M11- Gram- negative bacteria part 2 Flashcards
Name 3 non-motile gram negative anaerobic bacilli.
- tannerella
- fusobacterium
- leptotrichia
what is tannerella forsythia?
Saccharolytic , non-pigmented bacteria
pits the surface of blood agar
what is tannerella forsythia associated with?
periodontitis
chronic periodonititis and increased recovery with depth
Can tannerella forsythia demonstrate pathogenic activity in isolation?
NO
what does tannerella fit into?
RED complex
Name some virulence factors of tannerella forsythia.
- fibronectin/fibrinogen binding BspA
- apoptosis inducing factor -protease (take out compliment)
What does BspA do?
– Adhesion
– Invasion
– Induces release of bone reabsorbing pro-inflammatory cytokines
– Induces chemokines (recruit neutrophils, inflammation, tissue destruction)
why is tannerella forsythia pathogenicity limited (polymicrobial)?
– Murine skin abscess model & wound chamber model does not cause
disease
– Gnotobiotic rats does not colonize efficiently or induce alveolar bone loss
what interactions does tannerella forsythia make?
– P. gingivalis enhances attachment to epithelial cells
– Forms mixed films with Fusobacterium
What are features of fusobacterium nucleatum?
- Diversification of Plaque
- Periodontal Disease
- NG -necrotising gingivitis
- Still Births (gets in oral cavity and cross the placenta - so effects systemic health
- Colorectal Cancer
what type of bacteria is fusobacterium?
gram negative spindle shaped (fusiform) bacteria (often arranged in pairs)
what can fusobacterium nucleatum adhere?
Gm +ve and Gm -ve bacteria
what is fusobacterium nucleate FadA virulence factor involved in?
extra-oral infections
what does fusobacterium bind to?
epithelial cells, seen to enter fibroblasts in vitro
what is fusobacterium nucleatum associated with?
other microorganisms in disease
what is F. nucleatum and Treponema vincentii spirochaete normally associated with?
- necrotizing periodontal diseases
- acute necrotizing ulcerative gingivitis
what is the combination of F. nucleatum and treponema vincentii spirochaete?
fusospirochaetal infection
what is Vincent’s angina?
Old ANUG name for infection of
tongue/pharynx & mouth
what is cancrum oris or NOMA?
– AUG causing massive tissue destruction
– Linked to immunosuppression
who does necrotising gingivitis affect normally?
immunocompromised people
what are features of necrotising gingivitis?
- Young adults (mainly)
- Cigarette smokers & minor respiratory infections
- Ulcers spread along gingival margins
- Gingival soreness & bleeding
- Foul breath
- No swollen lymph nodes, fever or systemic symptoms
how does fusobacteria cause NG?
- Induce protein kinases associated with cell migration, proliferation & cell survival
– Stimulates collagenase 3 expression
– Secretes serine proteases
– Immune suppression via inducing apoptotic cell death in peripheral blood cells i.e. mononuclear & polymorphonuclear
what to remember about fusobacteria?
- sticks to other organisms
- mutilpe interactions (peridontal disease - stimulation of immune system)
- carry other cells into tissues
- key roles in cancer and still birth
what is Leptotrichia?
- gram negative anaerobic bacilli
- found in pairs or long filaments
what is the major fermentation product of leptotrichia?
lactic acid
what is the best described species of leptotrichia?
Leptotrichia buccalis
Describe Leptotrichia buccalis.
– present in dental plaque
-preferentially isolated from plaque overlying caries
– Possess galactosyl-binding lectins
– Extra-oral infections in seriously ill patients
Describe gram -ve facultative anaerobes.
• Prefer Oxygen • Often capnophilic (5 - 10% CO2) • important oral genera include: -Haemophilus -Eikenella -Aggregatibacter -Capnocytophaga
what is haemophilus?
• Gram -ve small bacilli (Parvobacteria)
– frequently isolated from mouth and dental
plaque
– Haemophili colonise the mouth in the first few days after birth
what is the most common haemolphilus species in dental plaque?
haemophilus segnis (supragingivial plaque)
Is haemophilus segnis regarded as pathogenic?
no
what species works on its own?
Aggregatibacter
what is aggregatibacter?
- Gram -ve, capnophilic (5-10%), cocco-bacillus – often found in association with Actinomyces
- Periodontopathogen (Localised Juvenile Periodontitis)
Name some virulence factors of aggregatibacter.
Leukotoxin (takes out white blood cells), collegenase, IgG proteases, surface proteins
Describe juvenile periodontitis.
- Puberty, more common in Girls
- Clusters in families
- West African & Asian (slightly more common)
- Localised J P (first permanent molars & incisors)
- Generalised J P (aggressive)
what does A. actinomycetemcomitans cause?
- Rapid destructive periodontitis
* Juvenile periodontitis (11-15)
what is eikenella?
• Gram -ve asaccharolytic small bacillus (coccobacilli) – that pits or corrodes agar
what does eikenella corrodes colonise?
the oral cavity and intestine
-subgingival plaque
what can eikenella cause?
Can produce periodontitis and alveolar bone loss when introduced into rats
– Increased numbers in gingivitis
what is clenched first injury?
- 21 year old cut hand
- 12 hours after hitting an opponent in the mouth
- Rapid onset/redness (erythema)
what is capnocytophaga?
Gram -ve, fusiform, CO2-dependent,
Parvobacteria
Describe curved gram -ve bacilli.
Many curved/spiral Gram -ve bacteria are found in the mouth. These are usually anaerobic with polar flagellae e.g.
• Campylobacter rectus
– plaque and periodontal pockets
what is the core knowledge of gram negative key species?
• Tannerella forsythia – Red complex, Perio-bone loss, BspA • Fusobacterium nucleatum – Bridging organism, perio, extra-oral, still births, FadA • Aggregatibacter actinomycetemcomitans – Perio, juvenile perio, leukotoxin,Amoxycillin & Metronidazole • Eikenella corrodens – Perio & clenched fist injuries
what makes up the RED complex?
– Tannerella forsythia
– Porphyromonas gingivalis
– Treponema denticola
what is the orange complex?
– Prevotella intermedia
– Prevotella nigrescens
– Fusobacterium nucleatum
