Streptobacillus moniliformis

Jump to: navigation, search
Scientific classification
Domain: Bacteria
Phylum: Fusobacteria
Class: Fusobacteria
Order: Fusobacteriales
Family: Leptotrichiaceae
Genus: Streptobacillus
Species: S. moniliformis
Binomial name
Streptobacillus moniliformis
This page is about microbiologic aspects of the organism(s).  For clinical aspects of the disease, see Rat bite fever.

Rat-bite fever Microchapters


Patient Information


Historical Perspective



Differentiating Rat-bite fever from other Diseases

Epidemiology and Demographics

Risk Factors

Natural History, Complications and Prognosis


History and Symptoms

Physical Examination

Laboratory Findings

Imaging Findings

Other Diagnostic Studies


Medical Therapy


Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Streptobacillus moniliformis On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides


American Roentgen Ray Society Images of Streptobacillus moniliformis

All Images
Echo & Ultrasound
CT Images

Ongoing Trials at Clinical

US National Guidelines Clearinghouse

NICE Guidance

FDA on Streptobacillus moniliformis

CDC on Streptobacillus moniliformis

Streptobacillus moniliformis in the news

Blogs on Streptobacillus moniliformis

Directions to Hospitals Treating Rat-bite fever

Risk calculators and risk factors for Streptobacillus moniliformis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Streptobacillus moniliformis is a non-motile, Gram-negative rod-shaped bacterium that is a member of the family Leptotrichiaceae.[1] The genome of S. moniliformis is one of two completed sequences of the order Fusobacteriales.[2] Its name comes the Greek word streptos for "curved" or "twisted", and the Latin words bacillus meaning "small rod" and moniliformis for "necklace".[3] S. moniliformis is microaerophilic, requiring less oxygen than is present in the atmosphere for its growth.[4]



S. moniliformis was first isolated from a rat-bitten man in 1914 by German microbiologist H. Schottmüller, who described it as Streptothrix muris ratti.[5] In the United States during the year 1916, S. moniliformis was determined to be the causative source of rat-bite fever.[6]


Some isolates of S. moniliformis have been collected from the upper respiratory tract of domestic and wild rats.[7] Two known variants of S. moniliformis have been identified. The bacillary type is pathogenic.[4] In contrast, the spontaneously occurring L form, which lacks a cell wall and whose colonies grow in a "fried egg" formation, is non-pathogenic.[4]


S. moniliformis has frequently been observed in the form of filamentous, non-branching chains and is highly pleomorphic.[4] For example, the normally straight rod can develop lateral bulbar swellings.[4] The bacteria vary in size from 0.1 to 0.5 μm by 2.0 to 5.0 μm, and can potentially grow up to 10 to 15 μm, with long, curved segments from 100 to 150 μm.[7]


S. moniliformis was previously classified under the Fusobacteriaceae family.[8] It was later regrouped with three other genera including Sebaldella, Sneathia, and Leptotrichia.[1][2][9] These four genera were classified under the family Leptotrichiaceae following comparative analyses of the 16S ribosomal RNA gene sequences[10] and 16S-23S rDNA internal transcribed spacer sequences among members of the phylum Fusobacteria.[9] Identification of conserved signature indels unique to Fusobacteria and its primary clades as well as phylogenetic analysis of members of Fusobacteria based on concatenated sequences of 17 conserved proteins further support the distinction between the two families.[9]

S. moniliformis was formerly classified as the only member of the Streptobacillus genus.[1] However, Streptobacillus strains HKU33T and HKU34 were isolated in Hong Kong in September 2014.[1] Streptobacillus HKU33T was found in pus isolated from the abscess of a 38-year-old patient with quinsy and HKU34 from the elbow joint fluid of a 64-year-old patient with septic arthritis.[1] Following analysis of the 16S rRNA gene sequences found in members of Leptotrichiaceae and partial sequences of the recA, groEl, and gyrB genes present in both isolates, the two strains were taxonomically grouped under the novel species Streptobacillus hongkongensis sp. nov.[1]


The U.S. Department of Energy's Joint Genome Institute (DOE JGI) sequenced the complete genome of S. moniliformis DSM 12112.[2] It is made up of one circular chromosome of 1,673,280 base pairs as determined from a combination of Sanger and 454 sequencing.[2] The mol% of guanine and cytosine in the DNA is 26.3% with 1,511 protein coding genes out of the 1,566 genes predicted.[2] These low G+C values were previously only seen in members of the order Mycoplasmatales, which includes the genus Mycoplasma, indicating a relationship between Mycoplasma and S. moniliformis.[2][11] However, 16S rRNA gene analysis showed this relation to be incorrect.[10] S. moniliformis also has a single circular plasmid pSMON01 that is 10,702 base pairs long with 1,511 protein coding genes.[2]

