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BDS4 Microbiology > Oral Surgery > Flashcards

Oral Surgery Flashcards

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Biology 101 flashcards
1
Q

What are the features of Gram Negative bacteria

A
  1. Has an inner and outer membrane (2 membranes)
  2. Releases endotoxins (LPS) + exotoxins
  3. Stains RED
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2
Q

What are features of Gram Positive bacteria

A
  1. No outer membrane but is surrounded by layers of peptidoglycan which is thicker than that of gram negative
  2. Contains teichoic acid + lipteichoic acid in cell wall
  3. Releases exotoxins only
  4. Stains purple
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3
Q

Why does gram negative stain pink

A

organic solvent used disrupts membrane and stain is washed out of cell

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4
Q

Why does gram positive stain violet

A

as it retains the fixed violet dye within the cell

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5
Q

What is an example of a gram positive cocci

A

s. anginosus
streptococcus mutans (facultative)

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6
Q

What is an example of a gram negative cocci

A

veillonella species

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7
Q

What is an example of a gram positive bacilli

A

actinomyces israelii (anaerobic)
clostridium difficile (anaerobic)

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8
Q

What is an example of a gram negative bacilli

A

prevotella intermedia

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9
Q

What does aerobic growth conditions mean

A

requires oxygen

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10
Q

What does capnophilic growth conditions mean

A

requires carbon dioxide

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11
Q

What does facultative growth conditions mean

A

can survive with/without oxygen

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12
Q

What does strictly anaerobic growth conditions mean

A

requires no oxygen, oxygen can be toxic. Metronidazole is the only antibiotic that works on these

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13
Q

What is antimicrobial resistance

A

occurs when microorganisms change in ways that render the medications used to cure the infections they cause ineffective

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14
Q

What are the 2 main types of resistance

A

intrinsic
acquired

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15
Q

What is intrinsic resistance

A

bacterial species is naturally resistant to a certain antibiotic/family of antibiotics without the need for mutation/gain of further genes

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16
Q

What are the 2 types of acquired resistance

A

mutation
acquisition of new DNA

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17
Q

How does mutations result in resistance

A
  • E.g single, spontaneous chromosomal mutation in one bacterial cell which results in synthesis of an altered protein
  • If this protein is a target site for a particular antibiotic then the antimicrobial effectiveness will be severely compromised in mutant cells giving them a selective advantage
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18
Q

What are the 3 methods that a bacterium can acquire new DNA

A

Transformation, transduction, conjugation

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19
Q

What are the 2 mechanisms of resistance

A

altered target
enzymatic deactivation

20
Q

Describe altered target mechanism of resistance and give an example

A

Target enzyme may change sufficiently e.g by mutation to cause a lower affinity for the drug

Additional target enzyme that is resistant to the drug may be produced

E.g is penicillin resistance due to modified penicillin binding proteins

21
Q

What is the enzymatic deactivation mechanism of resistance

A

 Production of enzymes that inactivate the antibacterial agent
 E.g prevotella and fusobacteriam species produce beta-lactamases which inactivate penicillins
 Carbapenem antibiotics protect from betalactamases

22
Q

What are the 2 types of antibiotic testing

A

diffusion and dilution

23
Q

What is the minimum inhibitory concentration

A

this is the lowest concentration of a chemical, usually a drug which prevents visible growth of a bacteria or bacteria

24
Q

What is the breakpoint

A

the chosen concentration of an antibiotic which defines whether a species of bacteria is susceptible or resistant to the antibiotic

25
Q

What is clinical resistance defined as

A

when infection is highly unlikely to respond even to a maximum dose of antibiotics

26
Q

Why are we trying to move more towards pen V in dentistry

A

Currently in Scotland, amoxycillin is prescribed more than Pen V

Amoxycillin is a broad spectrum AB and is more likely to encourage the development of resistance so there is a move in Scotland to make pen V the first line drug which is narrow spectrum for dentoalveolar infections

27
Q

Are dental abscesses usually endogenous or exogenous

A

endogenous

28
Q

Are dental abscesses usually aerobic or anaerobic bacteria

A

mixed

29
Q

What is the ideal specimen for dental abscess

A

pus aspirate

30
Q

What is the common microbiology for a dental abscess

A

streptococcus anginosus and prevotella intermedia

31
Q

What is the microbiology of pericoronitis

A
  • Predominantly mixed oral anaerobes
32
Q

What are predisposing factors of osteomyelitis

A
  • Bisphosphonate therapy (most common) - MRONJ
  • Impaired vascularity of the bone (radiotherapy, pagets disease)
  • Foreign bodies (implants)
  • Compound fractures
  • Impaired host defences (diabetes)
33
Q

What is the microbiology of osteomyelitis

A
  • Anaerobic gram negative rods
  • Anaerobic streptococci
  • Examples include streptococcus anginosus & staphylococcus aureus
34
Q

What is the microbiology of a salivary gland infection

A

o Mixed anaerobes
o S. aureus

35
Q

What is the treatment for a salivary gland infection

A

o Drain
o Flucloxacillin & metronidazole
o Flucloxacillin is for the staph. Aureus
o Metronidazole is for the mixed anaerobes

36
Q

What should you always document with any infection

A
  1. Document your diagnosis
  2. Document your antibiotic of choice, it’s dose, route & duration
  3. Document a review date (usually 24-48 hours)
  4. Document any deviation from guidance and justification
37
Q

What is Ludwig’s angina

A

bilateral infection of the submandibular space

38
Q

What is the most common bacteria in Ludwig’s angina

A

anaerobic gram negative bacilli but it can be caused by staphylococcus aureus

39
Q

What is the definition of sepsis

A

life threatening organ dysfunction caused by dysregulated host response to infection

40
Q

What is septic shock

A

sepsis + unresponsive + unresponsive to fluid resuscitation

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

41
Q

How does sepsis occur

A

bacteria enter blood stream and detected by culture –> bacteraemia

when this matches with certain signs and symptoms, called sepsis

host defence mechanisms activated, cascade of cytokines mediate systemic response

excessive/prolonged activation can lead to problems including development of organ dysfunction and circulatory septic shock

42
Q

What can microbial products can trigger sepsis

A

LPS (endotoxin) from gram negative bacteria and exotoxins, teichoic acid and peptidoglycan from gram-positive bacteria and exotoxins/supernatigens from both gram positive and gram negative bacteria

43
Q

What is SIRS

A

systemic inflammatory response syndrome

SIRS + infection = sepsis

need 2 or more signs

44
Q

What are the 4 signs of SIRS

A

o Temperature >38 or <36
o Heart rate > 90 BPM
o Respiratory rate > 20 breaths per minute
o White blood cell count >12000 or <4000

45
Q

What is the most common bacteria behind sepsis

A

ecoli

46
Q

What is the sepsis 6

A

o Give high flow oxygen
o Take blood cultures
o Give IV antibiotics
o Give a fluid challenge
o Measure lactate
o Measure urine output

BDS4 Microbiology (2 decks)

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