Objective To investigate the distribution and antibiotic resistance to pathogens isolated from children with acute pyelonephritis(APN) and explore the risk factors for it.Methods A retrospective analysis was performed on the distribution and antibiotic resistance to 173 pathogens isolated from 264 children with APN who hospitalized at Tianjin Children's Hospital from March 2012 to March 2017.The antibiotic resistance to pathogens was determined by using antimicrobial susceptibility.The clinical indicators of children were compared with APN and 200 children with lower urinary tract infection,including sex,age,index of blood and urine.The risk factors for APN were analyzed.Results Gram-negative bacilli were the main pathogen (61.3％),and involved Escherichia coil (E.coil) of 34.1％.Gram-positive cocci accounted for 38.7％,and involved enterococcus faecium of 24.3％.The resistance rate of E.coli to Ampicillin was the highest(89.8％),but the rate significantly decreased by adding Amoxicillin/Clavulanic acid(47.5％).Compared with Ampicillin,the difference was statistically significant(P ＜ 0.05).The resistance rate of E.coli to Tocefoperazone/Sulbactam was significantly lower than to other cephalosporins(P ＜ 0.01).E.coli had lowest resistance rate to Imipenem (0.03 ％).The resistance rate of enterococcus faecium was low to Linezolid and Vancomycin(＜ 5％).Single and multiple regression analysis revealed that younger than 1 year old,children with urinary tract malformation,increasing procalcitonin (PCT) of blood and β2-microglobulin (β2-MG) and neutrophil gelatinase-associated lipocalin (NGAL) of urine were all the risk factors of APN (all P ＜ 0.05).Conclusions E.coil is the major pathogen in children with APN and the enterococci-caused APN has been increasing.These pathogens have a high antibiotic resistance rate.Antimicrobial therapy should be based on the findings of urine culture and antimicrobial susceptibility test.In the children,less than 1 year old,with urinary tract malformation,the increasing PCT of blood,β2-MG and NGAL of urine are the risk factors for APN.