放线菌属的分类及描述

放线菌手册汇编放线菌科概述Actinomycetaceae描述：放线菌科是由Buchanan 在1918年创立的该科的一般特征是：革兰氏染色阳性，分支，偏直条状，大多数成员是属于球杆状或者类球形。

细胞长度一般小于0.5μm,平均长度在1.7μm 到2,9μm 之间。

群落可能形成丝状体形成类似菌丝体的外形，但是大多数菌落不分枝，而且主要是白色或者灰色，有一些特殊的菌落会形成深红色、淡红色、棕色、粉色、淡粉或淡黄色。

现在该科根据16s RNA 的核酸序列划分出包括五个不同的属：Actinomyces,Actionobaculum,Arcanobacterium,Aobiluncus,Aaribaculum.放线霉菌属Actinomyces该属包括的种有A. bovisA. bowdeniiA. canisA. cardiffensisA. catuliA. coleocanisA. dentalisA. denticolensA. europaeusFigure 1Scanning electron micrograph ofActinomyces israeliiA. funkeiA. georgiaeA. gerencseriaeA. graevenitziiA. hongkongensisA. hordeovulnerisA. howelliiA. humiferusA. hyovaginalisA. israeliiA. marimammaliumA. meyeriA. naeslundiiA. nasicolaA. neuiiA. odontolyticusA. oricolaA. radicidentisA. radingaeA. slackiiA. streptomyciniA. suimastitidisA. suisA. turicensisA. urogenitalisA. vaccimaxillaeA. viscosus一、Actinomyces bovisActinomyces bovis is a gram-positive, rod-shaped bacterium of the genus Actinomyces. It is the causative agent of Lumpy jaw in cattle, and occasionally causes infections in humansHistoryActinomyces bovis was first described in 1877 by C. O. Harz, as a microbe within the jaw tissue of cows with lumpy jaw. It was thought to be identical to Actinomyces israelii until 1940, when D. Erikson showed these to be two separate organisms.Figure 2Bovine actinomycosis. Granules (sulfa granules), consisting of colonies of bacteria (Actinomyces bovis) and club-shaped（球棒状的）reaction product, are within a purulent exudate.（脓性渗出物）二、Actinomyces georgiaeActinomyces georgiae is a species in the genus of Actinomyces. It isa part of the human periodontal flora（牙周菌群）.三、Actinomyces gerencseriaeActinomyces gerencseriae (Johnson et al. 1990) used to be known asActinomyces israelii serovar II.Actinomyces gerencseriae was named for the bacteriologist, Mary Ann Gerencser.Figure 3蜘蛛状高度分支的微菌落，26h在36°下培养（1500倍放大）Figure 4培养于BHIA上的微菌落，显示了一条带有分支的长丝（24h在36°条件下）四、Actinomyces israeliiActinomyces israelii is a species of Gram-positive, rod-shaped bacteria within the Actinomyces. Known to live commensally on and within humans, A. israelii is an opportunistic pathogen and a cause of actinomycosis. Many physiologically diverse strains of the species are known to exist, though all are strict anaerobes.Actinomycosis is most frequently caused by A. israelii. It is a normal colonizer of the vagina, colon, and mouth. Infection isestablished first by a breach of the mucosal barrier during various procedures (dental, gastrointestinal), aspiration, or pathologies such as diverticulitis. The chronic phase of this disease is also known the "classic phase" because the acute, early phase is often missed by health care providers. This is characterized by slow, contiguous growth that ignores tissue planes and forms a sinus(窦) tract that can spontaneously heal and recur, leading to a densely fibrotic lesion(纤维性病变). This lesion is often characterized as "wooden". Sulfur granules(瘤状颗粒) form in a central purulence（脓）surrounded by neutrophils（嗜中性粒细胞）. This conglomeration of organisms is virtually diagnostic of A. israelii.来源：Historically speaking the first written appearance of Actinomyces was made in 1877 when pathologist Otto Bollinger described their presence in cattle. Shortly after that James Israel discovered another specie of actinomyces or actinomycetes that are living in humans and in his honour these actinomyces have name actinomyces israelii. 概念性解释：Anaerobic organism represents any organism that doesn't require oxygen for its growth and in the presence of oxygen it may even die, while facultative anaerobic organism is usually a bacteria that creates adenosine triphosphate (ATP) that is one of the most used enzymes or cabalists or it can turn to the process of fermentation if it is exposed to the oxygen. Gram positive bacteria are those that according to Gram staining are dark blue or violet in colour. If a bacterium is Gram negative it will not be able to retain the violet strain of crystal.There is one difference between Actinomyces and other bacteria and that is that Actinomyces don't form endospores and they form branched networks of hyphae that looks like fungus while otherbacteria are in a shape of rod and they don't make branched networks. In fungi hyphae are the main mode of vegetative growth and their collective name is mycelium.