Originally published at Pediatric EM Morsels on April 15, 2016. Updated on April 14, 2017. Reposted with permission.

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Last week we discussed making the diagnosis of an urinary tract infection.  Essentially, we reinforced the fact that we can only make a presumptive diagnosis of UTI in the ED.  In some situations, you may prefer to await the urine culture for more definitive answers; however, there will be many occasions when it is deemed appropriate to initiate empiric antibiotics.  When that is the case, what should you choose? Let’s look at some options for Empiric Antibiotics for UTI.

UTI: The Bugs

• Worldwide, over the past several decades, antibiotic resistance has continued to evolve and increase. [Mishra, 2015; Echeverri, 2014; Mirsoleymani, 2014; Edlin, 2013]
• E. coli is responsible for majority of UTIs (~80%). [Edlin, 2013; Bhat, 2011]
• Other encountered uropathogens:
  • Klebsiella
  • Proteus
  • Group B Strep – consider in neonates and young infants.
  • Enterococcus – consider in neonates and young infants.
  • Staph saprophyticus
  • Pseudomonas
  • Fungi – seen in immunocompromised or diabetic patients or those with indwelling catheters or on long-term antbiotics.
• Common contaminants:
  • Cornebacterium species
  • Coag-negative staph
  • Lactobacillus species
  • Alpha-hemolytic strep

UTI: Management

• Local antimicrobial susceptibility patterns are the most important tool to help determine initial therapy. [Edlin, 2013; Jerardi, 2012; Subcommittee AAP, 2011]
• Duration of therapy:
  • Short course (5 days) is as effective as 7-14 days for uncomplicated cystitis in children
  • Consider short courses for older children.
• PO vs IV:
  • PO and IV therapies are equally efficacious. [Kowalsky, 2013; Subcommittee AAP, 2011]
  • Children with severe disease (ex, pyelonephritis) or medical complications (ex, immunocompromised) need to be treated with IV therapy until afebrile for 24 hours. Can be converted to oral afterwards.
  • Neonates require full sepsis evaluation and IV antibiotics!
  • >2 month olds:
    • Well appearing >2 month olds have low risk of UTI and concomitant meningitis. [Tebruegge, 2011]
    • If considering outpatient management:
      • Kid has to look awesome!
      • Kid has to have excellent access to care.
      • Discuss with Primary Care Provider to ensure that everyone is on the same management page!

UTI: The Bugs

• NO initial empiric choice is perfect.
  • Send the Culture!
  • Ensure follow-up!
• Cephalosporins [Subcommittee AAP, 2011]
  • Have become a commonly selected 1^st choice for UTI. [Bhat, 2011]
  • Some evidence that Nitrite-Negative U/A results may indicate increased risk for resistance to 1^st and 2^ndgeneration (Enterocococcus do not convert Nitrate to Nitrite). [Weisz, 2010]
  • Cefaclor
    • 50-100 mg/kg/Day divided in 3 doses
  • Cefixime
    • 8 mg/kg once a day
  • Cephalexin
    • Useful first generation cephalosporin.
    • Will NOT cover enterococcus.
    • 50-100 mg/kg/D divided in four doses.
  • Ceftriaxone
    • IM dosing can be used in those who won’t tolerate oral meds.
    • 50-100 mg/kg every 24 hours.

• Amoxicillin / Ampicillin [Subcommittee AAP, 2011]
  • A large percentage of E. coli are resistant to ampicillin. [Gaspari, 2006]
  • Does attain high levels in the urine and is effective against E. coli. [Betrosian, 2009]
  • Recommendation is to use Amoxicillin with Clavulanate (20-40 mg/kg/D divded TID).

• Trimehoprim-Sulfamethoxazole (TMP-SMZ) [Subcommittee AAP, 2011]
  • Ever increasing resistance, plus not an innocuous medicine. [Edlin, 2013]
  • Bacteria that are resistant to ampicillin are commonly also resistant to TMP-SMZ. [Gaspari, 2006]
  • The high resistance makes this a poor choice for empiric therapy of UTI. [Gaspari, 2006]

• Nitrofurantoin
  • Attains good levels in urine, but not serum.
  • Good for nitrite-negative UTIs. [Weisz, 2010]
  • Should not be used to treat pyelonephritis or febrile infants. [Bhat, 2011; Subcommittee AAP, 2011]

• Ciprofloxacin
  • Often avoided due to concern for cartilage injury, but this is not supported in the literature.
  • Reserved for resistant organisms. [Bhat, 2011]
  • Can use if need in special cases (ie, cystic fibrosis).

The Moral of the Morsel

• Know your local antibiotic resistance patterns.
• Avoid using TMP-SMZ empirically for UTI!
• Ensure the Urine Culture gets sent (it is crucial for the diagnosis and for tailoring therapy).
• Not every child needs empiric therapy for an abnormal urinalysis. Discuss with the Primary Care Physician when not clearly requiring empiric antibiotics.

References