| Actinomyces massiliensis | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Phylum: | Actinomycetota |
| Class: | Actinomycetia |
| Order: | Actinomycetales |
| Family: | Actinomycetaceae |
| Genus: | Actinomyces |
| Species: | A. massiliensis |
| Binomial name | |
| Actinomyces massiliensis Renvoise et al. 2009 | |
| Type strain | |
| 4401292 [1] [2] | |
Actinomyces massiliensis is an anaerobic, mesophilic, Gram-positive bacterium originally isolated from a human blood sample and belonging to the genus Actinomyces . [1]
The genus name, Actinomyces , borrows from the Greek words "aktinos" and "mykēs" which refer to ray and fungus, respectively. [3] When combined, Actinomyces translates to "ray fungus", reflecting the radial arrangement of filaments in addition to the presence of asexual spores, both of which are characteristic of filamentous fungus. [3] This corresponds to the misconception that upon discovery they were fungi due to their long cells branching into structures resembling filaments and hyphae. [3] Marseille, the town in France where the original type strain was found, is inspiration for the species name, massiliensis, with old Greek and Roman language origins. [1]
In December 2003, a middle-aged man was hospitalized due to the coughing up of blood accompanied by flu-like symptoms and weight loss. [1] Upon examination, the patient was found to have lesions on his lungs, which were surgically removed. [1] Four months later, he was readmitted with malaise, dyspnea, and thoracic pain. [1] The attending physicians diagnosed him with pleuropneumonia and treated it with two types of antibiotics. [1] The patient responded well and was discharged, however, blood samples were continually taken to monitor the progress of his recovery. Using the patient blood sample, Renvoise et al. performed blood cultures and the bacterium strain 4401292T was isolated. [1] Subsequent 16S rRNA gene sequencing analysis demonstrated that a novel strain of the genus Actinomyces had been identified. [1]
The DNA of the bacterial specimen was extracted using an isolation kit, which separates total nucleic acid from plasma/blood, followed by amplification of the 16s rRNA gene through polymerase chain reaction (PCR) with universal primer pair fD1 and rp2. [1] After purification, a DNA sequencing kit was used to execute sequencing reactions and the subsequent sequencing products were then compared to existing sequences in GenBank using the Basic Local Alignment Search Tool (BLAST). [1] Utilizing the maximum-parsimony method, the novel strain exhibited clustering with A. gerencseriae, A. israelii, A. oricola, and two other Actinomyces species, supported by bootstrap analysis. [1] The accompanying similarities between 16s rRNA gene sequences of these species to that of strain 4401292T, as measured by NALIGN computational software, yielded 95.1%, 95.2%, and 95.2%, respectively. [1] All values were found to be below the accepted threshold of 97%, confirming that the strain isolated from the patient blood sample represented a novel species proposed as Actinomyces massiliensis sp. Nov.. [1]
This bacterium is a member of the genus Actinomyces and its taxonomic classification is as follows: Bacteria, Actinomycetota, Actinomycetes, Actinomycetales, Actinomycetaceae, Actinomyces , Actinomyces massiliensis. [4] To date, there are over 30 species of Actinomyces documented in the literature. [5]
The closest relative to A. massiliensis is still currently debated. Those who first isolated the strain found A. gerencseriae , A. israelii , A. oricola [6] to be most similar in terms of 16s rRNA gene sequence similarity, as mentioned above. [1] However, the results of Cimmino et al.'s molecular phylogenetic analysis reveal that A. oricola [6] and A. dentalis [7] are more closely related. [8] The differences in the phylogenetic construction of A. massiliensis and related species reflect the need for whole genome sequencing to better understand and delineate the evolutionary history of closely related species of A. massiliensis. Although further investigation is necessary, A. oricola, A. dentalis, A. israelii, and A. gerencseriae have all been isolated from human sources, including mucosal surfaces and the oral cavity. [9] Additionally, these species have several traits in common with A. massiliensis including their role as agents of actinomycosis and shared phenotypic characteristics described below. [9]
