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Etiological spectrum and antimicrobial resistance of most frequently isolated pathogens, associated with urinary tract infections in ambulatory patients
* 1 , 2 , 2 , 2 , 3
1  1)Medical Diagnostic laboratory, “ Laborexpres 2000”Ltd -Varna,Varna, Bulgaria 2) Medical University of Varna, Varna, Bulgaria
2  Medical University of Varna, Varna, Bulgaria
3  2)Medical University of Varna, Varna, Bulgaria 3)Microbiology laboratory, University Hospital “St. Marina”- Varna, Varna, Bulgaria
Academic Editor: Manuel Simões


Objectives: The urinary tract infections (UTIs) are one of the most common community acquired infections, more often affecting women. The aim of this study is to investigate the etiological spectrum and antimicrobial resistance of most frequently isolated pathogens, associated with UTIs in ambulatory patients in Varna city, Bulgaria during a seven-month period (October 2020 - April 2021). Materials and methods: A total of 1600 urine sampes, collected from patients with suspected UTIs were tested. Screening for bacterial growth was done by HM&L Uroquattro instrument (ALIFAX, Italy). Species identification and antimicrobial susceptibility testing were performed by VITEK 2 Compact System (bioMerieux) and Kirby-Bauer disk diffusion method for 5-nitroxoline, fosfomycin and nitrofurantoin. Results: Escherichia coli was the most commonly isolated uropathogen regardless of the age group (48%, n=61), followed by Enterococcus faecalis (33%, n=42) and other representatives of order Enterobacterales (13.3%, n=18). The resistance rates in the group of Gram-negative isolates (n=79) in decreasing order were as follows: ampicillin, 64.5% > trimethoprim/sulphomethoxazole, 36% > ciprofloxacin, 29.1% > amoxicillin-clavulanate, 27.8% > cefuroxime, levofloxacin, 21.5% > fosfomycin, 13.1% > ceftriaxone, 12.6% > ceftazidime, 10.1% > gentamicin, nitrofurantoin, 6.5% > 5-nitroxoline, 4.9%. The resistance rates among the isolates of Enterococcus faecalis (n=42) were as follows: ciprofloxacin, 28.6% > gentamicin, 23.8% > levofloxacin, 19% > nitrofurantoin, 4.7% > amoxicillin, 2.4%. No resistance was detected to vancomycin and teicoplanin. Conclusion: High rates of resistance to ampicillin, trimethoprim/sulphomethoxazole and quinolones (60-30%) in the group of Gram negative uro-pathogens were detected, but 3rd generation cephalosporins, nitrofurantoin and 5-nitroxolin retained very good activity. Among Enterococcus faecalis, the second most commonly isolated bacterial species, a decreased activity of quinolones was found too, but the aminopenicillins and nitrofurantoin remain highly active.

Keywords: urinary tract infection; etiology; antimicrobial resistance