Tag Archives: chlamydia

Sterile Pyuria: Horses for Courses

Open most microbiology textbooks (particularly the older ones) and you will find tuberculosis high on the differential diagnosis of sterile pyuria.

This might be true in some parts of the world, but I suspect in a lot of places, and certainly where I work in New Zealand, renal tuberculosis is an extremely rare cause of sterile pyuria.


I would estimate about 1 in 1000 cases of sterile pyuria are due to TB here in NZ. There are much more common causes such as recently treated UTI, contamination with vaginal leucocytes secondary to chlamydia, candida infection, infection due to fastidious organisms etc etc.

GPs often reflexively order 3 Early Morning Urines for mycobacterial culture when they see a report suggesting sterile pyuria (because of those textbooks). In some areas of the world this might be appropriate, but in our lab in New Zealand, we like to see either repeated sterile pyuria results on the same patient or strong supporting clinical information before even accepting urines for TB culture.

Along the same lines if you have a young sexually active adult with sterile pyuria with no obvious cause, then excluding chlamydia should be at the forefront of your mind, and an appropriate comment to suggest this should always be added to such reports.

Horses for Courses….


I am away at a virus conference for the next few days…..