You must identify the pathogen tolerance to antibiotics and other bactericides first. Pseudomonas may have resistance to very different agents.  

Basically, there are two things to consider.

First, you are talking about bacteriuria. If your patient has no symptoms and no underlying risk factors (I guess, there are risk factors, however), an antimicrobial treatment may not be necessary.

However, if there is a need for treatment, you need a susceptibility test as mentioned already.  A calculated therapy might be risky and I would advocate to do check for the specific resistance pattern of the isolate to ensure appropriate therapy.

Recurrent Pseudomonas bacteriuria should be not treated with antibiotic if non symptomatic. If symptomatic the AST is needed to treat .

Should it be an asymptomatic bacteriuria, treatment is not neccesary unless there are underlying risk factors.. Should you have a significant bacteriuria with symptoms, or risk factors associated, you would need an antibiogram, since P. aeruginosa susceptibility profile can be very variable.

Depending on the risk factors of the client (e.g. immune-suppression, malnutrition etc). Perform antimicrobial susceptibility test to determine resistance pattern before initiating any treatment.

As mentioned above asymptomatic bacteriuria will not require treatment, unless there are risk factors (pregnancy...etc). It would certainly require therapy prior to cystoscopy, which is considered a surgical procedure involving the urinary tract. Any predisposing factors that could be reveresed?

I usually follow the IDSA guidelines...  (which I understand are due revision)

• If is it a bacteriuria with no clinical risk, do  not require antibiotic treatment, but if there are some risk factors (diabetes, or other), the antibiotic susceptibility is a good guide, and ciprofloxacino or norfloxacino are indicated.

For nonsymptomatic with no risk factors, it is not necessary, If treatment is required susceptibility tests is necessary before treatment to make sure that ciprofloxacin is working.