Comamonas testosteroni, formerly known as Pseudomonastestosteroni, is a non-fermenting, gram(-), oxidase(+) bacterium with a wide geographic distribution in water and soil, and a little apparent capacity of causing human infections. We present two cases of Com. testosteroni bacteraemia, occurred to our hospital within a month's period.
ref: http://www.blackwellpublishing.com/eccmid15/abstract.asp?id=37695 . Acessado em 27/01/11
quinta-feira, 27 de janeiro de 2011
Corynebacterium jeikeium
Corynebacterium jeikeium is an opportunistic pathogen primarily of immunocompromised (neutropenic) patients. C. jeikeium isolates are lipophilic (fat-loving), non-spore-forming, Gram-positive rods that vary from short coccobacilli to long bacillary forms. The organisms are non-motile.
The Coryneform bacteria are common inhabitants of healthy human skin and mucous membranes however C. jeikeium differs from other coryneforms by being pathogenic to humans and highly resistant to antibiotics. Although C. jeikeium is a significant opportunistic pathogen the presence of C. jeikeium in the hospital environment is probably the most clinically important aspect of the natural history of this organism. This is because there is recent evidence that drug resistance genes may have transferred from corynebacteria to a Proprionibacterium sp. clinical isolate. Thus, the high incidence of multiply drug-resistant C. jeikeium suggests that this organism may be an important environmental reservoir of drug resistance genes. C. jeikeium is the most frequently recovered medically significant corynebacterial species at intensive care facilities.
Corynebacterium jeikeium causes septicaemia and endocarditis. Infections include those of skin and soft tissue, septicaemia, native and prosthetic valve endocarditis, osteomyelitis, arthritis and ventricular cerebrospinal fluid shunts
The knowledge on the genome architecture of C. jeikeium will provide a fundamental step in understanding not only the cellular physiology and lifestyle but also the molecular and biochemical basis for multiresistance as well as the pathogenic potential of this clinically important species. It is also advantageous that complete genome sequences are available for some nonpathogenic species Corynebacterium for comparative genomic analysis.
REF http://www.ebi.ac.uk/2can/genomes/bacteria/Corynebacterium_jeikeium.html Acessado em 27/01/11
The Coryneform bacteria are common inhabitants of healthy human skin and mucous membranes however C. jeikeium differs from other coryneforms by being pathogenic to humans and highly resistant to antibiotics. Although C. jeikeium is a significant opportunistic pathogen the presence of C. jeikeium in the hospital environment is probably the most clinically important aspect of the natural history of this organism. This is because there is recent evidence that drug resistance genes may have transferred from corynebacteria to a Proprionibacterium sp. clinical isolate. Thus, the high incidence of multiply drug-resistant C. jeikeium suggests that this organism may be an important environmental reservoir of drug resistance genes. C. jeikeium is the most frequently recovered medically significant corynebacterial species at intensive care facilities.
Corynebacterium jeikeium causes septicaemia and endocarditis. Infections include those of skin and soft tissue, septicaemia, native and prosthetic valve endocarditis, osteomyelitis, arthritis and ventricular cerebrospinal fluid shunts
The knowledge on the genome architecture of C. jeikeium will provide a fundamental step in understanding not only the cellular physiology and lifestyle but also the molecular and biochemical basis for multiresistance as well as the pathogenic potential of this clinically important species. It is also advantageous that complete genome sequences are available for some nonpathogenic species Corynebacterium for comparative genomic analysis.
REF http://www.ebi.ac.uk/2can/genomes/bacteria/Corynebacterium_jeikeium.html Acessado em 27/01/11
Arthrobacter sp
Arthrobacter (from the Greek, "jointed small stick”) is a genus of bacteria that is commonly found in soil. All species in this genus are Gram-positive obligate aerobes that are rods during exponential growth and cocci in their stationary phase.
Colonies of Arthrobacter have a greenish metallic center on mineral salts pyridone broth incubated at 20°C. This genus is distinctive because of its unusual habit of "snapping division" in which the outer bacterial cell wall ruptures at a joint (hence its name). Microbiologists refer to the type of cell division in which rods break into cocci as reversion. Under the microscope, these dividing cells appear as chevrons ("V" shapes). Other notable characteristics are that it can use pyridone as its sole carbon source, and that its cocci are resistant to desiccation and starvation.
