“A simple approach to uncomplicated UTI”

We have a “no clinical details-no test” policy at my lab, so in general, we get accompanying clinical details with the vast majority of samples received for microbiology testing. After all, at the end of the day, clinicians just want their requests processed…

This is great, but it always irritates me slightly when we get a urine sample into the laboratory from a young adult female with symptoms of a straightforward cystitis with no supporting clinical information to suggest that a “complicated UTI” is being queried.

My first reaction when seeing this is “Why are you sending this urine sample to the lab? Do you think this is going to help your patient?”

In New Zealand, and I suspect most of the rest of the world, uncomplicated UTIs are treated empirically according to local antibiograms, usually with a short course of nitrofurantoin or trimethoprim. In most cases, this settles things down, and no further medical input is required.

We receive approximately 400 urine samples for microbiology processing into our lab each day. My rough estimate is that 5-10% of these urines have clinical details that suggest an uncomplicated UTI. It doesn’t sound much, but it certainly adds up over the course of a year, and the total cost of processing all these would likely cover a scientist’s salary.

...And if we received urine cultures into the lab on every uncomplicated UTI diagnosis, then we would be completely overwhelmed!

During the early stages of the COVID pandemic, when we were getting hammered by SARS-CoV-2 PCR requests, we urged clinicians to send us critical samples only. This certainly reduced the number of requests where the clinical details suggested uncomplicated UTI. But old habits die hard, and now we are more or less back to baseline.

I have often wondered whether we should only accept urines where the clinical details are suggestive of a complicated UTI, but we have not gone there yet. Some might wonder if such an approach is too “hardline”, but it remains an option and I think a very reasonable one at that.

People sometimes think diagnostic stewardship is all about optimising the use of very expensive laboratory tests, e.g multiplex PCR assays, but in actual fact, looking after less costly but higher volume tests such as urine culture is every bit as important…


4 thoughts on ““A simple approach to uncomplicated UTI”

  1. On the flip side we underprocess about the same number. We need to find ways to sort the wheat from the chaff. Clinical details are key. Maybe just measuring pyuria if not obviously complicated would be good? Easy fast and cheap. Need to think of ways of getting unbiased epidemiology too.

    1. Yes, an (automated) microscopy only approach might be an option for uncomplicated urines. Before processing we review the clinical details to check i) if the clinical details justify processing and ii) to check if the sample should proceed to culture regardless of the leucocyte count, e.g. pregnancy, immunocompromise, pre-urological surgery. We would just need to add an extra step/piece of logic to ensure that for uncomplicated urines, they proceed to IRIS microscopy but don’t proceed to culture on Kiestra, regardless of the leucocyte count. I am thinking aloud here! Thanks for comments.

  2. We also perform automated UF500 microscopy on all samples except defined patient populations similar to what you mentioned, we additionally include all children. We require presence of both bacteria and leuckocytes to proceed to culture based on our validation data. I lean towards continuing to include uncomplicated UTI for culture and sensitivity testing, it ensures our yearly antibiogram data isn’t skewed towards complicated/treatment failure UTI and served as a reminder to clinicians on the reports that the narrow spectrum antibiotics do work! Plus once clinicians figure out that clinical details of “uncomplicated UTI” ‘result in no test they might become unlikely to write that, or maybe I’m just overly cynical

    1. Yes, we suspect this happens for other sample types, such as faeces, sputa and ear swabs, where requestors are aware which specific clinical details will allow processing of the sample. One must accept that people will always play the system to some extent! Thanks for comments.

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