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BDS3 > Microbiology and Oral Pathology > Flashcards

Microbiology and Oral Pathology Flashcards

1
Q

Cariogenic microorganisms

A

Strep mutans
Veillonella
Actinomyces

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2
Q

Appropriate clinical specimen to study cariogenic microorganisms in children

A

Oral swab or rinse

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3
Q

Examples of oral biofilm diseases

A

Caries
Endo infections
Perio infections
Oral malodour
Mucosal infections - thrush, angular chelitis, denture stomatitis

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4
Q

What are host factor influences on oral microflora?

A

Systemic disease, antibiotics, OH, genetics, smoking, pregnancy, puberty,

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5
Q

What factors of diet affect oral microflora?

A

Chemical composition
Physical consistency
Frequency of intake

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6
Q

How does saliva affect oral microflora?

A

Flow rate
pH balance
Antimicrobial factors

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7
Q

How does gingival crevicular fluid affect oral microflora?

A

Antimicrobial components and humoral immunity

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8
Q

How do microbial interaction affect the oral microflora?

A

Competition and cooperation

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9
Q

What about the gaseous environment affects the oral microflora?

A

Oxygen concentrations

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10
Q

Oral biofilm diseases

A

Caries
Oral malodour
Endo infections
Mucosal infections
Periodontal infections

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11
Q

Influences on oral microflora

A

Host factors - systemic disease, antibiotic use, OH
Diet - chemical composition, physical consistency, frequency of intake
Saliva - flow rate, pH balance, antimicrobial factors
Gingival crevicular fluid - antimicrobial components and humoral immunity
Microbial interactions - competition and cooperation
Gaseous environment - oxygen conc

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12
Q

How does biofilm in mouth change from health to disease?

A

Beneficial bacteria, immune surveillance and tissue homeostasis in health
Pathogenic bacteria, non protective immune responses, disruption of tissue homeostasis in disease

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13
Q

What causes periodontitis?

A

High concentration of periodontopathogenic bacteria
Sever inflammation and pocket formation, degradation of soft and bone tissue as a result

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14
Q

Microbial progression expected from periodontal health to disease

A

Gram positive, aerobic bacteria -> gram negative, anaerobic bacteria

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15
Q

Important microorganisms in healthy biofilm

A

Oral streptococci
Actinomyces
Veillonella
Haemophilus
Neisseri
Fusobacterium

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16
Q

Important microorganisms in gingivitis

A

Actinomyces
Prevotella intermedia
Becteroides
Fusobacterium nucleatum

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17
Q

Important microorganisms in periodontitis

A

PORPHYROMONAS GINGIVALIS
Tannerella forsythia
Treponema denticola
Prevotella intermedia
AA

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18
Q

Effects of microbial competition

A

Metabolic products - acids, oxidants
Bacteriocins
Receptor antagonism

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19
Q

Effects of microbial cooperation

A

Metabolic products - saccharides, peptides, growth factors
Adhesion substrates
Immune avoidance

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20
Q

P gingivalis in periodontal disease

A

Increased number in PD
Suppressed or undetectable in successfully treated lesions

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21
Q

Size of candida compared to bacteria

A

Much bigger
Can be 100x the size

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22
Q

Risk factors for developing candidiases

A

Immuno compromised
Immunosuppresive drugs
Advanced HIV
Intra-abdominal surgery
Central venous catheter
Parental nutrition
Broad spectrum antibiotics
Dialysis
Colonisation at a sterile site
Diabetes
Burn unit pt
Trauma patient
Longterm coritcosteroid

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23
Q

Candidiasis infection types

A

Periodontits
Dental implants
Denture stomatitis
CF lung infections
Ventilator associated pneumonia
UTI
Infectious kidney stones/biliary tract infections
Mucoskeletal infections/osteomyelitis
Chronic wounds
Sutures
Endocarditis
Implant/medical device
Catheters and stent

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24
Q

Classification of oral candidosis

A

Confined to mouth and commisure - pseudomembrane (thrush), erythematous (atrophic HIV related, denture related), hyperplastic angular chelitis - candidial leukoplakia

Generalised candidosis with oral manifestation - chronic mucotaneous

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25
Q

Management of chronic hyperplastic oral candidosis

A

Biopsy
Usually long term anti fungals

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26
Q

Newton’s types of denture stomatitis

A

Newton’s type 1 - localised inflammation
Newton’s type II - diffuse inflammation
Newton’s type III - granular inflammation