Actinomyces massiliensis is a non-spore forming, non-motile, Gram-positive, rod-shaped bacterium. [1] [2] Cells measure at 0.5-1.7 μm in length and 0.35-0.74 μm in width, and they appear as straight rods. [1] [2] When plated on sheep-blood agar, colonies of A. massiliensis are circular, white, and have a glossy sheen. [1]
To determine metabolic and physiological properties, A. massiliensis colonies were grown on 5% sheep-blood agar and incubated at 37 °C. [1] No hemolytic activity was found, but growth was further evaluated at various atmospheric conditions, including ambient air, 5% CO2, aerobic, and microaerophilic environments. [1] The strain proved to be anaerobic and possessed the ability to grow in 5% CO2 and microaerophilic conditions. [1] In addition to atmospheric conditions, the strain's ability to grow at various temperatures was evaluated, specifically at 25, 30, 37, 44, and 50 °C. [1] While optimum growth occurred at 37 °C, growth continued at temperatures between 30 °C and 37 °C. [1] The mesophilic nature of the organism implies that it is adapted to growing at the human body temperature, and microbes that grow optimally at 37 °C are often associated with environments similar to the human body, such as the skin, mucous membranes, respiratory tract, gastrointestinal tract, and genitourinary tract. [1] Additionally, cells were susceptible to an array of antibiotics including penicillin G, amoxicillin, cefotetan, doxycycline, and gentamicin, so although the organism can inhabit and thrive in human-like conditions, it remains treatable with commonly employed antibiotics. [1] The organism is capable of utilizing various amino acids and carbohydrates for carbon and energy sources demonstrated by activity from multiple arylamidases, which catalyze the hydrolysis of amide bonds in aromatic compounds. Additionally, activity by b-galactosidase, which catalyzes the hydrolysis of β-galactosides, such as lactose into monosaccharides, and a-glucosidase, which catalyzes the hydrolysis of α-glucosides, such as maltose into glucose, was observed while other enzymatic assays were negative. [1] Both catalase and oxidase activity were also negative using conventional tests, emphasizing the anaerobic nature of A. massiliensis. [1] Catalase is used to catalyze the decomposition of hydrogen peroxide into oxygen and water, and oxidase catalyzes the oxidation of certain substrates, such as cytochrome C, in the presence of oxygen. [1] Anaerobic organisms normally lack such enzymes as both incorporate oxygen, which could be detrimental to their survival. Subsequently, fermentation capabilities are suggested through acid production observed from D-galactose, D-glucose, D-fructose, maltose, lactose, and sucrose. [1] The ability to ferment a wide range of sugars reflects adaptation of the microorganism to diverse environmental niches with fluctuating nutrient availability. Tests that used an analytical profile index for measurement of bacterial metabolism were positive for b-galactosidase, a-glucosidase, reduction of nitrates, proline arylamidase, phenylalanine arylamidase, and leucine arylamidase, but mannose fermentation and tyrosine arylamidase activity produced only minimally positive results. [1]
Using shotgun sequencing and 3-kb paired-end [10] (PE) sequencing, the draft genome for A. massiliensis, which is about 3.4 Mb, was found to contain 5 scaffolds and 27 contigs greater than 1500 base pairs. [11] G+C nucleotide content comprises 67% of the genome which also contains 54 tRNA genes, 1 tmRNA gene, and genes that encode for about 2,894 putative proteins. [11] Additionally, CRISPR loci were located and assumed to aid in resistance to plasmids and phages. [11] After sequencing and comparative measures were finalized, a reciprocal BLAST analysis of A. massiliensis showed over 1000+ orthologs with A. urogenitalis [12] and A. viscosus . [11] However, despite advances in the whole genome sequencing of A. massiliensis, there has not been greater success in phylogenetic placement of the species in relation to other similar species. Because bacteria have mechanisms like horizontal gene transfer, it is possible for two strains that are not each other's closest relative to have a high degree of genetic similarity. This underscores the complexity of microbial evolution and provides an explanation for why the exact relatives of A. massiliensis remains elusive.
