No it would not. A routine blood check for hematology would probably show a raised white cell count, CRP and sed rate, which are all possible indicators of infection. If all these were found in a routine blood test, then they would have to do further testing to isolate the organism causing the infection.
If it is a viral infection, then this will not show up on a blood test, however, if bacterial then blood cultrues would need to be done to isolate the organism, be it Staph or something else. Skin or throat swabs would also need to be taken and also swabs of any wound. Staph is most likely to occur in the throat, the skin or in wounds, so all these need to be cultured and wound swabs sent for M,C and S to isolate the organism.
If you had a Staph infection, you would probably be unwell also with a fever and other symptoms.
Hope this helps?
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staph aureous (sepsis) 
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