W4: Antimicrobial Therapy and LA in Dentistry

Question 1

What are the most common odontogenic infections?

Answer 1

Abcess
Cellulitis

Question 2

What is an abscess and what happens if the abscess is untreated?

Answer 2

• Localized area of inflammation with purulent exudate
• Pyogenic bacteria (e.g. Streptoccoi)
• Resists phagocytosis (capsule)
  -Fibroblasts “wall it off”

Untreated abscess:
- Macrophage enzymes breakdown hard and soft tissues
- Treat surgically
* drain pus by extraction or root canal)
* incision to drain soft tissues

• Cellulitis
• inflammation of the connecitive tissue

Question 2

What is maxillary sinusitis and of which origin?

Answer 2

Maxillary sinusitis of endodontic origin:
- spread from maxillary posterior teeth
- can be atypical infections
- often unilateral
- apical periodontitis -> periapical mucositis

Question 3

What is oral candidiasis?

Answer 3

Oral candidiasis (thrush)
- endogenous infection
- overgrowth of the yeast *Candida albicans *
* less common C.glabrata, C. tropicalis
- opportunistic pathogen

Question 4

What are the risk factors to develop oral candidiasis?

Answer 4

• very old or very young
• In poor health
• Overuse of antibiotics
• HIV infection or AIDs
• Chemotherapy or immunosuppressuve drugs
• Taking steriod medication
• Diabetic with high blood sugar
• Poorly fitting dentures

Question 5

Define antimicrobial resistance

Answer 5

Antimicrobial reistance:

• the strain of microorganism that is not inhibited or killed by that antimicorbial
• Failure of a treatment to manage a patients infection

Question 6

What is the relevance of antimicrobials to dentistry? What is the primary approach? When should antimicrobials be prescribed?

Answer 6

Significant portion of clincal work involved dealing with the impact of infection
* caries, periodontal disease, dental abscess, maxillary sinusitis of endodontic origin, candidiasis

Primary approach is surgical
* restorations, scaling and root planing, root canal therapy, properly fitting dentures

Antimicrobials are a useful ADJUNCT therapy but must be a clear need for them
* spreading infections, fever, risk groups

Question 7

What are the two most common dental prescriptions?

Answer 7

Antibiotics
Antifungal

*from the 2021 data

Question 8

Which bacteria in periodontal disease is developing antimicrobal resistance to which drug?

Answer 8

Prevotella resistant to Penicillin (Russia, Romania, Europe)

Question 9

How can bacteria be reistant to anti-microbial drug?

Answer 9

Innate
Acquired

Question 10

What is innate reistance?

Answer 10

• No mechanism to transport drug into cell
• Do not contain ore rely on the antibiotics target process or protein
• example: gram-negative bacteria are naturally resistant to beta-lactams

Question 11

What is acquired resistance?

Answer 11

• Microorganisms develop genetic mutations that allow them to resist antibiotics
• Develops with repeated exposure
• Resistant strains can become dominant

Question 12

When should antibiotics be used?

Answer 12

• Infection is spreading
  cellulitits
• Lymph node invovlement
• Signs of inflammation
• LA ineffective
• Systemic involvement (fever malaise)
• Periodontal disease

Question 13

When should antibiotics be used with periodontal disease and what is the management?

Answer 13

• Inflammation of the gingiva and periodontal tissues
• bacteria in plaque
• Surgical approach if SRP
• Chlorhexidine mouth wash
• Moderate to severe- SRP PLUS Amoxicillin/Metronidazole

Question 14

When should antibiotics be used with prophylaxis?

Answer 14

• Prophylaxis
• Commonly used to reduce the risk of infective endocarditis
• Side effect and risk of reistance
• Prescribe for patients with cardiac conditions and high risk of adverse outcomes
• Artificalheart valves, history of infective endocarditis, congenital heart conditions, transplant with problem in valve
• Low SES also a factor

Question 15

What is infective endocarditis?

