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DNAse and Catalase useful to pathogens?How why? - Really confusing! (Dec/14/2008 )

I am really struggling to understand why DNAse and Catalase are useful enzymes for pathogens to have? This comes while considering physiological characteristics of bateria and while using various test like DNAse test, catalase test, oxidase test etc.

Really appreciate any help. Many thanks. rolleyes.gif



You can download this article about identification of pathogenic bacteria, namely Staph aureus, in which DNase and coagulase are determinants. You can refer to the references to get more info. NOTE that DNase (increased activity in pathogenic) is meant as a means to differentiate between pathogenic vs non-pathogenic bacteria. DNase do not cause pathogenesis, but it does help us determine pathogenic Staph vs non-pathogenic. In other word, it differentiate the character of pathogenic bacteria vs not pathogenic.

Whereas for the catalase, read this article
GrĂ¼ner BM, Han SR, Meyer HG, Wulf U, Bhakdi S, Siegel EK, 2007. Characterization of a catalase-negative methicillin-resistant Staphylococcus aureus strain. J Clin Microbiol 45(8):2684-2685

NOTE: Production of catalase is important in the metabolism of cytotoxic hydrogen peroxide into water and oxygen. You see, H2O2 is produced by our defence system (namely white blood cells) to combat infection. If Staph has catalase activity, H2O2 will be well tolerated, therefore more virulence in the sense that they will survive the oxidative attack brought about by white blood cells.

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