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• Anaerobic bacteria


  Organisms that require a reduced oxygen tension for growth and fail to grow on solid media in the presence of oxygen
• Types of anaerobic infections

  • Exogenous (soil and environmental inhabitants)
  • Endogenous (microbiota)
• Anaerobic gram-positive spore-forming bacilli (Clostridia)

  • Gram-positive bacilli
  • Endospore-forming
  • Obligately anaerobic (or aerotolerant)
  • Catalase-negative
  • Motile with peritrichous flagella (except C. perfringens, C. ramosum and C. innocuum)
  • Non-encapsulated (except C. perfringens)
  • Have a single hemolytic reaction (except C. perfringens)
  • Have swollen sporangia (except for C. perfringens and C. bifermentans)
  • Carbohydrate fermenters (except C. tetani and C. histolyticum)

  
• Spore-forming Clostridia

  • Clostridium perfringens
  • Clostridium botulinum
  • Clostridium tetani
  • Clostridium difficile
  • Clostridium septicum
  • Clostridium sordellii
  • Other Clostridium spp.

  
• Clostridium perfringens

  Formerly known as C. welchii, also known as bacillus aerogenes capsulatus / gas gangrene bacillus / Frankel's bacillus, most commonly isolated member of Clostridium in blood cultures, non-motile, obligatory anaerobe, only encapsulated clostridia, spores are absent in solid media & thio, endospore: subterminal

  
• Clostridium perfringens


  • Causes myonecrosis (gas gangrene), pork poisoning (pig bell), enteritis necroticans
• Clostridium perfringens virulence factors

  • Alpha toxin (lecithinase, phospholipase C)
  • Beta toxin (Dambrand pigbel)
  • Lambda toxin
  • Theta toxin
  • Kappa toxin
  • Mu toxin
  • Nu toxin
  • Epsilon and iota toxin
  • Enterotoxin
  • Neuramidase
• Clostridium perfringens culture

  Double zone of beta hemolysis on BAP, inner: complete hemolysis (theta toxin), outer: complete hemolysis (alpha toxin/lecithinase), milk media: stormy fermentation with gas production
• Clostridium perfringens biochemical characteristics

  Does not ferment xylose, positive lecithinase test, positive Nagler reaction, positive reverse CAMP
• Clostridium tetani


  Also known as tack head bacillus, spores: terminal & swollen (drumstick/lollipop/tennis racket appearance), swarming colonies on BAP, exhibits Wasserman-Takaki phenomenon, does not ferment any carbohydrates (non-fermenter)
• Tetanus


  • Intoxication caused by C. tetani, typically occurs in non-immunized persons within the first 2 weeks following a traumatically acquired puncture, laceration, or abrasion, clinical manifestations: trismus (lock jaw), risus sardonicus (sardonic smile), opisthotonus, caused by tetanospasmin (neurotoxin causing spasmodic contraction/spastic paralysis)
• Clostridium botulinum


  Also known as canned good bacillus / Von Ermengen's bacillus / bacillus botulinus, heat resistant spores that are oval and subterminal beta hemolytic, potential bioterrorism agent

  
• Causes of botulism

  • Wound botulism
  • Food botulism (preformed toxin)
  • Infant botulism / floppy baby syndrome
• Botulinum/botulism toxin (Botox)


  One of the most potent exotoxins, a neurotoxin causing flaccid paralysis by preventing the release of acetylcholine, used for temporary smoothing of facial wrinkles, severe underarm sweating, cervical dystonia, blepharospasm, strabismus, overactive bladder
• Clostridium difficile

  Spores: oval & subterminal, on BAP: fluoresce yellow green colonies with horse stable odor, on CCFA: yellow ground glass colonies, major cause of nosocomial diarrhea, produces toxin A and toxin B, most common cause of antibiotic-associated diarrhea and pseudomembranous colitis
• Clostridium difficile

