Rectal swab in hospital.

Last year I had to spend a few days in hospital during the lockdown. I was tested for Covid-19 while I was still in the A & E department, and it was negative. However, when I got up to the ward, before I was even let in I was subjected to a rectal swab. Does anyone know what this could be all about? I have asked the hospital, but so far I haven't had a reply.

At least, in Germany, Hospitals are kind of afraid of MRSA https://en.wikipedia.org/wiki/Methicillin-resistant_Staphylococcus_aureus, which causes many deaths in hospitalized patients. Could be the same in the UK:

I had a rectal swab taken. The doctor wanted to test me for antibiotic efficacy . They were afraid of sepsis

I was on a very strong antibiotic drip, so it could have been as jackacorn has suggested. But it could also have been for MRSA as Nagus suggests because we do have an MRSA problem as well, mostly people catching it in hospital rather than bringing it in.

Usually they are testing for MRSA.