One species, A. crystallopoieties, has been shown to reduce hexavalent chromium levels in contaminated soil, suggesting that it may be useful in bioremediation. [1]
Arthrobacter chlorophenolicus sp. nov., a species capable of degrading high concentrations of 4-chlorophenol, may also be useful in bioremediation. [2] Arthrobacter sp. strain R1 has been shown to grow on a variety of aromatic compounds, including homocyclic compounds, such as hydroxybenzoates, as well as N-heterocycles, including pyridine and picoline.[3]
Colonies of Arthrobacter have a greenish metallic center on mineral salts pyridone broth incubated at 20°C. This genus is distinctive because of its unusual habit of "snapping division" in which the outer bacterial cell wall ruptures at a joint (hence its name). Microbiologists refer to the type of cell division in which rods break into cocci as reversion. Under the microscope, these dividing cells appear as chevrons ("V" shapes). Other notable characteristics are that it can use pyridone as its sole carbon source, and that its cocci are resistant to desiccation and starvation.
One species, A. crystallopoieties, has been shown to reduce hexavalent chromium levels in contaminated soil, suggesting that it may be useful in bioremediation. [1]
Arthrobacter chlorophenolicus sp. nov., a species capable of degrading high concentrations of 4-chlorophenol, may also be useful in bioremediation. [2] Arthrobacter sp. strain R1 has been shown to grow on a variety of aromatic compounds, including homocyclic compounds, such as hydroxybenzoates, as well as N-heterocycles, including pyridine and picoline.[3]
Cladosporium sp
Cladosporium is the most common of the so-called black molds. It produces a black pigment that protects it from ultraviolet light. This characteristic as well as its growth and dispersal characteristics is likely responsible for its presence and abundance in the environment.
REf: http://healthandenergy.com/cladosporium.htm . Acessado em 27/01/11
Cladosporium is a genus of fungi including some of the most common indoor and outdoor molds. Species produce olive-green to brown or black colonies, and have dark-pigmented conidia that are formed in simple or branching chains.
The many species of Cladosporium are commonly found on living and dead plant material. Some species are plant pathogens, others parasitize other fungi. Cladosporium spores are wind-dispersed and they are often extremely abundant in outdoor air. Indoors Cladosporium species may grow on surfaces when moisture is present
REf http://en.wikipedia.org/wiki/Cladosporium. Acessado em 27/01/11
REf: http://healthandenergy.com/cladosporium.htm . Acessado em 27/01/11
Cladosporium is a genus of fungi including some of the most common indoor and outdoor molds. Species produce olive-green to brown or black colonies, and have dark-pigmented conidia that are formed in simple or branching chains.
The many species of Cladosporium are commonly found on living and dead plant material. Some species are plant pathogens, others parasitize other fungi. Cladosporium spores are wind-dispersed and they are often extremely abundant in outdoor air. Indoors Cladosporium species may grow on surfaces when moisture is present
REf http://en.wikipedia.org/wiki/Cladosporium. Acessado em 27/01/11
Staphylococcus auricularis
It is one of the major species found living in the adult human, external auditory meatus and demonstrate a strong preference for this niche.
REf: The prokaryotes , 3 edition A Handbook on the Biology of Bacteria: BActeria: Firmicutes, Cyanobacteria. Edited by: Martin Dworkin,Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, ERcke Starckebrandt. Vol. 4. Springer.
http://books.google.com.br/books?id=C5tzLBabUh8C&pg=PA58&lpg=PA58&dq=Staphylococcus+auricularis&source=bl&ots=5WdiVyw03X&sig=5pfRbIT4Fi-5QPQRZHXTuwL5Fxc&hl=pt-BR&ei=sdxBTcujFYL78AbzmenKAQ&sa=X&oi=book_result&ct=result&resnum=10&ved=0CHYQ6AEwCTgU#v=onepage&q=Staphylococcus%20auricularis&f=false . Acesso em 27/01/11
REf: The prokaryotes , 3 edition A Handbook on the Biology of Bacteria: BActeria: Firmicutes, Cyanobacteria. Edited by: Martin Dworkin,Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, ERcke Starckebrandt. Vol. 4. Springer.
