Corynebacterium mastitidis

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1. Classification

a. Higher order taxa

Domain;Bacteria Phylum;Actinobacteria Order;Actinomycetales Family;Corynebacteriaceae Genus;Cornebacterium mastitidis

2. Description and significance

Describe the appearance, habitat, etc. of the organism, and why you think it is important.

• Include as many headings as are relevant to your microbe. Consider using the headings below, as they will allow readers to quickly locate specific information of major interest*

The Corynebacterium genus is comprised of multiple taxa of bacteria, and C. mastitidis differentiates itself due to its oxidative and lipophilic nature [1]. C. mastitidis is an irregular bacterium within the genus that works as an opportunistic pathogen in immunocompromised animals as well as an important microbe on the ocular surface of mice [2] and humans [3]. C. mastitidis was first discovered in 1997 after researchers isolated the strain from the milk of sheep infected with subclinical mastitis [4]. Significance

C. mastitidis is involved with mastitis, specifically subclinical mastitis, in cows [1] and sheep [4]. Mastitis results in the inflammation of the mammary glands, which leads to an increased number of somatic cells within the milk of animals affected by the disease. This creates a loss of milk production in as much as a 70% to 80% [5]. The bacterium is thought to play a role in pathogenesis for subclinical mastitis, however, this role is not well established. Additionally, related Corynebacterium species have been found in granulomatous lobular mastitis in humans [6].

C. mastitidis also has a role in the microbiome of the ocular surface in both mice [2] and humans [3]. In 2017, researchers determined that C. mastitidis stably colonized the ocular surface and enhanced the host’s ability to resist pathogenic fungal and bacterial infections [3]. Previously, very little was known about the microbiome of the human eye and the C. mastitidis discovery could potentially affect how the diagnostic and treatment of ocular disease in the human eye could change [3].

3. Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?

C. mastitidis was first proposed as a new species in 1997 when strains were isolated in pure culture from the milk of sheep with subclinical mastitis from different geographical regions of Spain [4]. Partial 16S rRNA sequences of each strain were examined and compared to other species of Corynebacteria with high GC contents. The 14 strains were found to be 100% similar, indicating genealogical homogeneity of the species [4]. Comparisons between species found high similarity between C. mastitidis and other species in the genus Corynebacterium, and lower levels of relatedness between C. mastitidis and other coryneform taxa [4]. C. mastitidis was determined to be its own distinct species with an approximate 5% divergence from the closest related species, Corynebacterium renale, and a 6-10% divergence from other Corynebacterium species [4].

There are two available genome sequences of C. mastitidis. The first genome was sequenced using C. mastitidis isolated from the milk of a sheep infected with subclinical mastitis [4]. The second, and most recent, genome sequence of C. mastitidis was isolated from the right eye of a 7-month old mouse [2]. The genome library of this isolate was created using the NEBNext Ultra DNA kit and the quality of the genome is 100% estimated completeness from 585 single-copy gene markers in the genus. The genome of the isolate consists of 2,264,319 base pairs. It has a 69.04% GC content along with 2,132 protein coding genes, 51 tRNA’s and 57 RNA’s [2]. The protein coding genes produce multiple enzymes that are used within C. mastitidis’ metabolic pathways such as esterase, esterase lipase, catalase, and urease [7]. In addition, the genome codes for the meso-diaminopimelic acid which is incorporated within the cell wall [4].

4. Cell structure

Interesting features of cell structure. Can be combined with “metabolic processes”

C. mastitidis displays typical coryneform morphology [4]. It is a short, Gram-positive, pleomorphic bacteria. Being pleomorphic means that the bacteria can alter its shape or size in response to a changing environment [2]. C. mastitidis is a small bacterium with irregular morphology [8]. C. mastitidis can appear in three different forms; coccoid, club, and rod [2]. Little is known about the arrangement of C. mastitidis cells, but similar species of Corynebacteria occur singly or in palisades (V-shapes) [4]. C. mastitidis colonies are whitish in appearance and less than 1mm in length [7]. C mastitidis cell wall contains meso-diaminopimelic acid and short-chain mycolic acids are present [4]. The dominant cellular fatty acids are hexadecanoic acid, and two forms of octadecanoic acid [4].

C. mastitidis is a Gram-positive bacteria, meaning the cell wall is made up of a thick peptidoglycan layer which retains the crystal violet stain during gram-staining [4]. C. mastitidis is also nonmotile and does not form spores [4].

5. Metabolic processes

Describe important sources of energy, electrons, and carbon (i.e. trophy) for the organism/organisms you are focusing on, as well as important molecules it/they synthesize(s).

C. mastitidis, like all other species of Corynebacteria, is aerobic, catalase positive, and oxidase negative [4]. Species of Corynebacteria do not reduce nitrate or hydrolyze esculin or gelatin. Some strains of Corynebacteria are able to hydrolyze urea, but this is a highly variable quality [4]. Several characteristics are present that distinguish C. mastitidis from other species in the genus Corynebacterium. C. mastitidis cells do not ferment glucose, maltose, sucrose, or ribose. C. mastitidis does not produce tuberculosteric acid, pyrrolidonylarylamidase, -Galactosidase, or -Glucoronidase. Its production of urea is variable and it is able to produce alkaline phosphatase and pyrazinamidase [4]. C. mastitidis is able to hyrdolyze 2-Naphthylmyristate, L-Leucyl-2-naphthylamide, L-Valyl-2-naphthylamide, L-Cystyl-2-naphthylamide, and 2-Naphthylphosphate (phosphatase acid). However, its hydrolysis of Naphthol-AS-BI- phosphate is variable [4]. In the lab, C. mastitidis formed small, rough, whitish colonies after three days of incubation at 37°C degrees on blood agar. The colonies formed were nonhemolytic [4]. C. mastitidis is susceptible to antibiotics including penicillin G and ampicillin [4].

