Modification and duration of intravenous therapy for acute pyelonephritis in nonpregnant adults
Fever may take 48 to 72 hours to resolve in acute pyelonephritis, but patients often report feeling systemically better before then. If the patient is not improving clinically, consider if the patient is at risk of a UTI caused by multidrug-resistant gram-negative bacteria, and reconsider the diagnosis of pyelonephritis.
Modify therapy for acute pyelonephritis in nonpregnant adults based on the results of culture and susceptibility testing.
If the results of susceptibility testing are not available by 72 hours after the initial empirical antibiotic dose, intravenous therapy is still required, and gentamicin or tobramycin was used initially, switch to ceftriaxone (as above).
If the isolate is shown to be susceptible, and further intravenous therapy is needed, replace the empirical regimen with:
1amoxicillin 2 g intravenously, 6-hourly. For dosage adjustment in adults with kidney impairment, see amoxicillin dosage adjustment amoxicillin amoxicillin amoxicillin
OR
1ampicillin 2 g intravenously, 6-hourly. For dosage adjustment in adults with kidney impairment, see ampicillin dosage adjustment. ampicillin ampicillin ampicillin
Intravenous ambulatory antimicrobial therapy should only be used when appropriate oral antibiotics are not available (eg for some multidrug-resistant infections) – seek expert advice. If susceptible, an option for intravenous ambulatory antimicrobial therapy for extended-spectrum beta-lactamase (ESBL)-producing bacteria is ertapenem because it is given once daily; however, susceptibility to ertapenem must be confirmed – discuss with a clinical microbiologist.
Switch to an oral antibiotic regimen once the patient is clinically stable and able to tolerate and absorb oral therapy – see Guidance for intravenous to oral switch. Oral therapy should be based on the results of culture and susceptibility testing. If the results of susceptibility testing are not available, see Oral antibiotic regimens for acute pyelonephritis in nonpregnant adults for oral regimens.
The total duration of therapy (intravenous + oral) for acute pyelonephritis in nonpregnant adults is 7 to 10 days, depending on clinical response, antibiotic used and route of administrationMcAteer, 2023. A duration of 7 days is reasonable ifMcAteer, 2023:
- intravenous therapy with a beta-lactam antibiotic (eg ceftriaxone, amoxicillin) is used for the entire course
- ciprofloxacin or trimethoprim+sulfamethoxazole is used for oral continuation therapy.
For all other patients, the total duration of therapy (intravenous + oral) is 10 days.
Oral fosfomycin (after 5 days of effective intravenous therapy) and oral pivmecillinam1 (after 3 days of effective intravenous therapy) have been studied for acute pyelonephritis, but more data are needed before they can be recommended for intravenous to oral switchHansen, 2022Ten Doesschate, 2022.
For patients with ongoing pyelonephritis symptoms following appropriate antibiotic therapy, seek expert urology advice.
Do not perform post-treatment urine culture to confirm resolution of infection for asymptomatic patients, except for pregnant patients and those with acute bacterial prostatitis.