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FINALS - Microbiology and Oral Pathology > Infection and Microbiology > Flashcards

Infection and Microbiology Flashcards

1
Q

What colour is gram positive?

A

Purple

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2
Q

What colour is gram negative?

A

Red/pink

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3
Q

Give an example of gram positive cocci?

A

S. anginosus

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4
Q

Give an example of gram negative cocci?

A

Veillonella species

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5
Q

Give an example of gram positive bacilli?

A

Actinomyces israelii

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6
Q

Give an example of gram negative bacilli?

A

P. intermedia

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7
Q

Which type of bacteria does metronidazole work on?

A

Strict anaerobes

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8
Q

What is the definition of anti-microbial resistance?

A

When micro-organisms change/adapt in ways which render medications used to cure the infections they cause inneffective.

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9
Q

What is the difference between intrinsic resistance and acquired resistance?

A

Intrinsic is where the micro-organism comes with a naturally occuring defence against microbials/immune cells.

Aquired is where it adapts in response to microbial/immune cell exposure, via mutaion or aquisition of new DNA.

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10
Q

Describe hpw bacteria can develop resistence to anti-biotics?

A

Altering the target site of the bacteria (Example of this is S. mitis).

Developing enzymes to inactivate the anti-biotic (Example of this is prevotella species).

Decreasing the uptake of antibiotics by creating a thick wall around the bacteria (Example of this is K. pneumoniae).

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11
Q

What is an ESBL?

A

An extended spectrum beta-lactum bacteria. Produced as a result of an ‘arms race’ between bacteria and anti-biotic.

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12
Q

What type of anti-biotic can be used to treat ESBLs?

A

Carbapenems.

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13
Q

Explain the two mechanisms by which oral health can cause periapical infection?

A

Via carious lesion, involving the pulp.

Via periodontal ligament.

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14
Q

What is meant by the term endogenous infection?

A

The infection is caused by our own micro-flora.

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15
Q

What is the ideal microbiology specimen for a periapical infection?

A

Aspirated pus, swab may be contaminated with salivary flora.

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16
Q

Give two examples of bacteria which are present in periodontal abscesses?

A

Anaeobic streptocci
Prevotella intermedia

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17
Q

Give to examples of bacteria present in pericoronitis?

A

P.intermedia
S.anginosus group
(mixed oral anaerobes)

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18
Q

Which bacteria can be found in alveolar osteitis?

A

Mixed oral flora

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19
Q

Which predisposing factors cause an increased risk of osteomyelitis of the jaw?

A

Bisphosphonates
Pagets disease
Radiotherapy
Foreign bodies (implants)
Compound fractures
Diabetes

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20
Q

Which micro-organisms can be found in osteomyelitis of the jaw?

A

Anaerobic gram negative rods, and anaerobic streptococci.

S. anginosus and S. aureus.

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21
Q

Which micro-organisms can be found in salivary gland infections?

A

S. aureus and mixed anaerobes.

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22
Q

What is the treatment for salivary gland infection?

A

Drainage
Flucloxacillin and metronidazole.

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23
Q

What is Ludwigs Angina?

A

A bilateral infection of the submandibular space, potentially from odontogenic infection.

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24
Q

What is SOI?

A

Severe Odontogenic Infection.

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25
Q

Which type of bacteria are typically involved in sever odontogenic infection of the submandibular space (Ludwig’s Angina)?

A

Anaerobic gram negative bacteria.

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26
Q

What is SIRS?

A

Systemic inflamatory Response Syndrome. A precurser to sepsis. Defined by:

  1. Temp <36C or >38C
  2. Pulse 90/min
  3. Resp rate >20/min
  4. WCC <4 or >12
    (^white cell count)
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27
Q

What is sepsis?

A

A life threatening organ dysfunction caused by dysregulated host immune response to infection.

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28
Q

What do the S, I, and R mean on a microbiology report?

A

S - bacteria susceptible to antibiotic

I - bacteria susceptible at increased dose

R - bacteria resistant even with increased dose

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29
Q

What is the anti-biotic breakpoint?

A

The point where even the maximum doses of anti-biotic would no longer be able to reduce culture number.

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30
Q

What clinical features indicate Ludwig’s Angina?

A

Intraorally
Raised tongue
Difficulty breathing
Difficulty swallowing
Drooling

Extraorally
Diffuse redness
Swelling bilaterally in submandibular region

Systemically
↑ heart rate
↑ respiratory rate
↑ temperature
↑ white cell count

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31
Q

Which spaces can lower anterior infection spread to?

A

Mental/submental space

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32
Q

Which spaces can lower posterior infection spread to?

A

Buccal space
Submasseteric space
Sublingual space
Submandibular space
Lateral Pharyngeal space

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33
Q

Which spaces can upper anterior infection spread to?

A

Lip
Nasolabial region
Lower eyelid

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34
Q

Which spaces can upper posterior teeth spread to?