Species belonging to Actinomyces are abundant in diverse environments, ranging from soil and aquatic habitats to the human microbiome. [9] [13] In soil environments, Actinomycetes act as decomposers breaking down organic compounds. This ability contributes to soil fertility, plant health, and nutrient cycling. [13] Additionally, Actinomyces have been identified as important members of the human microbiome, residing in various sites such as the oral cavity (mouth, pharynx, esophagus) and gastrointestinal tract. [9] While some Actinomyces species are commensal, others can cause opportunistic infections in humans, commonly Actinomycosis. [9] Unfortunately, the ecological significance of A. massiliensis specifically is not yet known.
Due to its relatively recent discovery, there is limited research on the specific impacts of A. massiliensis. Nonetheless, studies on Actinomyces in general, which may encompass A. massiliensis, offer valuable insights into potential areas of impact, particularly in clinical settings. Actinomyces and its associated species have, for a long time, been implicated in human infections, particularly those of the mouth, pharynx, distal esophagus, and genitourinary tract. [9] Within the last 10 years, A.massiliensis has been detected in blood, and most Actinomyces bacteremias stem from oral sources. [9] Moreover, bacteremia has been repeatedly observed in the aftermath of invasive dental procedures and in individuals experiencing gingivitis and periodontitis. [9] When gums are inflamed and/or bleeding after surgery or in the cases of gingivitis and periodontitis, they provide an easy entry point for actinobacteria into the bloodstream. Evidence of this phenomenon is presented in blood samples of patients who have undergone tooth extractions without antibiotic prophylaxis. [9] The increasing prevalence of Actinomyces species in infectious pathologies solidifies their clinical relevance and the need for further study on specific species' involvement.
In 2024, the characterization of the oral-brain axis hypothesis has garnered attention, with one study suggesting that oral-specific bacteria, including associated metabolites, may contribute to the development of Alzheimer's Disease (AD). [14] Focus was primarily isolated to periodontitis and subsequent "chronic subgingival microbial dysbiosis" as a potential contributor to AD development. [14] That is, microbiota associated with periodontal disease may affect cognitive abilities by activating microglia and/or releasing metabolites. [14] Additionally, being close to the cerebrum could encourage easier access by the oral microbiota in influencing brain diseases. [14] Analysis of gingival crevicular fluid revealed 19 different metabolites that were significantly correlated with 5 abundant species present in subgingival plaque samples, one of them being A. massiliensis. [14] These metabolite and species associations were further correlated with neurological/periodontal indices that served as a possible separator between AD patients and cognitively normal patients. [14] Thus, recent evidence supporting the oral-brain axis indicates potential consequences regarding the subgingival microbial community in which A. massiliensis is an inhabitant. However, it is important to note that a lot is still unknown, and what is known is largely about correlation, not causation.
Actinomyces naeslundii is a Gram-positive, rod-shaped bacterium found in the mouth of humans. The species has been implicated in periodontal disease, as well as various tooth cavities. In other cases, A. naeslundii is associated with good oral health. It is one of the first bacteria to occupy the oral cavity and colonize the tooth's surface. It has also been isolated from women with bacterial vaginosis.
Actinomyces is a genus of the Actinomycetia class of bacteria. They all are gram-positive and facultatively anaerobic, growing best under anaerobic conditions. Actinomyces species may form endospores, and while individual bacteria are rod-shaped, Actinomyces colonies form fungus-like branched networks of hyphae. The aspect of these colonies initially led to the incorrect assumption that the organism was a fungus and to the name Actinomyces, "ray fungus".
Actinomycosis is a rare infectious bacterial disease caused by the gram-positive Actinomyces species. The name refers to ray-like appearance of the organisms in the granules. About 70% of infections are due to either Actinomyces israelii or A. gerencseriae. Infection can also be caused by Streptomyces somaliensis and Propionibacterium propionicus. The condition is likely to be a polymicrobial anaerobic infection.
