Microbiology - Dentoalveolar Infections Flashcards

1
Q

Provide examples of gram positive bacteria found in dentoalveolar infections

A

cocci (round shaped) = S.anginosus

bacilli (rod shaped) = actinomyces israelii

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2
Q

Provide examples of gram negative bacteria found in dentoalveolar infections

A

cocci = veillonella

bacilli (rod) = prevotella intermedia

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3
Q

define aerobic organisms

A

oxygen is vital for survival

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4
Q

define capnophilic organisms

A

requires small amounts of carbon dioxide to survive

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5
Q

define facultative organisms

A

can survive with or without oxygen

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6
Q

What organisms does metronidazole act on?

A

Strict anaerobes

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7
Q

What is antimicrobial resistance?

A

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.

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8
Q

What are the 2 main resistance mechanisms and describe.

A

• Intrinsic resistance to certain antibiotics

• Acquired resistance
– From Mutation, slowly over time.
– From acquisition of new DNA via transformation, transduction and conjugation processes.

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9
Q

Define transformation resistance mechanisms.

A

when there is an uptake of short fragments of naked DNA by naturally transformable bacteria

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10
Q

Define transduction resistance mechanisms.

A

transfer of DNA from one bacterium into another via bacteriophages

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11
Q

Define conjugation resistance mechanisms.

A

transfer of DNA material via sexual pilus and requires cell to cell contact

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12
Q

Describe how alterations to target sites creates antibiotic resistance.

A

As a result of acquired resistance genes the bacteria changes the shape of the receptors for Antibiotics = cannot interact

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13
Q

Describe how enzymatic inactivation creates antibiotic resistance.

A

Enzymes destroy antibiotics or prevent AB’s binding to target sites

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14
Q

Describe how decreased uptake creates antibiotic resistance.

A

Uptake of antibiotics are decreased via large capsules surrounding the bacteria

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15
Q

How do prevotella and fusobacterium species create resistance to penicillins?

A

Enzymatic inactivation - Resistance mechanism (to penicillins) via beta-lactamase enzyme production.

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16
Q

Why are beta lactamases important?

A

Provide resistance of groups of gram negative bacilli to antibiotics
e.g. e.coli, psudomonas

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17
Q

What type of infections are dental abscesses commonly? (3)

A

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

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18
Q

What organisms are commonly found in dental abscesses? (2)

A

Streptococcus anginosus (facultative anaerobes) :

Prevotella intermedia (strict anaerobe)

19
Q

What is the best type of specimen to collect from a dental abscess?

A

Aspirated pus

20
Q

What organisms are commonly found in periodontal abscesses? (1)

A

Anaerobic streptococci - gram negative strict anaerobes e.g. Prevotella intermedia

21
Q

What organisms are commonly found in pericoronitis? (2)

A

Predominantly mixed oral anaerobes;
- P. intermedia
- S. anginosus group

22
Q

What are the predisposing factors to osteomyelitis of the jaws? (5)

A

• Biphosphonate therapy (BRONJ/MRONJ)
• Impaired vascularity of bone (radiotherapy, Pagets disease)
• Infection of foreign bodies (implants)
• Compound fractures
• Impaired host defences (uncontrolled diabetes)

23
Q

What organisms are present in osteomyelitits? (5)

A
  • 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
24
Q

What organisms are present in salivary gland infection? (2)

A

• S. aureus
• Mixed anaerobes

25
Q

How do we treat salivary gland infections? (2)

A
  1. Drainage
  2. Prescribe Flucloxacillin (to treat the s.aureus) & metronidazole (to treat mixed anaerobes)
26
Q

What do we document when prescribing antibiotics? (4)

A
  1. Document your diagnosis
  2. Document Antibiotic choice, dose, route & duration
  3. Document a review date
  4. Document deviation from guidance if appropriate and why.
27
Q

What organisms are present in Ludwig’s angina? (5)

A
  • Anaerobic Gram negative bacilli; p.intermedia
  • Streptococcus anginosus: most commonly found
  • Anaerobic streptococci
  • small proportion of s.aureus
  • Mixed anaerobes
28
Q

What is sepsis?

A

Life-threatening organ dysfunction caused by dysregulated host response to infection

29
Q

How do we diagnose sepsis?

A

When there is evidence of Systemic inflammatory response syndrome & suspected/confirmed infection present.

30
Q

how do we treat sepsis in primary care?(2)

A
  • Diagnose
  • Refer/seek advice
31
Q

how do we treat sepsis in secondary care? (2)

A
  • Diagnosis
  • Complete the sepsis 6
  1. Give high flow oxygen
  2. Take blood cultures
  3. Give IV AB’s
  4. Give a fluid challenge
  5. Measure lactate
  6. Measure urine output
  • assess national early warning signs
32
Q

List the sepsis 6.

A
  1. Give high flow oxygen
  2. Take blood cultures
  3. Give IV AB’s
  4. Give a fluid challenge
  5. Measure lactate
  6. Measure urine output
33
Q

what is septic shock?

A

px has Sepsis + is unresponsive to fluid resuscitation

Subset of sepsis with circulatory and cellular/metabolic dysfunction associated with higher risk of mortality

34
Q

What are the 2 ways we can define resistance?

A

Biological

Clinical

35
Q

Define biological reisstance.

A

Helps to define resistance from a labs perspective

36
Q

How is biological resistance carried out?

A
  • 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
37
Q

In terms of biological resistance what is the breakpoint?

A

= chosen concentration (mg/L) of an antibiotic which defines whether a species of bacteria is susceptible or resistant to the antibiotic

38
Q

Define clinical reisstance.

A

When infection is highly unlikely to respond even to maximum doses of antibiotic

39
Q

List laboratory resistance variables. (7)

A
  • Inoculum size
  • growth phase
  • planktonic (bacteria in solution)
  • pH,
  • atmosphere
  • Variance in Breakpoint calling
  • Biofilm
40
Q

List clinical resistance variables. (7)

A
  • 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
41
Q

What is antimicrobial stewardship?

A

Where a multidisciplinary workforce work together to preserve antimicrobial medicines by taking measure to promote their control.

42
Q

What is the new first choice antibiotic used for treating dental infection?

A

Penicillin V = narrow spectrum AB

43
Q

How do we prevent antimicrobial resistance?

A
  1. Promote prevention
  2. Prevent spread of disease – wash hands/SICP’s and get vaccinated
  3. Don’t provide AB’s for toothache