Microbio Lab
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Transcript of Microbio Lab
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Spherical
Diplococcus Pneumoniae
Diplococcus Pneumoniae is a minute, slightly lancet-shaped, non-motile, non-liquefying, optionally anaerobic diplococcus. Usually occurs in pairs, surrounded by acapsule that is not present when the organism is grown on culture medium.
It is found in the sputum of lobar pneumonia, in the exudate of meningitis, andsometimes in the saliva of healthy people. Is the common cause of croupouspneumonia, but is also found in inflammations of theserous membranes.
Stains
Ordinary methods and Gram's.
Fig. 83. - Gonococci in Urethral Pus (McFarland).
Culture
Grows best at 370 C, but has a range from 240 to 420 C. Will grow upon allculture media except potato. Gelatin plates (15 per cent, gelatin) give colonies thatare small, round, circumscribed white points. On agar-agar the growth is almost
invisible.
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Streptococcus
The RightHealth Community
Author: Steven Miller
Streptococcus is a spherical positive bacterium that is responsible for causingmeningitis, bacterial pneumonia, endocarditis, erysipelas and flesh eating bacteriacalled necrotizing fasciitis. There are some non-pathogenic streptococcus strand andthey are present in some varieties of cheese and the human mouth, skin, intestines,and upper respiratory tract.
When streptococcus bacteria are stained by the Gram Staining it turns dark
blue or violet. This means that this bacterium doesn't have an outer membrane likeother types of bacteria. This particular bacteria is also known to cause hemolysis andthis means that this particular bacteria can break down blood cells by digesting them.There are non-hemolytic streptococci and they rarely cause illness.
Streptococcus also is broken down in various groups which include A, B, C, Dand G. These groups define different kinds of the bacteria strain and the problemsthat they pose to the health of humans. Many strains of streptococcus can be treatedwith antibiotics.
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Staphylococcus
Staphylococcus, bunch of grapes", is a genus ofGram-positivebacteria.Under the microscope they appear round (cocci), and form in grape-like clusters.The Staphylococcusgenus includes at least forty species. Of these, nine have twosubspecies and one has three subspecies. Most are harmless and reside normallyon the skin and mucous membranes of humans and other organisms. Foundworldwide, they are a small component of soil microbial flora.
Spherical Gram-positive parasitic bacteria that tend to form irregular colonies;
some cause boils, septicemia or infections.
Sarcina lutea
Sarcina lutea is an older name (not used anymore) for Micrococcus luteus. It
is a Gram positive bacterium in the Firmicutes phylum. It is found in soil and air, andcan also live on human skin, and in the mouth. Micrococcus luteus is a Gram-positive, spherical, saprotrophicbacterium that belongs to the
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family Micrococcaceae. An obligate aerobe, M. luteus is found in soil, dust, waterand air, and as part of the normal flora of the mammalian skin. The bacterium alsocolonizes the human mouth, mucosae,oropharynx and upper respiratory tract.
Considered a contaminant in sick patients, M. luteus is resistant to
reduced water potential and can tolerate drying and high salt concentrations.M. luteus is coagulase negative, bacitracin susceptible, and forms bright
yellow colonies on nutrient agar. To confirm it is not Staphylococcus aureus, abacitracin susceptibility test can be performed.
M. luteus has been shown to survive in oligotrophic environments forextended periods of time. Recent work by Greenblat et al. demonstratethat Micrococcus luteus has survived for at least 34,000 to 170,000 years on thebasis of 16S rRNA analysis, and possibly much longer. [Micrococcus luteus wasformerly known as Micrococcus lysodeikticus.Micrococcus luteus reclassifyas Kocuria rhizophila.
Rod-shaped
Bacillus subtilis
Bacillus subtilis, known also as the hay bacillus orgrass bacillus, isa Gram-positive, catalase-positive bacterium commonly found in soil. A member ofthe genusBacillus, B. subtilis is rod-shaped, and has the ability to form a tough,protective endospore, allowing the organism to tolerate extreme environmentalconditions. Unlike several other well-known species, B. subtilis has historically beenclassified as an obligate aerobe, though recent research has demonstrated that thisis not strictly correct.
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Clostridium botulinum
Clostridium botulinum is a Gram-positive, rod-shaped bacterium thatproduces neurotoxins, known as botulinum neurotoxins types A-G, that cause theflaccid muscularparalysis seen in botulism. It is also the main paralytic agentin botox. C. botulinum is an anaerobic spore-former, which produces oval,subterminal endospores and is commonly found in soil.
