Streptococcus equinus

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Streptococcus equinus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Phylum: Bacillota
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Streptococcus
Species:
S. equinus
Binomial name
Streptococcus equinus
Andrewes FW, Horder TJ 1906
Synonyms [1] [2] [3] [4]

Streptococcus equinus is a Gram-positive, nonhemolytic, nonpathogenic, lactic acid bacterium of the genus Streptococcus . [5] It is the principal Streptococcus found in the alimentary canal of a horse, [6] and makes up the majority of the bacterial flora in horse feces. [7] Equivalence with Streptococcus bovis has been contested. [4]

Contents

History

S. equinus, which is always abundant in the feces of horses, was first isolated from the air in 1906 by Andrewes and Horder due to the presence of dried horse manure, common in most cities at the time. [8]

In 1910, Winslow and Palmer verified the findings of Andrewes and Horder and reported further findings in both cattle and human feces. [9]

Phylogeny

After the bacterium was discovered in 1906, the term Streptococcus equinus became a convenient “wastebasket” into which nonhemolytic streptococci that do not ferment lactose and mannitol were categorized. [9] The classification of all streptococci that fail to ferment lactose into one large category has made the classification of S. equinus very difficult.

Figure 1: The unrooted tree shows some of the phylogenetic relationships of some Streptococcus species Phylogeny of Streptococcus equinus.png
Figure 1: The unrooted tree shows some of the phylogenetic relationships of some Streptococcus species

However, as shown to the left, it is known that S. equinus, a nonenterococcal, group D streptococcus, is most closely related to the species S. bovis . [7] In 2003, S. bovis and S. equinus were found to have a 99% 16S rRNA sequence similarity. [4] While particularly similar in phylogeny they differ in biochemical reactions and physiological characteristics. [4]

The taxonomy of the organisms designated as S. bovis and S. equinus has a very complex history. S. equinus and S. bovis were reported to be synonyms by Farrow et al. in 1984, but were listed as separate species in Bergey's Manual of Systematic Bacteriology in 1986. [11] Recently, the situation has become more complex by the description of two novel species for strains originally identified as S. bovis as actually S. caprinus, and S. gallolyticus. [11] The taxonomy of S. equinus has yet to be fully resolved. [12]

Characteristics

A prominent characteristic of S. equinus is its inability to ferment lactose and mannitol. [8] Moreover, it is nonhemolytic and not known to be pathogenic for animals.

Morphology

Generally, it appears as short chains of spherical or ovoid cells. These chains are somewhat longer in broth cultures than milk. Some cultures form extremely long chains in broth. [9]

Temperature of growth

S. equinus has a high minimum temperature of growth, evidenced by little or no growth in gelatin cultures at temperatures lower than 21 °C. [8] [9] No growth occurs at 10 or 15 °C, and growth is very slow at 21 °C. [9] The maximum temperature of growth takes place at 45 °C, and 47 °C where growth seldom occurs. [9] No growth occurs at 48 °C. [9]

Growth medium

It does not grow well in nor can it coagulate milk. [8] [9] However, it has a high fermentative power in glucose broth. [9] The organism grows with vigor in glucose-peptone-litmus milk. [9]

Thermal resistance

It has a higher resistance to temperature than that possessed by pathogenic streptococci, but substantially lower than that of thermoduric streptococci.

Most of the other properties of S. equinus have not yet been determined.

Clinical significance

S. equinus is one of the rare Gram-positive bacteria that may cause bacteremia and endocarditis in humans, but infection with this organism is very rare in humans. [13]

Rare incidences

Among the rare published cases of S. equinus reported are: infective endocarditis, [14] and peritonitis. [15]

In 1993, a case was reported of a farmer with documented aortic valve disease who developed bacterial endocarditis due to S. equinus. [14] The case report also noted that S. equinus is a rare pathogen in man and its acquisition may be related to the subject’s occupation. [14]

In 1998, a case of S. equinus peritonitis in a patient on continuous ambulatory peritoneal dialysis (CAPD) was reported. [15] This case reported that S. equinus is a rare but easily treatable cause of peritonitis in CAPD patients. [15]

In 2000, a woman with no underlying cardiac abnormalities developed S. equinus endocarditis. [16] However, the patient also had pulmonary histiocytosis X. [16] While this may have been a coincidence, such patients have many abnormalities of the immune system including imbalance of the immunoregulatory cell system and a decreased production of natural antibodies. [16] Such abnormalities can predispose the patients with histiocytosis X to the development of bacterial infections, and a similar mechanism may have taken place in this patient. [16]