http://books.google.com.br/books?id=C5tzLBabUh8C&pg=PA58&lpg=PA58&dq=Staphylococcus+auricularis&source=bl&ots=5WdiVyw03X&sig=5pfRbIT4Fi-5QPQRZHXTuwL5Fxc&hl=pt-BR&ei=sdxBTcujFYL78AbzmenKAQ&sa=X&oi=book_result&ct=result&resnum=10&ved=0CHYQ6AEwCTgU#v=onepage&q=Staphylococcus%20auricularis&f=false . Acesso em 27/01/11
Phialemonium sp
Paraná river delta wetlands soil microfungi
The Paraná River Delta soils are affected by seasonal flooding coupled with rapidly flowing water from the Paraná River and by the de la Plata River estuary tidal regime which reduces the seasonality of the Paraná River regime. The present study is the first investigation undertaken to determine the fungal composition of different site soils and to evaluate if flooding and flowing water energy induced differences on fungal community. Five sites were selected and three plots at each site along a topographical gradient were examined. From all soil samples, 23041 isolates belonging to 74 taxa were obtained. Talaromyces flavus and Eupenicillium brefeldianum were the most frequent species and present with high densities. Several taxa were soil or site specific. A black yeast, Pseudeurotium zonatum, Phialemonium dimorphosporum, Eladia saccula, Phialophara spp., Aspergillus japonicus, Eupenicillium abidjanum, Arachnotheca albicans, Fusarium oxysporum and Westerdykella spp. also were common. Correspondence analysis evidenced differences among sites characterized by a set of several species. The distribution of these species shows little or no relationship with the overlying vegetation. The low microfungal biomass, the high number of taxa by 100 isolates, and the mainly dematiaceous and cleistothecial forms suggest that these soil fungal communities are disturbed. Differences among fungal communities at each site could reflect difterent disturbance conditions derived from the effect of flooding and flowing water at the Upper, Medium and Lower Paraná River Delta as well as the Rio de la Plata estuary tidal regime.
REfhttp://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CW5-4DS31MJ-5T&_user=10&_coverDate=01%2F01%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1622277236&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=fd72b9857da329081b5e5da3bc9a7173&searchtype=a Acessado em 27/01/11
Lina Bettuccia, , , Inez Malvarezb, Joëlle Dupontc, Edith Buryc and Marie-France Roquebertc
aLaboratio de Micolgía, Facultad de Ciencias-Facultad de Ingeniería, Julio Herrera y Reissig, 565. Montevideo, Uruguay
bLaboratio de Ecología Regional. Departamento de Ciencias Biológicas. Pabellón II. Ciudad Universitaria. 1428 Buenos Aires, Argentina
cLaboratoire de Cryptogamie, MNHN, 12 rue Buffon, 75005, Paris
Received 12 April 2001; accepted 1 December 2001. Available online 10 November 2004
The Paraná River Delta soils are affected by seasonal flooding coupled with rapidly flowing water from the Paraná River and by the de la Plata River estuary tidal regime which reduces the seasonality of the Paraná River regime. The present study is the first investigation undertaken to determine the fungal composition of different site soils and to evaluate if flooding and flowing water energy induced differences on fungal community. Five sites were selected and three plots at each site along a topographical gradient were examined. From all soil samples, 23041 isolates belonging to 74 taxa were obtained. Talaromyces flavus and Eupenicillium brefeldianum were the most frequent species and present with high densities. Several taxa were soil or site specific. A black yeast, Pseudeurotium zonatum, Phialemonium dimorphosporum, Eladia saccula, Phialophara spp., Aspergillus japonicus, Eupenicillium abidjanum, Arachnotheca albicans, Fusarium oxysporum and Westerdykella spp. also were common. Correspondence analysis evidenced differences among sites characterized by a set of several species. The distribution of these species shows little or no relationship with the overlying vegetation. The low microfungal biomass, the high number of taxa by 100 isolates, and the mainly dematiaceous and cleistothecial forms suggest that these soil fungal communities are disturbed. Differences among fungal communities at each site could reflect difterent disturbance conditions derived from the effect of flooding and flowing water at the Upper, Medium and Lower Paraná River Delta as well as the Rio de la Plata estuary tidal regime.
REfhttp://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CW5-4DS31MJ-5T&_user=10&_coverDate=01%2F01%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1622277236&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=fd72b9857da329081b5e5da3bc9a7173&searchtype=a Acessado em 27/01/11
Lina Bettuccia, , , Inez Malvarezb, Joëlle Dupontc, Edith Buryc and Marie-France Roquebertc
aLaboratio de Micolgía, Facultad de Ciencias-Facultad de Ingeniería, Julio Herrera y Reissig, 565. Montevideo, Uruguay
bLaboratio de Ecología Regional. Departamento de Ciencias Biológicas. Pabellón II. Ciudad Universitaria. 1428 Buenos Aires, Argentina
cLaboratoire de Cryptogamie, MNHN, 12 rue Buffon, 75005, Paris
Received 12 April 2001; accepted 1 December 2001. Available online 10 November 2004
Cellulomonas sp
A genus of gram-positive, irregular rods in the coryneform group of bacteria; metabolism is respiratory; most strains produce acid from glucose, and cellulose is attacked by all strains.
