Effectiveness of oral antibiotics for treating pyelonephritis caused by extended‐spectrum beta‐lactamase‐producing Enterobacteriaceae: A case series

BACKGROUND: Recently, the spread of multidrug‐resistant bacteria has become a global problem. Extended‐spectrum beta‐lactamase (ESBL)‐producing Enterobacteriaceae (enterobacteria) is one example. The incidence of urinary tract infections caused by ESBL‐producing enterobacteria has been increasing in some Japanese community settings. Currently, there is insufficient evidence on the effectiveness of oral antibiotics used for the treatment of pyelonephritis caused by ESBL‐producing enterobacteria. We investigated the effectiveness of oral antibacterial agents against pyelonephritis caused by ESBL‐producing Enterobacteriaceae. METHODS: The records of patients who had been treated for pyelonephritis caused by ESBL‐producing enterobacteria with oral antibiotics between April 1, 2014, and March 31, 2019, were reviewed retrospectively to assess the effectiveness of oral antibiotic treatment. RESULTS: A total of seven cases were identified, including 1 patient with a positive blood culture and one patient with a Pitt bacteremia score of four points, indicating that the infections were severe. The antibiotics used to treat pyelonephritis were amoxicillin‐clavulanic acid (n = 3), minocycline (n = 1), levofloxacin (n = 3), and sulfamethoxazole‐trimethoprim with amoxicillin‐clavulanic acid (n = 1). None of the patients had recurrence of pyelonephritis in the 60 days following oral antibiotic treatment, and there were no deaths during the 60‐day follow‐up period. CONCLUSIONS: These antibiotics should be considered for oral treatment of pyelonephritis caused by ESBL‐producing enterobacteria. However, as there is insufficient evidence available on the effectiveness of these antibiotics for the management of ESBL‐producing enterobacterial infections, further large‐scale prospective studies are needed.