''Streptobacillus moniliformis'' is a non-motile,

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

rod-shaped

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

that is a member of the family Leptotrichiaceae. The

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

of ''S. moniliformis'' is one of two completed sequences of the order

Fusobacteriales Fusobacteriota are obligately anaerobic non-sporeforming Gram-negative bacilli. Since the first reports in the late nineteenth century, various names have been applied to these organisms, sometimes with the same name being applied to different s ...

. Its name comes from the Greek word ''streptos'' for "curved" or "twisted", and the Latin words ''

bacillus ''Bacillus'' (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacilli ...

'' meaning "small rod" and ''moniliformis'' for "necklace". ''S. moniliformis'' is

microaerophilic A microaerophile is a microorganism that requires environments containing lower levels of dioxygen than that are present in the atmosphere (i.e. < 21% O₂; typically 2–10% O₂) for optimal growth. A more re ...

, requiring less

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

than is present in the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

for its growth.

Background

History

''S. moniliformis'' was first isolated from a rat-bitten man in 1914 by German

microbiologist A microbiologist (from Ancient Greek, Greek ) is a scientist who studies microscopic life forms and processes. This includes study of the growth, interactions and characteristics of Microorganism, microscopic organisms such as bacteria, algae, f ...

H. Schottmüller, who described it as ''Streptothrix muris ratti''. In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

during the year 1916, ''S. moniliformis'' was determined to be the causative source of

rat-bite fever Rat-bite fever (RBF) is an acute, febrile human illness caused by bacteria transmitted by rodents, in most cases, which is passed from rodent to human by the rodent's urine or mucous secretions. Alternative names for rat-bite fever include stre ...

Microbiology

Some isolates of ''S. moniliformis'' have been collected from the upper

respiratory tract The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose to th ...

of domestic and wild

rats Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' (pack rats), ''Bandicota'' (bandicoot ...

. Two known variants of ''S. moniliformis'' have been identified. The bacillary type is

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

ic. In contrast, the spontaneously occurring L form, which lacks a

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...

and whose

colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

grow in a "fried egg" formation, is non-pathogenic.

Morphology

The bacterium S. moniliformis, is a gram-negative pleomorphic rod, occurring frequently in chains and tangled filaments with bulbous or “Monilia”-like swellings. The organism presents phenotypically as being facultatively anaerobic, non-motile, weakly ferments glucose and maltose, is catalase and oxidase-negative does not reduce nitrate and exhibits no growth on MacConkey agar. Morphologically, colonies of S. moniliformis are 1–2 mm in size, smooth, convex, non-hemolytic (varied presentation with an α-hemolysis is not uncommon) and gray in color. When cultured in broth, a typical “puff-ball” appearance is seen.Szewc AM, Bell ME, Kelly AJ, Humrighouse BW, McQuiston JR. Using the BDFX40 Automated Continuous Blood Culture System to Isolate and Recover Streptobacillus moniliformis in the Presence of 0.05% SPS: A 55-Year, 56-Strain Retrospective Study. Lab Med. 2021 Nov 2;52(6):536-549. doi: 10.1093/labmed/lmab009. PMID 33693831.

Taxonomy

''S. moniliformis'' was previously classified under the family Fusobacteriaceae. It was later regrouped with three other

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

including Sebaldella,

Sneathia ''Sneathia'' is a Gram-negative, rod-shaped, non- spore-forming and non-motile genus of bacteria from the family of Leptotrichiaceae. Species have been identified as pathogens associated with bacterial vaginosis Bacterial vaginosis (BV) is ...

, and Leptotrichia. These four genera were classified under the family Leptotrichiaceae following comparative analyses of the

16S ribosomal RNA 16 S ribosomal RNA (or 16 S rRNA) is the RNA component of the 30S subunit of a prokaryotic ribosome (SSU rRNA). It binds to the Shine-Dalgarno sequence and provides most of the SSU structure. The genes coding for it are referred to as 16S rRNA ...

gene sequences and 16S-23S rDNA

internal transcribed spacer Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. I ...

sequences among members of the phylum Fusobacteria. Identification of

conserved signature indels Conserved signature inserts and deletions (CSIs) in protein sequences provide an important category of molecular markers for understanding phylogenetic relationships. CSIs, brought about by rare genetic changes, provide useful phylogenetic markers ...