Ref:http://encyclopedia2.thefreedictionary.com/Cellulomonas . Acesso em 27/01/11
In young cultures, slender, irregular rods, are straight or slightly curved; some rods are in pairs at an angle to each other giving V formations; rods occasionally show branching, but no mycellium is formed. In old cultures, the rods are usually short, and a few cocci may occur. Strain Gram positive but easily decolorized. Often motile by one or few flagella. Nonsporing, non-acid-fast. Facultative anaerobes, but some grow very poorly anaerobically. Growth on peptone-yeast extract agar gives usually convex, yellow colonies. The metabolism is respiratory and also fermentative, giving acid from glucose and various other carbohydrates, both aerobically and anaerobically. Catalase positive. Widely distributed in soils and decaying vegetable matter.
REF: Bergey's Manual of DEterminative BActeriology 9 edition, John G. Holt; Noel R. Krieg, Peter H. A. Sneath, James T. Staley, Stanley T. Williand. Williams & Wilkis , 1994
Ref:http://encyclopedia2.thefreedictionary.com/Cellulomonas . Acesso em 27/01/11
In young cultures, slender, irregular rods, are straight or slightly curved; some rods are in pairs at an angle to each other giving V formations; rods occasionally show branching, but no mycellium is formed. In old cultures, the rods are usually short, and a few cocci may occur. Strain Gram positive but easily decolorized. Often motile by one or few flagella. Nonsporing, non-acid-fast. Facultative anaerobes, but some grow very poorly anaerobically. Growth on peptone-yeast extract agar gives usually convex, yellow colonies. The metabolism is respiratory and also fermentative, giving acid from glucose and various other carbohydrates, both aerobically and anaerobically. Catalase positive. Widely distributed in soils and decaying vegetable matter.
REF: Bergey's Manual of DEterminative BActeriology 9 edition, John G. Holt; Noel R. Krieg, Peter H. A. Sneath, James T. Staley, Stanley T. Williand. Williams & Wilkis , 1994
Candida parapsilosis
Candida parapsilosis is a fungal species of the yeast family that has become a significant cause of sepsis and of wound and tissue infections in immuno-compromised patients. The immune system is a major player in Candida parapsilosis infections. Unlike Candida albicans and Candida tropicalis, Candida parapsilosis is not an obligate human pathogen, having been isolated from nonhuman sources such as domestic animals, insects or soil. Candida parapsilosis is also a normal human commensal and it is one of the fungi most frequently isolated from the human hands. There are several risk factors which can help Candida parapsilosis to colonize human host. Immuno-compromised individuals and surgical patients, particularly those having surgery of the gastrointestinal tract are at high risk for infection with Candida parapsilosis. There is currently no consensus on the treatment of invasive Candida parapsilosis diseases, although the therapeutic approach typically includes the extraction of any removable foreign bodies and the administration of a systemic anti fungal. Historically, Amphotericin B has been the most frequently used anti fungal. Fluconazole is a frequently administrated alternative to Amphotericin B.
REF: http://en.wikipedia.org/wiki/Candida_parapsilosis . Acessado em 27/01/11
REF: http://en.wikipedia.org/wiki/Candida_parapsilosis . Acessado em 27/01/11
Aeromonas veronii
Aeromonas veronii is a gram-negative, rod-shaped bacterium found in fresh water and in association with animals. It can be a pathogen of humans and a beneficial symbiont of leeches. In humans A. veronii can cause diseases ranging from wound infections and diarrhea to septicemia in immunocompromised patients. In leeches, this bacterium is thought to function in the digestion of blood, provision of nutrients or preventing other bacteria from growing.
