Introduction. Pyelonephritis is an infectious and inflammatory disease in which the renal cup system and the renal parenchyma are affected.

Objective: To establish the etiological structure of the upper urinary tract infection (UUTI), sensitivity and resistance of pathogens to antibiotics of patients in Orel and the Orel region.

Materials and methods. The case reports of 37 patients with pyelonephritis (PN) who received treatment in the specialized department of the Orel State Clinical Hospital in 2017 were analyzed. The laboratory research material was the average portion of the morning freely released urine. The result of bacteriological research was assessed both qualitatively and quantitatively. The etiological structure of the acute and chronic pyelonephritis, the sensitivity and resistance of isolated pathogens to antibiotics were studied.

Results. We revealed some differences in the etiology of the acute PN and exacerbations of the chronic PN. E. Coli, K. Pneumonia and K. oxytoca are the most frequent infection pathogens of the upper parts of the UUTI in patients of Orel and the Orel region. At the same time, the high sensitivity of E. coli to carbapenems and the increase in resistance to fluoroquinolones were noted.

K. Pneumonia demonstrated the resistance to carbapenems and preservation of sensitivity to the third-generation cephalosporins.

Discussions. Our results reflect the increasing trend in recent years of a significant increase in the resistance of microflora to penicillins and fluoroquinolones.

Conclusion. The results of this study indicate the need to continue the epidemiological studies in this direction, however, they can already now contribute to the choice of the optimal antibacterial therapy of patients with the infection of the upper UT in Orel and the Orel region.

Authors declare lack of the possible conflicts of interests.