Staphylococcus intermedius
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1. Classification
a. Higher order taxa
Cellular organisms; Bacteria; Terrabacteria group; Bacillota; Bacilli; Bacillales; Staphylococcaceae; Staphylococcus; Staphylococcus intermedius group[1].
2. Description and significance
Staphylococcus intermedius (S. intermedius) is a Gram-positive, coagulase-positive cocci,2,3 that is found over the skin and mucus of animals like dogs, pigeons, minks, cats, horses, foxes, raccoons, goats, and gray squirrels.4,5 S. intermedius has veterinary importance, as it’s the predominant cause of skin and soft tissue infections in dogs.6-10 Although S. intermedius is pathogenic to animals and rare in humans, it can transfer from animal to human and cause infections.3,5 The number of case reports of serious invasive infections of S. intermedius in humans is rising.11 Additionally, in 1991, there was an outbreak of S. intermedius-related food intoxication of over 265 in western United States.12 However, even with the rise of infections, there is still a lack of useful tools to accurately clinically diagnose S. intermedius.3 Before its description, S. intermedius had been grouped together with Staphylococcus aureus.13 It wasn’t until 1976 when S. intermedius could be separated from S. aureus using its cell wall structure and guanine-cytosine content.3 It also wasn’t until 2005 when researchers, using more advanced molecular technologies, were able to reclassify S. intermedius into the Staphylococcus Intermedius Group (SIG), which include the three bacterial species S. intermedius, Staphylococcus pseudintermedius, and Staphylococcus delphini.3,4,14 There is no distinction between the SIG cell morphology or phenotypes.3,4 Recently, modern molecular sequencing approaches have been developed to differentiate between the SIG species.3,15,16
3. Genome structure
Whole genome sequencing of S. intermedius NCTC11048, isolated from the nares of a Pigeon,2 was carried out and compared with the genomes of S. pseudintermedius ED99 and S. delphini 8086, as well as other Staphylococcal species.17 The draft genome of S. intermedius was ~2,780,000 base pairs, significantly larger than S. pseudintermedius and S. delphini. Average G+C content of the three Staphylococcus Intermedius Group species (37.4% to 38.3%) is higher than other Staphylococcal species.17 Analysis revealed a high level of conservation and synteny between the Staphylococcus Intermedius Group and S. aureus Mu50, S. epidermidis RP62A, S. haemolyticus JCSC1435, S. saprophyticus ATCC15305, and S. carnosus TM300, sharing a core genome of 1214 genes. However, they differ in the oriC environ,17 a chromosomal region among Staphylococci that has many species-specific coding sequences (CDS).18 Occurrences of CRISPR are rare among Staphylococci, but S. intermedius contain a CRISPR locus of the Nmeni and Mtube subtype,17 which is associated exclusively with vertebrate pathogens and commensals.19 The presence of CRISPR in S. intermedius correlates with an absence of plasmids and prophages.20,21
4. Phylogenetics
The nomenclature and the phylogenetic relationships among staphylococci species are categorized by their metabolism mechanisms, pathogenicity, and clinical significance.24 Based on Bayesian Estimation of Species Trees (BEST) analysis and Individual Gene Trees analysis, the Staphylococcus genus into 15 cluster groups and 6 species groups. It identified two major clades within Staphylococci: oxidase-positive and oxidase-negative species.24 S. intermedius, S. delphini, and S. pseudintermedius belong to the same clade, forming the Staphylococcus Intermedius Group. As part of the same clade, members of the SIG share a common trait as pathogens in animal mucus, but rarely cause infection in healthy individuals.24 Additionally, average nucleotide identity value (ANIs) of 93.61% confirmed the genetic similarity among SIG, compared to other Staphylococci.17
5. Cell structure
S. intermedius appear as Gram-positive, irregular clumps of pairs or individual cocci ranging from 0.8 to 1.50 μm. Cells are non-motile, non-spore forming, and grow well at 45°C.2 Colonies appear as white, circular, glistening colonies.2 Cell walls do not contain protein A or polysaccharide Aβ (β-N-acetylglucosaminyl ribitol teichoic acid). The peptidoglycan of the cell wall is of the L-LysGly4_5,L-Ser0,.2-10 type.2 A high content of serine in the peptidoglycan causes resistance to the bacteriocin lysostaphin.2 S. intermedius contains genes coding for adhesins that help mediate binding to extracellular matrix proteins. Adhesins include elastin-binding protein, intercellular adhesion proteins, and several putative cell surface proteins identified in S. pseudintermedius (SpsA, B, C, E, H, N, and R).17
6. Metabolic processes
S. intermedius is a chemoorganotrophic, facultatively anaerobic bacteria that is catalase and coagulase positive.2 It does not produce acid from maltose, arabinose, and xylose, nor use anaerobic respiration with mannitol. However, it produces acid from glucose, galactose, fructose, mannose, sucrose, trehalose, glycerol, mannitol, and lactose.2 S. Intermedius does not utilize a metabolic pathway to produce acetylmethylcarbinol during the fermentation of sugar.25 S. intermedius does not produce arginine dihydrolase and caseinase.2 In contrast to S. aureus, S intermedius is positive for pyrrolidonyl arylamidase and β-galactosidase positive.26 Positive results in the urease test showed that S. intermedius has urease to produce ammonia and carbon dioxide to raise the pH in the environment.15
S. intermedius has several mechanisms for iron acquisition, including the use of siderophores to transport staphyloferrin A and heme,27 as well as the production of staphylobactin A and ABC transporters for ferrichrome, iron-manganese, and ferrous iron.17
7. Ecology
S. intermedius had been historically identified to be predominantly found in animals, particularly in dogs and other domesticated species, but they can also be found in cow’s milk.28 S. intermedius’ prevalence in dogs is 39%.6 However, more recent research identified its dominant presence in pigeons, rather than domesticated animals.4 S. intermedius typically resides in the skin and mucous membranes of individuals, which can cause infection. However, this mainly occurs in non-human mammals,29 as S. intermedius’ prevalence–based on saliva cultures and anti-DNase antibodies–in humans is less than 20%.30-34 There is the potential for bacteria to be transferred indirectly from household items, for recolonization purpose and as a source for recurring infections within the community.29
S. intermedius contains a diverse set of genes coding for proteins that may be involved in osmo-protection and resistance to oxidative stress that allow it to survive in distinct host-dependent environments, such as putative nitroreductase and several sodium/salt transporters.17 S. Intermedius also produces a heat-stable nuclease capable of cleaving nucleic acids under high-temperatures.35
8. Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
9. Current Research
Include information about how this microbe (or related microbes) are currently being studied and for what purpose
10. References
It is required that you add at least five primary research articles (in same format as the sample reference below) that corresponds to the info that you added to this page. [Sample reference] Faller, A., and Schleifer, K. "Modified Oxidase and Benzidine Tests for Separation of Staphylococci from Micrococci". Journal of Clinical Microbiology. 1981. Volume 13. p. 1031-1035.