REf: . Acessado em 25/jan/2011
Classification
Higher order taxa
Bacteria; Proteobacteria; Gammaproteobacteria; Aeromonadales; Aeromonadaceae; Aeromonas
Species
Aeromonas veronii
NCBI:[1]
Description and significance
A. veronii is a rod shaped, motile, gram negative, facultative anaerobe. The bacteria are usually not found in groups or pairs but as individual cells.[5] A. veronii is commonly found in soil and various water systems all over the world. It is most often associated with the leech. The blood digested by the bacteria in the leech has been found to contain various antimicrobial properties. It is capable of lowering high concentrations of bacteria through the activatons of the membrane attack complex. This complex creates permeable membranes in a foreign bacteria, essentially inactivating the bacteria. The A. veronii seem to be unsusceptible to this complex, allowing it to proliferate while other bacteria can not. This leads to a very limited number of microbial flora in the digestive tract of the leech, which is extremely uncommon.[4] The population of Aeromonas veronii is greatly effected by the consumption of blood. Tests have shown that dramatic changes occur during this time, the majority of A. veronii bacteria are found not in the epithelial tissue but in the IntraLuminal Fluid (ILF).[5]
Genome structure
The bacteria is made up of 2758 bp of linear DNA. Studies have found that certain genes ( Ast, Alt, and Act) may play a significant role in infection of host organisms. The aeroslysin-hemolysin genes were found to cause diarrhea in some patients who had A. veronii in their digestive system. [2]
Cell structure and metabolism
The bacterial cell contains a cytoplasm membrane , a thin layer of peptidoglycan and an outer layer composed of lipopolysaccharides (LPS). The catalase gene is important for the degradation of toxic hydrogen peroxide to much more useful molecules, water and oxygen. The expression of the catalase gen is influenced by introduction to extremely low levels of H2O2 during growth and the stationery phases.It has been suggested that H2O2 is used as an antimicrobial by the host cell to damage the DNA, RNA, proteins of invading pathogens. Only those microbes that are able to metabolize hydrogen peroxide would be able to survive in a host cell. [6]
Ecology
The A. veronii bacteria can be found in a number of habitats, including humans, mosquitos and leeches. It is primarily found in the digestive tract of the leech where it maintains a symbiotic relationship with its host. The medicinal leech, Hirudo medicinalis is capable of consuming six times its own body weight. The crop is the area of the digestive tract colonized by A. veronii. It is also the area where blood is stored after ingestion, and where water and salt are absorbed from the blood. . Blood is stored in the crop of the digestive tract. Studies have suggested that one of the reasons A. veronii is one of the two predominant microbial flora of the digestive tract is due to the antimicrobial properties of ingested blood.[4] A. veronii provides a number of contributions to the symbiotic relationship it share with the leech. It appears the bacteria helps maintain the flora of the digestive tract, helps in digestion of blood and it also provides necessary nutrients, such as vitamin B complex, not found in abundance in blood.[5][12]
Pathology
Medicinal leeches are used after reconstructive or plastic surgery due to their anticoagulating properties and relative inexpense. Studies have shown that without prior antibiotic treatment, up to 20% of patients receiving leech treatment become infected with Aeromonas.[4] Aeromonas species have been shown to have pathogenic properties in a human host. The problem arises if other more pathogenic bacteria are transmitted by leech therapy. Studies looked at whether other bacteria could proliferate or or persist inside the digestive tract for an extended period of time.[4] Virulence is caused by a number of factors such as the pili, flagella and S-layer though non e have been shown to be the sole cause of symptoms during infection.[2]
Current Research
Currently, studies are being conducted on the medicinal leech, Hirudo medicinalis due to its popularity as an anticoagulant after plastic and reconstructive surgery. These studies focus on the flora of the digestive tract, primarily to determine how effective they are against bacteria that may be pathogenic to humans. The studies look at the whether or not A. veronii is able to contain growth of other bacteria and remain the dominating flora.[4] Current research is also studying the role of A. veronii in a human host. Without antibiotic treatment prior to leech therapy, patients are highly susceptible to infections caused by the bacteria. Though leech therapy is a cost effective treatment with many benefits, it can pose harm to humans.[8] Continual studies of the H. medicinalis and its microial flora are essential to learning more about the complexity of communities withing a host organism. The simple community within the H. medicinalis makes it a perfect model for future studies.[8] Research has been done on the catalase gene of the A. veronii and the role it plays in the symbiotic realtionship between symbiont and host. This is a great model for studying other symbiotic relationships and how their environment may effect growth.[6]
References
1. Abdullah, A.I., Hart, C.A., and Winstanley, C. 2003. Molecular characterization and distribution of virulence-associated genes amongst Aeromonas isolates from Libya. Journal of Applied Microbiology, v. 95, p. 1001-1007.
