Uncomplicated UTIs

Acute Uncomplicated Cystitis and Pyelonephritis

A common presentation to every Emergency Department, but practice variation is amazing.  What does the literature show?

Acute cystitis refers to an infection of the bladder (lower track) and it can occur alone or in conjunction with pyelonephritis (infection of the kidney, the upper track). 

We will focus on uncomplicated cases, in an otherwise healthy, non-pregnant adult. 

• So, what makes it a complicated urinary tract infection?  Complicated UTIs are associated with underlying conditions that increase the risk of infection or of failing therapy (obstruction, anatomical abnormality, urologic dysfunction or multi-resistant uropathogens). 

The vast majority of uncomplicated cystitis and pyelonephritis in women are the result of E. coli (75-95%), with other common causes being Proteus mirabilis, Klebsiella penumoniae and Staph saprophyticus.  Therefore, your local antimicrobial susceptibility patterns to E. coli should be the basis for treatment (contact your ID colleagues and/or lab for this information).

 

Clinical manifestations of cystitis consist of dysuria, urinary frequency, urinary urgency, suprapubic pain, and/or hematuria (note: these can be subtle in the extremes of age).

Clinical manifestations of pyelonephritis consist of those of cystitis plus fever (>38^oC), chills, flank pain, costrovertebral angle tenderness and nausea/vomiting. 

Diagnosis: on physical make note of temperature, costovertebral angle tenderness and an abdominal examination

Labs:

Urinalysis (either dipstick of microscopic) and urine culture with susceptibility

o   A urinalysis in the absence of a urine culture is sufficient for the diagnosis of uncomplicated cystitis if the symptoms are consistent with a UTI, unless there is reason to suspect antimicrobial resistance or other complicating features

• Urinalysis: Pyuria (in a clean catch, mid-stream urine specimen) is the most valuable diagnostic test for UTI, as it is present in almost all women with acute cystitis or pyelonephritis; its absence prompts the evaluation for another diagnosis. 

o   An abnormal result is ≥ 10 leukocytes/mL

o   If white cell casts are noted, they are diagnostic of an upper tract infection. 

o   The presence of hematuria is helpful since it is common in UTI but not in urethritis or vaginitis. 

• Urine Dipsticks look for the presence of:

o   Leukocyte esterase (an enzyme released by leukocytes, thus reflecting pyuria)

o   Nitrite (reflecting the presence of Enterobacteriaceae, which converts urinary nitrate to nitrite). 

o   The dipstick is most accurate for predicting UTI when it is positive for either leukocyte esterase or nitrite, with a sensitivity or 75% and a specificity of 82%

• Urine culture. Routine cultures are not generally necessary.  Consider obtaining prior to initiation of therapy if: the symptoms are not characteristic of UTI, if the symptoms persist or if they have recur within 3 months following prior treatment or if a complicated UTI is suspected. 

Differential Diagnosis: vaginitis, urethritis, structural uretheral abnormalities, painful bladder syndrome, pelvic inflammatory disease, nephrolithiasis

           

Treament:

• Cystitis:

·      Nitrofurantoin monohydrate/macrocrystals: 100mg PO BID for 5 days

o   Avoid if there is a suspicion for pyelonephritis and it is in contraindicated when creatinine clearance if < 60mL / min

·      Trimethoprim-sulfamethoxazole: 1 double strength tablet (160/800) BID for 3 days         

o   Avoid if location resistance is >20% or if the patient has taken TMP-SMX in the preceding 3 months

·      Fosfomycin trometamol: 3g in a single dose.  (more expensive and slightly less effective)

·      Fluoroquinolones (ciprofloxacin, levofloxacin, ofloxacin) for 3 days

o   Should be reserved for other uses other than acute cystitis

·      Beta-Lactams (amoxicillin-clavulanate, cefpodoxime, cefdinir & cefaclor) for duration of 7 days are less effective than TMP-SMX or the fluoroquinolones

o   Cephalexin is not well studied

o   Generally have inferior efficacy and more adverse effects compared with other agents, so they should be used with caution for uncomplicated cystitis

• Pyelonephritis

·      Urine culture should be obtained

·      Outpatient management is appropriate for patients with mild-moderate illness who can be stabilized with rehydration and have adequate follow-up

·      Fluoroquinolones are the only oral antimicrobials recommend for the outpatient empirical treatment of acute complicated pyelonephritis

o   Ciprofloxacin 500mg BID for 7 days or 1000mg ER for 7 days; consider an initial 400mg intravenous dose

o   Levofloxacin 750mg PO for 5-7 days

o   An initial dose of a long-acting parental antimicrobial (ceftriaxone 1g or an aminoglycoside) can be considered prior to starting oral treatment, especially if local resistance to fluoroquinolones is greater than 10%. 

o   If allergic to fluoroquinolones, give an initial dose of a long-acting parental antimicrobial (ceftriaxone 1g or an aminoglycoside) and then start TMP-SMX or an oral beta-lactam for 14 days

o   Other alternative is aztreonam 1g IV every 8-12 hours

What about men?

• Asymptomatic bacteriuria and symptomatic urinary tract infection are much less common in men due to the longer urethral length, drier periurethral environment and antibacterial substances in prostatic fluid. 
• Risk factors: insertive anal intercourse and lack of circumcision
• Treatment is similar to the treatment in women, except, nitrofurantoin and beta-lactams should not be used (do not achieve reliable tissue concentrations and are less effective for occult prostatitis. 

o   A 7 day course of antibiotics are recommended

References:

International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women: A 2010 Update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Disease.  Clinical Infectious Disease. 2011; 52(5):e103-e120

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