Clostridium botulinum is a rod-shaped microorganism. It is an obligateanaerobe, meaning that oxygen is poisonous to the cells. However, C.botulinumtolerates traces of oxygen due to the enzyme superoxide dismutase (SOD)which is an important antioxidant defense in nearly all cells exposed to oxygen.C.botulinum is only able to produce the neurotoxin during sporulation, which can onlyhappen in an anaerobic environment. Other bacterial species produce spores in anunfavorable growth environment to preserve the organism's viability and permit
survival in a dormant state until the spores are exposed to favorable conditions.
In the laboratory Clostridium botulinum is usually isolated in tryptosesulfite cycloserine (TSC) growth media in an anaerobic environment with less than2% of oxygen. This can be achieved by several commercial kits that use a chemicalreaction to replace O2 with CO2 (E.J. GasPak System). C. botulinumisa lipase negative microorganism that grows between pH of 4.8 and 7 and it can'tuse lactose as a primary carbon source, characteristics important during abiochemical identification.
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Corynebacterium diphtheria
Corynebacterium diphtheriae is a pathogenic bacterium thatcauses diphtheria. It is also known as the Klebs-Lffler bacillus, because it wasdiscovered in 1884 by GermanbacteriologistsEdwin Klebs (1834 1912)and Friedrich Lffler(1852 1915).
Escherichia coli
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Escherichia coli is a Gram-negative, rod-shapedbacterium that is commonlyfound in the lowerintestine ofwarm-blooded organisms (endotherms). Most E.colistrains are harmless, but some serotypes can cause serious foodpoisoning in humans, and are occasionally responsible forproduct recalls. Theharmless strains are part of the normal flora of the gut, and can benefit their hosts by
producing vitamin K2, and by preventing the establishment ofpathogenicbacteriawithin the intestine.[4][5]
E. coliand related bacteria constitute about 0.1% ofgut flora, and fecal-oraltransmission is the major route through which pathogenic strains of the bacteriumcause disease. Cells are able to survive outside the body for a limited amount oftime, which makes them ideal indicator organisms to test environmental samplesforfecal contamination. The bacterium can also be grown easily and inexpensively ina laboratory setting, and has been intensively investigated for over 60 years. E.coliis the most widely studied prokaryotic model organism, and an important speciesin the fields ofbiotechnology and microbiology, where it has served as the hostorganism for the majority of work with recombinant DNA.
German peadiatrician and bacteriologist Theodor Escherich discovered E. coliin1885, and it is now classified as part of the Enterobacteriaceae family ofgamma-proteobacteria.
Mycobacterium tuberculosis
Mycobacterium tuberculosis (MTB) is a pathogenicbacterial species in thegenus Mycobacterium and the causative agent of most cases oftuberculosis.First
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discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coatingon the cell surface (primarily mycolic acid), which makes the cells imperviousto Gram staining so acid-fast detection techniques are used instead. The physiologyofM. tuberculosis is highlyaerobic and requires high levels of oxygen. Primarily apathogen of the mammalian respiratory system, MTB infects the lungs. The most
frequently used diagnostic methods for TB are the tuberculin skin test, acid-faststain, and chest radiographs.
The M. tuberculosisgenome was sequenced in 1998.
Proteus vulgaris
Proteus vulgaris is a rod-shaped, Gram negativebacterium that inhabits theintestinal tracts of humans and animals. It can be found in soil, water and fecalmatter. It is grouped with the enterobacteriaceae and is an opportunistic pathogen ofhumans. It is known to cause urinary tract infections and wound infections.
The term Proteus signifies changeability of form, as personified in theHomeric poems in Proteus, "the old man of the sea," who tends the sealflocks ofPoseidon and has the gift of endless transformation. The first use of the termProteus in bacteriological nomenclature was made by Hauser (1885) whodescribed under this term three types of organisms which he isolated from putrefiedmeat. One of the three species Hauser identified was Proteus vulgaris so thisorganism has a long history in Microbiology.
Over the past two decades the genus Proteus, and in particularP. vulgaris,has undergone a number of major taxonomic revisions. In 1982, P. vulgaris wasseparated into three biogroups on the basis ofindole production. Biogroup one was
indole negative and represented a new species: P. penneri; while biogroup two andthree remained together as P. vulgaris.