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. ''S. moniliformis'' was formerly classified as the only member of the genus ''Streptobacillus''. However, ''Streptobacillus'' strains HKU33T and HKU34 were isolated in Hong Kong in September 2014. ''Streptobacillus'' HKU33T was found in

pus Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during bacterial or fungal infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection ...

isolated from the

abscess An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends b ...

of a 38-year-old patient with quinsy and HKU34 from the

elbow The elbow is the region between the arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the media ...

joint fluid of a 64-year-old patient with

septic arthritis Acute septic arthritis, infectious arthritis, suppurative arthritis, osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, hea ...

. Following analysis of the 16S rRNA gene sequences found in members of Leptotrichiaceae and partial sequences of the ''rec''A, ''gro''El, and ''gyr''B genes present in both isolates, the two strains were

taxonomically In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...

grouped under the novel

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

''Streptobacillus hongkongensis sp. nov.''

Genomics

The U.S. Department of Energy's

Joint Genome Institute The U.S. Department of Energy (DOE) Joint Genome Institute (JGI), first located in Walnut Creek then Berkeley, California, was created in 1997 to unite the expertise and resources in genome mapping, DNA sequencing, technology development, and i ...

(DOE JGI) sequenced the complete genome of ''S. moniliformis'' DSM 12112. It is made up of one circular

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

of 1,673,280

base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

s as determined from a combination of Sanger and 454 sequencing. The

mol% In chemistry, the mole fraction or molar fraction (''xi'' or ) is defined as unit of the amount of a constituent (expressed in moles), ''ni'', divided by the total amount of all constituents in a mixture (also expressed in moles), ''n''tot. This ex ...

guanine Guanine () ( symbol G or Gua) is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside is called ...

and

cytosine Cytosine () ( symbol C or Cyt) is one of the four nucleobases found in DNA and RNA, along with adenine, guanine, and thymine (uracil in RNA). It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an am ...

in the DNA is 26.3% with 1,511 protein coding

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

s out of the 1,566 genes predicted. These low G+C values were previously only seen in members of the order Mycoplasmatales, which includes the genus ''

Mycoplasma ''Mycoplasma'' is a genus of bacteria that, like the other members of the class ''Mollicutes'', lack a cell wall around their cell membranes. Peptidoglycan (murein) is absent. This characteristic makes them naturally resistant to antibiotics ...

'', indicating a relationship between ''Mycoplasma'' and ''S. moniliformis''. However,

16S rRNA gene 16S or 16s may refer to: * Ribosomal RNAs, in biology: ** prokaryotic 16S ribosomal RNA ** mitochondrial 16S ribosomal RNA * Myrtle Creek Municipal Airport's FAA identifier * Fujitsu Micro 16s, a 1983 Business personal computer *Sulfur Sulfu ...

analysis showed this relation to be incorrect. ''S. moniliformis'' also has a single circular

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; how ...

pSMON01 that is 10,702 base pairs long with 1,511 protein coding genes.

Isolation and identification

The fastidious nature of S. moniliformis makes it difficult to culture, with current published recommendations stating it requires media supplemented with 20% serum, ascitic fluid, or whole blood in order to grow. Numerous published reports also state that the organism is inhibited by the polyanionic detergent sodium polyanethole sulfonate, (SPS-trade name; Liquoid; Hoffman-La Roche, Inc., Nutley, N.J.), the main anticoagulant in modern commercially available blood culture bottles, used in automated continuous blood culture instruments. Optimizing the best chances for organism recovery should include, the aseptic collection of blood or sterile body fluid(s) into commercial blood culture bottles (documenting the amount of blood drawn from the patient if applicable) during the acute phase of infection and collected in duplicate with optimal volumes of inoculation for the isolation and growth of S. moniliformis being 10 ml for adolescent to adult patients and extrapolated to 4-5 ml in a pediatric population. Bottles should be incubated minimally for 7 days to ensure the best chance for organism recovery when working with low levels of bacteremia and if not yet detected by day 7, blind sub-cultured to rule out a false-negative blood culture result. Automated continuous blood culturing instrumentation growth and fluorescent detection data should be checked manually during the course of incubation, in order to rule out missed false-negative samples. Once a bottle shows signs of organism growth and detection, a Gram stain should be performed followed by inoculation of blood onto rabbit or sheep blood agar and brain heart infusion broth and incubated aerobically at 35 °C 35-37 °C or 5% enriched (microaerophilic) environment for a minimum of 3–4 days. While the organism has been reported to be inhibited by specific blood culture additives, specifically SPS in the clinical lab, current research has proposed methods to overcome this limitation with "100% culture, growth success rates" According to Szewc et al., their research into the "reported" fastidious nature of S. moniliformis, and its inhibition by the anticoagulant SPS showed, that when using a specific volume of blood for inoculum, it resulted in 100% recovery and successful growth of this organism and appeared to overcome the inhibitions and limitations that historically have been observed when using SPS for blood culturing and recovering S. moniliformis in a clinical setting.

