Microbiology of Infection

Question 1

What micro-organisms might be present in a dental abscess?

Answer 1

Mixed microbial lesion
- Anaerobes play a key role.

Streptococcus Anginosus
Prevotella Intermedia

Question 2

What would be the ideal specimen from a dental abscess?

Answer 2

Aspirational biopsy of pus from the abscess.
- this means that the sample is not contaminated by the aerobic environment.
- Will determine the bacteria that is causing the abscess.

Question 3

What bacteria might be present in a periodontal abscess?

Answer 3

Streptococcus Anginosus
Prevotella Intermedia

Question 4

What bacteria might be present in pericoronitis?

Answer 4

Mixed oral anaerobes
- Prevotella Intermedia
- S.Anginosus.

Question 5

What bacteria is present in Osteomyelitis?

Answer 5

Anaerobic Gram negative rods

Streptococcus Anginosus
Staphylococcus Aureus

Question 6

What bacteria is commonly found in Ludwig’s Angina?

Answer 6

Anaerobic gram negative bacilli- Prevotella Intermedia
Streptococcus Anginosus

Staph Aureus may also be present.

Question 7

What is an SOI?

Answer 7

Severe odontogenic infection.

Question 8

Give examples of SOIs.

Answer 8

Ludwig’s Angina
Osteomyelitis

Question 9

What can SOIs lead to if not treated?

Answer 9

Sepsis.

Question 10

What is sepsis?

Answer 10

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

Systemic inflammatory response syndrome (SIRS)+ suspected/confirmed infection.

Question 11

What signs would suggest systemic inflammatory response syndrome?

Answer 11

Temperature- less than 36 or greater than 38

Pulse- greater than 90 beats per minute

Respiratory rate- greater than 20 breaths a minute

WCC less than 4 or greater than 12

Do they seem confused?
Have they passed urine in the last 24 hours?
Cold or blotchy hands and feet
Uncontrolled shivering
Signs of infection

Question 12

What guidance can GDPs use to assess sepsis?

Answer 12

General practice Sepsis Decision Support Tool.

Question 13

What questions would you ask the patient?

Answer 13

Do you feel systemically unwell- fever, fatigue, malaise, lymphadenopathy.
Are carers/family members concerned?
Has there been deterioration?
Confusion?
Passed urine in the last 18 hours?

Question 14

What red flags symptoms would warrant you to phone 999?

Answer 14

Heart rate- greater than 130 beats per minute
Respiratory rate- greater than 25 breaths in a minute
Blood pressure- systolic blood pressure less than 90mmHg
Needs oxygen to keep oxygen saturation above 98%
Not passed urine in the last 18 hours.
Non blanching rash or mottles/ashen/cyanotic.

Question 15

What antibiotics would you prescribe for a dental abscess?

Answer 15

Phenoxymethylpenicillin- 250mg tablets, 2 tablets 4 times a day for 5 days.

If allergic to penicillin- can prescribe metronidazole- 400mg tablets, 1 tablet 3 times a day for 5 days.

Question 16

If antibiotics were required for a gingival or periodontal condition, what would you prescribe?

Answer 16

Metronidazole- 400mg tablets, 1 tablet 3 times a day for 5 days.

Question 17

What is antibiotic resistance?

Answer 17

Micro-organisms no longer respond to anti-microbials- they have changed in ways that render the medication ineffective.

Question 18

How might bacteria become resistant to antibiotics?

Answer 18

Intrinsic resistance- naturally resistant to the antibiotic- i.e. from having a thick capsule.

Acquired resistance- mutation, acquisition of new DNA.

Question 19

Describe some of the mechanisms of antibiotic resistance.

Answer 19

Altered target site- Streptococci

Enzymatic inactivation- Prevotella Intermedia, Fusobacterium.
- usually from beta-lactamase.

Decreased uptake of antibiotic

Question 20

When it comes to choosing an antibiotic, what does S, I and R mean?

Answer 20

S- Susceptible at standard dose
- High likelihood of therapeutic success using standard dosing regimen of the agent.

I- Increased exposure (requires increased dose)

R- resistant even with increased exposure.
- High likelihood of therapeutic failure even when there is increased exposure.

Question 21

What is antimicrobial stewardship?

Answer 21

An organisational or health-care system wide approach to promoting and monitoring judicious use of antimicrobials to preserve their future effectiveness.

Question 22

What can be done to improve antimicrobial stewardship?

Answer 22

Educate members of the dental team- not just prescribers

Guidelines about appropriate clinical indications for antibiotic use

Undertake audit and feedback of prescribing against the guidelines

Patient-facing material to help deliver key messages in relation to antibiotic stewardship ind dentistry.

Reducing the need for antibiotics- patient education in OH, diet advice, prevention.

Question 23

Why is Pen V recommended for use in dentoalveolar infections instead of amoxicillin?

Answer 23

Amoxicillin is a more broad spectrum antibiotic.
- Both active against gram negative anaerobes but Amox is also active against gram negative cocci and members of the family Enterobacteriaceae.

So there is a greater impact on selection of resistance in the host microflora compared to pen V.

Question 24

If you are prescribing Pen V to a patient, what should you do in the days after prescribing it?

Answer 24

Arrange to review the patient after 24 hours- either in person or over the phone.