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27
Q

Denture induced stomatitis

A

Adhere and colonise on acrylic surfaces, co aggregation, biofilm formation
Signs and symptoms
Inflamed mucosa
Burning
Discomfort
Bad taste
Most pts unaware of the problem

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28
Q

Opportunistic pathogenic yeasts

A

CANDIDA GLABRATA
CANDID ALBICANS
Candida parapsilosis
Candida tropicalis

29
Q

Main difference between candida albicans and candida glabrata

A

CA - sensitive to fluconazole and metraconazole
CG - not

30
Q

Candida albicans

A

Present in 71% of healthy individuals
Variable anatomical sites (oral carriage 35-55%)
Nutrient limitation/competition with bacteria keep it in check, when broad spectrum antibiotics given, can cause thrush

31
Q

Microscopic difference between albicans and glabrata

A

Albicans has hyphae

32
Q

What is used to treat candida glabrata

A

Nystatin

33
Q

Two functions of microbiology lab

A

Clinical - diagnosis of infection in an individual for everyday management of infections
Epidemiological - Support for infection prevention and control in searching for source and route of transmission of healthcare associated infections

34
Q

Minimal requirements for microbiology services

A

1 Set up inside the facility - if not possible, negotiate contract for diagnostic microbiology with the nearest lab
2 Available every day including sundays and holidays, ideally 24h
3 Able to examine blood, cerebrospinal fluid, urine, stool, wound exudate or swabs, respiratory secretions and perform basic serological tests
4 Identify common bacteria and fungi to species level
5 Perform susceptibility testing using disc-diffusion methodology
6 Perform basic phenotyping such as serotyping and biotyping

35
Q

Clinical specimens for oral biofilm infections

A

Swab for wound/lesion usually taken chairside, culture on agar plate with incubation

36
Q

What clinical sample would be taken for an abscess?

A

Pus

37
Q

Roles of microbiology lab in prevention and control of HAIs

A

Outbreak investigation
Surveillance of HAIs
Alert microorganisms reports
Designing antibiotic policy

38
Q

Chain of infection

A

Infectious agent - bacteria, fungi, virus
Source - people, equipment, water
Exit - Aerosols, splatter
Mode of transmission - direct contact, inhalation, airborne
Portal of entry - mucous membrane, resp tract, broken skin
Susceptible host

39
Q

Bacterial involvement in caries

A

Bacteria produces acid from fermentable carbohydrate

40
Q

Organism most associated with caries

A

Strep mutans

41
Q

Microbial flora associated with caries examples

A

Actinomyces
Abiotrophia
Atopobium
Bifidobacterium
Lactobacillus
Veillonella
Proprionibacterium
Prevotella
Strep mutans

42
Q

Endodontic infection

A

Normally, intact enamel and dentine protect pulp - no infection
Infections to pulp generally secondary to tooth infections/trauma - e.g. caries, streptococci and lactobacilli
Endodontic infections derived from endogenous microflora
Opportunistic infections

43
Q

Cause of endodontic infection

A

Acute immune response followed by chronic immune response to bacteria at apex

44
Q

Bacteria involved with endodontic infection examples

A

Bacteroides
Prevotella
Streptococcus
Clostridium
Fusobacterium
Lactobacillus
Propionibacterium

45
Q

Enterococcus faecalis

A

Important endo bacteria
Primary endo infections are polymicrobial, dominated by grain negative anaerobic rods, enterococcus faecalis in 4-40%

Secondary endodontic infections are composed of one or a few bacterial specie
Predominantly gram +ve
9 times more likely to find enterococcus faecalis

46
Q

Virulence factors

A

Factors making more damaging pathogens
Endotoxins
Adhesins
Collagenases
Hyaluronidase
Immune evasion

47
Q

Enterococcus faecalis

A

Gram +ve coccus (single or pairs)
Facultative anaerobe
Aggregative, adhesion
Superoxide formation
Gelatinase
Cytolysin
Lipotechoic acid

48
Q

Bacteria associated with root canal infections

A

Porphyromonas endodontalis
Fusobacterium nucleatum

49
Q

Bacterial detection methods

A

Microbiological culture - on agar medium, isolate bacteria, identify by characterisation of enzyme activities, sugar fermentation tests