五、Actinomyces naeslundiiActinomyces naeslundii is a Gram-positive, rod-shapedbacterium found in the mouth of humans. The species has beenimplicated in periodontal disease, as well as various tooth cavities.In other cases, A. naeslundii is associated with good oral health. It isone of the first bacteria to occupy the oral cavity and colonize thetooth's surface. It has also been isolated from women with bacterialvaginosis.Any species of the genus Actinomyces, including A. naeslundii, cause a chronic disease called actinomycosis, which is characterized by swelling and formation of an abscess （脓肿） which may exude pus.This can beaccompaniedby tissue fibrosis.六、Actinomyces radicidentisActinomyces radicidentis is a species in the genus of Actinomyces, first isolated from infected root canals of teeth. ITs type strain is CCUG 36733. Once characterized, it has since been found to be present in failed root canal treatments. Its pathogenicity has been suggested to be due to an ability to form cell aggregates, held together by embedding in an extracellular matrix in host tissues. Like other pathogenic Actinomyces, by collectively finding itself in Figure 5Histopathological changes due to en:Actinomycesnaeslundii bacteria. en:Silver stain, brain abscess. Obtained fromthe CDC Public Health Image Library.a protected biofilm（生物膜）environment can evade elimination by host defenses, including phagocytosis.Figure 6 Scanning (a-d) and transmission electron micrographs (e-g) of A radicidentis, strain CCUG 36733. Cells grown on Brucella blood agar exhibit coccoid shape (a), similar to cells grown in serum-supplemented Tryptic soy broth, where fimbriae-like bundles can be seen (b). When cells were grown in RPMI-1640 broth with serum (c, d), they were rod-shaped with intertwining bundles of fimbriae-like cell appendices in a netlike arrangement. In thin section (e), bundle of fimbriae can be observed emerging from cell surface; demarcated area in (e) is magnified in (f). Further thin section (g) shows radially placed fimbriae emerging from fuzzy-coated cell surface. Bars = 1 µm.七、Actinomyces viscosusActinomyces viscosus is a human and animalpathogen/pathobiont which colonizes the mouths of most adult humans.It is Gram-negative, anaerobic, rod-shaped, and filamentous.It causes periodontal disease（牙周病）in animals, and has been isolated from human dental calculus（牙结石）and root surface caries, as well as the oral cavity hamsters and actinomycotic lesions in swine, cats, and dogs. Furthermore, it has been shown to cause endocarditis（心内膜炎）.Actinomyces viscosus is aGram-positive, anaerobic,filamentous bacterium that ispart of the human oral flora.This rod shaped filamentousbacteria occur around the teeth,gums（牙龈）and throat inhealthy humans. Species of this bacterium can cause actinomycosis - a granulomatous infection with the formation of abscesses in the mouth, lungs, or the gastrointestinal tract. Oral actinomycosis may occur due to trauma such as a tooth extraction or bleeding gums. Abdominal actinomycosis may follow appendicitis. Treatment is with antibiotics. Actinomyces spp.normally are soil or aquatic fungi feeding off decaying matter (saprophytes，sapro,spoiled). They resemble fungi and form fungi-like mats (mycelia)关于gram-staining:染色效果：Figure 7A Gram stain of mixed Staphylococcus aureus (S. aureus ATCC 25923, gram-positive cocci, in purple) and Escherichia coli (E. coli ATCC 11775, gram-negative bacilli, in red), the most common Gram stain reference bacteria.Gram-positive bacteria havea thick mesh-like cell wallmade of peptidoglycan(50–90% of cell envelope), andas a result are stainedPurple by crystal violet, whereasGram-negative bacteriahave a thinner layer(10% of cell envelope), so donot retain the purple stainand are counter-stained pink by safranin.八、Actinomyces odontolyticusActinomyces odontolyticus is an anaerobic, facultativecapnophilic, gram-positive, nonsporulating, non–acid fast(不耐酸的),non-motile, irregularly staining bacterium. Sometimesshort or medium-sized rods resembling diphtheroids（白喉）areseen. Shorter rods resembling propionibacteria are frequentlyseen with A. odontolyticus and may be arranged inpalisades（栅栏）as well as other diphtheroidal arrangements. Onblood agar, the bacteria develop as small, irregular, whitishcolonies that are smooth to slightly granular and show adark red pigment when mature (2–14 days). This pigmentationis most obvious when the cultures are left standing inair at room temperature after primary anaerobic isolation.The organism also grows well on CNA and Brucella agar. Definitive identification is madeby negative catalaseand oxidasetests, the reduction of nitrate（硝酸盐）to nitrite（亚硝酸盐）,filamentationof microcolonies,and absence of growth at pH5.5.Generally, the fermentation（发酵）reactions are variable.。