Anaerococcus is a genus of bacteria. Its type species is Anaerococcus prevotii.[1] These bacteria are Gram-positive and strictly anaerobic.[2][3][4] The genus Anaerococcus was proposed in 2001.[2][4] Its genome was sequenced in August 2009. The genus Anaerococcus is one of six genera classified within the group GPAC (Gram-Positive Anaerobic Cocci).[5] These six genera (Peptostreptococcus, Peptoniphilus, Parvimonas, Finegoldia, Murdochiella, and Anaerococcus) are found in the human body as part of the commensal human microbiota.[6][7][5]
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| Genus: | Anaerococcus Ezaki et al. 2001 |
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It is commonly found in the human microbiome and is associated with various infections.[8] Most of the species in this genus can be found among microbes of the skin, human vagina, nasal cavity, oral cavity and feces, often as a pathogen found in ovarian abscesses, chronic wounds and vaginal discharge.[9] Moreover, some of the species can be isolated from foot ulcers and knee arthritis.[2] It can be present in urinary tract infections, chronic ulcers, pleural empyema, blood infections, and soft tissue infections. It is involved in polymicrobial infections.[10] Strains of Anaerococcus were found in the armpit microbiota suggesting some species in this genus could play a role in axillary odor.[10][11]
Physiology
The genus Anaerococcus are non motile bacteria who can not form spores.[4][12][2] Depending on the species the arrangement can be different. The most common arrangements within this genus are pairs, tetrads, short chains and irregular formations.[10][4] Their cells size can differ from 0.6μm to 0.9μm.[10] However, when they are grown using enrinched blood agar their size can go from 0.5μm to 2μm.[10] In this genus, there are more than one major cellular fatty acids: C18:1, C16:1, C18 and C16.[12] Most species in this genus are indole-negative and coaguase-negative.[10] In general, the species of Anaerococcus presents susceptibility to penicillins but are resistant to tetracycline, erythromycin and clindamycin.[9]
Metabolism
The genus Anaerococcus are classified as saccharolytic bacteria.[2][13] Its species can be arranged from weakly saccharolytic (ex. A. prevotii, A. lactolyticus) to strongly saccharolytic (ex. A. hydrogenalis).[13] This genus can ferment carbohydrates weakly.[6] The major sources of energy use in the metabolism of Anaerococcus are peptones and aminoacids.[4][10] The three major sugars fermented within this genus are glucose, mannose, fructose and sucrose.[12][4] After fermenting the sugars, Anaerococcus produce weak acids as their metabolic end product.[13] Within these metabolic end products, this genus ca produce butyric acid, lactic acid, and some propionic and succinic acid.[12] Nonetheless, the major metabolite produced by Anaerococcus is butyrate.[13][10][2]
Species
Until recently, the genus Anaerococcus have 14 known species.[14][9] Six of the species were initially classified in the genus Peptostreptococcus but then based on their characteristics were re-classified in the new genus Anaerococcus: A. hydrogenalis, A. lactolyticus, A. octavius, A. prevotii, A. tetradius, and A. vaginalis.[5][2] Throughout the years, the specie who has been more commonly found on the body within this genus is A. prevotii.[9]
Anaerococcus octavius
Contrary to most of the species in the genus, Anaerococcus octavius was not related to human infections.[9] Nevertheless, recently a new case revealed A. octavius can cause bacteremia.[9] Even though it is uncommon, Anaerococcus octavius can be the cause for human infections.[9] Other studies have found A. octavius as part of the nasal, skin and vaginal normal flora.[9][4] This bacteria can ferment ribose, glucose, and mannose.[4]
Anaerococcus prevotii
A. prevotii is normally found in vaginal discharge, human plasma and some types of abscesses - such as ovarian, peritoneal sacral and/or lung abscesses.[9][6] Anaerococcus prevotii is part of the normal flora in the skin, oral cavity and the gut.[6] Studies has shown Anaerococcus prevotii presents resistance to Ceftazidime, Clindamycin, Levofloxacin.[9] Unlike the other species, A. prevotii can not ferment glucose.[15]
Anaerococcus vaginalis
A. vaginalis was first recovered from vaginal discharges and ovarian abscesses although this bacteria can also be found in pressure ulcers and diabetic foot.[4][9] Some strains from this species can be indole-positive.[4]
Anaerococcus provencensis
A. provencensis was isolated from a cervical abscess.[16] This species can ferment lactose, unlike A. tetradius, A. prevotii, and A. octavius.[16] The first analysis made on Anaerococcus provencensis showed it is susceptible to penicillin G, imipenem, amoxillin, metronidazole, cefotetan and vancomycin.[16]
Anaerococcus senegalensis
A. senegalensis is one of the few species in the genus whose genome has been sequenced.[2] The genome has a size of 1,790,835 bp.[2] Analysis did not show presence of a plasmid.[2] Initially, Anaerococcus senegalensis was found in the fecal flora of a healthy person.[2]
Anaerococcus rubiinfantis
A. rubiinfantis was discovered from a stool sample taken from an infant with severe acute malnutrition in Senegal.[17] Based on a genomic analysis, Anaerococcus rubiinfantis has high antibiotic susceptibility.[17] For that reason this bacteria can be treated with common oral antibiotics.[17] A. rubiinfantis have catalase activity, which is not common from an anaerobic bacteria.[17]
Anaerococcus marasmi
A. marasmi was first found in 2016 from a stool sample on a child with marasmus.[14] Just like A. rubiinfantis, Anaerococcus marasmi is catalase positive.[14] A. marasmi can grow in a range of pH between 6.5 and 8.[14] Moreover, A. marasmi has a high 16S rRNA sequence similarity (97.6%) with A. prevotii [14]
Anaerococcus urinomassiliensis
A. urinomassiliensis was isolated from a urine sample of a male adolescent with membranoproliferative glomerulonephritis and autoimmune hepatitis.[18] It took 10 days of anaerobic incubation to observe growth from this bacteria.[18] Anaerococcus urinomassiliensis does not have either oxidase or catalase activity.[18]