We report a case of a 63-year-old female patient who developed a recurrent urinary tract infection (UTI) with extensively drug-resistant Klebsiella pneumoniae (ERKp). In the initial two rounds of phage therapy. phage resistant mutants developed within days. Although ERKp strains were completely resistant to sulfamethoxazole-trimethoprim. https://cariumaes.shop/product-category/pos/