A 29 y.o. woman is critically ill. The illness is presented by high fever, chills, sweating, aching pain in lumbar area, discomfort during urination and frequent voiding. Pasternatsky's sign is positive in both sides. On lab examination: WBC-20 × 109/l; on urine analysis: protein -0,6g/L, leukocyturia, bacteriuria. Your preliminary diagnosis.