Hiba Siddig Ibrahim Mustafa
Background: Staphylococcus aureus is one of the most virulent gram positive bacteria. It produces a lot of toxins and enzymes, most of which are virulent factors. Among the enzyme that produces is the catalase which is very useful in differentiating staphylococci from streptococci [1]. Since the catalase is nearly ubiquitous among some of organisms that can grow in the presence of oxygen (air). It promotes the conversion of hydrogen peroxide, a powerful and potentially harmful oxidizing agent, to water and molecular oxygen; so the major function of catalase within cells is to prevent the accumulation of toxic levels of hydrogen peroxide formed as a by-product of metabolic processes - primarily that of the electron transport pathway [2].
Objectives: The main aim of this study is to prove that human WBCs can produce H2O2, this H2O2 when react with catalase producing S. aureus can easily be degraded to H2O + O2.
Methodology: In this study a total of 40 subjects were included. Aliquots of 2.5 ml of venous blood were collected by venous puncture after disinfectant the site of collection with 70% alcohol and the collected blood was drawn into EDITA containers (20 subject) and anticoagulant free containers (other 20 subject), centrifugation for 5 minute at 1500 RPM, then the separated sera and plasma were converted to new sterile eppendrof tubes and freezing until used (before used we will leaves the eppendrof tubes at room temperature for DE freezing). Standard catalase producing S. aureus were used by taking 1 colony from Mac- conkey media by using applicator wooden stick, and inserted in eppendrof tube, then after that waited for the appearance of air bubbles to indicate occurrence of the reactions.
Results: According to this study, it was proved that WBCs in human plasma or serum can produce H2O2, this H2O2 were reacted with colony of S. aureus to produce air bubbles and water when S. aureus producing catalase enzyme and so on there were no differences between using H2O2 or human plasma / serum that contains WBCs to detect and identify of S. aureus by both techniques
Conclusion: Based on the results of this study, we can use WBCs that were found in human plasma or serum to identify catalase producing S. aureus.
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