Overall, while this organism has been isolated from the human intestine, currently it has not been reported to cause endocarditis in patients without history of cardiac disease or another underlying condition. [17]

Future studies

To obtain a definitive discrimination between S. equinus and S. bovis, extensive further studies are required. Additional DNA-DNA hybridization studies or genomic and proteomic comparison experiments of the two species could lead to more definitive results. [18] Also, further studies using new techniques such as MALDI-TOF may also be effective. [18]

Related Research Articles

<i>Streptococcus</i> Genus of bacteria

Streptococcus is a genus of gram-positive coccus or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales, in the phylum Bacillota. Cell division in streptococci occurs along a single axis, so as they grow, they tend to form pairs or chains that may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes.

<i>Lactococcus</i> Genus of bacteria

Lactococcus is a genus of lactic acid bacteria that were formerly included in the genus Streptococcus Group N1. They are known as homofermenters meaning that they produce a single product, lactic acid in this case, as the major or only product of glucose fermentation. Their homofermentative character can be altered by adjusting environmental conditions such as pH, glucose concentration, and nutrient limitation. They are gram-positive, catalase-negative, non-motile cocci that are found singly, in pairs, or in chains. The genus contains strains known to grow at or below 7˚C.

<span class="mw-page-title-main">Infective endocarditis</span> Medical condition

Infective endocarditis is an infection of the inner surface of the heart, usually the valves. Signs and symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cell count. Complications may include backward blood flow in the heart, heart failure – the heart struggling to pump a sufficient amount of blood to meet the body's needs, abnormal electrical conduction in the heart, stroke, and kidney failure.

<i>Acinetobacter</i> Genus of bacteria

Acinetobacter is a genus of Gram-negative bacteria belonging to the wider class of Gammaproteobacteria. Acinetobacter species are oxidase-negative, exhibit twitching motility, and occur in pairs under magnification.

<i>Enterobacter</i> Genus of bacteria

Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. It is the type genus of the order Enterobacterales. Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised hosts and in those who are on mechanical ventilation. The urinary and respiratory tracts are the most common sites of infection. The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms group of bacteria, unlike Escherichia coli, because it is incapable of growth at 44.5 °C in the presence of bile salts. Some of them show quorum sensing properties.

Streptococcus bovis is a species of Gram-positive bacteria that in humans is associated with urinary tract infections, endocarditis, sepsis, and colorectal cancer. S. gallolyticus is commonly found in the alimentary tract of cattle, sheep, and other ruminants, and may cause ruminal acidosis or feedlot bloat. It is also associated with spontaneous bacterial peritonitis, a frequent complication occurring in patients affected by cirrhosis. Equivalence with Streptococcus equinus has been contested.

<i>Alcaligenes</i> Genus of bacteria

Alcaligenes is a genus of Gram-negative, aerobic, rod-shaped bacteria in the order of Burkholderiales.

Mycobacterium boenickei is a member of the Mycobacterium fortuitum third biovariant complex. They are rapidly growing ubiquitous environmental organisms that normally inhabit soil, dust and water. These organisms frequently are human pathogens that cause a wide spectrum of clinically significant disease. It is important for practitioners to be aware of these organisms as possible etiological agents, as they are resistant to most first-line anti-tuberculous agents.

Mycobacterium brisbanense is a member of the Mycobacterium fortuitum third biovariant complex. They are rapidly growing ubiquitous environmental organisms that normally inhabit soil, dust and water. These organisms frequently are human pathogens that cause a wide spectrum of clinically significant disease. It is important for practitioners to be aware of these organisms as possible etiological agents, as they are resistant to most first-line anti-tuberculous agents.

Abiotrophia is a genus of lactic acid bacteria, a family in the phylum Bacillota (Bacteria).

<span class="mw-page-title-main">Fermented milk products</span>

Fermented milk products or fermented dairy products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented with lactic acid bacteria such as Lactobacillus, Lactococcus, and Leuconostoc. The fermentation process increases the shelf life of the product while enhancing its taste and improving the digestibility of its milk. There is evidence that fermented milk products have been produced since around 10,000 BC. A range of different Lactobacilli strains has been grown in laboratories allowing for many cultured milk products with different flavors and characteristics.