A

Cheek
Infra-temporal region
Maxillary Antrum
Palate

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35
Q

What are the main methods for managing odontogenic infection?

A

Establishment of drainage
Removal of source
Anti-biotic therapy (if systemic)

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36
Q

What micro-organisms are found in periodontal samples in healthy oral tissue?

A

Oral steptococci, actinomyces, veillonella.

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37
Q

What micro-organisms are found in periodontal samples in tissues with gingivitis?

A

Actinomyces, P. intermedia, bacteroides.

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38
Q

What micro-organisms are found in periodontal samples in tissues with gingivitis?

A

P. gingivalis, T. forsythia, T. denticola.

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39
Q

What is P. gingivalis?

A

Keystone pathogen in periodontal disease. Gram negative, strict anaerobe.

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40
Q

What are the viralence factors of P. gingivalis?

A
  • Adhereance and invasion
  • Cocktail of digestive enzymes
  • Endotoxin (LPS)
  • Tissue toxic metabolic birpoducts
  • Capsuplar polysaccharide outer membrane vesicles.
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41
Q

What tools does P.gingivalis have to help it adhere to surfcaes and other cells?

A

Fimbrillar adhesins.

42
Q

How is P. gingivalis adapted to survive from a hosts cells?

A

Gingipains, which break down haem to produce peptides.

43
Q

What can P.gingivalis do to subvert the host immune system?

A
  • Biofilm helps
  • Gingipains degrade cytokines and innate receptors
  • Produce MMPs to start tissue destruction
  • Tricking host immune system
44
Q

What are the system implications of periodontal disease?

A

Increase risk of cardiovascular disease
Suggested risk of rheumatoid arthritis
Increased risk of diabetes

45
Q

What is an endodontic infection?

A

Infection of the pulp, derived from endogenous microflora. Typical opportunistic infections.

46
Q

What are the four most common micro-organisms found in an endodontic infection?

A

S. mutans
C. albicans
E. faecalis
Actinomyces

47
Q

What is the microbial difference between primary endodontic infections and secondary endodontic infections?

A

Secondary infections are 9 times more likely to contain E.faecalis than primary infections.

48
Q

What are the virulence factors for a micro-organism?

A
  • Endotoxins
  • Adhesins
  • Collagenases
  • hyaluronidase
  • Immune evasion
49
Q

What is E.faecalis?

A

A gram positive coccus, facaultive anaerobe.

50
Q

Describe the mechanism by which bacteria in caries break down teeth.

A

A bacterial biofilm absorbs fermentable carbohydrates, and produces weak acids. This then demineralizes tooth tissue over time, leading to dental caries.

51
Q

What is the progression by which caries happens?

A

Adhesion
Survival and Growth
Biofilm formation
Complex plaque
Acid production
Caries

52
Q

What is the key pathogen thought to be involved in caries?

A

S. mutans, but there can be a large mixed population of bacteria contributing to caries.

53
Q

What is important about understanding the caries microbiome?

A

It may help to predict risk.

54
Q

What bacteria are associated with periodontal disease?

A

P. Gingivalis
A. Actinomycetemcomitans
P. Intermedia
B. Forsythus

55
Q

What bacteria are associated with caries?

A

S. Mutans, lactobacillus species

56
Q

What bacteria are associated with root canal infections?

A

P. Endodontalis
F. Nucleatum

57
Q

What methods are there to detect a bacterial strain?

A
  • Microbiological culture on agar medium
  • Molecular detection from DNA probes and PCR
58
Q

What agar plate should be used for gram positive bacteria?

A

Fastidious Anaerobe Agar (FAA)

59
Q

What agar plate should be used for gram negative bacteria?

A

Fastidious Anaerobe Agar (FAA) with vancomycin

60
Q

How can you identify a bacteria?

A
  1. Metronizadole disc sensitivity
  2. Gram stain
  3. Rapid API 32
61
Q

What RNA gene is found in all bacteria?

A

16S ribosomal RNA gene. Necessary for bacteria’s survival.

62
Q

How would you collect a microbiological sample from a child?

A

A minimally invasive saliva swab.

63
Q

Why would you not isolate bacteria in a study with a large sample size?

A

May take too much time to differentiate diverse colonies.

64
Q

What molecular sequencing methods are available to identify bacteria?

A

Next-gen sequencing and microbiome analysis of 16s rDNA.

65
Q

What is the purpose in identifying the levels of carriage of a bacteria with regards to public health?

A
  • Establish a baseline with data
  • Inform oral health measures
  • Compare with other data internationally
66
Q

If you were investigating a patients gingivitis, what biological sample could you take and how would you take it?

A

Subgingival plaque biofilm taken with a paper point from the gingival crevice on site of inflammation.

67
Q

What methods could you use to identify the culprit organism in a patient with gingivitis?

A

Selective agars, PCR, NGS, sensitivity testing.

68
Q

Does the knowledge of what bacteria is involved change what your treatment would be clinically?

