My 70 year old male patient is admitted with 1 day of fever, dysuria, and urinary frequency and urgency, but has a negative urine dipstick test for nitrites and leukocyte esterase. Could he still have acute bacterial prostatitis?

Short answer: Yes! In fact, no routine clinical imaging test can adequately rule out prostatic involvement in men with urinary tract infection (UTI) symptoms (1)! 

Although the presence of nitrites and leukocyte esterase (LE) may have a high positive predictive value for acute bacterial prostatitis (ABP) (~95%), their combined absence has a negative predictive value of only ~70%; ie, we may miss about one-third of patients with UTI symptoms if we relied solely on the results of nitrite and LE urine dipstick (2,3). Negative nitrites alone has a negative predictive value of only ~ 45%, while a negative LE has a negative predictive value of ~60% (3).

To evaluate for ABP, our patient should undergo rectal exam for prostatic tenderness, as should all men with UTI symptoms. The finding of a tender prostate in this setting is supportive of ABP, although its absence will still not rule out this diagnosis because the reported sensitivity of rectal exam may vary from 9% to 100% in ABP (1). 
Although there may not be a general agreement on the definition of ABP, 2 studies utilizing indium-labeled leukocyte scintigraphy or a combination of PSA levels and transrectal ultrasound have provided evidence for frequent prostatic involvement in men with UTI symptoms (4,5).  In these studies, an inflammatory reaction within the prostate was seen in the majority of cases, even when the digital rectal examination was not painful or when clinicians diagnosed pyelonephritis without prostatitis.
Bonus pearl: Did you know that the lifetime probability of a man receiving a diagnosis of prostatitis is >25% (1)? 

Also see a related P4P pearl: https://pearls4peers.com/2017/07/27/should-male-patients-with-suspected-urinary-tract-infection-routinely-undergo-a-prostate-exam/

 

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References
1. Etienne M, Chavanet P, Sibert L, et al. Acute bacterial prostatitis: heterogeneity in diagnostic criteria and management. Retrospective multicentric analysis of 371 patients diagnosed with acute prostatitis. BMC Infect Dis 2008, 8:12 doi:10.1186/1471-2334-8-12. https://bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-8-12
2. Lipsky BA, Byren I, Hoey CT. Treatment of bacterial prostatitis. Clin Infect Dis 2010;50:1641-1652. https://academic.oup.com/cid/article/50/12/1641/305217
3. Etienne M, Pestel-Caron M, Chavanet P, et al. Performance of the urine leukocyte esterase and nitrite dipstick test for the diagnosis of acute prostatitis. Clin Infect Dis 2008; 46:951-53. https://academic.oup.com/cid/article/46/6/951/351423
4. Velasco M, Mateos JJ, Martinez JA, et al. Accurate topographical diagnosis of urinary tract infection in male patients with (111)indium-labelled leukocyte scintigraphy. Eur J Intern Med 2004;15:157-61. https://www.ncbi.nlm.nih.gov/pubmed/15245717
5. Ulleryd P, Zackrisson B, Aus G, et al. Prostatic involvement in men with febrie urinary tract infection as measured by serum prostate-specific antigen and transrectal ultrasonography. BJU Int 1999;84:470-74. https://onlinelibrary.wiley.com/doi/full/10.1046/j.1464-410x.1999.00164.x

 

My 70 year old male patient is admitted with 1 day of fever, dysuria, and urinary frequency and urgency, but has a negative urine dipstick test for nitrites and leukocyte esterase. Could he still have acute bacterial prostatitis?

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