Med Lab Science: Testing times in the laboratory?

While testing a blood sample for haemoglobin levels, your colleague and good friend accidentally spills some of the sample and some of the blood falls onto her arm. A few days previous she had scratched a mosquito bite and she notices that it has created a small open wound. While the amount spilt is very minimal, it is standard procedure to test the sample for HIV and Hepatitis B due to the possibility of transmission to the laboratory worker.
Your colleague comes to you for advice. She tells you what has happened but then tells you that since you two are alone in the laboratory, she plans to test the sample herself but without seeking consent from the provider of the blood sample. She is concerned that she could be severely reprimanded by her supervisor, if found out, as only last week the laboratory received a training session on safety and consent for use in such situations.
You agree to help and to test the blood sample. It tests positive for hepatitis B and while your colleague has been immunised against this as part of her employment contract you are now unsure as to whether you should contact the patient. They will not have given consent for the test but you can see that they may want to know this information. At the same time you do feel some degree of loyalty to your friend and colleague to keep quiet.
What should you do?