Hello and thank you for your question.
That is great that you went directly to a clinic for treatment once you were named as a contact to a case of Chlamydia. It is true that if it was only 36 hours after the potential exposure it would have likely been too early for the Chlamydia to show up positive on an STI test as the test is checking for your body’s antibody response to the bacteria and that time interval wouldn’t have given the body enough time to build enough of an immune response to be detectable on the test. That said, treatment is appropriate at this time as the antibiotic it will still kill off the Chlamydia bacteria. Please hold off from having sex for 7 days after treatment as it takes that long for all of the bacteria to be killed.
Let us know if this does not answer your question or if you have any more questions or concerns.