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The coagulase test has traditionally been used to differentiate Staphylococcus aureus from coagulase-negative staphylococci. S.aureus produces two forms of coagulase (i.e., bound coagulase and free coagulase). Bound coagulase, otherwise known as "clumping factor", can be detected by carrying out a slide coagulase test, and free coagulase can be ...
However, not all S. aureus strains are coagulase-positive [20] [22] and incorrect species identification can impact effective treatment and control measures. [ 23 ] Natural genetic transformation is a reproductive process involving DNA transfer from one bacterium to another through the intervening medium, and the integration of the donor ...
These species belong to two separate groups – the S. aureus (S. aureus alone) group and the S. hyicus-intermedius group (the remaining five). An eighth species has also been described – Staphylococcus leei – from patients with gastritis. [19] S. aureus is coagulase-positive, meaning it produces
S. epidermidis, a coagulase-negative staphylococcus species, is a commensal of the skin, but can cause severe infections in immune-suppressed patients and those with central venous catheters. S. saprophyticus , another coagulase -negative species that is part of the normal vaginal flora , is predominantly implicated in uncomplicated lower ...
[20] [8] Colonies of S. pseudintermedius on sheep agar are described as medium in size and non-pigmented or grey-white. [20] [8] This can be useful for differentiating S. pseudintermedius from coagulase-negative staphylococci, and from S. aureus which tends to be yellow and displays more variable hemolytic patterns on agar.
It is now widely recommended by national and international bodies for the isolation of coagulase-positive staphylococci. [5] Baird-Parker agar is commonly used as a method for the enumeration of coagulase-positive staphylococci (Staphylococcus aureus and other species) in food and animal feedstuffs. [6]
Resistance to antibiotics in S. aureus can be quantified by determining the amount of the antibiotic that must be used to inhibit growth. If S. aureus is inhibited at a concentration of vancomycin less than or equal to 4 μg/ml, it is said to be susceptible. If a concentration greater than 32 μg/ml is necessary to inhibit growth, it is said to ...
It can be produced by Clostridium perfringens, Staphylococcus aureus, Pseudomonas aeruginosa or Listeria monocytogenes. C. perfringens alpha toxin (lecithinase) causes myonecrosis and hemolysis. The lecithinase of S. aureus is used in detection of coagulase-positive strains, because of high link between lecithinase activity and coagulase activity.