Microbiology - Dentoalveolar Infections Flashcards
Provide examples of gram positive bacteria found in dentoalveolar infections
cocci (round shaped) = S.anginosus
bacilli (rod shaped) = actinomyces israelii
Provide examples of gram negative bacteria found in dentoalveolar infections
cocci = veillonella
bacilli (rod) = prevotella intermedia
define aerobic organisms
oxygen is vital for survival
define capnophilic organisms
requires small amounts of carbon dioxide to survive
define facultative organisms
can survive with or without oxygen
What organisms does metronidazole act on?
Strict anaerobes
What is antimicrobial resistance?
Antimicrobial resistance occurs when microorganisms such as bacteria, viruses, fungi and parasites change (as a result of selection pressures applied by antimicrobial agents) in ways that render the medications used to cure the infections they cause ineffective.
What are the 2 main resistance mechanisms and describe.
• Intrinsic resistance to certain antibiotics
• Acquired resistance
– From Mutation, slowly over time.
– From acquisition of new DNA via transformation, transduction and conjugation processes.
Define transformation resistance mechanisms.
when there is an uptake of short fragments of naked DNA by naturally transformable bacteria
Define transduction resistance mechanisms.
transfer of DNA from one bacterium into another via bacteriophages
Define conjugation resistance mechanisms.
transfer of DNA material via sexual pilus and requires cell to cell contact
Describe how alterations to target sites creates antibiotic resistance.
As a result of acquired resistance genes the bacteria changes the shape of the receptors for Antibiotics = cannot interact
Describe how enzymatic inactivation creates antibiotic resistance.
Enzymes destroy antibiotics or prevent AB’s binding to target sites
Describe how decreased uptake creates antibiotic resistance.
Uptake of antibiotics are decreased via large capsules surrounding the bacteria
How do prevotella and fusobacterium species create resistance to penicillins?
Enzymatic inactivation - Resistance mechanism (to penicillins) via beta-lactamase enzyme production.
Why are beta lactamases important?
Provide resistance of groups of gram negative bacilli to antibiotics
e.g. e.coli, psudomonas
What type of infections are dental abscesses commonly? (3)
Endogenous infections (bacteria that cause the infection mostly originate from own flora)
mixed infections of aerobic and anaerobic working together
- strict anaerobes play an important role too