Streptococcus constellatus is a species of Streptococcus that is part of the normal flora in the oral cavity, urogenital region, and intestinal tract. However, it can frequently cause purulent infections in other parts of the body. DNA homology studies and 16S rRNA sequence analysis demonstrate S. constellatus belongs to the Streptococcus anginosus group along with Streptococcus intermedius and Streptococcus anginosus.

<i>Streptococcus anginosus</i> Species of bacterium

Streptococcus anginosus is a species of Streptococcus. This species, Streptococcus intermedius, and Streptococcus constellatus constitute the anginosus group, which is sometimes also referred to as the milleri group after the previously assumed but later refuted idea of a single species Streptococcus milleri. Phylogenetic relatedness of S. anginosus, S. constellatus, and S. intermedius has been confirmed by rRNA sequence analysis.

<i>Streptococcus anginosus</i> group Species of bacterium

The Streptococcus anginosus group (SAG), also known as the anginosus group streptococci (AGS) or the milleri group streptococci (MGS), are a group of several species of streptococci with clinical similarities. The group is named after a principal member species, Streptococcus anginosus. The older name Streptococcus milleri is now pseudotaxonomic, as the idea that these streptococci constituted a single species was incorrect. The anginosus group streptococci are members of the viridans streptococci group. They have been implicated as etiologic agents in a variety of serious purulent infections, but because of their heterogeneous characteristics, these organisms may be unrecognized or misidentified by clinical laboratorians. The unique characteristic of them from other pathogenic streptococci, such as S. pyogenes and S. agalactiae, is their ability to cause abscesses.

<i>Streptococcus dysgalactiae</i> Species of bacterium

Streptococcus dysgalactiae is a gram positive, beta-haemolytic, coccal bacterium belonging to the family Streptococcaceae. It is capable of infecting both humans and animals, but is most frequently encountered as a commensal of the alimentary tract, genital tract, or less commonly, as a part of the skin flora. The clinical manifestations in human disease range from superficial skin-infections and tonsillitis, to severe necrotising fasciitis and bacteraemia. The incidence of invasive disease has been reported to be rising. Several different animal species are susceptible to infection by S. dysgalactiae, but bovine mastitis and infectious arthritis in lambs have been most frequently reported.

Mycolicibacillus trivialis is a species of Mycolicibacillus. It is known to cause relapsing peritonitis.

Mycobacterium rhodesiae is a species of Mycobacterium.

<span class="mw-page-title-main">Lancefield grouping</span>

Lancefield grouping is a system of classification that classifies catalase-negative Gram-positive cocci based on the carbohydrate composition of bacterial antigens found on their cell walls. The system, created by Rebecca Lancefield, was historically used to organize the various members of the family Streptococcaceae, which includes the genera Lactococcus and Streptococcus, but now is largely superfluous due to explosive growth in the number of streptococcal species identified since the 1970s. However, it has retained some clinical usefulness even after the taxonomic changes, and as of 2018, Lancefield designations are still often used to communicate medical microbiological test results.

Bartonella bovis is a pathogenic bacteria first isolated from European ruminants. It is small, fastidious, aerobic, oxidase-negative, gram-negative and rod-shaped. Its type strain is 91-4T.

Streptococcus infantarius is a species of bacteria.

