Oral microbiology Flashcards
1
Q
What are the main features of the mouth as a habitat that are relevant for bacteria?
A
- Teeth
- Mucosal surfaces
- Saliva
- Gingival crevice fluid
2
Q
True/false: plaque is found on the teeth of both healthy and diseased animals.
A
True
3
Q
What makes teeth a good place for bacteria to colonise?
A
- Non-shedding surface
- Number of surfaces/crevices/ridges
- Bacteria can accumulate in a biofilm
4
Q
What features of the oral mucosa are relevant for bacteria if they try and colonise?
A
- Stratified, non-keratinised epithelium with layers that can be worn off and replaced
- Non-sterile: has a population of commensal bacteria that can stop others colonising
- Houses immune cells in the tissue; if damaged can initiate inflammation
5
Q
What features of saliva are relevant for bacteria trying to colonise the mouth?
A
- Washes mouth to help physically remove material
- Has a buffering capacity
- Contains antimicrobial factors important to control microorganisms
- Provides a source of nutrition for microbes, can help aggregation of bacteria
6
Q
What features of the gingival crevice fluid are relevant for bacteria trying to colonise the oral cavity?
A
- GCF: serum-like fluid
- Increased production of GCF e.g. during infection can lead to localised rise in pH, changing the type of bacteria that can grow
- Contains a variety of enzymes e.g. collagenase, elastase, trypsin
- GCF has antimicrobial properties: IgG and sometimes leucocytes
7
Q
Give some non-specific antimicrobial factors in the oral cavity
A
- Saliva flow
- Mucins and agglutinin
- Sloughing of surface epithelial cells
All the above physically remove microorganisms
8
Q
Give some innate (general) antimicrobial defenses in the oral cavity and describe their modes of action
A
- Lysozymes cause bacterial cell lysis
- Lactoferrins sequester iron, block some viral receptors and have anti-bacterial and anti-yeast activity
- Sialoperoxidase inhibits glycolysis
- Antimicrobial peptides disrupt the microbial membranes of bacteria or yeast
- Neutrophils patrol tissue and engulf pathogens
9
Q
Give some adaptive (specific) immune defenses in the oral cavity
A
- Serum antibodies (sIgA) prevent/disrupt adhesion, reducing the capacity of bacteria to colonise
- Complement binds to and promotes phagocytosis of pathogens. Also activates neutrophils.
10
Q
List the clinical signs of periodontal disease
A
- Problems picking up food
- Bleeding/red gums/blood in water bowl or on toys
- Loose teeth
- Halitosis
- Unusual noises when eating
- Chewing on one side of the mouth
- (If advanced) sneezing/nasal discharge
11
Q
Explain the causes and mechanisms of gingivitis development in companion animals
A
- Plaque develops, changing the micro-environment
- This allow anaerobes to establish
- Mineral deposition can occur
- Sub-gingival deposits and growth will trigger inflammation
- Bacteria also secrete enzymes, weakening the tissue and causing more damage
12
Q
Plaque
A
a biofilm that builds up on teeth
13
Q
Calculus
A
a.k.a. tartar
calcified dental plaque
14
Q
Briefly describe, using this diagram, how plaque develops
A
- Glycoproteins enable pioneer (aerobic) species to establish.
- Bacteria in a biofilm contribute to each others’ metabolism, allowing complex plaque to develop
- As bacterial growth/plaque builds up, the environment becomes one of reduced oxygen –> eventually anaerobic bacteria can establish
- Plaque formation is not uniform: some sites are more at risk - gingival sulchus vs. smooth surfaces
- Mineralised phosphates are deposited around the bacteria (sub- or supra-gingivally) forming calculus
- Periodontal pathogens cause tissue to secrete cytokines, which leads to activation of odontoclasts which resorb bone and enamel
15
Q
How is calculus formed?
A
- Mineralised phosphates are deposited around the bacteria. This can occur sub- or supra-gingivally
- The contact between pathogens and tissue can cause the tissue to secrete cytokines which activate odontoclasts, leading to bone resorption
- Once formed, calculus takes a lot of force to remove
- Dental products may contain compounds to reduce mineralisation
16
Q
Describe how dental caries (decay) arises
A
- Occurs due to increased acids causing local mineralisation
- The change to the environment (e.g. reduced pH) can lead to altered cell activity
- Example: Feline Odontoclastic Resorptive Lesions
17
Q
Describe the formation of Feline Odontoclastic Resorptive Lesions
A
- Chronic accumulation of microorganisms leads to endothelial and eptihelial cytokine production
- Initiation and stimulation of odontoclastic activity
- Stem cells are attracted to the sulchus area by cytokines
- Instead of forming macrophages, stem cells become clast cells
- Clast cells dissolve in mineralised tissue, forming a multinucleated giant. They dissolve tooth tissue, leading to bone and enamel resorption.
18
Q
List some bacteria commonly found in the oral cavity
A
- Streptococcus sp.
- Actinomyces sp.
- Neisseria sp.
- Fusobacterium sp.
- Porphyromonas sp.
19
Q
Name and describe a yeast organism commonly found in the oral cavity
A
- Candida sp
- Normal component of oral microflora
- When normal control mechanisms fail, can overgrow leading to pseudomembranous candidiasis (oral thrush). Thrush can also happen on other mucosal surfaces.
20
Q
Give the causative agent, route of infection, pathology and treatment for lumpy jaw (actinomycosis)
A
Cause: Actinomyces bovis
Pathology: Mucosal commensal that invades tissues through breaks in the lining of the mouth (rough forage, sharp teeth)
- Tumour like swellings slowly develop.