2. Aguilera-Arreola, M.G. Hernandez-Rodriguez, C., Zuniga, G., Figueras, M.J., Garduno, R. A., and Castro-Escarpulli, G. 2007. Virulence potential and genetic diversity of Aeromonas caviae, Aeromonas veronii, and Aeromonas hydrophilia clinical isolates from Mexico and Spain: a comparative study. Canadian Journal of Microbiology, v. 53, p. 877-887.
3. Han, H., Taki, T., Kondo, H., Hirono, I., and Aoki, T. 2008. Pathogenic potential of a collagenase gene from Aeromonas veronii. Canadian Journal of Microbiology, v. 54, p. 1-10.
4. Indergand, S., and Graf, J. 2000. Ingested blood contributes to the specificity of the symbiosis of Aeromonas veronii biovar sobria and Hirudo medicinalis, the medicinal leech. Applied and Environmental Microbiology, v. 66, p. 4735-4741.
5. Kikuchi, Y., and Graf J. 2007. Spatial and temporal population dynamics of a naturally occurring two-species microbial c ]ommunity inside the digestive tract of the medicinal leech. Applied and Environmental Microbiology, v. 73, p. 1984-1991.
6. Rio, R.V.M., Anderegg, M., and Graf, J. 2007. Characterization of a catalase gene from Aeromonas veronii, the digestive-tract symbiont of the medicinal leech. Microbiology, v. 153, p. 1897-1906.
7. Sen, K., and Lye, D. 2007. Importance of flagella and enterotoxins for Aeromonas virulence in a mouse model. Canadian journal of Microbiology, v. 53, p. 261-269.
8. Silver, A.C., Rabinowitz, N.M., Kuffer, S., and Graf, J. 2007. Identification of Aeromonas veronii genes required for colonization of the medicinal leech, Hirudo verbena. Journal of Bacteriology, v. 189, p. 6763-6772.
9. Thomsen, R.N., and Kristiansen, M.M. 2001. Three cases of bacteraemia caused by Aeromonas veronii biovar sobria. Scandinavian Journal of Infectious Diseases, v.33, p.718-719.
10. Vazquez-Juarez, R.C., Romero, M.J., and Ascencio, F. 2004. Adhesive properties of a LamB-like outer membrane protein and its contribution to Aeromonas veronii adhesion.
11. Vila , J., Ruiz, J., Gallardo, F., Vargas, M., Soler, L., Figueras, M.J., and Gascon J. 2003. Aeromonas spp. and traveler’s diarrhea: clinical features and antimicrobial resistance. Emerging Infectious Diseases, v. 9, p. 552-555.
12. Worthen, P.L., Gode, C.J., and Graf J. 2006. Culture-independent characterization of the digestive-tract microbiota of the medicinal leech reveals a tripartite symbiosis. Applied and Environmental Microbiology, v. 72, p. 4775-4781.
REF.: http://microbewiki.kenyon.edu/index.php/Aeromonas_veronii . Acessado em 25/jan/2011
REf: . Acessado em 25/jan/2011
Classification
Higher order taxa
Bacteria; Proteobacteria; Gammaproteobacteria; Aeromonadales; Aeromonadaceae; Aeromonas
Species
Aeromonas veronii
NCBI:[1]
Description and significance
A. veronii is a rod shaped, motile, gram negative, facultative anaerobe. The bacteria are usually not found in groups or pairs but as individual cells.[5] A. veronii is commonly found in soil and various water systems all over the world. It is most often associated with the leech. The blood digested by the bacteria in the leech has been found to contain various antimicrobial properties. It is capable of lowering high concentrations of bacteria through the activatons of the membrane attack complex. This complex creates permeable membranes in a foreign bacteria, essentially inactivating the bacteria. The A. veronii seem to be unsusceptible to this complex, allowing it to proliferate while other bacteria can not. This leads to a very limited number of microbial flora in the digestive tract of the leech, which is extremely uncommon.[4] The population of Aeromonas veronii is greatly effected by the consumption of blood. Tests have shown that dramatic changes occur during this time, the majority of A. veronii bacteria are found not in the epithelial tissue but in the IntraLuminal Fluid (ILF).[5]
Genome structure
The bacteria is made up of 2758 bp of linear DNA. Studies have found that certain genes ( Ast, Alt, and Act) may play a significant role in infection of host organisms. The aeroslysin-hemolysin genes were found to cause diarrhea in some patients who had A. veronii in their digestive system. [2]
Cell structure and metabolism
