staphylococcus aureus

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Staphylococcus aureus is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe that can grow without the need for oxygen. Although S. aureus usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins, and the expression of a cell-surface protein that binds and inactivates antibodies. S. aureus is one of the leading pathogens for deaths associated with antimicrobial resistance and the emergence of antibiotic-resistant strains such as methicillin-resistant S. aureus (MRSA) is a worldwide problem in clinical medicine. Despite much research and development, no vaccine for S. aureus has been approved.

An estimated 20% to 30% of the human population are long-term carriers of S. aureus which can be found as part of the normal skin flora, in the nostrils, and as a normal inhabitant of the lower reproductive tract of women. S. aureus can cause a range of illnesses, from minor skin infections, such as pimples,impetigo, boils, cellulitis, folliculitis, carbuncles, scalded skin syndrome, and abscesses, to life-threatening diseases such as pneumonia, meningitis, osteomyelitis, endocarditis, toxic shock syndrome, bacteremia, and sepsis. It is still one of the five most common causes of hospital-acquired infections and is often the cause of wound infections following surgery. Each year, around 500,000 patients in hospitals of the United States contract a staphylococcal infection, chiefly by S. aureus. Up to 50,000 deaths each year in the United States are linked with S. aureus infections.

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classificationsstaphylococcus aureustypes
  1. Dr Md shahriar kabir B H M S; MPH
    Dr Md shahriar kabir B H M S; MPH Enlightened dr.basuriwala

    The genus Staphylococcus consists of Gram-positive, non-spore-forming cocci that are often found as normal human microbiota of the skin and nasal cavity. There are five organisms to consider as potential human pathogens in this genus: 1. S. aureus 2. S. epidermidis 3. S. saprophiticus 4. S. haemolytRead more

    The genus Staphylococcus consists of Gram-positive, non-spore-forming cocci that are often found as normal human microbiota of the skin and nasal cavity. There are five organisms to consider as potential human pathogens in this genus:
    1. S. aureus
    2. S. epidermidis
    3. S. saprophiticus
    4. S. haemolyticus, and
    5. S. hominis.

    The major test reaction to use in Staphylococcus identification is the coagulase test reaction, which divides the genus Staphylococcus into 2 groups:
    1. Coagulase-negative species, and
    2. Coagulase-positive species.
    The test media that you will run for identification depends on which category your organism falls in.

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Asked: 6 years agoIn: , , ,
Nasim

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staphylococcus aureus
  1. Dr Md shahriar kabir B H M S; MPH
    Dr Md shahriar kabir B H M S; MPH Enlightened dr.basuriwala

    Staphylococcus bacteria can cause a wide range of infections, from minor skin infections to life-threatening illnesses. Some of the diseases that can be caused by Staphylococcus include: 1. Boils, 2. Impetigo, 3. Food poisoning, 4. Cellulitis, 5. Toxic shock syndrome. 6. Skin infections, 7. PneumoniRead more

    Staphylococcus bacteria can cause a wide range of infections, from minor skin infections to life-threatening illnesses. Some of the diseases that can be caused by Staphylococcus include:
    1. Boils,
    2. Impetigo,
    3. Food poisoning,
    4. Cellulitis,
    5. Toxic shock syndrome.
    6. Skin infections,
    7. Pneumonia,
    8. Endocarditis, and
    9. Osteomyelitis.

    Symptoms of a staph infection vary depending on the location and severity of the infection. For example, a localized staph infection may cause a collection of pus, such as a boil or abscess. The area may be tender or painful and may be reddened and swollen.

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staphylococcus aureus
  1. Dr Md shahriar kabir B H M S; MPH
    Dr Md shahriar kabir B H M S; MPH Enlightened dr.basuriwala

    Staphylococcus aureus is a bacterium that produces a variety of toxins and enzymes, many of which are virulence factors. Among the more common toxins secreted by S. aureus are hemolysin, leukotoxin, exfoliative toxin, enterotoxin, and toxic-shock syndrome toxin-1 (TSST-1). Aside from toxins, staphylRead more

    Staphylococcus aureus is a bacterium that produces a variety of toxins and enzymes, many of which are virulence factors. Among the more common toxins secreted by S. aureus are hemolysin, leukotoxin, exfoliative toxin, enterotoxin, and toxic-shock syndrome toxin-1 (TSST-1). Aside from toxins, staphylococcal virulence factors also include enzymes and surface proteins.

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diagnosislab diagnosisstaphylococcus aureus
  1. Dr Md shahriar kabir B H M S; MPH
    Dr Md shahriar kabir B H M S; MPH Enlightened dr.basuriwala

    Medical laboratory diagnosis: The primary objective in laboratory diagnosis is to identify whether the diagnosed S. aureus isolate is methicillin-resistant. Since MRSA emerged as a problematic pathogen, a systematic diagnostic approach is necessary for early diagnosis so that treatment with appropriRead more

    Medical laboratory diagnosis:
    The primary objective in laboratory diagnosis is to identify whether the diagnosed S. aureus isolate is methicillin-resistant. Since MRSA emerged as a problematic pathogen, a systematic diagnostic approach is necessary for early diagnosis so that treatment with appropriate antibiotics can be initiated as early as possible. For species identification, slide and tube coagulase tests, latex agglutination tests, and PCR-based tests are used. For detection of MRSA, determination of minimum inhibitory concentration (MIC) of methicillin or oxacillin or cefoxitin using broth micro-dilution method, cefoxitin disk screen, oxacillin agar screen and latex agglutination test for PBP2a and molecular methods for detection of mecA are employed.

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morphologystaphylococcus aureus
  1. Dr Md shahriar kabir B H M S; MPH
    Dr Md shahriar kabir B H M S; MPH Enlightened dr.basuriwala

    1. Microscopic morphology: S. aureus cells are Gram-positive and appear in a spherical shape. They are often in clusters resembling a bunch of grapes when observed under a light microscope after Gram staining. The name ‘Staphylococcus’ was derived from Greek, meaning a bunch of grapes (staphyle) andRead more

    1. Microscopic morphology:
    S. aureus cells are Gram-positive and appear in a spherical shape. They are often in clusters resembling a bunch of grapes when observed under a light microscope after Gram staining. The name ‘Staphylococcus’ was derived from Greek, meaning a bunch of grapes (staphyle) and berry (kokkos). The scanning electron microscopic observation reveals roughly spherical-shaped cells with smooth surfaces. The diameter of the cells ranges from 0.5 to 1.0 μM. The transmission electron microscopy of cells shows a thick cell wall, distinctive cytoplasmic membrane, and amorphous cytoplasm.

    2. General cultural and biochemical characteristics:
    S. aureus is an aerobic and facultative anaerobic organism that forms fairly large yellow or white colonies on nutrient-rich agar media. The yellow colour of the colonies is imparted by carotenoids produced by the organism. The term ‘aureus’ is derived from Latin, which refers to the colour of gold. The organism is often haemolytic in blood agar due to the production of four types of haemolysins (alpha, beta, gamma, and delta). Nearly all isolates of S. aureus produce coagulase enzyme, a virulence factor that also helps in the identification of the organism. The organism is salt tolerant and is able to grow in a mannitol-salt agar medium containing 7.5% sodium chloride. The organism is catalase-positive and oxidase negative.

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