  • Overgrowth due to side effect of antibiotics (clindamycin, ampicillin, cephalosporin), should be considered a cause of diarrhea in patients on antibiotic therapy or hospitalized for more than 3 days
• Miscellaneous Clostridia

  • Clostridium ramosum (normal flora of large bowel, important in intra-abdominal infections)
  • Clostridium septicum (cause of bacteremia associated with malignancies like colon, breast cancer, leukemia, produce oval and subterminal spores)

  
• Anaerobic gram-negative non-spore-forming bacilli


  • Actinomyces (branching & beaded, has sulfur granules, facultative anaerobe, found as normal flora), Bifidobacterium (diphtheroidal and long branching rods with bifurcated or forked ends, normal flora of GI and GU tract), Lactobacillus, Mobiluncus, Propionibacterium, Atopobium, Eggerthella, Eubacterium

  
• Actinomyces israelii


  Most common cause of actinomycosis (lumpy jaws), part of indigenous microbiota of oral cavity, culture: brain heart infusion agar (molar tooth, bread-crumb like, raspberry or smooth colonies), thioglycollate (fluff ball colonies), young cultures: "spider-like" and "wooly", old cultures: "raspberry" or "molar tooth"
• Other Actinomyces species

  • Actinomyces naeslundii (fluff balls with sulfur granules)
  • Actinomyces viscosus (pink flocculent colonies in thioglycollate)
  • Actinomyces odontolyticus (red colored colonies on BAP)
• Bifidobacterium


  Diphtheroidal and long branching rods with bifurcated or forked ends (resemble "dog bone" shape), normal flora of GI and GU tract, small, white, shiny and convex colonies, Bifidobacterium dentium (formerly B. eriksonii), acidophilic

  
• Probiotics

  Live microorganisms which, when administered in adequate amounts, confer a health benefit on the host (FAO definition), used in the food industry
• Fusion Agar

  Molar tooth colonies<|>Bread-crumb like, raspberry or smooth colonies
• Thioglycollate

  Fluff ball colonies
• Young cultures


  "Spider-like" and "wooly" colonies
• Old cultures

  "Raspberry" or "Molar tooth" colonies
• Actinomyces spp.

  • Actinomyces naeslundii
  • Actinomyces viscosus
  • Actinomyces odontilyticus
• Actinomyces naeslundii

  Fluff balls with sulfur granules
• Actinomyces viscosus

  Pink flocculent colonies in Thioglycollate
• Actinomyces odontilyticus


  Red colored colonies on BAP
• Bifidobacterium


  Diphtheroidal and long branching rods<|>Bifurcated or forked ends<|>Resemble the shape of a "dog bone"<|>Normal flora of GI and GU tract<|>Small, white, shiny and convex colonies

  
• Bifidobacterium dentium

  Formerly B. eriksonii<|>Acidophilic
• Probiotics

  Live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host<|>Used in the food industry to relieve and treat many intestinal disorders<|>Some supplements contains probiotic bifidus BL which supports healthy immune and digestive systems<|>Two principal kinds are members of the genera Lactobacillus and Bifidobacterium
• Eubacterium

  • E. alactolyticum
  • E. nodatum
  • E. lentum

  
• E. alactolyticum


  sea-gull-wing shape forms<|>Now Pseudoramibacter alactolyticus
• E. nodatum

  filamantous & branching
• E. lentum


  most common Eubacteria<|>now Eggerthella lenta

  
• Lactobacillus acidophilus


  aka Doderlain bacilli<|>Most abundant normal flora of vagina<|>Non-pathogenic: has little clinical significance<|>Produces lactic acid<|>Grows on tomato juice agar
• Lactobacillus gasseri

  appears to be the main species of lactobacilli that inhabits the human gastrointestinal tract<|>Lowers pH, suppresses overgrowth of mobiluncus, prevotella and G. vaginalis
• Lactobacillus casei strain Shirota


  Yakult contains