hi...thanks for writing...i have understood your concerns... your mother is in late stage of dementia..but why the doctor suspected UTI? whether she has fever, any complaints of itching or burning sensations in the urine? u shud go for total WBC count in blood investigation and see if they are increased or not..in case of active infection the neutrophils are more than 80%..so look for that..u can treat her blindly with floroquinolones like levofloxacin...be cautious while using it, allergic reaction may occur.. there are tests don in dermatology for detecting the allergic reaction to variuos drugs...can go for that.. flagyl does not help in UTI.. so there is no need of using it... the stage of your mother predisposes her to delirium..and all the symptoms can be explained by the delirium..if there is nothing that causing problem [like infection, nutritional deficiency etc..], then it is a part of normal course of the dementia..in late stages of dementia, due to significant cognitive decline, person repeatedly goes into delirium..u can learn more about delirium from the internet... during moderate to severe dementia, the patient has behavioral and psychological symptoms [BPSD] and it includes variety of symptoms, the fearfullness, suspiciousness and all other symptoms can be explained by it..so read BPSD also... there are no medications for dementia..in ate stages all we have is supportive and palliative care with behavioral management..so attend alzheimer s support groups..there are groups running for caregivers also... for the sample collection..remove the old catheter and when the new catheter is inserted, the urine that comes u shud collect it in a container and send it for urine routine and microscopy and another sample for culture and sensitivity..collect in two different containers... i hope u ll find this advice helpful..best luck...