Hi Eddie
Would'nt worry too much if they've used a steamer prior to your visit it is likely any hazardous agents have been killed off. When dealing with any urine stains (human) it is always worth pre-treating with an anti-microbial just to make sure any bacteria or viruses have been dealt with, especially Hepatitis. Anti-microbial needs to be allowed to dwell for the specified time for that specific product, usually around ten minutes. It is then still advisable to take extra care, especially when emptying the tank on portables, how many times have you had a splash back on your face?
MRSA is an increasing problem in care homes, we sell air purifiers specifically designed to destroy MRSA, however the lack of knowledge and ignorance of the infection by the people concerned in the care of sufferers is frightening.
I would advise anyone carrying out work in care homes or hospitals for that matter to take extreme care and to use suitable PPE. Might seem over the top but these infections can cripple you for life. Just look at some of the MRSA forums on the web and you'll realise how common they are contrary to government statistics.