Molecular biological - DNA probes, PCR

50
Q

How to ID anaerobes

A

Sensitivity to metronidazole disc

51
Q

Advantages and disadvantage of culture methods

A

Advantages - yields bacterial isolates for future testing and study (such as antibiotic sensitivities)

Disadvantages - required viable cells, insensitive, only small numbers analysed at once, inconclusive results, labour intensive

52
Q

DNA probes

A

Segments of DNA that have been labelled with chemoluminescent, fluorescent or radioactive agents
Types = whole genomic, cloned gene, oligonucleotide (20-50- bases)

53
Q

16s ribosomal RNA

A

Found in all bacteria
Essential for survival
Gene sequenced for all known bacteria
Highly variable regions provide unique signatures to any bacterium -> species specific probes or primers
Conserved regions -> broad range probes or PCR primers

53
Q

16s ribosomal RNA

A

Found in all bacteria
Essential for survival
Gene sequenced for all known bacteria
Highly variable regions provide unique signatures to any bacterium -> species specific probes or primers
Conserved regions -> broad range probes or PCR primers

54
Q

PCR

A

Highly specific, sensitive, can be used to directly detect bacteria in clinical specimens
Double stranded DNA mixed with primers, dNTPs, DNA polymersase, then denatured
Primers bind to target sequences, polymerase synthesises the other strand
Repeat cycle

55
Q

PCR primers

A

Usually target 16s rRNA gene
Types - general bacterial primers, group specific primers, species specific primers

56
Q

Advantages and disadvantages of DNA probes and PCR

A

Less time consuming than culturing
Very sensitive
Can directly detect bacterial DNA within clinical samples
Do not require viable cells
Can detect uncultivatable species
BUT
May detect dead cells
Detect only pre-selected species

57
Q

Why is it important to subtype bacteria?

A

Sufficient genetic diversity exists to allow ID of different clones (strains) among isolates of the same species
Track routes of transmission during disease outbreaks
Study pathogenicity of specific strains

58
Q

What are serotyping and biotyping?

A

Traditional methods for subtyping bacteria
Limited discriminatory capacity
Organism specific methods
Specialised reagents required

59
Q

Molecular (genetic) typing methods

A

Restriction enzyme analysis REA- digest whole genome with restriction enzymes, too many fragments obtained makes interpretation difficult
Gene probe typing - can reduce number of DNA fragments generated by using a suitable gene probe
Ribotyping - use E.coli rRNA operon as DNA probe following REA, rRNA operon present in multiple copies in bacterial genomes, well conserved in structure and sequence, variation in number and size of fragments in bacterial DNA
16s-23s intergenic spacer region - very variable sequence, amplified by PCR using consensus primers, digest PCR product with restriction enzymes to obtain strain specific fingerprints
DNA sequencing - ultimate typing method, can detect single base differences

60
Q

Molecular identification of uncultivable and novel bacteria

A

Genomic DNA extracted from sample
PCR amplifies 16s rRNA gene from bacterial DNA in specimen
16s rRNA genes are cloned
50 clones are randomly chosen and sequenced
Clone sequences are analysed to determine bacterial identity

61
Q

Appropriate clinical specimen to study cariogenic microorganisms in population of 4-5 year olds

A

Oral swab of saliva or tooth surface

62
Q

What organisms are important to detect in a study of cariogenic microorganisms?

A

Streptococcus mutans
Lactobacillus species

63
Q

What sample would you investigate in gingivitis patient?

A

Paper point from gingival crevice, subgingival plaque biofilm

64
Q

What organisms are important for gingivitis patient?

A

Porphyromonas gingivalis

65
Q

Microorganisms associated with denture stomatitis

A

Candida albicans
Candida glabrata
Any oral bacteria

66
Q

What specimen would be taken to study denture stomatitis microorganisms?

A

Oral rinse or swab from area, or foam pad

67
Q

Systemic danger of denture stomatits

A

Aspiration, pneumonia

68
Q

Pt with throbbing swelling on lower right
Face tender and swollen
Elevated temp and evidence of abscess

A

Microbiological concerns - systemically unwell
Pus sample (needle aspirate?)
Possible oral anaerobes
Standard plate culture and microscopy used to ID microorganism

BDS3 (20 decks)

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