A

what bacteria is involved change what your treatment would be clinically?
Probably not for a dentist, may be useful in selecting which systemic anti-biotic to prescribe.

69
Q

What is the cause of denture stomatitis?

A

Denture associated biofilm.

70
Q

What micro-organisms are associated with denture stomatitis?

A

C. Albicans, C. Glabrata, any oral bacteria. Bacteria use candida as scaffold to stick.

71
Q

What types of specimens can be taken from a patient with denture stomatitis?

A

Oral rinse/swab from the localised area, foam pad for imprint.

72
Q

Why is it important to identify which species of candida are present in a patient with stomatitis?

A

G. Glabrata is resistant to azoles, so you what anti-fungal you prescribe would depend on which strain is present.

73
Q

What are the systemic complications of a poorly maintained denture?

A

Possibility of aspiration pneumonia, and possible links to cardiovascular disease.

74
Q

What microbiological sample would you take from a patient with a dental abscess and systemic infection?

A

Pus sample with needle aspiration.

75
Q

What are the common micro-organisms found in the pus of a dental abscess?

A

Any oral anaerobes, s. aureus

76
Q

What are some constraints when taking a pus sample?

A

Bacteria in question are usually obligate anaerobes, so getting them to the lab with little oxygen exposure is key. Think about packing and lab turn around time.

77
Q

What are the systemic implications if a dental infection is not managed?

A

Spreading odontogenic infections, possibility of sepsis.

78
Q

What are the signs of sepsis?

A
  • Feeling dizzy or faint.
  • A change in mental state - like confusion or disorientation.
  • Diarrhoea.
  • Nausea and vomiting.
  • Slurred speech.
  • Severe muscle pain.
  • Severe breathlessness.
79
Q

What are the risk factors for developing candidiasis?

A

Immuno-compromised
HIV infection
Central venous catheter
Dialysis
Diavetes
Trauma patient
Burn patient
Long-term corticosteroid use

80
Q

What types of infection can be caused by candida?

A
  • Perio
  • Dental implants
  • Denture stomatitis
  • Ventilator associated pneumonia
  • Osteomyelitis
  • Sutures
  • Endocarditis
81
Q

What are some examples of erythemous candida infections?

A

Denture stomatitis, atrophic (HIV related)

82
Q

What is an example of a pseudomembranous candida infection?

A

Thrush

83
Q

What is an example of hyperplastic candida infection?

A

Candida leukoplakia.

84
Q

What generalized candida infection can have oral manifestations?

A

Chronic mucocutaneous infection

85
Q

What are some of the signs of denture stomatitis?

A

Inflamed mucosa
Burning sensation
Discomfort
Bad taste in mouth

86
Q

What are candida?

A

Opportunistic pathogenic yeasts.

87
Q

Give two examples of candida species?

A

Candida albicans, and Candida glabrata.

88
Q

Which genes are key to biofilm formation for candida infection?

A

ADH genes.

89
Q

Describe the diagnostic process of identifying a candida infection of the oral cavity?

A
  • Collect sample (smear, oral rinse, swab, culture, foam pad, biopsy)
  • Microscopy, histology, and culture (in sabouraud’s agar)
  • Lab tests for germ tube formation, sugar assimilation, AF sensitivity, and typing.
90
Q

What topical treatment would you use for a candida infection?

A

Nystatin or amphotericin B, as they are effective on all candida species.

91
Q

What topical treatment would you use on pathology that could be bacterial or candida in nature?

A

Miconazole, as it works on most candida species but also possesses some anti-staphyloccal activity.

CHX also works on both candida and bacteria.

92
Q

What candida does fluconazole work on?

A

Works on C albicans, which is the most common, but some resistant strains can develop. C. Krusei and C. Glabrata are naturally resistant.

93
Q

What should you do if an immunocompromised patient is diagnosed with a candida infection?

A

Provide systemic anti-fungal (fluconazole) and topical antifungal (nystatin)/CHX.

94
Q

What clinical sample would you take for investigation of an abscess?

A

Pus sample.

95
Q

What is a typical investigative process for microbiological investigations?

A

Specimen, direct examination, culture, pure culture and species ID, species name established, typing/fingerprinting.

96
Q

What information can gram staining tell you about a bacteria?

A
  • Can help identify it
  • Cell wall composition
  • Anti-microbial sensitivity
  • Virulence factors
97
Q

What must be done to identify the cause of a HAI?

A

The causative agent must be defined and identified.

98
Q

What are microbes?

A

Infectious agents which are not visible to the naked eye, widespread in nature and some casue human disease.

99
Q

Why should a microbiology lab determine the most frequent microbes causing infections and HAI pathogens?

A

To assess their risk, and to create alerts for serious ones. Furthermore can determine the nature of the HAI.

100
Q

What basic role should all microbiology labs perform?

A

Basic typing of micro-organisms, and production of routine reports for IP&C personnel.

FINALS - Microbiology and Oral Pathology (7 decks)

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