- These are immovable and hard swellings on the upper/lower jawbones around central molar level.
- They consist of honeycombed thin bone filled with pus. Advanced cases can show pus discharge/gritty yellow granules in this.
Treatment is tetracyclines/iodine therapy or PTS
21
Q
Describe the causative agent and pathology of Wooden tongue (a.k.a. timber tongue)
A
Cause: Actinobacillus lignierseii
- Commensal of mucous membranes, invades tissue through breaks in the lining of the mouth
Pathology: sudden onset with tongye becoming hard, swollen and painful.
- There is then chronic pyogranulomatous inflammation of soft tissue
- Infection is limited in most cases to soft tissue of tongue and lymph nodes of head
22
Q
Describe infections of Fusobacterium necrophorum
A
- This is an obligate anaerobe found in the alimentary tract of animals, humans, and the respiratory tract of cattle
- Infections involve mucous membranes and underlying oral cavity tissues. To invade, pathogen needs to breach epidermis via an injury.
- Infection is self-limiting
- Commonly seen in calves, pigs, sometimes goats.
- Clinical signs include reducing/stopping drinking
23
Q
List some common viral infections of the oral cavity
A
- Feline immunodeficiency virus (FIV)
- Papillomavirus
- Feline calcivirus
- Foot and mouth disease
24
Q
Describe the transmission and clinical signs of FIV
A
Transmission: primarily by deep bite wounds though saliva of infected cats
Clinical signs:
- Lethargy
- Anorexia
- Fever
- Lymphadenopathy
- Leaves cats vulnerable to secondary infections including FAIDS
25
Describe the pathology and treatment of canine papillomavirus
* Causes benign tumours of epithelial lining of mouth and throat. In severe cases, oesophagus may be affected.
* Incubation period = 1 month, recovery = 2-3 months.
* Once removed, immune to further infections.
Treatment
* Tumours usually removed surgically for diagnostic purposes, but will disappear spontaneously on their own
* Medication can be given to relieve pain and reduce inflammation
26
**Vesicle**
Circumscribed epidermal elevations in the skin containing clear fluid. Usually less than 5mm in diameter.
27
**Bulla**
Vesicle with a diameter over 5mm
28
**Erosion**
partial loss of the epidermis that does not penetrated beneath the basal lamina zone
29
**Ulcer**
loss of epidermis, dermis and sometimes deeper tissue
30
Name some common vesicular diseases caused by viruses
* Foot and mouth disease (FMD)
* Swine vesicular disease (SVD)
* Vesicular stomatitis (VS)
* Vesicular exanthema (VE)
31
Describe the clinical signs of FMD
Clinical signs
Cows
* Fever
* Loss of appetite
* Marked milk drop
* Profuse salivation
* Foot and oral lesions; Vesicles on tongue and gums; smacking of lips causes rupture
* Ruptured vesicles form large denuded ulcerative lesions
* Secondary bacterial infection can lead to mucoprurulent nasal discharge
* Pregnant cows may abort (due to high fever; virus doesn't cross placenta)
Pigs
* First sign often lameness; severe and painful foot lesions
* Large vesicles that quickly rupture on snout
Other animals
* Mild clinical signs characterised by foot lesions and lameness
32
Describe the epidemiology and transmission of FMD
* Respiratory infections/aerosols. Can spread for miles in airstreams
* Ingestion of contaminated food/direct inoculation
* Transmitted by animals and contaminated items/people
* Short incubation period; virus can be excreted up to 4 days before clinical signs appear
* Can have carriers where the virus persists in the pharynx
33
Describe the diagnosis of FMD
* Lab diagnosis essential
* Samples from vesicular fluid/epithelial tissue at edge of vesicle, blood/serum, pharyngeal fluid
* Detection of FMD antigen by ELISA/PCR detection of viral nucleic acid
* FMD is notifiable
34
Describe the clinical signs, diagnosis and control of swine vesicular disease virus
Clinical signs
* Lesions on the coronary bands; less commonly snout, lips, tongue
* Main sign is lameness
Diagnosis
* ELISA/virus isolation needed to distinguish from other vesicular diseases
Control
* Susceptible and in-contract animals are culled
35
36
Describe the causes and clinical signs of cat flu caused by FCV
Cats present with upper respiratory tract disease.
2 main causes: Feline calcivirus (FCV) and Feline herpes virus (FHV)
Clinical signs
* Conjunctivitis
* Rhinitis
* Tracheitis
* Pneumonia
* Vesiculation/ulceration of oral epithelium
* Fever
* Lethargy
* Anorexia
* Stiff gait
37
Describe the causes and clinical signs of cat flu caused by FHV
Cats present with upper respiratory tract disease.
2 main causes: Feline calcivirus (FCV) and Feline herpes virus (FHV)
Clinical signs
* Sneezing
* Nasal discharge
* Dehydration
* Anorexia
* Pyrexia
* Ocular signs including chemosis, keratoconjunctivitis, corneal ulceration
38
Describe the treatment and control for cat flu caused by FCV or FHV
Treatment
* Supportive nursing
* Fluid therapy
* Broad spectrum antibiotics to prevent secondary infection
Prevention
* Inactivated/attenuated vaccines
* Quarantine for hospitalised cases
39
Feline Viral Rhinotracheitis
* Acute disease similar to FCV
* Clinical signs include profuse frothy salivation
40
Why are disease notifiable?
* Significant morbidity/mortality in animals
* Potential to affect trade in animal products
* Zoonotic
41
Name some notifiable vesicular diseases
* Foot and mouth disease (FMD)
* Swine vesicular disease (SVD)
* Vesicular stomatitis (VS)
