With a high clinical suspicion of pyelonephritis (costa-vertebral pain, fever, chills, dysuria), a urinalysis and urine cultures are obtained, in addition to other diagnostic test. The urinalysis is positive for macro-hematuria, and protein, but negative nitrates. The urine culture showed absolutely no growth. What could the potential reasons for the non-growth be? Can a delay in transport, inadequate storage, or inadequate temperature cause this? Or is there some other explanation?
Thank you Niklas for the quick response.
Yes, the patient had Leukocytes in the urine, which was taken before starting Ciprofloxacin i.v. Too my knowledge, no "Hemmstofftest" was performed. Also, no compromise of urinary function is present, although the last creatinine was increased from .76 to .9, although urinary output is adequate and clear.
Once I get more information, I will post it here.
We use to have same problem. According my experience the antibiotic concentration is critical as said Niklas. The kind of culture media is important. If there is bacteriuria you can see by microscopy even in wet mount or Gram stain. I use to compare this two results.
Ciprofloxacin is very powerful.
other important factor the patient must collect middle urine not first or last part of urine.
TryTry again....Age and history of the patient need to be considered. STD's can cause uti symptoms as can prostatitis in men. You may need to collect a genital swab for culture and/or PCR for exclusion of eg. Ureaplasma, chlamydia/gono etc.
Thank you all for the feedback. The patient was young, did not have any STD's nor any underlying pathologies, basically healthy, except for a strong clinical suspicion of Pyelonephritis. The patient underwent an MRI, which apparently confirmed this finding. Also, Ciprofloxacin was traded for Meropenem, due to persisting Fever and Leukocytosis. First day after Meropenem, the leukocyte concentration has decreased, and the patient reports feeling "better" (ie no fever, increased apetite). What is still puzzling though is the negative Urine Culture. How can that occur? Furthermore, what are the temperature ranges considered for "freezing" and "boiling" in a urine culture specimen?
Dear Michael Nordine
Since you indicated that the urine was collected before you initiated antibiotics, then growth is expected bearing in mind that there should also be normal flora in urine. From my experience, if one is sterilising the culture loop by heating, then insufficient cooling of loop may destroy/ burn the organism when transfering it from urine jar onto culture media thus nothing is likely to grow. This is more of technical error. Probably repeat culture taking into account such possible errors.
Are you sterilising your loop by heating or are you using sterile disposable loops?
Hello everyone and thank you for the feedback.
I wish I could give more information regarding the circumstances of this case. Im not directly involved in the care, but rather I am following the case, and RG is always a good platform to turn to to get rapid informed information.
Blood cultures were surprisingly not performed. I am unaware of how the urine was collected (mid-stream I suppose), nor how the urine was stored and transported after collection. Also I am unaware of how the laboratory performed there diagnostics. I would imagine a second collection is in order, possibly via catheterization. The patient has improved clinically on a second day of Meropenem (is afebrile, can freely move without complaints, no dysuria, negative shock index), and should be discharged pending completion of i.v antibiotics.
Oh last update, the patient does report moderate right flank pain still, but other than that, reports no other symptoms.
Pyuria without bacteriuria may be seen in truma,stone disease,tumor and AFB.other hand in patients with UTI which get antibiotics before urine specimen and or overhydration.
Dear Michael,
A simple mistake could be collection into the wrong collection vessel, one that contained a bacterio static agent. In clinical chemistry I have to make sure bacterial contamination doesn't intefere ....as already detailed Early and first void urine are usually taken for culture as it is more likely to containn bacteria..that is why Mid-Stream urine is generally good for Clin Chemistry measurements but not great for bacterial culture. The attached link is a nice small article on preanalytical errors in urine analysis
http://www.specimencare.com/main.aspx?cat=711&id=62747
Check if patient is on antibiotic therapy. This can lead to zero growth.
I really agree with Rajinder. Gram stain is a simple test we can see bacteria in urine
It's pretty normal for a well obtained and processed urine sample to b free of bacteria as urine is normally sterile, are you sure the patient suffers from UTI? If not, the chills and fever may be due to a resolving infection if the patient is on antibiotics, or in other words the bacterial cells are present but dead, why not try a gram stain or western blotting!
Please check following 2 articles:
1.“Sterile Urine” and the Presence of Bacteria A. J. Wolfe, PhD.1 and L. Brubaker, MD MS2 1Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Chicago IL USA 2Departments of Obstetrics & Gynecology and Urology, Stritch School of Medicine, Loyola University Chicago, Chicago IL USA
2.Lindsay E Nicolle, Kalpana Gupta, Suzanne F Bradley, Richard Colgan, Gregory P DeMuri, Dimitri Drekonja, Linda O Eckert, Suzanne E Geerlings, Béla Köves, Thomas M Hooton, Manisha Juthani-Mehta, Shandra L Knight, Sanjay Saint, Anthony J Schaeffer, Barbara Trautner, Bjorn Wullt, Reed Siemieniuk. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of Americaa. Clinical Infectious Diseases, 2019; DOI: 10.1093/cid/ciy1121
Thank you
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