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Spirals
Spiral shaped cells can be one of two types: either rigid called spirilla (singularspirillum) or flexible called spirochaetes (singular spirochaete). Spiral-shapedbacteria are distinguished by their length, the number and size of the spirals, anddirection of the coil. Short segments or incomplete spirals are common, as thecomma-shaped Vibrios. The spirochetes ofsyphilisare typical spiral bacteria.Diseases caused by spirochaetes include the following: syphilis, yaws, leptosporosis,and Lyme disease.
Spirals come in one of three forms, a vibrio, a spirillum, or a spirochete.
A. vibrio: a curved or comma-shaped rod
Vibrio is a genus ofGram-negativebacteria possessing a curved rodshape, several species of which can cause food borne, usually associated with
eating undercooked seafood. Typically found in saltwater, Vibrio is facultative
anaerobes that test positive foroxidase and do not form spores. All members of the
genus are motile and have polarflagella with sheaths. Recent phylogenies have
been constructed based on a suite of genes (multi-locus sequence analysis).
The name Vibrio derives from Filippo Pacini who isolated microorganisms he
called "vibrions" from cholera patients in 1854.
http://www.daviddarling.info/encyclopedia/S/syphilis.htmlhttp://www.daviddarling.info/encyclopedia/S/syphilis.htmlhttp://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/shape/u1spiral.htmlhttp://en.wikipedia.org/wiki/Genushttp://en.wikipedia.org/wiki/Gram-negativehttp://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/Seawaterhttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Oxidasehttp://en.wikipedia.org/wiki/Motilityhttp://en.wikipedia.org/wiki/Flagellumhttp://en.wikipedia.org/wiki/Filippo_Pacinihttp://www.daviddarling.info/encyclopedia/S/syphilis.htmlhttp://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/shape/u1spiral.htmlhttp://en.wikipedia.org/wiki/Genushttp://en.wikipedia.org/wiki/Gram-negativehttp://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/Seawaterhttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Oxidasehttp://en.wikipedia.org/wiki/Motilityhttp://en.wikipedia.org/wiki/Flagellumhttp://en.wikipedia.org/wiki/Filippo_Pacini -
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Pathogenic strains
Several species ofVibrio are pathogens. Most disease causing strains are
associated with gastroenteritis but can also infect open wounds and
cause septicemia. It can be carried by numerous sea-living animals, such as crabsor prawns, and has been known to cause fatal infections in humans during exposure.
Pathogenic Vibrio include V. cholerae (the causative agent ofcholera), V.
parahaemolyticus, and V. vulnificus.Vibrio cholerae is generally transmitted via
contaminated water. Pathogenic Vibrio can cause foodborne infection, usually
associated with eating undercooked seafood.
Vibrio vulnificus outbreaks commonly occur in warm climates and small,
generally lethal, outbreaks occur regularly. An outbreak occurred in New Orleans
after Hurricane Katrina and several lethal cases occur most years in Florida.
V. parahaemolyticus is also associated with the Kanagawa phenomenon, in
which strains isolated from humanhosts (clinical isolates) are hemolytic on blood
agar plates, while those isolated from non-human sources are non-hemolytic.
Many Vibrio are also zoonotic. They cause disease in fish and shellfish, and
are common causes of mortality among domestic marine life.
Other strains
Vibrio fischeri, Photobacterium phosphoreum, and V. harveyiare notable for
their ability to communicate. BothV. fischeriandPh. phosphoreum are symbiotes of
other marine organisms (typicallyjellyfish, fish, orsquid), and produce light
via bioluminescence through the mechanism ofquorum sensing.Vibrio harveyiis a
pathogen of several aquatic animals and notable as a cause of luminous vibriosis in
shrimps (prawns)
Flagella
The "typical", early-discovered Vibrio such as V. cholerae have a single polar
flagellum (monotrichous) with sheath. Some species such as V.
parahaemolyticus and V. alginolyticus have both a single polar flagellum with sheath
and thin flagella projecting in all directions (peritrichous), and the other species such
as V. fischerihave tufts of polar flagella with sheath (lophotrichous).
B. spirillum: a thick, rigid spiral
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Spirillum in microbiology refers to a bacterium with a cell body that twists like
a spiral. It is the third distinct bacterial cell shape type besides coccus and bacillus
cells. Spirillum is a genus ofGram-negative bacteria.