Isolation and identification

Isolation and identification is challenging because growth of the bacteria is inhibited by sodium polyanethol sulfonate, an anticoagulant present in most commercial aerobic blood culture bottles that are used as enriched growth media.[4] Trypticase soy agar or broth containing 10-20% blood, serum, or ascites fluid, as well as anaerobic culture bottles and resin bead culture systems can be used for growth because sodium polyanethol sulfonate is not normally present.[12] Samples from the inner ear of rats have been used to inoculate 5% sheep blood agar,[7] which ranges in pH from 7.2 to 7.6. The samples were incubated at 37 °C, the same as the average temperature of the human body.[7] It typically takes 2 to 3 days for colonies to appear, however it may take as long as 7.[4] Colonies appear round, convex, smooth, shiny, and greyish in color on solid agar but, in liquid media, colonies appear as "cotton balls."[13] Once they have been cultured, confirmation of their identity can be made using conventional biochemical analyses, such as tests for the production of oxidase, catalase, indole, nitrate, as well as carbohydrate fermentation.[11] S. moniliformis can be biochemically differentiated by similar bacteria by their negative production of indole, catalase, and oxidase, and reduction of nitrate to nitrite.[11] S. moniliformis has been shown to be sensitive to penicillin, cephalosporins, macrolides, tetracyclines[4] and other broad spectrum antibiotics.[14]


  1. 1.0 1.1 1.2 1.3 1.4 1.5 Woo, Patrick (2014). "Streptobacillus Hongkongensis Sp. Nov., Isolated from Patients with Quinsy and Septic Arthritis, and Emended Descriptions of the Genus Streptobacillus and Streptobacillus Moniliformis". International Journal of Systemic and Evolutionary Microbiology: 3034–039. doi:10.1099/ijs.0.061242-0.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Nolan, M; Gronow, S; Lapidus, A; Ivanova, N; Copeland, A; Lucas, S; Glavina Del Rio, T; Chen, F; Tice, H; Pitluck, S; et, al. (2009). "Complete genome sequence of Streptobacillus monoiliformis type strain (9901T)". Stand. Genomic Sci. 1: 300–07. doi:10.4056/sigs.48727.
  3. Skerman VBD, Vicki McGowan, and Sneath PHA. Approved Lists of Bacterial Names (Amended). ASM Press. Washington D.C. 1989 ISBN 978-1-55581-014-6. PMID 20806452 (PMID 20806452)
    Citation will be completed automatically in a few minutes. Jump the queue or expand by hand
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Elliot, Sean P. (2007). "Rat Bite Fever and Streptobacillus moniliformis". Clinical Microbiology Review. 20 (1): 13–22. doi:10.1128/CMR.00016-06.
  5. Hagelskjaer, Lena; Sørensen, Inger; Randers, Else. "Streptobacillus Moniliformis Infection: 2 Cases And A Literature Review". Scandinavian Journal Of Infectious Diseases. 30 (3): 309–11. doi:10.1080/00365549850161016. PMID 9790145.
  6. Blake, F.G. "The etiology of ratbite fever". J. Exp. Med. (23): 39–60. doi:10.1084/jem.23.1.39. PMID 19867970.
  7. 7.0 7.1 7.2 7.3 Koopman, J.P.; Brink Van Den, M.E.; Vennix, P.P.C.A.; Kuypers, W.; Boot, R.; Bakker, R.H. (1991). "Isolation of Streptobacillus moniliformis from the middle ear of rats". Lab Anim. 25: 35–39. PMID 1826334.
  8. Gaastra, Wim; Boot, Ron; Ho, Hoa T.K.; Lipman, Len J. A. (2009). "Rat bite fever". Veterinary Medicine. 133 (3): 211–228. doi:10.1016/j.vetmic.2008.09.079. PMID 19008054.
  9. 9.0 9.1 9.2 Gupta, Radhey, S.; Sethi, Mohit (August 2014). "Phylogeny and molecular signatures for the phylum Fusobacteria and its distinct subclades". Anaerobe. 28: 182–198. doi:10.1016/j.anaerobe.2014.06.007.
  10. 10.0 10.1 Staley, James T.; Whitman, William B.; Krieg, Noel R.; Brown, Daniel R.; Hedlund,, Brian P.; Paster, Bruce J.; Ward, Naomi L.; Ludwig, Wolfgang. Bergey's Manual of Systematic Bacteriology Volume 4 (2nd ed.). Springer. p. 789. ISBN 978-0-387-95042-6.
  11. 11.0 11.1 11.2 Wullenweber, Michael (1995). "Streptobacillus moniliformis-a zoonotic pathogen. Taxonomic considerations, host species, diagnosis, therapy, geographical distribution". Lab Anim. 29: 1–15. doi:10.1258/002367795780740375. PMID 7707673.
  12. Rordorf T, Zuger C, Zbinden R, et al. 2000. "Streptobacillus moniliformis endocarditis in an HIV-positive patient." Infection; 28:393-4.
  13. Rygg, M., and C. F. Bruun. 1992. "Rat bite fever (Streptobacillus moniliformis) with septicemia in a child." Scand. J. Infect. Dis. 24:535-540.
  14. Roughgarden, J. W. 1965. "Antimicrobial therapy of ratbite fever." Arch. Intern. Med. 116:39-53.PMID 14338952 (PMID 14338952)
    Citation will be completed automatically in a few minutes. Jump the queue or expand by hand

External links