['Acute pyelonephritis (APN) is one of the most common bacterial infections. Because health care-associated (HCA) infections in the community setting have similar characteristics to hospital-acquired infections, HCA infections should be distinguished from community-acquired (CA) infections. However, the impact of HCA-APN on treatment outcomes has not been clearly defined. This study aimed to analyze the impact of HCA-APN on the appropriateness of empiric antibiotic therapy and outcomes in community-onset APN.', 'We prospectively identified women older than 18years who were hospitalized with APN via the emergency department and whose urine culture grew bacteria at 10 acute care hospitals in South Korea.', 'Of the 388 APN episodes that were included, 99 (25.5%) were HCA-APN and 289 (74.5%) were CA-APN. Compared with patients with CA-APN, patients with HCA-APN had comorbid conditions and septic shock more frequently. Health care-associated APN was caused by resistant uropathogens more often. Patients with HCA-APN had poorer outcomes (ie, early/final clinical and microbiologic failures); however, this was not statistically significant. Patients with HCA-APN had significantly longer hospital stays than did patients with CA-APN. In the multivariable logistic regression analysis for inappropriate empiric therapy, HCA-APN (odds ratio, 1.96; 95% confidence interval, 1.07-3.57; P=.03) and being bed-ridden (odds ratio, 3.04; 95% confidence interval, 1.31-7.07; P=.01) were significant.'] Is health care-associated acute pyelonephritis associated with inappropriate empiric antibiotic therapy in the ED?