The bacterial cell contains a cytoplasm membrane , a thin layer of peptidoglycan and an outer layer composed of lipopolysaccharides (LPS). The catalase gene is important for the degradation of toxic hydrogen peroxide to much more useful molecules, water and oxygen. The expression of the catalase gen is influenced by introduction to extremely low levels of H2O2 during growth and the stationery phases.It has been suggested that H2O2 is used as an antimicrobial by the host cell to damage the DNA, RNA, proteins of invading pathogens. Only those microbes that are able to metabolize hydrogen peroxide would be able to survive in a host cell. [6]
Ecology
The A. veronii bacteria can be found in a number of habitats, including humans, mosquitos and leeches. It is primarily found in the digestive tract of the leech where it maintains a symbiotic relationship with its host. The medicinal leech, Hirudo medicinalis is capable of consuming six times its own body weight. The crop is the area of the digestive tract colonized by A. veronii. It is also the area where blood is stored after ingestion, and where water and salt are absorbed from the blood. . Blood is stored in the crop of the digestive tract. Studies have suggested that one of the reasons A. veronii is one of the two predominant microbial flora of the digestive tract is due to the antimicrobial properties of ingested blood.[4] A. veronii provides a number of contributions to the symbiotic relationship it share with the leech. It appears the bacteria helps maintain the flora of the digestive tract, helps in digestion of blood and it also provides necessary nutrients, such as vitamin B complex, not found in abundance in blood.[5][12]
Pathology
Medicinal leeches are used after reconstructive or plastic surgery due to their anticoagulating properties and relative inexpense. Studies have shown that without prior antibiotic treatment, up to 20% of patients receiving leech treatment become infected with Aeromonas.[4] Aeromonas species have been shown to have pathogenic properties in a human host. The problem arises if other more pathogenic bacteria are transmitted by leech therapy. Studies looked at whether other bacteria could proliferate or or persist inside the digestive tract for an extended period of time.[4] Virulence is caused by a number of factors such as the pili, flagella and S-layer though non e have been shown to be the sole cause of symptoms during infection.[2]
Current Research
Currently, studies are being conducted on the medicinal leech, Hirudo medicinalis due to its popularity as an anticoagulant after plastic and reconstructive surgery. These studies focus on the flora of the digestive tract, primarily to determine how effective they are against bacteria that may be pathogenic to humans. The studies look at the whether or not A. veronii is able to contain growth of other bacteria and remain the dominating flora.[4] Current research is also studying the role of A. veronii in a human host. Without antibiotic treatment prior to leech therapy, patients are highly susceptible to infections caused by the bacteria. Though leech therapy is a cost effective treatment with many benefits, it can pose harm to humans.[8] Continual studies of the H. medicinalis and its microial flora are essential to learning more about the complexity of communities withing a host organism. The simple community within the H. medicinalis makes it a perfect model for future studies.[8] Research has been done on the catalase gene of the A. veronii and the role it plays in the symbiotic realtionship between symbiont and host. This is a great model for studying other symbiotic relationships and how their environment may effect growth.[6]
References
1. Abdullah, A.I., Hart, C.A., and Winstanley, C. 2003. Molecular characterization and distribution of virulence-associated genes amongst Aeromonas isolates from Libya. Journal of Applied Microbiology, v. 95, p. 1001-1007.
2. Aguilera-Arreola, M.G. Hernandez-Rodriguez, C., Zuniga, G., Figueras, M.J., Garduno, R. A., and Castro-Escarpulli, G. 2007. Virulence potential and genetic diversity of Aeromonas caviae, Aeromonas veronii, and Aeromonas hydrophilia clinical isolates from Mexico and Spain: a comparative study. Canadian Journal of Microbiology, v. 53, p. 877-887.
3. Han, H., Taki, T., Kondo, H., Hirono, I., and Aoki, T. 2008. Pathogenic potential of a collagenase gene from Aeromonas veronii. Canadian Journal of Microbiology, v. 54, p. 1-10.
4. Indergand, S., and Graf, J. 2000. Ingested blood contributes to the specificity of the symbiosis of Aeromonas veronii biovar sobria and Hirudo medicinalis, the medicinal leech. Applied and Environmental Microbiology, v. 66, p. 4735-4741.