References

  1. ↑ POYART (C.), QUESNE (G.) and TRIEU-CUOT (P.): Taxonomic dissection of the Streptococcus bovis group by analysis of manganese-dependent superoxide dismutase gene (sodA) sequences: reclassification of 'Streptococcus infantarius subsp. coli' as Streptococcus lutetiensis sp. nov. and of Streptococcus bovis biotype II.2 as Streptococcus pasteurianus sp. nov. Int. J. Syst. Evol. Microbiol., 2002, 52, 1247-1255.
  2. ↑ FARROW (J.A.E.), KRUZE (J.), PHILLIPS (B.A.), BRAMLEY (A.J.) and COLLINS (M.D.): Taxonomic studies on Streptococcus bovis and Streptococcus equinus: description of Streptococcus alactolyticus sp. nov. and Streptococcus saccharolyticus sp. nov. Syst. Appl. Microbiol., 1984, 5, 467-482.
  3. ↑ WHILEY (R.A.) and KILIAN (M.): International Committee on Systematics of Prokaryotes Subcommittee on the taxonomy of staphylococci and streptococci. Minutes of the closed meeting, 31 July 2002, Paris, France. Int. J. Syst. Evol. Microbiol., 2003, 53, 915-917. Minutes of the closed meeting, 31 July 2002, Paris, France in IJSEM Online
  4. 1 2 3 4 Schlegel, L.; Grimont, F; Ageron, E; Grimont, PA; Bouvet, A (2003). "Reappraisal of the taxonomy of the Streptococcus bovis/Streptococcus equinus complex and related species: Description of Streptococcus gallolyticus subsp. Gallolyticus subsp. Nov., S. Gallolyticus subsp. Macedonicus subsp. Nov. And S. Gallolyticus subsp. Pasteurianus subsp. Nov". International Journal of Systematic and Evolutionary Microbiology. 53 (3): 631–45. doi: 10.1099/ijs.0.02361-0 . PMID   12807180.
  5. ↑ Wood JB, Holzapfel WHN (1995). The Genera of Lactic Acid Bacteria. pp. 431–4. ISBN   978-0-7514-0215-5.
  6. ↑ Fuller R, Newland LG (July 1963). "The serological grouping of three strains of Streptococcus equinus". J. Gen. Microbiol. 31 (3): 431–4. doi: 10.1099/00221287-31-3-431 . PMID   13960231.
  7. 1 2 Boone R, Garrity G, Castenholz R, Brenner D, Krieg N, Staley J (1991). Bergey's Manual of Systematic Bacteriology. Williams & Wilkins. p. 678. ISBN   978-0-387-68489-5.
  8. 1 2 3 4 Hagan WA (1988). Hagan and Bruner's Microbiology and Infectious Diseases of Domestic Animals. p. 195.
  9. 1 2 3 4 5 6 7 8 9 10 Hodge HM, Sherman JM (March 1937). "Streptococcus equinus". J Bacteriol. 33 (3): 283–289. doi:10.1128/JB.33.3.283-289.1937. PMC   545391 . PMID   16559995.
  10. ↑ Logan, N (July 2009). Bacterial Systematics. p. 194. ISBN   9781444313932.
  11. 1 2 Devriese L, Vandamme P, Pot B, Vanrobaeys M, Kersters K, Haesebrouck F (Dec 1998). "Differentiation between Streptococcus gallolyticus Strains of Human Clinical and Veterinary Origins and Streptococcus bovis Strains from the Intestinal Tracts of Ruminants". J. Clin. Microbiol. 36 (12): 3520–3. doi:10.1128/JCM.36.12.3520-3523.1998. PMC   105232 . PMID   9817865.
  12. ↑ Deibel RH (Sep 1964). "The Group D Streptococci". Bacteriol Rev. 28 (3): 330–366. doi:10.1128/MMBR.28.3.330-366.1964. PMC   441228 . PMID   14220658.
  13. ↑ Wallace S (September 2005). "Group D non-enteroccal streptococcus". Johns Hopkins.
  14. 1 2 3 Elliott PM, Williams H, Brooks IAB (1993). "A case of infective endocarditis in a farmer caused by Streptococcus equinus". European Heart Journal. 14 (9): 1292–1293. doi: 10.1093/eurheartj/14.9.1292 . PMID   8223744.
  15. 1 2 3 Tuncer, M; Ozcan, S; Vural, T; Sarikaya, M; Süleymanlar, G; Yakupoglu, G; Ersoy, FF (1998). "Streptococcus equinus peritonitis in a CAPD patient". Peritoneal Dialysis International. 18 (6): 654. doi: 10.1177/089686089801800617 . PMID   9932668.
  16. 1 2 3 4 Sechi LA, Ciani R (1999). "Streptococcus equinus endocarditis in a patient with pulmonary histiocytosis X". Scandinavian Journal of Infectious Diseases. 31 (6): 598–600. doi:10.1080/00365549950164526. PMID   10680994.
  17. ↑ Noble CJ. (1978). "Carriage of group D streptococci in the human bowel". J Clin Pathol. 31 (12): 1182–1186. doi:10.1136/jcp.31.12.1182. PMC   1145528 . PMID   107199.
  18. 1 2 Hinse T, Vollmer M, Erhard M, Welker ERB, Moore K, Kleesiek J (Jan 2011). "Differentiation of species of the Streptococcus bovis/equinus-complex by MALDI-TOF Mass Spectrometry in comparison to sodA sequence analyses". Dreier Syst Appl Microbiol. 34 (1): 52–57. doi:10.1016/j.syapm.2010.11.010. PMID   21247715.
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