Answer 15

• Reapted Group A Strep infecton
• Strep throat, impetigo, scabies
• Acute rheumatic fever
• Autoimmune response, damages heart valves
• Rheumatic heart disease
• Bacteremia following dental procedures

Question 16

What and when is prophylactic therapy?

Answer 16

• Recommended dose 2g amoxicilln orally 1 hour before procedure
• clindamycin for patients with immediate hypersensitvity to penicillin or cefalexin for non-immediate hypersensitvities
• Not all procedures
• only ones with high bacteremia (extraction, SRP)
• Oral health of patient (full mouth probing with periodontitis)
• Not restorations, LA administration or probing healthy teeth

https://tgldcdp.tg.org.au/viewTopic?topicfile=infection-prevention-endocarditis&sectionId=abg16-c98-s2#toc_d1e251

Question 17

What are examples narrow spectrum antibiotics?

Answer 17

Penicillin V
Amoxicilln

Question 18

What are examples broad spectrum antibiotics?

Answer 18

Co-amoxylav (Augmetin)
Azithromycin
Metronidazole
Clindamycin

*metronidazole is debateable?

Question 19

Which antibiotics are bacteriocidal?

Answer 19

Metronidazole
Penicillin

Question 20

Which antibiotics are bacteriostatic?

Answer 20

Trimethoprim
Sulfonamides
Tetracycline
Azithromycin

Question 21

Which antibiotics are used for odontogenic infections?

Answer 21

• First line antibiotics
• Amoxicillin or Penicillin V
• Allergies (Clindamycin)
  *Second line if necessary
• Allergy (?)
• Unresponsive infection
• Cellulitis

Question 22

Which type of antibiotics contributes to resistance?

Answer 22

Broad spectrum

Question 23

Which antibiotics should be used for unresponsive infections?

Answer 23

• Metronidazole plus Amoxicillin or Penicillin V
• Co-AmonyClav

Question 24

Which antibitoics should be used for: Maxilliary Sinusitis? Periocoronitis? Candidiasis? Patients on bicillin?

Answer 24

Maxilliary Sinusitis: Augmentin Periocoronitis: Metronidazole or Amoxicillin Candidiasi: Ampgotericin B Patients on bicillin: Amoxicillin

Question 25

What is selective toxicity?

Answer 25

* Drug work by disrupting metabolic processes * Need drugs that kill or inhibit the microorganism without damaging the host cells - side effects * Exploit the differences - Bacteria (prokaryotes) - Fungi, protozoa, helminths (eukaryotes) - Viruses (obligaet intracellular)

Question 26

What are adverse reactions?

Answer 26

* Unexpected or unintended effect - range from headaches, comiting to liver or kidney injury * Dose-related - Extension effects or side effects * Allergic reaction - requires sensitization - penicillin * Idiosyncratic - Not really understood, but may have genetic causes

Question 27

What are the risks and side effects with antibiotics?

Answer 27

* GI upsets are common -Nausea, vomitting, diarrhoea - Colitis * Clostridium dificile infections -Broad spectrum antibiotic use (Clindamycin, Co-Amoxyclav) -Health-care associated infection -Vulnerable people (elderly, history of GI disease) * Other infections -Fungal infections (on increase) * **Hypersensitivity** **reactions** *Known issue with beta-lactams and sulphonamides * -medical history is important -immediate hypersensitivity reactions *anaphylaxis (trouble breathing, low BP, swelling of tongue, swelling of throat- ADRENALINE INJECTION NEEDED)* -Delayed *rashes (antihistamines)*

Question 28

Which medications do antibiotics interact with?

Answer 28

* Warfarin (clotting factors) * Oral contraceptives (enterohepatic cycling)

Question 29

What are risk and side effects of Tetracyclines?

Answer 29

*Dental staining, enamel hypoplasia, bone deformation* **NOT FOR CHILDREN UNDER 12, PREGNANT WOMEN**

Question 30

What are the risks and side effects of Metronidazole?

