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91 Cards in this Set
- Front
- Back
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where anaerobes can be found
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soil, food, animal
human: oral, GI esp. colon, genital tract, skin |
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types of anaerobes
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+ve spore rods (Clostridia)
+ve non-spore rods (Actinomyces) -ve rods and cocci +ve cocci |
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morphology of clostridia
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+ve rods
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what is spore stain
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can stain the spore
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how is C. tetani appears with spore stain
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drum-stick appearance
terminal spore |
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O2 requirement of C. tetani
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obligate anaerobe
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where is C. tetani commonly found
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soil
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disease of tetani
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tetanus
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pathogenesis of tetanus
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- wound contaminated with spores/C. tetani
- local vegetative multiplication - tetanospasmin produced - axonal transport via motor neurons to CNS and systemic spread by blood - acts on inhibitory neuron - prevent release of GABA - sustained muscle contraction |
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Dx of C. tetani
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clinical picture
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CDC definition of tetanus
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acute onset of hypertonia and/or painful muscular contractions and generalised muscle spasm without other apparent medical cause
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does C. tetani ferment carbohydrates
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no
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what does C. tetani do to proetin
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slightly proteolytics
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how many types of C. tetani
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at least 10
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how many types of toxin produced by the different types of C. tetani
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tetanospasmin
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morphology of C. botulinum
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subterminal spore
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how is C. botulinum usually transmitted
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food
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pathogenesis C. botulinum
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- C. botulinum produce toxin on food
- ingestion and absorption in the GI tract - toxin binds irreversibly to peripheral neurons blacks Ach release at the NMJ - muscle paralysis |
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O2 requirement of C. botulinum
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obligate anaerobe
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what is Nagler reaction
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- C. perfringens produces lecithinase
-split lipoprotein complexes - opalescence in serum or egg-yolk media |
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which bacteria can be identified by Nagler reaction
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C. perfringens
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what can inhibit Nagler reaction
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alpha-antitoxin
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what is the commonest cause of gas gangrene
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C. perfringens
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is gas gangrene usually caused by one bacteria
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almost always polymicrobial infection involving anaerobes and facultative organism, C. perfringens most common
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pathogenesis of gas gangrene
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- inoculation of sores to damaged tissue which has impaired blood supply
- alpha-toxin production - myonecrosis with gas gangrene |
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pathogenesis of C. perfringens
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- inoculation of sores to damaged tissue which has impaired blood supply
- alpha-toxin production - myonecrosis with gas gangrene |
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clinical diseases of C. perfringens
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- food poisoning
- gas gangrene |
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pathogenesis of C. perfringens food poisoning
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- ingestion of contaminated food
- enterotoxin stimulate loss of fluid and electrolytes from intestinal mucosa |
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Tx for C. perfringens food poisoning
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no
self-limiting |
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which clostridium species have subterminal spore
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C. difficile
C. botulinum |
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morphology of C. difficile
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subterminal spore
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who are carriers of C. difficile
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<3% healthy adults
neonates |
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clinical disease of C. difficile
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pseudomembranous colitis
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pathogenesis of pseudomembranous colitis
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- overgrowth of C. difficile after antibiotics use
- Toxin A and Toxin B produce by C. difficile - fluid loss and tissue damage - pseudomembranous colitis |
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who is prone to be affected by C. difficile
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elderly
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what is associated with C. difficile
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post-antibiotics colitis
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pathogenesis of post-antibiotics colitis
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- overgrowth of C. difficile after antibiotics use
- Toxin A and Toxin B produce by C. difficile - fluid loss and tissue damage - pseudomembranous colitis |
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Dx of C. difficile
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- cell culture to detect toxin production and cytopathic effect
- toxin detection by EIA |
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can C. difficile isolated from stool be diagnostic?
