inpatient / infectious disease

Urinary Tract Infection (UTI) and Pyelonephritis

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If You Remember Nothing Else

UTI is commonly treated in the outpatient setting, but in those at risk, is the most common cause of septic shock. UTIs are commonly caused by gram negative bacteria and (provided the patient isn't septic) the inpatient treatment reflects this (cephalosporins, fluoroquinolones). Look for pyuria and symptoms (including AMS). Asymptomatic pyuria or colonization (i.e in those with indwelling catheters) is usually not treated. A UTI is complicated if the patient is male, has hardware, recent procedure or catheter, renal failure or transplant, diabetes, and immunosuppresion.
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Clinical Pearls

• UTIs are the most common infection leading to septic shock; 40% of women will have a UTI sometime in their lives
• UTI is only when bacteria are in the urinary tract AND are causing inflammation leading to clinical symptoms, otherwise can represent colonization and no underlying infection; note that AMS in patients (especially the elderly) should be considered a possible symptom of UTI
• Pyruria is if >=5-10 WBC on UA microscopy - this is the most important part of the diagnosis; If neutropenic, possibly will not see pyuria on the dip
• Symptoms of UTI are more commonly atypical in the elderly (e.g., back pain, pelvic pain, constipation, urinary incontinence, and altered mental status).
• Asymptomatic bacteriuria or pyuria should not be treated UNLESS pregnancy, recent renal transplant, or planning to undergo a urologic procedure
• Cystitis is considered a “lower” UTI and generally felt to hold lower risk in those without anatomic or function concerns; “upper” UTI is more likely to be complicated and involve renal parenchyma
• In order for cystitis to be considered complicated, only one of the following needs to be present: Male, Urinary catheter within last 48 hours, Presence of stent, nephrostomy tube, or urinary diversion, Recent urinary tract instrumentation, Pregnancy, Renal failure, Renal transplantation, Diabetes, Immunosuppression, Symptoms for ≥ 7 days before seeking care, Hospital-acquired infection
• If dipstick has both nitrite and LE positive, sensitivity is 68-88%; enteobacterales (E. Coli) convert nitrate to nitrite; however, note that dipstick is not always helpful
• Seeing bacteria on UA is pretty much useless since there is almost always some contamination from clean catch
• Common UTI bugs include E. Coli (80%), Klebsiella (3%), proteus, staph saprophyticus (10%) - these numbers are likely different in the inpatient setting
• If you see staph aureus in urine, think bacteremia; If see candida on urine culture its usually a contaminant
• The most common risk is intercourse in women 15-30 years old; more common risks in older women include prolapse, loss of normal flora
• Pyelonephritis is a complicated UTI which can further be complicated by abscess; Pyelonephritis is being called more often now on CTAP scans
• There is a risk of developing vulvovaginits (espeically yeast infection) after being treated with abx for UTI
• If you see hematuria, consider adenovirus, CMV, and BK virus as causes of hemorrhagic cystitis
• Alkaline urine pH >8 can suggest proteus, klebsiella, and staph saprophyticus which can all cause struvite crystals
• Interstitial cystitis or “painful bladder syndrome” is chronic cystitis-like pain without etiology, pain often relieved with voiding and worsened by bladder filling - generally clinical diagnosis and associated with anxiety, depression, fibromyalgia - can treat with bladder training, therapy, PT, amitriptyline
• All catheters will eventually become colonized with bacteria so a positive urine dip and even a positive urine culture in such patients means very little

Trials and Literature

• Complicated Urinary Tract Infections (STATPearls, 2022)

Other Resources

• Clinical Problem Solvers - UTI Dx Schema