GRAM -VE Flashcards
Name 3 gram negative cocci
- Neisseria
- Moraxella
- Veillonella
What type of bacteria is Neisseria?
Gram-negative cocci that is facultative aerobic
Appearance of Neisseria on gram stain?
Pink;
Cocci - found in pairs, tetrads, short chains & clusters
List 2 species of Neisseria that are pathogens
- Neisseria gonorrhoeae
2. Neisseria meningitidis
List 2 species of Neisseria that can be found in the oral cavity
- Neisseria subflava
2. Neisseria sicca
Are the Neisseria species early or late colonizers of tooth?
Early
Name a similarity and a difference between Neisseria subflava and Neisseria sicca
S: N. subflava and N. sicca are saccharolytics and polysaccharide producing bacteria found in the mouth
D: N. subflava produces a yellow-green pigment but N. sicca does not produce pigment.
State a difference between Neisseria and Moraxella
Neisseria is saccharolytic (i.e. produces polysaccharide) but Moraxella is asaccharolytic (i.e. does not produce polysaccharide)
Name a species of Moraxella
Moraxella catarrhalis
What do most strains of Moraxella produce? Why is that a danger?
Most strains produce B-lactamase –> complicates antibiotic therapy
Where can Moraxella catarrhalis be found?
Commensal of the mouth and upper respiratory tract
What is Moraxella catarrhalis a significant pathogen of?
Meningitis, endocarditis, otitis media, maxillary sinusitis
Similarity between Moraxella and Veillonella
Both are asaccharolytics (both do not ferment carbohydrates)
Where can Veillonella be found?
Mouth and dental plaque
Function of Veillonella
Catabolises lactic acid to weaker organic acids (acetate and propionate); hence raising pH of the oral cavity
Name the most common species of Veillonella
Veillonella parvula
Where can veillonella parvula be found?
Oral cavity and intestines
Name 3 species of Veillonella
- Veillonella Parvula
- Veillonella Dispar
- Veillonella Atypica
Define GNAB
GNAB = Gram negative anaerobic bacteria - They are a large proportion of oral bacteria found especially in the gingival sulcus and periodontal pocket that is difficult and fastidious to study.
Name 3 motile GNAB
- Selenomonas
- Centipeda
- Helicobacteria
Name 6 non-motile GNAB
- Bacteriodes
- Porphyromonas
- Prevotella
- Tannerella
- Fusobacterium
- Leptotrichia
What are selenomonas associated with?
Periodontitis / Periodontal disease
Describe the appearance of Selenomonas
Cresent (moon-shaped) with many flagellae
Name 3 species of Selenomonas
- Selenomonas Sputigena
- Selenomonas Flueggei
- Selenomonas Noxia
Name a species of Centipeda
Centipeda Periodontii
Describe the appearance of Centipeda
flagellae arising from all around the cell
Name a species of Helicobacter
Helicobacter pylori
What does helicobacter pylori cause?
gastritis, gastric cancer, peptic ulcers
Describe the appearance of bacteroides on a CBA
Produces a dark pigment
Name a species of bacteroides. Where can it be found?
Bacteroides fragilis; found in mouth and GI tract (esp in the colon)
Where does the dark appearance of certain species of bacteria on CBA come from?
Dark appearance comes from the iron scavenging molecules on the surface which require an external heme as the iron source
Where can porphyromonas be found?
Exclusively in gingival sulcus and periodontal pocket
Name a species of Porphyromonas and the associated disease
Porphyromonas gingivalis; frequently associated with periodontitis
Name 3 black pigmented bacteria
- Porphyromonas gingivalis
- Prevotella intermedia
- Prevotella nigrescens
Are porphyromonas saccharolytic or asaccharolytic?
Asaccharolytic
What is the source of energy for Porphyromonas?
Environmental amino acids and peptides - Porphyromonas produce proteases to access them. They degrade serum albumin, immunoglobulins, haemoglobins and host tissue proteins
Name 3 species of Prevotella
- Prevotella Intermedia
- Prevotella Nigrescens
- Prevotella Dentalis
Are Prevotellas saccharolytic or asaccharolytic?
Saccharolytic - Breaks down sucrose into acetic acid and succinic acid
Which Prevotella species correlates with periodontitis severity?
Prevotella intermedia
Which Prevotella species is present in high numbers at healthy sites?
Prevotella Nigrescens
List the bacteria involved in gum disease in sequence
- Streptococcus
- Actinomyces
- Porphyromonas gingivalis & Prevotella intermedia
How do the conditions for bacterial growth below the gingival margin differ from the tooth surface?
- Conditions are more anaerobic (requires carbon dioxide)
2. Nutrients come from the gingival tissues rather than food and saliva (gingival crevicular fluid)
Describe the structure of Spirochaetes
Spirochaetes are helical shaped bacteria with a central protoplasmic cell and 3-5 axial filaments or flagellae within the outer cell envelope
What disease does a fuso-spirochaetal complex cause?
ANUG (Acute Necrotizing Ulcerative Gingivitis)
Bacteria involved in Acute Necrotising Ulcerative Gingivitis
Fusobacterium nucleatum
Treponema vincentii
Periopathogens
Treponema Denticola
Porphyromonas Gingivalis
Aggregatibacter Actinomycetemcomitans