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no
not specific enough |
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O2 requirement of actinomyces
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facultative anaerobes
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actinomyces is normal at which sites of human
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oral
female genital tract |
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the most suitable environment for actinomyces
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anaerobic or micro-aerophilic conditions with addition of 5-10% CO2
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which is the commonest species of actinomyces
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A. israelii
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period of culture of actinomyces
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7-14 days
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clinical diseases of Actinomyces
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peridental disease
actinomycosis |
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principal forms of actinomycosis
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cervicofacial
thoracic abdominal genital |
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which is the most common form of actinomycosis
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cervicofacial
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how is cervicofacial actinomycosis presented
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- indurated sewlling in lower jaw
- discharging sinus and sulphur granules(yellow) |
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predisposing factor for cervicofacial actinomycosis
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poor oral hygiene and neglected dental care
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cause for thoracic actinomycosis
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- aspiration of actinomyces from the mouth (start at the lung)
- haematogenous spread - direct invasion from other lesion |
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presentation of thoracic actinomycosis
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sinuses on the chest wall
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where does abdominal actinomycosis usually commence
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appendix
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cause of genital actinomycosis
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intrauterine contraceptive device
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Dx of actinomycosis
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prolonged incubation of the specimen
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morphology of actinomyces
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filamentous
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appearance of actinomyces after 14-days of prolonged incubation
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molar-tooth like colony
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what groups of bacteria give foul odor
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anaerobes
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why anaerobes give foul odor
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99% of anaerobes give short chain FA
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what is Gas-Liquid chromatography used for
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detect volatile short FA produced by anaerobes
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what medium are used for culture of anaerobes
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brain-heart-infusion agar(BHIA)
blood agar + VK1 thioglycollate broth cook-meat broth |
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what is selective media
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agar incorporated with antibiotics
--> suppress other non-anaerobes commonly seen in polymicrobial infections |
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what are the anaerobi -ve bacilli
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Bacteroides
Prevotella Fusobacterium |
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where in human can Bacteroides be found
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bowel
genitourinary tract oral |
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where in human can Prevotella be found
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bowel
genitourinary tract oral |
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where in human can Fusobacterium be found
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bowel
genitourinary tract oral |
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where in human can -ve anaerobic rods be found
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bowel
genitourinary tract oral |
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morphology of Fusobacterium
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fusiform rod with tapering end
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culture of Prevotella melaninogenica on blood agar
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black pigmented colonies
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reason for black pigment on blood agar of Prevotella melaninogenica
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derived from haem
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what does Prevotella melaninogenica do to protein
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proteolytic
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what does Prevotella melaninogenica do to carbohydrates
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saccharolytic
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how do specimens containing Prevotella melaninogenica appears
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red fluorescence under UV light
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O2 requirement for Fusobacterium
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anaerobic or micro-aerophilic
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O2 requirement for Bacteroides
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strict anaerobes
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which non-sporing -ve bacilli show pleomorphism
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Fusobacterium
Bacteroides |
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what does Bacteroides fragilis do to protein
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not proteolytic
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what does Bacteroides fragilis do to carbohydrates
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saccharolytic
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which anaerobic -ve rods is proteolytic
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Prevotella melaninogenica
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which anaerobic -ve rods are saccharolytic
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Bacteroides fragilis
Prevotella melaninogenica |
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which anaerobic -ve rods is small
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Prevotella melaninogenica
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which anaerobic -ve rods is large
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Fusobacterium necrophorum
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which anaerobic -ve rods are non-motile
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Fusobacterium necrophorum
Prevotella melaninogenica bacteroides fragilis |
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how do culture of Bacteroides fragilis on blood agar appear
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non-haemolytic smooth circular convex colonies
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what is the bacteria of anaerobic +ve cocci
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Peptostreptococcus
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where is anaerobic +ve cocci found in human
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GI
oral URT female genital tract |
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what is the bacteria of anaerobic -ve cocci
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Veillonella parvula
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clinical significance of anaerobic -ve cocci
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doubtful
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where is anaerobic -ve cocci found in human
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oral
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pathogenesis of anaerobic -ve rods
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- endogenous infection
- anaerobic condions (eg trauma) are provided to allow growth - polymicrobial infections (mixture of aerobic and anaerobic organisms are found, and they act synergically to cause tissue damage), esp abscess formation |
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pathogenesis of anaerobic +ve cocci
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- endogenous infection
- anaerobic condions (eg trauma) are provided to allow growth - polymicrobial infections (mixture of aerobic and anaerobic organisms are found, and they act synergically to cause tissue damage), esp abscess formation |
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pathogenesis of Veillonella parula
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- endogenous infection
- anaerobic condions (eg trauma) are provided to allow growth - polymicrobial infections (mixture of aerobic and anaerobic organisms are found, and they act synergically to cause tissue damage), esp abscess formation |
