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Staphylococcus

 
Staphylococcus

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Staphylococcus



 
 
Staphylococcus (from the , staphyle, "bunch of grapes" and ??????, kókkos, "granule") is a genus of Gram-positive
Gram-positive

Gram-positive Bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink....
 bacteria. Under the microscope
Microscope

A microscope is an Laboratory equipment for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy....
 they appear round (cocci), and form in grape
Grape

File:Table grapes on white.jpgA grape is the non-Climacteric #In_botany fruit that grows on the Perennial plant and deciduous woody vines of the genus Vitis....
-like clusters.

The Staphylococcus genus
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
 include just thirty-three species. Most are harmless and reside normally on the skin
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 and mucous membranes of humans and other organisms. Found worldwide, they are a small component of soil microbial flora.

taphylococcus can cause a wide variety of diseases in humans and other animals through either toxin production or invasion.






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Staphylococcus (from the , staphyle, "bunch of grapes" and ??????, kókkos, "granule") is a genus of Gram-positive
Gram-positive

Gram-positive Bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink....
 bacteria. Under the microscope
Microscope

A microscope is an Laboratory equipment for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy....
 they appear round (cocci), and form in grape
Grape

File:Table grapes on white.jpgA grape is the non-Climacteric #In_botany fruit that grows on the Perennial plant and deciduous woody vines of the genus Vitis....
-like clusters.

The Staphylococcus genus
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
 include just thirty-three species. Most are harmless and reside normally on the skin
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 and mucous membranes of humans and other organisms. Found worldwide, they are a small component of soil microbial flora.

Role in disease

Staphylococcus can cause a wide variety of diseases in humans and other animals through either toxin production or invasion. Staphylococcal toxins are a common cause of food poisoning, as it can grow in improperly-stored food.

Classification

The main classification of staphylococcus is by presence or absence of coagulase
Coagulase

Coagulase is an enzyme produced by Staphylococcus aureus that converts fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates....
 production. Coagulase is a protein product, which is an enzyme, that causes clot formation

Coagulase-positive

  • The coagulase
    Coagulase

    Coagulase is an enzyme produced by Staphylococcus aureus that converts fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates....
    -positive Staphylococcus :e.g Staph Aureus and Pseudintermedius.coagulase-positive (meaning that it can produce "coagulase", a protein product, which is an enzyme) that causes clot formation while most other Staphylococcus species are coagulase-negative.
However, while the majority of S. aureus are coagulase-positive, some may be atypical in that they do not produce coagulase. S aureus is catalase positive (meaning that it can produce the enzyme "catalase") and able to convert hydrogen peroxide (H2O2) to water and oxygen, which makes the catalase test useful to distinguish staphylococci from enterococci and streptococci. Staphylococci that inhabits and sometimes infects the skin of domestic dogs and cats is Staphylococcus pseudintermedius. This organism, too, can carry the genetic material that imparts multiple bacterial resistance. It is rarely implicated in infections in humans, as a zoonosis
Zoonosis

A zoonosis or zoonose is any infectious disease that is able to be transmitted from other animals, both wild and domestic, to humans or from humans to animals ....
.

Coagulase-negative

  • S. epidermidis
    Staphylococcus epidermidis

    Staphylococcus epidermidis is one of thirty three known species belonging to the genus Staphylococcus. It is part of our normal flora and consequently found on the skin....
    , a coagulase
    Coagulase

    Coagulase is an enzyme produced by Staphylococcus aureus that converts fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates....
    -negative staphylococcus species, is a commensal of the skin
    Skin

    The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
    , but can cause severe infections in immune-suppressed
    Immunosuppression

    Immunosuppression involves an act that reduces the activation or efficacy of the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other conditions....
     patients and those with central venous catheters.


  • S. saprophyticus
    Staphylococcus saprophyticus

    Staphylococcus saprophyticus is a coagulase-negative species of Staphylococcus bacteria. S. saprophyticus is often implicated in urinary tract infections....
    , another coagulase
    Coagulase

    Coagulase is an enzyme produced by Staphylococcus aureus that converts fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates....
    -negative species that is part of the normal vaginal flora
    Vaginal flora

    The human vagina region has a higher concentration of bacteria than any other part of the body other than the Colon . The bacteria of the vaginal flora were discovered by the german gynecologist Albert D?derlein in 1892....
    , is predominantly implicated in genitourinary tract infections in sexually-active young women.


  • In recent years, several other Staphylococcus species have been implicated in human infections, notably S. lugdunensis
    Staphylococcus lugdunensis

    Staphylococcus lugdunensis is a member of the genus Staphylococcus, consisting of Gram-positive bacteria with spherical cells that appear in clusters....
    , S. schleiferi, and S. caprae
    Staphylococcus caprae

    Staphylococcus caprae is a Gram positive, spherical bacteria and a member of the genus Staphylococcus. S. caprae is coagulase-negative....
    .


Biochemical identification


Staphylococcus species can be differentiated from other aerobic and facultative anaerobic gram positive cocci by several simple tests. Staphylococcus spp. are facultative anaerobes. Facultative anaerobes are capable of growth both aerobically and anaerobically. All species grow in the presence of bile salts and are catalase positive. Growth also occurs in a 6.5% NaCl solution. On Baird Parker Medium Staphylococcus spp. show as fermentative, except for S. saprophyticus which is oxidative. Staphylococcus spp. are resistant to Bacitracin (0.04 U resistance = <10mm zone of inhibition) and susceptible to Furazolidone (100µg resistance = <15mm zone of inhibition).

Further biochemical testing is needed to identify down to the species LEVEL

Genomics and molecular biology

The first S. aureus genome
Genome

In classical genetics, the genome of a diploid organism including eukarya refers to a full set of chromosomes or genes in a gamete; thereby, a regular somatic cell contains two full sets of genomes....
s to be sequenced where those of N315 and Mu50 in 2001. Many more complete S. aureus genomes have been submitted to the public database
Database

A database is a structured collection of records or data that is stored in a computer system. The structure is achieved by organizing the data according to a database model....
s, making S. aureus one of the most extensively sequenced bacteria. The use of genomic data is now widespread and provides a valuable resource for researchers working with S. aureus. Whole genome technologies such as sequencing projects and microarray
Microarray

Different kinds of biological assays are called microarrays:*DNA microarrays, such as cDNA microarrays and oligonucleotide microarrays*MMChips, for surveillance of microRNA populations...
s have shown there is an enormous variety of S. aureus strains. Each contains different combinations of surface proteins and different toxin
Toxin

A toxin is a poisonous substance produced by living cells or organisms. For a toxic substance not produced by living organisms, "toxicant" is the more appropriate term, and "toxics" is an acceptable plural....
s. Relating this information to pathogenic behaviour is one of the major areas of staphylococcal research. The development of molecular typing methods has enabled the tracking of different strains of S. aureus. This may lead to better control of outbreak strains. A greater understanding of how the staphylococci evolve, especially due to the acquisition of mobile genetic elements encoding resistance and virulence genes is helping to identify new outbreak strains and may even prevent their emergence.

See also

  • Staphylus
    Staphylus

    Staphylus is almost always associated with Grapes or wine. In Greek mythology, he was:# The son of wine-god Dionysus and Ariadne. In this version the marriage of Dionysus with Ariadne is localized on the island of Naxos Island near Crete....
  • Staphylococcus aureus
    Staphylococcus aureus

    Staphylococcus aureus is the most common cause of staph infections. It is a spherical Bacteria, frequently found in the nose and skin of a person....
  • MRSA