Spirillum minus is associated with rat-bite fever.
Appearance
It is a genus comprising elongated forms having tufts offlagellae at both poles
and usually living in stagnant water rich in organic matter. They are twisted and
aerobic; certain species are pathogenic for humans.
It is the type genus for the family Spirilliaceae in some bacterial
classifications.
C. spirochete: a thin, flexible spiral
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Spirochaetes (also spelled spirochetes) belong to a phylum of
distinctive Gram-negativebacteria, which have long, helically coiled (spiral-shaped)
cells. Spirochaetes are chemoheterotrophic in nature, with lengths between 5 and
250 m and diameters around 0.1-0.6 m.
Spirochaetes are distinguished from other bacterial phyla by the location of
theirflagella, sometimes called axial filaments, which run lengthwise between the
bacterial inner membrane and outer membrane in periplasmic space. These cause a
twisting motion which allows the spirochaete to move about. When reproducing, a
spirochaete will undergo asexual transverse binary fission.
Most spirochaetes are free-living and anaerobic, but there are numerous exceptions.
Classification
The spirochaetes are divided into three families
(Brachyspiraceae, Leptospiraceae, and Spirochaetaceae), all placed within a single
order (Spirochaetales). Disease-causing members of this phylum include the
following:
Leptospira species, which causes leptospirosis
Borrelia burgdorferi, which causes Lyme disease
Borrelia recurrentis, which causes relapsing fever
Treponema pallidum subspeciespallidum, which causes syphilis
Treponema pallidum subspeciespertenue, which causes yaws
Brachyspira pilosicoliand Brachyspira aalborgi, which cause intestinal
spirochetosis
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Cavalier-Smith has postulated that the Spirochaetes belong in a
largerclade called Gracilicutes.
Historical
Salvarsan, the first partially organic antimicrobial drug in medical history, was
effective against spirochaetes only and was primarily used to cure syphilis.
Leptospira
Leptospira (Greekleptos, "fine, thin" and Latinspira, "coil") is a genus
ofspirochaete bacteria, including a small number
ofpathogenic and saprophytic species. Leptospira was first observed in 1907
in kidney tissue slices of a leptospirosis victim who was described as having died of
"yellow fever."
Taxonomy
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Genus species serovar Serovar_name
For example:
Leptospira interrogans serovar Australis
Leptospira biflexa serovar Patoc
Morphology
Although over 200 serotypes ofLeptospira have been described, all members
of the genus have similar morphology. Leptospira are spiral-shaped bacteria that are
6-20 m long and 0.1 m in diameter with a wavelength of about 0.5 m. One or
both ends of the spirochete are usually hooked. Because they are so thin,
live Leptospira are best observed by darkfield microscopy.
The bacteria have a number of degrees of freedom; when ready to proliferate
via binary fission, the bacterium noticeably bends in the place of the future split.
Cellular structure
Leptospira have a Gram-negative-like cell envelope consisting of a
cytoplasmic and outer membrane. However, the peptidoglycan layer is associated
with the cytoplasmic rather than the outer membrane, an arrangement that is uniqueto spirochetes. The two flagella ofLeptospiraextend from the cytoplasmic membrane
at the ends of the bacteria into theperiplasmic space are necessary for the motility
ofLeptospira.
The outer membrane contains a variety of lipoproteins and
transmembraneouter membrane proteins. As expected, the protein composition of
the outer membrane differs when comparing Leptospira growing in artificial medium
with Leptospira present in an infected animal. Several leptospiral outer membrane
proteins have been shown to attach to the hostextracellular matrix and to factor H.
These proteins may be important foradhesion ofLeptospira to host tissues and in
resisting complement, respectively.
The outer membrane ofLeptospira, like those of most other Gram-negative
bacteria, contains lipopolysaccharide (LPS). Differences in the highly immunogenic
LPS structure account for the numerous serovars ofLeptospira. Consequently,
immunity is serovar specific; current leptospiral vaccines, which consist of one or
several serovars ofLeptospiraendemic in the population to be immunized, protect
only against the serovars contained in the vaccine preparation. Leptospiral LPS has
low endotoxin activity. An unusual feature of leptospiral LPS is that it activates host
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binding protein, LipL41, may account for their ability to use hemin as a source of
iron. Although they do not secrete siderophores, L. biflexa and L. interrogans may be
capable of obtaining iron from siderophores secreted by other microorganisms.
