Indication for urine culture within several unique UTI patient groups
74-year-old female presents with recurrent falls. She denies dysuria, urgency, incontinence, and frequency. A urinalysis sent from triage demonstrates 5 WBCs,trace LE, and 5 squamous cells, but nitrites are negative. A diagnosis of UTI is made. But does this patient really have a UTI, and should the work up be stopped based on this diagnosis?
Urine testing and assessment in the ED is a part of every shift. While urine cultures can provide important information for some patients, the majority of UTIs do not require cultures. These cultures provide little to no utility in the ED for routine UTIs. Literature demonstrates 80-95% of UTIs are due to E. coli.(1-6) In the setting of infection due to S. saprophyticus, enterococci, or group B streptococci, the typical antimicrobials used provide adequate treatment.
On a routine basis, cultures do not affect patient outcomes and do not change management (1-4). So when should you obtain a urine culture? Urine cultures are recommended for patients with complicated infection (basically anyone with a UTI who is not a nonpregnant, reproductive-aged adult female), pyelonephritis,those on recent antibiotic therapy, or those with continued symptoms who have failed antibiotics (1-3). UTI in a patient with simple UTI does not require urine culture. Let’s save the time of physicians everywhere and not order cultures unless they are specifically indicated.
The elderly patient with pyuria, bacteriuria, and UTI symptoms is straightforward. However, what happens
when symptoms are not present? Bacteria in the urine without symptoms of UTI defines asymptomatic bacteriuria (ASB), specifically in women with two consecutive clean-catch voided specimens consisting of one organismin > 105 cfu/mL and in men with one specimen and the same organism count.(2,7) This finding does not definitively diagnose UTI, and ASB rates increase with age.(7-9) One study found 5% of sexually active young women to have ASB.(10) Rates of ASB approach 25-50% of women and 15-49% of men without indwelling catheters.(11) These rates increase in the elderly due to altered elimination, anatomical variations of the urogenital tract, poor hygiene, hormonal changes, and neurologic impairment.(7)
Many of these organismsare not harmful but rather commensal organisms.(9) Asymptomatic UTI in the elderly patient is less common than ASB,(12) and ASB is not associated with poor long term outcomes including pyelonephritis, sepsis, and renal failure.(13) Clinical signs and symptoms of UTI are needed for
treatment, but many patients are not able to provide these.(9) Emergency physicians regularly evaluate older patients unable to provide history and exam. A study released in 2014 from JAMA recommended treatment for patients if they demonstrated bacteriuria and pyuria with two of the following: fever, worsening urinary frequency or urgency, acute dysuria, suprapubic tenderness, or costovertebral angle
tenderness.(14) Another possible formula to differentiate UTI and bacteriuria is the following: pyuria + bacteriuria + nitrites = infection; bacteriuria but no pyuria = colonization/bacteriuria; pyuria alone but no bacteria = inflammation.(15)
Patients undergoing instrumentation or surgery of the bladder may require antibiotics in the setting of bacteriuria alone.(16) Treating patients without true UTI can increase antimicrobial resistance, as well as expose patients to dangerous side effects and diseases such as C. difficile colitis.(7,17,18) In fact, antibiotics are used inappropriately in close to half of patients with ASB.(19) However, educational programs and knowledge of ASB can effectively reduce inappropriate treatment.(19)
OLDER PATIENTS WITH ALTERED MENTAL STATUS OR RECURRENT FALLS
Altered mental status, “the dwindles,” or recurrent falls in an elderly patient has a large differential.(9) The history and exam are often unrevealing, thus resulting in a fishing expedition with a net of tests. If UTI is a contributor, systemic signs or symptoms should be present, along with evidence of UTI such as dysuria.(20) In patients with clinical suspicion of UTI without a catheter, acute change in mental status was associated with bacteriuria and pyuria.(21)
However, several studies suggest falls without signs or symptoms of UTI are not associated with pyuria or bacteriuria.(22,23) It’s challenging to evaluate a patient with chronic dementia and falls or a patient who is altered and can’t provide a history of urinary symptoms. An exam evaluating for suprapubic or CVA tenderness in conjunction with UA canbe helpful, as UA with positive nitrites, pyuria, and bacteriuria
is suggestive of UTI.(9,15) In patients for which history and exam are unreliable but exhibit no other explanation for AMS, one study recommends using bacteriuria with other markers of systemic inflammation including fever/hypothermia, elevated WBC/CRP, elevated blood glucose in absence of diabetes, and acutely altered mental status to diagnose UTI and begin treatment.(24) If a urine dipstick
demonstrates negative LE and no nitrites, then UTI is not present.(24) Other causes of altered mental status (remember AEIOU TIPS) must be excluded before chalking altered mental status to UTI. If the patient meets criteria for sepsis or displays marker of inflammation and UA is consistent with UTI, then treatment is warranted.(9,24)
BACK TO OUR CASE
The patient displays normal mental status and denies urinary symptoms. She displays no other markers of systemic inflammation, is afebrile, and displays no CVA tenderness.You reconsider the diagnosis of UTI…
SPECIAL POPULATIONS: HARDWARE AND GU SURGERY
Urinary stents consist of an indwelling, hollow, endoluminal splint within the ureter to facilitate urine drainage from the kidney to the bladder.(25-27) Several indications include benign or malignant obstruction, urolithiasis therapy, perioperative management, and urinary leak.(25-27) These stents are associated with several complications, most commonly irritative symptoms in up to 80-90% of patients.(25,26)
Suprapubic pain is also common, as is hematuria. Complications include UTI, stent migration, encrustation, stent fracture, ureteral erosion/fistulization, incontinence, vesicorenal reflux, and inadequate relief of obstruction.(25-27)
UTI develops as a result of instrumentation or later as an underlying disease process, and organisms causing the infection are associated with development of a biofilm. Newer coatings and stent materials may reduce the risk ofinfection.(25,26) For patients with systemic findings of UTI or symptoms consistent with UTI in the setting of evidence on urinalysis/dipstick (pyuria, positive nitrites, positive LE), antibiotics are likely warranted. The patient should be discussed with urology as well.
