Cytobacteriological urine test: how to read it

This article arises from the following question in the Facebook group “Recurrent cystitis”:

“Is a cytobacteriological urine test with a polymorphic flora necessarily a sign of a contaminated one? I don’t have hematuria and 18,000 leukocytes (I usually have a lot of white blood cells in my urine). Thank you very much”.

The existence of an urinary tract infection or not based on the result of the cytobacteriological urine test is very delicate. It is equivalent to the interpretation of objective (laboratory and background analysis) and subjective (symptomatology, personal perception, smell and urine color, etc.) data to arrive at what could be defined as a diagnosis, that is to say, an act that falls within the medical competence and, therefore, must be left to the discretion of the doctor.

However, if we take some precautions, it is possible to use “tools” to try to “read” this situation as best as possible:

– the first thing is to get into the right perspective the results of the cytobacteriological urine test with the symptomatology

While it is true that abacterial cystitis is identical in all aspects to urinary tract infection in its symptomatology, the fact is that the interpretation of the results of this test should be contextualized with the reasons that led the person to perform it.

It should be remembered that the current recommendations do not advise systematic antibiotic therapy in case of asymptomatic bacterial cystitis.

presence of leukocytes

This first parameter is extremely difficult to interpret since leukocytes do not necessarily increase in parallel with the germ count, but rather are markers of the immune response:

– specific immune response -> directed against a pathogen (case of urinary tract infection)

– non-specific immune response -> in response to aggression, irritation, bladder or pelvic solicitation, pelvic inflammatory event (abacterial cystitis but also post ovulation, sexual intercourse, vaginal atrophy or vaginitis, etc.)

For these reasons, significant leukocyturia should always be “taken with a pinch of salt” and should be contextualized with the general framework, symptoms and culture results.

NB: in practice, it is completely possible to have significant leukocyturia without infection or, otherwise, absence of significant leukocyturia in the presence of uropathogenic germs.

presence of red blood cells

Microscopic hematuria corresponds to the presence of red blood cells in the urine and, although it is very impressive to see, is a parameter that is not necessarily correlated with the “severity” of the situation.

In case of significant hematuria, we can assume an alteration of the bladder wall. This idea is reinforced by the presence of epithelial cells in the sample. It is a sign of a form of abrasion of the bladder wall (urothelium) in case of urothelial “suffering”.

polymorphic bacteriological culture

This is the only ambiguous situation that requires a bit of lucidity since this result can be a sign of different situations:

-> contamination of the urine sample with or without an ongoing infection (one thing does not exclude the other)

-> an infection backed by the presence of a polymicrobial biofilm (which combines several bacterial strains)

-> an infection with atypical germs (mycoplasmas or ureaplasmas)

-> urethritis

In all cases, the ECBU should be repeated.

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