Retrospective study of children with acute pyelonephritis. Evaluation of bacterial etiology, antimicrobial susceptibility, drug management and imaging studies.

The purpose of the study was to investigate the management of pyelonephritis in a large Italian pediatric population. A total of 1,333 patients (36% male) were considered. Escherichia coli was the most frequently isolated agent (89.9%), followed by Proteus mirabilis (3.6%) and Klebsiella oxytoca (2.1%). 27% of microorganisms were resistant to amoxicillin, 4% to amoxicillin/clavulanic acid, 11% to trimethoprim-sulfamethoxazole, 2.4% to gentamicin and less than 2% to ceftazidime. Despite this resistance pattern showing that oral antibiotics, such as amoxicillin/clavulanic acid, are effective in vitro as well as parenteral antimicrobials, a parenteral antibiotic was given initially to 756 (57.2%) children. A prophylactic regimen was started in 922 patients with a rate of reinfection during prophylaxis of 9.5%; a higher rate of reinfection was observed in patients with reflux (25%) compared to children without reflux (3%) (p < 0.0001). Vesicoureteral reflux was demonstrated in 30% of patients. The number of renal abnormalities detected by DMSA in patients with and without reflux was significantly different (p < 0.001). CRP was higher in patients with scars (p < 0.02). In conclusion, pyelonephritis represents a common disease with about 2,500 days of hospitalization per year in the Veneto Region where there is a pediatric population of about 800,000 under 15 years of age. The results of antimicrobial in vitro tests indicate that amoxillicin/clavulanic acid could represent the antibiotic of choice. The high frequency of malformations, observed even in children between 6 and 12 years of age, may suggest the need of an imaging study including DMSA scan and VCUG in all age groups.