PATIENTS WITH URINARY DIVERSION
Patients with obstruction – most commonly bladder carcinoma- may require diversion of the normal urogenital tract. Types of diversion include diversion with cystectomy versus diversion without.(28) The noncontinent urinary diversion consists of anastomosis of the ureters to one end of a segment of detached intestines, with the other end used for a stoma. The continent nonorthotopic diversion requires self-catheterization of the constructed intestinal pouch. The orthotopic urinary diversion consists of a
neobladder constructed from an intestinal segment anastomosed to native urethra.
Due to connection of the intestinal tract with the urinary tract, the normal urinary tract integrity is compromised, and a mixed population of gram-positive and gram-negative bacteria and yeast develop
in the conduit.(28,29) As a result, up to 23% of patients develop UTI, with pyelonephritis occurring in 11-20%.(28-31) Similar to patients with a ureteral stent, urinalysis/dipstick with pyuria/LE and nitrites and patient symptoms warrant consultation and treatment for UTI.
Patients with indwelling catheters often present to the ED with catheter-associated issues. Unfortunately, catheter-associated UTI (CA-UTI) is one of the most common nosocomial infections, defined by signs or symptoms of UTI with > 103 colony forming units/mL from a single catheter specimen or midstream voided specimen, andthe catheter must have been in place > 2 days.(32-36) Close to 100% of patients with indwelling Foley catheter are colonized by 2-5 organisms within 2 weeks (77% polymicrobial) of catheter placement.(9,32-34) The rate of bacteriuria from urinary catheter is close to 10% per day, and of these,10-25% of patients develop symptoms of UTI.(20,33-36)
CAUTI is also associated with significant risk of bacteremia.Close to 20% of hospital-acquired bacteremia comes from the urinary tract with mortality approaching 10%.(32,34,37) The presence of a urinary catheter is also a predisposing factor to septic shock with UTI,(38-41) and a greater number of patient comorbidities increases the risk of septic shock in patients with indwelling catheter.(42)
UTI in the setting of a catheter occurs with greater frequency in females, older patients, diabetes, bacteria colonization in the drainage bag, and errors in care of the catheter.(32,43-45) UTI can be extraluminal (66%) or intraluminal (34%), with extraluminal occurring from bacteria entry into the bladder from the catheter biofilm and intraluminal occurring due to urinary stasis or contamination of the collection
bag.(20,46-50) Signs and symptoms of CA-UTI include new or worsening fevers, rigors, altered mental status, malaise, lethargy, flank pain, CVA tenderness, new hematuria,and pelvic discomfort.(9,32) Fever is the most common symptom. Pyuria is not diagnostic, but the absence of pyuria strongly suggests a diagnosis other than CA-UTI.(9,32,51) If LE and nitrites are absent with < 10 WBCs/hpf, CA-UTI
can be excluded.(51)
Treatment is a little more complex than your run-of-the-mill UTI. The IDSA recommends obtaining a urine culture before treatment.(32) If the catheter has been in place for over two weeks at the time of the UTI and the catheter is needed, then the catheter should be replaced and urine obtained from the new catheter before antibiotics are provided.(9,32) Patients with signs and symptoms of UTI including fever and suprapubic pain or tenderness should be treated by removal of the catheter, if possible, and antibiotics.
Unfortunately due to the catheter, dysuria is not reliable alone for diagnosis of UTI. Overtreatment can result in selection of more resistant bacteria, and prophylactic therapy is not recommended for patients with long term catheters (more than 2 weeks).(9,32,51-54) Candiduria is also common in patients with catheters, most commonly due to colonization.(9,32,55) Treatment with antifungals is only needed in
specific situations including signs of infection and no other source of infection.(32,55) If the patient is immunocompromised (transplant patient or those receiving chronic steroids), candiduria should be treated with antifungals. Otherwise, conservative management with catheter exchange and observation is recommended.(52)
You closely go over the patient’s medication list, and she was recently placed on Ambien for difficulty sleeping. She is also on hydrocodone for chronic back pain. Her primary care physician is thankful for your close eye and is willing to see her tomorrow. You discuss the medications with the patient and counsel her to stop the Ambien. Her family feels comfortable with discharge and the follow-up plan.
With the patient having no symptoms, you decide against prescribing an antibiotic for the patient and discharge her home.
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