Rat Bite Fever and Streptobacillus moniliformis

Sean P. Elliot

Clinical Microbiology Reviews

Jan. 2007.p.13-22

petechial and purpuric lesions on the foot of a rat bite fever patient

Sean P. Elliot

Clinical Microbiology Reviews

Jan. 2007.p.13-22


hemorrhagic vesicles on the first and third toes of a patient with advanced rat bite fever

Sean P. Elliot

Clinical Microbiology Reviews

Jan. 2007.p.13-22


Streptobacillus moniliformis

  • General information

    • the following information is not yet verified
      General Information
      This organism is known to spontaneously develop L forms (bacteria without cell walls) which may allow its persistence in some sites

      Family: Leptotrichiaceae

      Natural habitats
      In the upper respiratory tract of rats (mice, gerbils, squirrels, ferrets, weasels and other rodents)

      Clinical significance
      They are pathogenic for humans and are transmitted by 2 routes
      1. rat bite or contact with rat feces or saliva
      ►Rat-bite fever
      2. ingestion of contaminated food
      ► Haverhill fever

      The patient develop acute onset of chills, fever, headache, vomiting and often severe joint pains.

      Complication can occur, including endocarditis, brain abscess, prostatitis and pancreatitis

  • Gram stain

    • the following information is not yet verified
      Gram negative rods
      occuring singly or in long wavy chains or filaments (up to 150 µm).

      Some may be highly pleomorphic.

      Singly rods may show central swelling.

      Chains or filaments may have a series of swellings (1-3 µm wide) resulting in a "string of beads" appearance.

      0.1-0.7 x 1.0-5.0 µm with rounded or pointed ends.

      are coccobacillary or bipolar-staining coccoid forms, usually a special stain is required because of their lack of cell wall

      (Giemsa, acridine orange)

  • Culture characteristics

    • the following information is not yet verified

      Facultative anaerobic (capnophilic)

      They require serum, ascitic fluid and blood for growth and incubated with 5-10% CO2

      They grow slowly (2-3 days) and that may take as long as 7 days.

      The colonies are small, circular, convex, grayish, smooth, and glistening.

      may develop in the same culture (after 5 days) are considered not pathogenic

      These colonies are embedded in the agar and may also have a “fried egg” appearance, with a dark center and a flattened lacy edge.

      They have undergone spontaneous transformation to the L-form.

      McC no growth

      Thioglycollate broth + 10-30% ascitic fluid
      Growing colonies as "bread crumbs" on the bottom of the tube.

      Blood Culture Media with SPS inhibits the growth

  • Characteristics

  • References

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