5. Kikuchi, Y., and Graf J. 2007. Spatial and temporal population dynamics of a naturally occurring two-species microbial c ]ommunity inside the digestive tract of the medicinal leech. Applied and Environmental Microbiology, v. 73, p. 1984-1991.
6. Rio, R.V.M., Anderegg, M., and Graf, J. 2007. Characterization of a catalase gene from Aeromonas veronii, the digestive-tract symbiont of the medicinal leech. Microbiology, v. 153, p. 1897-1906.
7. Sen, K., and Lye, D. 2007. Importance of flagella and enterotoxins for Aeromonas virulence in a mouse model. Canadian journal of Microbiology, v. 53, p. 261-269.
8. Silver, A.C., Rabinowitz, N.M., Kuffer, S., and Graf, J. 2007. Identification of Aeromonas veronii genes required for colonization of the medicinal leech, Hirudo verbena. Journal of Bacteriology, v. 189, p. 6763-6772.
9. Thomsen, R.N., and Kristiansen, M.M. 2001. Three cases of bacteraemia caused by Aeromonas veronii biovar sobria. Scandinavian Journal of Infectious Diseases, v.33, p.718-719.
10. Vazquez-Juarez, R.C., Romero, M.J., and Ascencio, F. 2004. Adhesive properties of a LamB-like outer membrane protein and its contribution to Aeromonas veronii adhesion.
11. Vila , J., Ruiz, J., Gallardo, F., Vargas, M., Soler, L., Figueras, M.J., and Gascon J. 2003. Aeromonas spp. and traveler’s diarrhea: clinical features and antimicrobial resistance. Emerging Infectious Diseases, v. 9, p. 552-555.
12. Worthen, P.L., Gode, C.J., and Graf J. 2006. Culture-independent characterization of the digestive-tract microbiota of the medicinal leech reveals a tripartite symbiosis. Applied and Environmental Microbiology, v. 72, p. 4775-4781.
REF.: http://microbewiki.kenyon.edu/index.php/Aeromonas_veronii . Acessado em 25/jan/2011
segunda-feira, 24 de janeiro de 2011
RISK ASSESMENT
Risk assessment is a step in a risk management procedure. Risk assessment is the determination of quantitative or qualitative value of risk related to a concrete situation and a recognized threat (also called hazard). Quantitative risk assessment requires calculations of two components of risk: R, the magnitude of the potential loss L, and the probability p, that the loss will occur.
Ref. http://en.wikipedia.org/wiki/Risk_assessment Access date: 23/01/11
How to assess the risks in your workplace
Follow the five steps in our leaflet: Five steps to risk assessment [1].
1.Identify the hazards[2]
2.Decide who might be harmed and how[3]
3.Evaluate the risks and decide on precaution[4]
4.Record your findings and implement them[5]
5.Review your assessment and update if necessary[6]
Don’t overcomplicate the process. In many organisations, the risks are well known and the necessary control measures are easy to apply. You probably already know whether, for example, you have employees who move heavy loads and so could harm their backs, or where people are most likely to slip or trip. If so, check that you have taken reasonable precautions to avoid injury.
If you run a small organisation and you are confident you understand what’s involved, you can do the assessment yourself. You don’t have to be a health and safety expert.
Ref. Access date: 24/01/11
Ref. http://en.wikipedia.org/wiki/Risk_assessment Access date: 23/01/11
How to assess the risks in your workplace
Follow the five steps in our leaflet: Five steps to risk assessment [1].
1.Identify the hazards[2]
2.Decide who might be harmed and how[3]
3.Evaluate the risks and decide on precaution[4]
4.Record your findings and implement them[5]
5.Review your assessment and update if necessary[6]
Don’t overcomplicate the process. In many organisations, the risks are well known and the necessary control measures are easy to apply. You probably already know whether, for example, you have employees who move heavy loads and so could harm their backs, or where people are most likely to slip or trip. If so, check that you have taken reasonable precautions to avoid injury.
If you run a small organisation and you are confident you understand what’s involved, you can do the assessment yourself. You don’t have to be a health and safety expert.
Ref. Access date: 24/01/11
domingo, 23 de janeiro de 2011
API
API - means /analytical Profile Index
Ref:http://www.jlindquist.net/generalmicro/102bactid2.html . Acesso em 23/01/11
Ref:http://www.jlindquist.net/generalmicro/102bactid2.html . Acesso em 23/01/11
domingo, 16 de janeiro de 2011
Assinar:
Postagens (Atom)