Mycobacterium mucogenicum
Etymology: mucogenicum, from the organism's highly mucoid appearance.
Pseudomonas stutzeri is a Gram-negative soil bacterium that is motile, has a single polar flagellum, and is classified as bacillus, or rod-shaped. While this bacterium was first isolated from human spinal fluid, it has since been found in many different environments due to its various characteristics and metabolic capabilities. P. stutzeri is an opportunistic pathogen in clinical settings, although infections are rare. Based on 16S rRNA analysis, this bacterium has been placed in the P. stutzeri group, to which it lends its name.
Capnocytophaga is a genus of Gram-negative bacteria. Normally found in the oropharyngeal tract of mammals, they are involved in the pathogenesis of some animal bite wounds and periodontal diseases.
Aggregatibacter actinomycetemcomitans is a Gram-negative, facultative anaerobe, nonmotile bacterium that is often found in association with localized aggressive periodontitis, a severe infection of the periodontium. It is also suspected to be involved in chronic periodontitis. Less frequently, A. actinomycetemcomitans is associated with nonoral infections such as endocarditis. Its role in aggressive periodontitis was first discovered by Danish-born periodontist Jørgen Slots, a professor of dentistry and microbiology at the University of Southern California School of Dentistry.
Actinomycosis is an infection caused by a bacterium of the genus Actinomyces, usually Actinomyces bovis; the disease it causes has several common names. When it is a moveable tumour or lump on the jaw area, it is referred to as lump jaw; when it spreads into the hard bone of the jaw, it is referred to as big jaw; and when it affects the tongue, it is referred to as wooden tongue.
Staphylococcus is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. Staphylococcus species are facultative anaerobic organisms.
Lautropia mirabilis is a Gram-negative, facultatively anaerobic, oxidase- and catalase-positive, motile bacterium of the genus Lautropia and family Burkholderiaceae, isolated from the mouth of children who were infected with human immunodeficiency virus.
Diplorickettsia massiliensis species is an obligate intracellular, gram negative bacterium isolated from Ixodes ricinus ticks collected in Slovak republic forest geographically from southeastern part of Rovinka in 2006. They belong to the gammaproteobacteria class and are non endospore forming, small rods usually grouped in pairs. The bacteria are non-motile, and 16S rRNA, rpoB, parC and ftsY gene sequencing indicate that this bacterium is clearly different from all other recognized species. An initial phylogenetic analysis based on 16S rRNA, clustered D. massiliensis with Rickettsiella grylli. Because of its low 16S rDNA similarity (94%) with R. grylli, it was classified as a new genus Diplorickettsia into the family Coxiellaceae and the order Legionellales. D. massiliensis strain 20B was identified in three patients with suspected tick-borne infections that exhibited a specific seroconversion. The evidence of infection was further reconfirmed by using PCR-assay, thus established its role as a human pathogen and later whole genome sequencing was performed.
Campylobacter showae is a Gram-negative, chemoheterotrophic, microaerophilic, motile bacteria belonging to the Campylobacter Genus. The type strain of this species, SU A4, was first isolated from plaque samples taken from the gingival crevices of the human oral cavity but has since also been found in colonic tissues and stool. Since its discovery, C. showae has been implicated in various medical conditions including Crohn's disease, periodontitis, inflammatory bowel disease, and ulcerative colitis due to its pathogenic nature.
Treponema socranskii was isolated from gum swabs of people with periodontitis and clinically-induced periodontitis. It is a motile, helically coiled, obligate anaerobe that grows best at 37 °C, and is a novel member of its genus because of its ability to ferment molecules that other Treponema species cannot. T. socranskii’s growth is positively correlated with gingival inflammation, which indicates that it is a leading cause of gingivitis and periodontitis.
