Normal Oral Microflora Flashcards
Oral cavity microbial habitats
teeth
gingival sulci
attached gingiva
lips, tongue, cheeks
hard and soft palate
Normal flora
called commensals
Supragingival bacteria
predominantly streptococci
mutans
salivarius
mitis
anginosus
Subgingival bacteria
actinomyces
prevotella
prophyromonas
fusobacterium
veillonella
Gram (+) bacteria
Cocci:
Streptococcus –> Mutans, salivarius, mitis, anginosus
Bacilli and filaments:
Lactobacilli, eubacteria, propionibacterium acnes and propionicus, actinomyces
What are the four groups of streptococcus
mutans, salivarius, mitis, anginosus
What is the the mutans group
colonizes tooth or denture surfaces
rapidly produces acid
can grow in an acidic environment
What is the primary pathogen in dental caries
Streptococcus mutans
What can streptococcus mutans cause
root surface caries in elderly
pit and fissure caries
smooth surface (enamel) caries
What is the important virulence property of mutans group
ability to form bioflim
What is salivarious group
found on mucosal surfaces, including the tongue
What are the two groups of salivarius group
strept. salivarious & strept. vestibularis
Strept. Salivarious
Opportunistic pathogen capable of infecting immunocomprised patients
Strongly cariogenic, but less than S. mutans
Strept. vestibularis
Normal inhabitant of oral vestibules
Mitis group
S. sanguinis, strept. gordonii, strept. mitis, and strept. oralis may become opportunistic pathogens and cause infective endocarditis
early colonizers in biofilm formatoin
What mitis group bacteria is not an opportunistic pathogen
S. mitis
What is the anginosus group
Found in dental plaque and mucosal surfaces
opportunistic pathogens
involved in maxillofacial infections
includes: strept. anginosus, strept. intermedius, and strept. constellatus
What are the gram (+) cocci bacteria
Streptococcus: Mutans, Salivarius, Mitis, Anginosus
What are gram (+) bacilli and filaments
Lactobacilli, Eubacteria, Propionbacterium, Actinomyces
Lactobacilli
Constitute about 1% of the total cultivable microflora in the oral cavity
Increases in advanced caries lesions of the enamel and root surface
Acidogenic and also acid tolerant
Testing for lactobacilli in the saliva of patients is one way to monitor patients’ dietary intake of carbohydrates
Eubacteria
pleomorphic, obligate anaerobes found in dental plaque
constitute more than 50% of the anaerobes of periodontal pockets
propionibacterium
propionibacterium acnes and propionibacterium propionicus
strict anaerobic bacilli found in dental plaque
Actinomyces species
Major compoenet in dental plaque
In subgingival microbiota of healthy individuals
Actinomyces israelii can be an opportunistic pathogen: can cause actinomycosis chronic inflammation in the orofacial region
Gram (-) bacteria
cocci: veillonella species
bacilli: aggregatibacteria actino,
fusobacterium
porphyromonas prevotella
Spiral shaped: campylobacter rectus,
treopnema
Pleomorphic: Tannerella forsythia
Veillonella species
Gram (-) cocci
Anaerobic gram (-) cocci
Found mostly in plaque
AAA
gram (-) bacilli
found occasionally in subgingival plaque
associated with aggressive periodontitis
stimulate bone resorption
Fusobacterium species
gram (-) bacilli
Strict anaerobes
Fusobacterium nucleatum:
present in low numbers in healthy subgingival dental biofilm
enriched in periodontal pockets
key bridging organism between the early colonizers and periodontal pathogens
opportunistic pathogen due to its association with systemic diseases
Porphyromonas
gram (-) bacilli
Utilize proteins and peptides for their metabolism
Porphyromas gingivalis: found almost exclusively at subgingival sites, especially in advanced periodontal lesions; major flora in dental plaque
Porphyromas endodontalis:
identified primarily in infected root canals
Prevotella
gram (-) bacilli
Strict anaerobes
P. intermedia associated with periodontitis and endodontic infections
Major flora in dental plaque
Gram (-) spiral-shaped bacteria
Campylobacter rectus
Treponema
Campylobacter rectus
strict anaerobe and is often found in sites of periodontal disease
agent of chronic periodontal disease
Treponema
Strict anaerobes
spirochete
T.denticola: associated with progression of periodontal diseases
increase in number in advanced periodontal disease
Gram (-) pleomorphic bacteria
Tannerella forsythia
Tannerlla forsythia
gram (-) anaerobe
inhabits subgingival cavity
initiates connective tissue destruction and alveolar bone resorption in periodontal disease
Fungi: Candida species
Constitute the largest fraction of fungi in the mouth
prevalence of candida in asymptomatic adults is 2-71% and 100% in immunocompromised individuals and those on broad-spectrum antibiotics
Most common site is dorsum of the tongue
Use of dentures and orthodontic appliances increases the incidence
Candida albicans: most common species
Viruses
Herpes simplex virus type 1
Coxsackievirus
Human papillomavirus types 2,4,6,11 and 16
Hepatitis B and HIV
Herpes simplex virus type I
Most frequently found in saliva and orofacial region
cause of cold sores, which occur when the latent virus in the trigeminal nerve is activated by stress or ultraviolet light
Coxsackievirus
detected in saliva and oral epithelium
True/false:Human papillomavirus types 2,4,6,11, and 16 are detected in oral lesions of patients with HIV/AIDS
True
True/false: Hepatitis B and HIV in saliva may pose a cross-infection threat, emphasizing the need for universal precautions
True
Protozoa
Trichomonas tenax and entamoeba gingivalis found in frequently in oral cavity
only 2% of healthy population carries T. tenax but increases to 21% in patients with periodontal disease
Factors contributing to disease
salivary flow rate: can be affected by medications
diet
tobacco use
integrity of the immune system
Main oral habitats:
Mucosal surface
teeth
saliva
gingival crevicular fluid
Dorsum of tongue
Has papillary structures that provide a niche for bacteria that would otherwise be removed by salivary flow
Environment suitable for gram (-), obligately anaerobic bacteria that are involved in periodontal disease and malodor (halitosis)
Teeth
Constitute a non-shedding surface for bacterial colonization
Bacteria and their polysaccharide products accumulate on tooth surface to produce dental plaque, which is generated both in health and in disease
More present in pits and fissures
Subgingival surfaces are in a more anaerobic environment that supragingival surfaces
Saliva
Can clear potentially damaging acids produced by plaque bacteria after metabolizing carbohydrates
saliva buffers the pH between 6.75 and 7.25
Proteins and glycoproteins in saliva
generate the acquired pellicle on tooth surfaces
provide nutrients for normal oral microflora
Aggregate microorganisms to facilitate their removal by swallowing
Inhibit the growth of exogenous microoganisms
Gingival crevicular fluid
Can remove non-adherent bacteria, introduce igG and neutrophils, and provide peptides and carbohydrates that bacteria can use for their metabolism
The pH increases in the presence of gingivitis and periodontitis, providing a favorable environment for periodontopathogens such as p. gingivalis and P. intermedia
Appliances
Prosthodontic and orthodontic appliances may act as reservoirs for bacteria and yeasts
one of the causes of candida-associated denture stomatitis is poor denture hygiene