Relevance

Rat bite fever and Haverhill fever

In the U.S.,

rat bite fever Rat-bite fever (RBF) is an acute, febrile human illness caused by bacteria transmitted by rodents, in most cases, which is passed from rodent to human by the rodent's urine or mucous secretions. Alternative names for rat-bite fever include strep ...

is primarily caused by transmission of ''S. moniliformis'' from the bite of a rat. However, approximately 30% of patients diagnosed with rat bite fever do not recall being scratched or bitten by an infected animal.Parker RH. "Rat-bite fever." Hoeprich PD, Jordan MC, editors., eds. Infectious disease, 4th ed. Philadelphia: Lippincott, 1989: 1310-1312 Transmission of the bacterium is also known to occur via consumption of infected water, close contact with, or handling of rats.

Haverhill fever Haverhill fever (or epidemic arthritic erythema) is a systemic illness caused by the bacterium '' Streptobacillus moniliformis'', an organism common in rats and mice. If untreated, the illness can have a mortality rate of up to 13%. Among the two t ...

, named after the 1926 outbreak of the disease in

Haverhill, Massachusetts Haverhill ( ) is a city in Essex County, Massachusetts, United States. Haverhill is located 35 miles north of Boston on the New Hampshire border and about 17 miles from the Atlantic Ocean. The population was 67,787 at the 2020 United States Cen ...

, is a form of rat bite fever that can result from ingesting food contaminated with ''S. moniliformis''. In 1986 at a boarding school in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

, another outbreak of Haverhill fever was reported. Some 304 people were reported to have been afflicted.Pilsworth, R. 1983."Haverhillfever." Lancetii:336–337 Infection was suspected to have resulted from the consumption of either

unpasteurized Pasteurization or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mild heat, usually to less than , to eliminate pathogens and extend shelf life. Th ...

milk or water contaminated with rat feces. Infected individuals described symptoms including a sudden development of vomiting, severe headache, and cold sweats with a high fever. Parker and Hudson first isolated the cause of this outbreak, which they named ''Haverhilia multiformis''. This organism was later matched to ''S. moniliformis'' after further research. Symptoms of rate bite fever include the abrupt onset of fever ranging from 38.0 °C to 41 °C. Approximately 75% of infected individuals develop a rash in addition to

hemorrhaging Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...

vesicles Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle ; In human embryology * Vesicle (embryology), bulge-like features o ...

. Both the rash and vesicles are usually located on the hands and feet, although the rash has been known to spread to other parts of the body. The microaerophilic nature of ''S. moniliformis'' makes identification difficult. PCR testing is being utilized more for its identification. However, there is still a 13%

mortality rate Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of de ...

for untreated cases.

Immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

individuals, such as

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

-positive individuals, are more at risk of death from this disease. Lab personnel and pet store workers, who work closely with animals on a daily basis, also have an increased risk of infection. Although ''S. moniliformis'' is believed to be part of the

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...

bacteria of the respiratory tract of rats, rats have occasionally shown signs of the disease.

Antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...

used to treat infection may cause the formation of the L-form, which persists in the body although this form is not pathogenic.

References

External links

DOE Joint Genome Institute
''S. moniliformis'' Genome Portal
KEGG (Kyoto Encyclopedia of Genes and Genomes)
''S. moniliformis'' genome information
Phylogenetic neighborhood of ''S. moniliformis''Type strain of ''Streptobacillus moniliformis'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q3500345 Fusobacteriota