Actinomyces bovis is a branching, Gram-positive, rod-shaped bacterium of the genus Actinomyces. It is the causative agent of lumpy jaw in cattle, and occasionally causes actinomycosis infections in humans. A. bovis normally populates the gastrointestinal tract of healthy ruminants, but is opportunistic in nature and will move into tissues through ulcerations or abrasions of the mucosa to cause infection. The disease occurs when there is physical damage to the tissue of the mouth, allowing the bacteria to colonize the deep tissue and bone, typically affecting the mandible and maxilla. Actinomycosis is pathognomonic for abscesses containing "sulfur" granules, and its colonies appear basophilic with club-shaped reaction products on a histological preparation. Lumpy jaw is commonly treated with broad-spectrum antibiotics with varying success, and can be a major economic loss for producers in countries where it is endemic. Because this organism is zoonotic, it is a human health concern and can cause granulomas, abscesses, skin lesions, and bronchopneumonia.
Actinomyces viscosus is a human and animal pathogen/pathobiont which colonises the mouths of 70% of adult humans. A. viscosus has a low level of virulence and is often mistaken with other actinomycetes.
Cetobacterium somerae is a microaerotolerant, Gram-negative, and rod-shaped anaerobic bacteria found in the gastrointestinal tract of fish living in freshwater ecosystems. The bacteria is also immobile and non-spore forming. C. somerae was first isolated from the feces of children with Autism spectrum disorder. Members of bacteria within the Cetobacterium genus tend to dominate the microbiota of fish in freshwater ecosystems. Cetobacterium somerae also produces vitamin B-12 within the gastrointestinal tract of fish in order to provide nutritional support for growth.
Leptotrichia goodfellowii is a Gram-negative, non-spore-forming and non-motile anaerobic bacterium from the genus of Leptotrichia which has been isolated from human blood of an endocarditis patient. It is associated with infections in the oral cavity and respiratory tract. While primarily associated with opportunistic infections in immunocompromised individuals, its exact pathogenic mechanisms and clinical significance warrant further investigation.
TM7x, also known as Nanosynbacter lyticus type strain TM7x HMT 952. is a phylotype of one of the most enigmatic phyla, Candidatus Saccharibacteria, formerly candidate phylum TM7. It is the only member of the candidate phylum that has been cultivated successfully from the human oral cavity, and stably maintained in vitro. and serves as a crucial paradigm. of the newly described Candidate Phyla Radiation (CPR). The cultivated oral taxon is designated as Saccharibacteria oral taxon TM7x. TM7x has a unique lifestyle in comparison to other bacteria that are associated with humans. It is an obligate epibiont parasite, or an "epiparasite", growing on the surface of its host bacterial species Actinomyces odontolyticus subspecies actinosynbacter strain XH001, which is referred to as the "basibiont". Actinomyces species are one of the early microbial colonizers in the oral cavity. Together, they exhibit parasitic epibiont symbiosis.
Christensenella hongkongensis is a species of clinically relevant gram-positive coccobacilli, first isolated from patients in Hong Kong and Canada in 2006. Although the species remains relatively rare, it has a high mortality rate of up to 50%. Christensenella is thought to be broadly distributed globally, as it has been isolated from patient blood cultures around the world including Hong Kong, South Korea, New Zealand, Canada, Sweden, France and Italy. Fewer than 15 cases of C. hongkongensis have been observed worldwide.
Peptidiphaga gingivicola is a Gram-positive, non-spore forming, coccus shaped bacterium. Coccus are spherical and generally round in shape. Coccus are differentiated by their groupings that can range from chains, groups, or grape-like clusters. Peptidiphaga gingivicola was observed to grow in groups of 2-5 cocci between 0.2-0.9 mm in diameter. Growth was observed when cultured under anaerobic conditions between 33 and 40 degrees celsius on Blood Brucella agar for 4 days. Peptidiphaga gingivicola has been cultured from patients with periodontal disease, primarily caused by bacterial plaque formation on the gum and teeth of the oral cavity. The microbe is known to break down peptides of the gum causing tissue damage and tooth decay, leading to serious implications for oral health.