Intravenous vs Oral Antimicrobial Therapy for Acute Pyelonephritis

acute pyelonephritis
Compared with intravenous treatment, oral antimicrobial therapy reduced hospital stays for patients with acute pyelonephritis caused by extended-spectrum, β-lactamase-producing Enterobacteriales.

Compared with intravenous (IV) treatment, oral antimicrobial therapy reduced hospital stays for patients with acute pyelonephritis caused by extended-spectrum, β-lactamase-producing Enterobacteriales (ESBL-PE). Oral treatment was not associated with adverse effects on treatment outcomes, indicating that oral antimicrobial therapy may be used as a carbapenem-saving option for the treatment of acute pyelonephritis, according to a study published in the European Journal of Clinical Microbiology & Infectious Diseases.

This retrospective cohort study was designed to determine the efficacy of oral antimicrobial agents compared with the standard of treatment with intravenous antimicrobial agents for acute pyelonephritis caused by ESBL-PE. The study cohort included 238 patients who were treated at the tertiary care Samsung Medical Center in Seoul, South Korea, from January 2014 to December 2016. Patients were divided into 2 groups: oral antimicrobial treatment (OAT), in which patients were treated with appropriate oral antimicrobial agents following therapy with < 7 days of IV antibiotics, and IV only antimicrobial treatment.

Baseline characteristics were compared using data from electronic medical records. The primary end point was overall treatment failure, defined as microbiological and/or clinical failure. Microbiologic failure was identified as blood culture and/or urine results not turning negative within 7 days, and clinical failure was defined as patient symptoms not resolving within 7 days or recurring during treatment. Treatment success was defined as patients with clinical recovery from acute pyelonephritis without microbiological follow-up. Secondary end points were length of hospital stay, recurrences within 2 months and 1 year, and adverse treatment-related events. To minimize bias, propensity score matching and multivariable Cox proportional hazard modeling were used.

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The most common pathogen was Escherichia coli (83.6%, 199/238) across the entire cohort. The OAT group comprised 60 patients receiving oral antimicrobial therapy after a median of 4-day appropriate intravenous therapy, and the IV-only group comprised 178 patients. Ertapenem was the most commonly prescribed in the IV only group; oral fluoroquinolones were the most commonly used in the OAT group (76.4% and 58.3%, respectively), followed by trimethoprim-sulfamethoxazole and amoxicillin-clavulanate. Hospitalization length was shorter by roughly 4.5 days in the OAT group compared with the IV only group (6.15 days vs 10.65 days; P < .001). The risk for treatment failure in the OAT group was not statistically superior to IV alone treatment (adjusted odds ratio [OR] 0.66; 95% CI, 0.18-24.3; P =.538). After 2 months, recurrence of acute pyelonephritis caused by ESBL-PE infection was also not significantly different between groups (adjusted hazard ratio [HR] 0.56; 95% CI, 0.16-2.00; P =.366), and recurrence within 1 year was also similar between the OAT and IV groups (HR 0.78; 95% CI, 0.35-1.77; P =.519).

Study investigators concluded, “[Oral antimicrobial agents] can be used to treat [acute pyelonephritis] caused by ESBL-PE infections and reduce the length of hospital stay without adverse effects on clinical outcomes as a carbapenem-sparing strategy.” In addition, they highlighted that the results demonstrated that greater than than half of all ESBL-PE isolates from the IV group were susceptible to oral antimicrobial agents, further evidencing that oral treatment is noninferior to IV treatment. Researchers also noted that more prospective studies in a larger population are needed to ensure the efficacy and safety of OAT for acute pyelonephritis caused by ESBL-PE.


Kim SH, Lim KR, Lee H, et al. Clinical effectiveness of oral antimicrobial therapy for acute pyelonephritis caused by extended-spectrum β-lactamase-producing Enterobacteriales [published online September 13, 2019]. Eur J Clin Microbiol Infect Dis. doi:10.1007/s10096-019-03705-w