Answer 30

* "Dislfirum-like" reactions- nausea, vomiting, flushing of the skin, tachycardia, shortness of breath *** AVOID ALCOHOL**

Question 31

What are the target sites of antibacterial drugs?

Answer 31

1. Cell wall synthesis 2. Protein synthesis 3. Nucleic acid synthesis 4. Cell membrane function

Question 32

Which antibiotics affect cell wall synthesis?

Answer 32

* Beta lactams and Cephalosporins -Example: Penicillin and Flucloxacillin * Glycopeptides -Exampl: Vancomycin (Gram-positive bacteria only) * Target peptidoglycan * Allergies

Question 33

Which antibiotics affect protein synthesis?

Answer 33

* Aminoglycosides * Tetracyclines * Macrolides * Chloraphenicol *Clindamycin -Prokaryote ribosomes are 70S -These drugs interfere with the binding of mRNA to ribosome or translation

Question 34

What antibiotics affect nucleic acid synthesis?

Answer 34

* Sulfonamides * Trimethoprim -Structure of DNA is the same in prokaryotes and Eukaryotes -Target process ## Footnote *both of these drugs are BACTERIOSTATIC

Question 35

Which antibiotics target cell membrane function?

Answer 35

* Polymixins -Example: Colistin -bind to LPS and interact with phospholipids in outer and inner membranes (catinic detergents) -Effective against MDR Gram-Negatives (Pseudomonas aeruginosa)

Question 36

What is the target of anti-fungal drugs?

Answer 36

- Cell membrane: β-glucan synthesis - Amohotericin B - Azoles: Ergosterol

Question 37

What are the genetic aspects of antibiotics resistance?

Answer 37

Antibiotic resistance may arise by: * Spontaneous chormosomal mutation -alterged protein -selective advantage * Horizontal gene transfer -acquire pieces of DNA from other bacteria

Question 38

What are the mechanisms antibiotic resistance?

Answer 38

* Altered target -target enzyme may change sufficiently (by mutation to cause lowered affinity for the antimicrobial drug) -Example: mutations in DNA Gyrase and Quinilones * Alteration in access to the target site (altered reuptake) -Decreased permeability (Vancomycin and Gram-negative bacteria) -Active transport (E.Coli and Tetracycline, P.falciparum and Chloroquine, C.albicans and azoles) * Drug inactivation -production of enzymes that inactive the anti-nacterial agent -Example: Beta-lactamases inactivate beta lactams * Horizontal gene transfer -Plasmids containig reistance genes

Question 39

What is the mechanisms of reistance for Fungi?

Answer 39

Similar to bacteria * efflux pumps * Decreased permeabilty * Altered drug targets * Degradtive enzymes * Overproduction of target

Question 40

What are local anaethetics sometimes described as?

Answer 40

"Membrane stablizers"

Question 41

What do local anaesthetics block?

Answer 41

Local anaesthetics are essentially voltage-gated *sodium channel* blockers

Question 42

What are commonly used local anaesthetics in dentistry and what are local anaesthetics typically delievered with?

Answer 42

Commonly used local anaesthetics in dentistry are aminoamides to be metabolized in the liver. These include lignocaine, mepivacaine, articaine, prilocaine. Typically local anaesthetics are delievered with a vasoconstrictor like adrenalne or fenylpressin.

Question 43

What is local anaesthetic ionization?

Answer 43

Ionization: Most local anaesethics are **weak bases and mostly ionized at physiological pH**. Local anaesthetics usually exist as salts. Terminal amine can exist as tertiary (lipid soluble) or quaternary (ionized/water soluble forms). The degree of ionization changes as molecules cross the axon membrane. Non-ionized (tertiary amine) have a weak channel blocking activity. The local anaesthetics **act on cystosolic side on S6 transmembrane domain. The time of onset is dependent on the solubility. ** Those molecules that are highly lipid soluble cross the interstitial spaces slowly and may be sequestered in myelin and adipose tissues. Inflamed tissues have a lower pH and may therefore be more difficult in achieveing effective local anaesthesia.