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
What organisms are commonly found in dental abscesses? (2)
Streptococcus anginosus (facultative anaerobes) :
Prevotella intermedia (strict anaerobe)
What is the best type of specimen to collect from a dental abscess?
Aspirated pus
What organisms are commonly found in periodontal abscesses? (1)
Anaerobic streptococci - gram negative strict anaerobes e.g. Prevotella intermedia
What organisms are commonly found in pericoronitis? (2)
Predominantly mixed oral anaerobes;
- P. intermedia
- S. anginosus group
What are the predisposing factors to osteomyelitis of the jaws? (5)
• Biphosphonate therapy (BRONJ/MRONJ)
• Impaired vascularity of bone (radiotherapy, Pagets disease)
• Infection of foreign bodies (implants)
• Compound fractures
• Impaired host defences (uncontrolled diabetes)
What organisms are present in osteomyelitits? (5)
- Anaerobic Gram negative rods: p.intermedia
- Anaerobic streptococci
- Streptococcus anginosus
- Staphylococcus aureus (common in infection of the bones – difficult to treat and require a minimum of 6 week AB therapy)
- Sometimes actinomyses israelii
What organisms are present in salivary gland infection? (2)
• S. aureus
• Mixed anaerobes
How do we treat salivary gland infections? (2)
- Drainage
- Prescribe Flucloxacillin (to treat the s.aureus) & metronidazole (to treat mixed anaerobes)
What do we document when prescribing antibiotics? (4)
- Document your diagnosis
- Document Antibiotic choice, dose, route & duration
- Document a review date
- Document deviation from guidance if appropriate and why.
What organisms are present in Ludwig’s angina? (5)
- Anaerobic Gram negative bacilli; p.intermedia
- Streptococcus anginosus: most commonly found
- Anaerobic streptococci
- small proportion of s.aureus
- Mixed anaerobes
What is sepsis?
Life-threatening organ dysfunction caused by dysregulated host response to infection
How do we diagnose sepsis?
When there is evidence of Systemic inflammatory response syndrome & suspected/confirmed infection present.
how do we treat sepsis in primary care?(2)
- Diagnose
- Refer/seek advice
how do we treat sepsis in secondary care? (2)
- Diagnosis
- Complete the sepsis 6
- Give high flow oxygen
- Take blood cultures
- Give IV AB’s
- Give a fluid challenge
- Measure lactate
- Measure urine output
- assess national early warning signs
List the sepsis 6.
- Give high flow oxygen
- Take blood cultures
- Give IV AB’s
- Give a fluid challenge
- Measure lactate
- Measure urine output
what is septic shock?
px has Sepsis + is unresponsive to fluid resuscitation
Subset of sepsis with circulatory and cellular/metabolic dysfunction associated with higher risk of mortality
What are the 2 ways we can define resistance?
Biological
Clinical
Define biological reisstance.
Helps to define resistance from a labs perspective
How is biological resistance carried out?
- Use in-vitro quantitive testing of bacterial suspensions to antibacterial agents
- Use a plastic strip with a high concentration of AB at the top and a lower conc at the bottom and allows a numerical value to be recorded where the bacteria become inhibited.
This is called the minimum inhibitory conc
In terms of biological resistance what is the breakpoint?
= chosen concentration (mg/L) of an antibiotic which defines whether a species of bacteria is susceptible or resistant to the antibiotic
Define clinical reisstance.
When infection is highly unlikely to respond even to maximum doses of antibiotic
List laboratory resistance variables. (7)
- Inoculum size
- growth phase
- planktonic (bacteria in solution)
- pH,
- atmosphere
- Variance in Breakpoint calling
- Biofilm
List clinical resistance variables. (7)
- Co-morbidities (some more susceptible),
- pus collections,
- foreign bodies (can lead to formation of biofilms),
- site of infection
- Biofilm (almost impossible to treat)
- Pharmacokinetics
- Pharmacodynamics
What is antimicrobial stewardship?
Where a multidisciplinary workforce work together to preserve antimicrobial medicines by taking measure to promote their control.
What is the new first choice antibiotic used for treating dental infection?
Penicillin V = narrow spectrum AB
How do we prevent antimicrobial resistance?
- Promote prevention
- Prevent spread of disease – wash hands/SICP’s and get vaccinated
- Don’t provide AB’s for toothache