6. Ecology

Habitat; symbiosis; contributions to the environment.

C. mastitidis is a member of the genus Corynebacterium. Members of the Corynebacterium obtain a commensal relationship with their host, meaning they derive food and resources from the host without hurting or benefitting the host [2]. They commonly colonize the skin and mucous membranes of different mammals [2]. Corynebacteria are a part of the normal flora on human skin [9].

7. Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

C. mastitidis are known to cause opportunistic infections in immunocompromised mammals [2]. C. mastitidis has been found in several mammals including sheep, humans and mice. C. mastitidis has been isolated from the milk of sheep with subclinical mastitis [4]. Corynebacteria have also been identified as the most common bacterial group associated with historical diagnosis of granulomatous lobular mastitis (GLM) in humans [6]. GLM is an inflammatory disease that affects the breast tissues of mature human females within a few years of their last childbirth [6]. Symptoms of GLM include breast mass, inflammation, abscess, and mammary duct fistula [9]. GLM can become chronic. It is of unknown etiology and there is no standard treatment [9]. Possible pathologies for GLM include microbial, autoimmune, and hormonal, however, none of these pathologies has been confirmed or denied [9].

C. mastitidis has also been identified as a part of the normal microbiota of the human ocular surface and also identified on the ocular surface of mice [2]. In mice, C. mastitidis initiates the release of antimicrobials into the tears of the mice to protect the eyes from different pathogens. C. mastitidis has also been discovered to play a role in the suppurative inflammation and preputial gland abscesses associated with fight wounds [2]. C. mastitidis has been identified in lesions formed on mice preputial glands, which suggests that C. mastitidis plays a role in the formation of the lesions [8]. The origin of C. mastitidis on the mice is unknown, but a theory is that C. mastitidis is also a natural commensal flora of the murine oral cavity and is transmitted to the preputial glands through biting where C. mastitidis causes the development of lesions [8]. This theory is supported through the presence of bacteria similar to C. mastitidis, like C. kutscheri, that have isolated from the oral cavity of healthy rodents and have been found to cause infections in bite wounds [8].

8. Current Research

Include information about how this microbe (or related microbes) are currently being studied and for what purpose

C. mastitidis was recently discovered as an important immunoresponse factor in ocular health of mice [3]. Using a mouse model of an ocular surface, C mastitidis was isolated and proved to play a role in the immunological response to several eye infections [2]. C. mastitidis was found to have a commensal relationship with the ocular microbiome by initiating the production of interleukin-17 by γδ T cells in the ocular mucosa [3]. The interleukin-17 response induces the recruitment of neutrophil into the conjunctiva, which then releases antimicrobial molecules into the tears. The antimicrobial molecules protect against invasive infections like Candida albicans and Pseudomonas aeruginosa [3]. This immune response initiated by C. mastitidis was found to be essential to the local ocular immunity in the mice that had been exposed to the bacterium. While a consistent ocular microbiome signature is lacking and controversial due to the constant tear washing and antimicrobial environment of the eye, C. mastitidis was found to have the ability to colonize the ocular surface of both humans and mice [3]. The role of C. mastitidis in the conjunctiva immune response sets a platform for future research in the ocular microbiome and the diseases that originate there [3].

9. 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.

[1] Hommez, J., Devriese, A., Vaneechoutte, M., Riegel, P., Butaye, P., Haesebrouck, F., 1999. Identification of nonlipophilic corynebacteria isolated from dairy cows with mastitis. Journal of Clinical Microbiology 37: 954-957.

[2] Cheleuitte-Nieves, C. et al. 2018. Draft Reference Genome Sequence of Corynebacterium mastitidis 16-1433, Isolated from a Mouse. Genome Announcements 6(7): e00050-18.

[3] St Leger, AJ. et al. 2017. An ocular commensal protects against corneal infection by driving an interleukin-17 response from mucosal γδ T cells. Immunity 47: 148-158.

[4] Fernandez-Garayzabal, J.F., Collins, M.D., Hutson, R.A., Fernandez, E., Monasterio, R., Marco, J., Dominguez, L. 1997. Corynebacterium mastitidis sp. nov., isolated from milk of sheep with subclinical mastitis. International Journal of Systematic and Evolutionary Biology 47: 1082-1085.

[5] Gianneechini, R., et al. 2002. Occurrence of Clinical and Sub-Clinical Mastitis in Dairy Herds in the West Littoral Region in Uruguay. Acta Veterinaria Scandinavica 43: 221–230.

[6] Paviour, S., Musaad, S., Roberts, S., Taylor, G., Taylor, S., Shore, K., Lang, S., Holland, D. 2002. Corynebacterium species isolated from patients with mastitis. Clinical Infectious Diseases 35: 1434-1440.

[7] Reimer, L. C., Sarda Carbasse, J., Soehngen, C., Podstawka, A., Gleim, D., & Overmann, J. 2018. Corynebacterium mastitidis Fernandez-Garayzabal et al. 1997 (Version 3.0) [Data set]. DSMZ. https://doi.org/10.13145/bacdive3178.20180622.3

[8] Radaelli, E., Manarolla, G., Pisoni, G., Balloi, A., Aresu, L., Sparaciari, P., Maggi, A., Caniatti, M., Scanziani, E. 2010. Suppurative adenitis of preputial glands associated with Corynebacterium mastitidis infection in mice. J Am Assoc Lab Anim Sci 49:69–74.

[9] Zhou, F., Yu, L., Ma, Z., Yu, Z. 2016. Granulomatous lobular mastitis. Chronic Diseases and Translational Medicine. 2: 17-21.