patients with a history of anaphylaxis, urticaria or rash immediately after
penicillin administration as these individuals are at risk of immediate hypersensitivity.
Routes of administration
Systemic
Oral
IV
Local
Types
Penicillins
Penicillin V (phenoxymethylpenicillin)
o Narrow spectrum against gram -ve bacteria
o drug of first choice for most dental infections / pyogenic infections, but is ineffective against
lactamase-producing bacteria
o route
oral, IV
o Important side effects: hypersensitivity rash, anaphylaxis.
Amoxicillin
o Broad spectrum
o May be useful for short course oral regimens.
o Uses
dental infection / pyogenic infections, surgical prophylaxis, endocarditis prophylaxis.
o Route: oral, iv.
o Important side effects: skin rash, anaphylaxis, candidosis or antibiotic associated colitis if prolonged
use.
Ampicillin
o Borad spectrum
Co-amoxiclav
o Amoxicillin + clavulanic acid
o Is active against beta-lactamase-producing bacteria that are resistant to amoxicillin, and can be used
to treat severe dental infection with spreading cellulitis or dental infection that has not responded to
first-line antibacterial treatment.
o Co-amoxiclav 250/125 tablets are amoxicillin 250 mg as trihydrate and clavulanic acid 125 mg as
potassium salt.
o Cholestatic jaundice can occur either during or shortly after the use of co-amoxiclav; this condition is
more common in patients above the age of 65 years and in men. Do not prescribe co-amoxiclav to
patients who have a history of co-amoxiclav-associated or penicillin-associated jaundice or hepatic
dysfunction
Metronidazole
Anaerobic bacteria
It acts of DNA synthesis
Definitions
Antimicrobial
an agent that kills microorganisms or stops their growth
Antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria
Antiseptic
An agent which slows down the growth of bacteria, but doesn’t kill them
Mechanisms of action
Drugs that inhibit cell wall synthesis
Penicillins, cephalosporins and vancomycin.
o Their actions are bactericidal
Drugs that inhibit protein synthesis
Aminoglycosides, tetracyclines, chloramphenicol, macrolides and fusidic acid.
Drugs that inhibit bacterial DNA synthesis and degrade existing bacterial DNA
Metronidazole
Indications
Bacterial infections
Antibiotics are only appropriate for oral infections where there is evidence of spreading infection (cellulitis,
lymph node involvement, swelling) or systemic involvement (fever, malaise).
o Temperatures <36C or >38C are indicative of systemic involvement.
Usually antibiotics are used in combination with local measures
Acute periodontal conditions (Necrotising periodontal diseases, pericoronitis, abscesses)
o NUG - associated with anaerobic fuso-spirochaetal bacteria and is more common in patients who
smoke, the immuno-suppressed and those with poor oral hygiene
o Pericoronitis – associated with anaerobic bacteria
o This agrees with the clinical use of antibiotics, because antibiotics tends to be used to manage acute
infections where there is systemic involvement or persistent swelling despite local treatment.
o Especially if there is lymphadenopathy and increased temperature
Periodontitis
o Antimicrobials are used for susceptible patients and grade C periodontal disease as an adjunct to
mechanical therapy
RSD can be used to disrupt the biofilm so that antibiotics will be effective
o Systemic antibiotics are effective for periodontal treatment because they are present in high
concentrations in the GCF, thus can act in the desired area
o Systemic antibiotics are used to achieve better clinical outcomes
Osteomyelitis
Sinusitis
o where there are persistent symptoms and/or purulent discharge lasting at least seven days or where
symptoms are severe
Prophylaxis for dental treatment
Osteoradionecrosis prevention
Patients who are medically compromised to prevent infective endocarditis
o Only some groups apply
Contra-indications
, Antibiotics: types, indications, doses for each condition
Chronic infections
Pulpitis
Prevention of dry socket
Allergy
Do not prescribe amoxicillin to patients with a history of anaphylaxis, urticaria or rash immediately after
penicillin administration as these individuals are at risk of immediate hypersensitivity.
Routes of administration
Systemic
Oral
IV
Local
Types
Penicillins
Penicillin V (phenoxymethylpenicillin)
o Narrow spectrum against gram -ve bacteria
o drug of first choice for most dental infections / pyogenic infections, but is ineffective against
lactamase-producing bacteria
o route
oral, IV
o Important side effects: hypersensitivity rash, anaphylaxis.
Amoxicillin
o Broad spectrum
o May be useful for short course oral regimens.
o Uses
dental infection / pyogenic infections, surgical prophylaxis, endocarditis prophylaxis.
o Route: oral, iv.
o Important side effects: skin rash, anaphylaxis, candidosis or antibiotic associated colitis if prolonged
use.
Ampicillin
o Borad spectrum
Co-amoxiclav
o Amoxicillin + clavulanic acid
o Is active against beta-lactamase-producing bacteria that are resistant to amoxicillin, and can be used
to treat severe dental infection with spreading cellulitis or dental infection that has not responded to
first-line antibacterial treatment.
o Co-amoxiclav 250/125 tablets are amoxicillin 250 mg as trihydrate and clavulanic acid 125 mg as
potassium salt.
o Cholestatic jaundice can occur either during or shortly after the use of co-amoxiclav; this condition is
more common in patients above the age of 65 years and in men. Do not prescribe co-amoxiclav to
patients who have a history of co-amoxiclav-associated or penicillin-associated jaundice or hepatic
dysfunction
Metronidazole
Anaerobic bacteria
It acts of DNA synthesis
