Infection- Antimicrobials and antibiotics Flashcards
(46 cards)
What are examples of gram positive microbes? (purple)
- Cocci- s. aginosus
- Bacilli- actinomyces israelli
What are examples of gram negative microbes? (pink/red)
- Cocci- veillonella
- Bacilli- Prevotella Intermedia
What are the different classifications of microbes based on their growth conditions?
Aerobic = Oxygen
Capnophilic = Carbon dioxide
Facultative = With & without oxygen
Strictly Anaerobic = without oxygen
What is the only antimicrobial that works on strict anaerobes?
Metronidazole
Why are facultative anaerobes resistant to metronidazole?
Due to their metabolic pathways
What is antimicrobial resistance?
Occurs when microorganisms such as bacteria, viruses, fungi and parasites change in ways (due to selection pressures) that render the medications used to cure the infections they cause ineffective
What are the types of resistance?
Intrinsic
-> prevotella to vancomycin
Acquired- via mutation OR acquisition of new DNA (transformation, transduction, conjugation)
What are some examples of resistance mechanisms?
- Alteration of target site- changed receptor for antibiotics (e.g. penicillin resistance in strep. Mitis)
- Enzymatic inactivation- destroy antibiotics or prevent binding (Beta lactamase can destroy penicillin)
- Decreased uptake- Klebsiella pneumoniae
What occurred in the beta-lactam arms race?
Penicillinase previously developed by microbes to destroy beta-lactam in penicillin
Resistant penicillin was produced with side chains- but then bacteria developed beta-lactamase
Extended spectrum antibiotics were produced- but bacteria also produced extended spectrum beta-lactamase
What are carbapenems?
New AB- protect beta lactams in penicillin
What are the issues with carbapenems?
Bacteria have developed carbapenemase to destroy this
-> some bacteria are resistant to all ABs (Multi-drug resistant microorganisms can be found in dento-alveolar infections)
What are the microbes present in PA infections/abscesses? (endogenous)
Mixed- aerobic and anaerobic (synergy)
* Facultative- s.aginosus
* Strict anaerobe- prevotella intermedia (gram-)
What would be the ideal method to take a specimen from a dental abscess?
Pus apsirate
-> might be difficult to achieve (likely only done in hospital setting- severe infections)
What microbes are present in periodontal abscesses?
Anaerobic streptococci
Prevotella intermedia
What are the treatment options for removing dental infection?
Open pulp cavity
Extirpation of pulp
RCT
I/D of abscess
Extraction
What microbes are present in pericoronitis?
Mixed anaerobes :
P.intermedia
S.aginosis group
What are the treatment options for pericoronitis?
Local measures
Systemic (only if systemic signs/symptoms)
What is Dry Socket?
Blood clot becomes dislodged, so healing socket is exposed to oral flora
-> localised alveolar osteitis
How is dry socket treated?
LA, debridement and packing with AM gels (not antibiotics)
What occurs in osteomyelitis?
Dental infection spreads into ramus and lower border of mandible
What are the predisposing factors for Osteomyelitis of the jaws?
Biphosphonate therapy (BRONJ/MRONJ)
Impaired vascularity of bone (radiotherapy, Pagets disease)
Foreign bodies (implants)
Compound fractures
Impaired host defences (diabetes)
Which microbes are involved in osteomyelitis of the jaws?
Anaerobic Gram negative rods- p.intermedia
Anaerobic streptococci
Streptococcus anginosus
Staphylococcus aureus (common in bone infections- difficult to treat)
How is OM treated?
Curette bone out
6 weeks course of IV antibiotics
Which microbes are associated with MRONJ?
S. anginosus
Mixed anaerobes
Actinomyces israelii- gram + bacilli