Genome
The genome of pathogenic Leptospira consists of two chromosomes. The size
of the genomes ofL. interrogans serovars Copenhageni and Lai is approximately 4.6
Mb. However, the genome ofL. borgpeterseniiserovar Hardjo is only 3.9 Mb in size
with a large number of pseudogenes, gene fragments, and insertion
sequences relative to the genomes ofL. interrogans.L. interrogans and L.
borgpeterseniishare 2708 genes from which 656 are pathogenic specific genes. The
guanine plus cytosine (GC) content is between 35% and 41%. L.
borgpeterseniiserovar Hardjo is usually transmitted by direct exposure to infected
tissues, whereas L. interrogans is often acquired from water or soil contaminated by
the urine of carrier animals harboring Leptospirain their kidneys. The high number of
defective genes and insertion sequences in L. borgpeterseniiHardjo together with
the poor survival outside of the host and difference in transmission patterns
compared to L. interrogans suggest that L. borgpeterseniiis undergoing insertion-
sequence mediated genomic decay, with ongoing loss of genes necessary for
survival outside of the host animal.
Genotyping
Genome sequence determination (of Leptospira) lead to the development
ofMultilocus sequence typing (MLST) based scheme for species level identification
of pathogenic Leptospira species. The pioneering MLST method developed by Niyaz
Ahmed in Hyderabad, India and colleagues is widely used for molecular
epidemiology studies and holds the potential to replace the highly
ambiguous, serotyping method currently in vogue for leptospiral strain identification.
Borrelia
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Borrelia is a genus ofbacteria of the spirochete phylum. It causes borreliosis,
a zoonotic, vector-borne diseasetransmitted primarily by ticks and some by lice,
depending on the species. There are 36 known species ofBorrelia.
Lyme disease
Of the 36 known species ofBorrelia, 12 of these species are known to
cause Lyme disease orborreliosis and are transmitted by ticks. The
majorBorrelia species causing Lyme disease are Borrelia burgdorferi, Borrelia
afzelii, Borrelia gariniiand Borrelia valaisiana.
Relapsing fever
Relapsing fever borreliosis often occurs with severe bacteremia. Borrelia
recurrentis is transmitted by the human body louse; no other animal reservoir ofB.
recurrentis is known. Lice that feed on infected humans acquire
the Borreliaorganisms that then multiply in the gut of the louse. When an infected
louse feeds on an uninfected human, the organism gains access when the victim
crushes the louse or scratches the area where the louse is feeding. B.
recurrentis infects the person via mucous membranes and then invades the
bloodstream.
Other tick-borne relapsing infections are acquired from other species, such
as Borrelia hermsiiorBorrelia parkeri, which can be spread from rodents, and serve
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as a reservoir for the infection, via a tick vector. Borrelia hermsiiand Borrelia
recurrentis cause very similar diseases, although the disease associated
withBorrelia hermsiihas more relapses and is responsible for more fatalities, while
the disease caused by B. recurrentis has longer febrile and afebrile intervals and a
longer incubation period.
Laboratory test
Immunoflourascent or confirm by serology by observing the organism in blood
of patient.
Genetics
All members of the Borrelia genus that have been examined harbor a
linearchromosome that is about 900 kbp in length as well as a plethora of both linear
and circularplasmids in the 5-220 kbp size range. Genome sequences have been
determined forB. burgdorferi, B. garinii, B. afzelii, B. duttoniiand B. recurrentis. The
chromosomes, which carry the vast majority of the housekeeping genes, appear to
be very constant in gene content and organization across the genus. The content of
the plasmids, which carry most of the genes that encode the differentially-expressed
surface proteins that interact with Borrelia'sarthropod andvertebrate hosts, are much
more variable. B. burgdorferistrain B31, the B. burgdorferitype strain, has been
studied in the most detail and harbors twelve linear and nine circular plasmids thatcomprise about 612 kbp. The plasmids are unusual, as compared to most bacterial
plasmids, in that they contain many paralogous sequences, a large number of
pseudogenes and, in some cases, essential genes. In addition, a number of the
plasmids have features suggesting that they are prophages. Some correlations
between genome content and pathogenicity have been deduced and comparative
whole genome analyses promise future progress in this arena.
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