How many strains of Staphylococcus epidermidis are there?

aureus by lacking the enzyme coagulase. The species shows a high degree of diversity with 74 identified sequence types (STs)6.

Are there pathogenic strains of S. epidermidis?

Further studies have indicated that clinical strains of S. epidermidis were pathogenic, virulent and invasive after intraperitoneal infection in mice causing macroscopic pathological changes in the spleen, kidney, liver, and the peritoneum [9].

Does S. epidermidis have DNase?

epidermidis or other DNase negative staphylococci, and for the differentiation of Serratia from Klebsiella/Enterobacter. 3-5 Organisms other than Staphylococcus aureus and Serratia marcescens may be DNase positive.

What tests are used to identify Staphylococcus epidermidis?

Tests for clumping factor, coagulase, hemolysins and thermostable deoxyribonuclease are routinely used to identify S aureus. Commercial latex agglutination tests are available. Identification of S epidermidis is confirmed by commercial biotyping kits.

How do you identify Staphylococcus epidermidis?

Identification. The normal practice of detecting S. epidermidis is by using appearance of colonies on selective media, bacterial morphology by light microscopy, catalase and slide coagulase testing. On the Baird-Parker agar with egg yolk supplement, colonies appear small and black.

Is Staphylococcus epidermidis DNase positive or negative?

Biochemical Test and Identification of Staphylococcus epidermidis

Are there any staphylococci that cannot be tested for DNase?

Limitation of DNase Test. Some MRSA strains do not give positive DNase test result and some strains of the coagulase-negative staphylococci such as Staphylococcus capitis may give weak reactions. Serratia and Moraxella species also produce deoxyribonuclease. 1N HCl is bactericidal for Staphylococci.

How is DNase used to detect Stenotrophomonas maltophilia?

To detect this enzyme, first, the organisms are destroyed by heat, and then the free DNase reacts with the medium. Gram-negative bacilli that are suggestive of Stenotrophomonas maltophilia (positive) and are colistin or polymyxin B resistant to separate from Burkholderia cepacia (negative).

What is the purpose of a DNA hydrolysis test?

Deoxyribonuclease (DNase) Test: Principle, Procedure and results. DNA Hydrolysis test or Deoxyribonuclease (DNase) test is used to determine the ability of an organism to hydrolyze DNA and utilize it as a source of carbon and energy for growth.

How is Staphylococcus aureus tested in developing countries?

Several laboratories in developing countries screen for presumptive Staphylococcus aureus based on growth on Mannitol salt agar (MSA) and/or DNase tests and confirmation is done with the TCT.