Which factors should be considered in the selection of an antibiotic regimen for acute pyelonephritis (kidney infection) inpatient treatment?

Updated: Jul 01, 2021
  • Author: Tibor Fulop, MD, PhD, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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In patients with acute pyelonephritis who require hospitalization, treatment begins with IV antibiotics. IV therapy should be given for 24-48 hours or until severe symptoms improve. A systematic review of 8 randomized, controlled trials in hospitalized patients with acute pyelonephritis found that early switching to oral antibiotic treatment appears to be as effective and safe as exclusively IV regimens. [37]

Selection of a regimen should be based on local resistance data, and the regimen should be tailored on the basis of susceptibility results. Recommended regimens are listed in Table 3, below. However, a multinational study in 184 patients found that cefazolin is non-inferior to ceftriaxone for the empirical treatment of acute pyelonephritis in hospitalized patients. At 72 hours, defervescence or normalization of white blood cell count had occurred in 87.0% of the cefazolin group versus 85.9% of the ceftriaxone group; in addition, no difference was observed between the two groups for length of stay or 30-day readmission for cystitis or pyelonephritis. [38]

Table 3. Inpatient Treatment for Acute Pyelonephritis (Open Table in a new window)

First-line therapy

  • Ciprofloxacin (Cipro) 400 mg IV q12h for 10-14d or

  • Levofloxacin (Levaquin) 250 mg IV q24h for 10d or

  • Levofloxacin (Levaquin) 750 mg IV q24h for 5d

Second-line therapy

Extended-spectrum cephalosporins or penicillins:

  • Ampicillin-sulbactam (Unasyn) 1.5 g IV q6h or

  • Piperacillin-tazobactam (Zosyn) 3.375 g IV q6h or

  • Ticarcillin-clavulanate (Timentin) 3.1 g IV 4-6h or

  • Cefotaxime (Claforan) 1-2 g IV q8h or

  • Ceftriaxone (Rocephin) 1 g IV q24h or

  • Ceftazidime (Fortaz, Tazicef) 2 g IV q8h

  • All of the above can be administered with or without an aminoglycoside (except in pregnant patients); see Aminoglycosides, below


  • Meropenem (Merrem) 500 mg IV q8h or

  • Ertapenem (Invanz) 1 g IV q24h or

  • Doripenem (Doribax) 500 mg IV q8h

Monobactam (for patients with penicillin allergy):

  • Aztreonam (Azactam) 1 g IV q8-12h

Alternative therapy

Aminoglycosides (because of their potential nephrotoxicity, aminoglycoside antibiotics should be reserved for patients with serious and potentially life-threatening infections, and their dosage and blood levels should be carefully monitored to minimize the risk of nephrotoxicity):

  • Gentamicin 3 mg/kg/day IV/IM in 3 divided doses or 7 mg/kg/day pulsed dosing or

  • Tobramycin 3 mg/kg/day IV/IM in 3 divided doses or 7 mg/kg/day pulsed dosing or

  • Amikacin 10 mg/kg/day IV/IM in 3 divided doses or 20 mg/kg/day pulsed dosing

  • Plazomicin 15 mg/kg IV q24hr infused over 30 minutes

However, an Israeli medical center that instituted a program of initial empirical treatment of pyelonephritis with aminoglycosides reported higher rates of in vitro activity and lower overall mortality than with non-aminoglycoside antibiotic therapy, without excess nephrotoxicity. In the study, which included 2026 patients, 715 treated with aminoglycosides and 1311 treated with non-aminoglycoside drugs, aminoglycosides were more likely to have in vitro activity against clinical isolates (odds ratio 2.0; P < 0.001); death at 30 days occurred in 55 (7.6%) versus 145 (11%) patients treated with aminoglycosides and non-aminoglycoside drugs, respectively (adjusted hazard ratio 0.78; P = 0.013).  The incidence of acute kidney injury was 2.5% versus 2.9%, respectively; P = 0.6). [39]

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