Antimicrobial agents in the management of perio diseases

• Benefits vs risk of antimicrobials

  Pros:

  • stop spreading infection
  • Eliminate infectious MO

  Cons:

  • microbial resistance
  • Adverse reactions
• What 4 main areas should you consider when justifying use?

  1. infective element
  2. Nature of infection
  3. Host
  4. antimicrobial
• What should be considered of the infection element?

  specific or non specific
• What should be considered about the Host ?

  • side effects
  • adverse reactions
  • Drug elimination
• What should be considered about the nature of infection ?

  • anaerobe or aerobe
  • Biofilm
  • Tissue invasion
  • Facultative anaerobe
  • resistance
  • virulence factors
• What should be considered about the Antimicrobial ?

  • its mode of action - bacteriostatic or bactericidal
  • Site of action
  • Microbial reservoirs
• Example of gram positive Mos

  Stpahylococcus

  streptococcus
• Gram positive more MOs are more susceptible to what ?

  Penicillin
• Gram negative are?

  • periodontopathogens
  • have LPS which tiggers immune response
  • Resistant to penecillin
• What are examples of bacterial resevoirs?

  Tongue, tonsils, tooth grooves, opercula
• MOS can either be in...

  biofilm or planktonic
• What is the minimum inhibitory concentration?

  the lowest concentration that stops replication of the microbe
• Minimum lethal concentration

  the lowest concentration that will kill the microbe
• What does MIC need to be achieved in?

  Blood and serum for tissue invasion microbes

  GCF for pocket dwelling microbes
• Biofilm interferes with what?

  GCF delivery of an antimicrobe
• System delivery of antimicrobials considerations ?

  • appropriate drugs
  • Microbe sensitivity and resistance
  • High enough and long enough dose to achieve MIC in serum and GCF
  • Compliance of pt to take as prescribed
• Tx for microbial reservoirs ?

  • Chlorhexidine Rinse
  • Brush tongue
  • Chlorhexidine gel subgingivally
  • Gargle (tonsils)
• Cochrane rv found that full mouth disinfection is

  modest and implication for perio care not profound
• Bactericidal mode of action


  Kills microbe in diff ways by breaching cell wall by either:

  1. inhibition of cell wall synthesis (transpeptidation) eg. penicillins
  2. Detergent like action on cell wall sterols eg. polyenes like nystatin

  and then acts of cell contents by either

  1. inhibition of nucleic acid synthesis eg. nitromidazoles
  2. interferences with cell enzyme system eg. sulphonamides
• Bacteriostatic mode of action?


  stop replication of microbe by:

  
  

  1. selective inhibition of bacterial protein synthesis eg. tetracylcines and clindamycin
  2. host response then kills cell
• When should caution be taken when prescribing bacteriostatics?

  Immunosuppression eg:

  • HIV
  • transplant
  • Rheumatology
  • Dermatology
• Antimicrobial spectrum can be either?

  broad or narrow
• Broad spectrum activity ?

  • acts against a wide range of disease causing bacteria
  • Acts against gram positive and negative
• Example of a broad spectrum AM?

  Amoxicillin or tetracyclines
• Example of a narrow spectrum AM?

  penicillin or metronidazole
• Narrow spectrum AM?

  • limited activity against particular species or orgs
  • Acts against gram positive and negative bacteria
• MOS showing resistance?

  • Tb
  • E coli
  • Syphillis
  • Tetanus
  • Streptococci
  • salmonella
  • Staphylococcis
• Example of a penicillin resistance bacteria

  Aa

  Pg

  Pi

  Bacterioides forsythus
• Example of a metronidazole resistance bacteria

  Aa

  Pi
• Example of a tetracycline resistance bacteria

  Aa

  Pg

  Pi

  fusobacterium nucleatum
• Penicillin resistance?

  • B lactamase (penicillinase)
  • Interspecies transfer of resistance (plasmids)
  • Alteration to penicillin binding proteins (streptococci)
• Metronidazole resistance?

  mutations leads to:

  • Decreased entry of drug into cell
  • Affect enzymes that reduce drug to active form
  • Increased efflux of drug
• Tetracycline resistance?

  via a tet gene (27 types in oral bacteria)

  • Ribosome protection proteins
  • Synthesis of efflux proteins
  • Enzyme modification of antibiotic
• Chx resistance

  plasmid mediated
• Which bacteria are resistant to CHx

  S. aureus

  Step. sanguis
• Aa strains ?

  • 19+
  • a, b, c assoc. w disease
  • d assoc with non diseased sites
• Tf strains

  6+
• Pi strains

  10+
• Td strains

  5+
• Pg strains ?

  • 22+
  • Strains hW83 , h49417 & hHG1691 associated with disease