Antibiotic resistance in adult female patients hospitalized for acute pyelonephritis: rates and predicting factors.

INTRODUCTION: The empiric treatment of acute pyelonephritis (APN) with third generation cephalosporins (3GC) or fluoroquinolones (FQ) has been challenged by Escherichia coli resistance reported by community surveillance networks. But these could overestimate resistance because they do not discriminate between uncomplicated and complicated, or between community and care-related infections.

OBJECTIVES: We had for aim to: quantify resistance rates in hospitalized patients presenting with APN; identify subgroups with resistance <10% that could still be treated empirically with FQ or 3GC.

PATIENTS AND METHODS: We retrospectively analyzed files of patients presenting with documented APN, hospitalized in an Infectious Diseases Department from October 2010 to December 2012.

RESULTS: Hundred and fifty-six female patients (median age: 66, interquartile range: 37), were admitted for uncomplicated APN (36%) or APN (64%) at risk of complications by 1 (46%), 2 (40%), or 3 or more (14%) risk factors. Bacteremia was associated in 44% of uncomplicated and 8% of APN at risk of complications. E. coli was predominant (82%), resistant to 3GC in 6% of patients (including 4% ESBL) and to FQ in 15% of patients. The rate of resistance to FQ increased with the number of risk factors for complication, from 6% in uncomplicated APN, to 25% in patients with ≥3 risk factors. No enterobacteria was resistant to either 3GC or aminoglycosides.

CONCLUSION: The resistance rates of 3GC and aminoglycosides were <10% in patients hospitalized for APN. FQ resistance rates reached 15% but only 6% in uncomplicated APN. Hence, FQ empiric regimen should now be restricted to the treatment of uncomplicated APN without severe sepsis.