[Renal calculus microflora in urolithiasis and search for agents of control of biofilms formed by uropathogenic bacteria].

AIM: Study bacterial biofilms in native material (renal calculus) by electron microscopy method and developmeit of biofilm model by isolates in vitro on sterile calculi of various chemical composition. MATERIALS AND METHODS: Bacterial spectra of microflora of renal calculus lavages were studied, isolated pure cultures were identified up to species. Comparisons of urine microflora obtained before operation in patients with urolithiasis with microflora of removed renal calculi were carried out. RESULTS: Urease activity and genes coding pathogenicity factors were detected, and the ability to form biofilms by isolates was studied. Model of formation of biofilms in vitro on sterile renal calculi was developed and candidate agents reducing the biofilm forming ability were tested. CONCLUSION: Uropathogenic microorganisms infecting renal calculi and forming biofilms on them not only support chronic infection by increased resistance to therapy but also facilitate novel lithogenesis.

[Choice of antibacterial drugs in urinary infection].

A rise in efficacy of the treatment of acute infection affecting the lower urinary tract (LUTI) and prolongation of recurrence-free interval in chronic LUTI can be achieved only by an optimal antibacterial treatment. The study was made of 987 community-acquired strains of uropathogens from the patients living in 20 cities of the Russian Federation, Belarus and Kazakhstan (of them, 903 strains were from Russia). Enterobacteriaceae comprised 83.5%. E. coli infection of LUTI was found in 63.5% patients. The incidence of this infection was about the same both in uncomplicated and complicated cases (64.6 and 62.1%, respectively). Most active oral drugs against E.coli were phosphomycin (98.4%), furasidin (95.7%), nitrofurantoin (94.1%) and oralcefalosporins of the third generation (ceftibuten and cefixim). As to Enterobacteriaceae, only phosphomycin had activity against these bacteria above 90%, i.e. 91.5%. Furasidin and nitrofurantoin activity was 86.3 and 76.8%, respectively. From parenteral drugs, most active against E. coli were carbapenems (ertapenem, meropenem, imipenem. Strains resistant to them were not isolated. High in vitro activity was demonstrated also by cefoperason/sulbactam (97.4%), piperacillin/tasobactam (95.7%), cefalosporins of the third/fourth generation and amikacin (98.9%). Carbapenems were also highly active against Enterobacteroaceae. Empiric treatment of uncomplicated urinary infection should be performed with medicines which are not used for other indications.

[Infectious genesis of nephroliths (electron-microscopic study)].

Scanning electron microscopy and x-ray microstructural analysis were employed in the study of nephroliths from patients suffering from nephrolithiasis. Bacterial biofilms, urease producing microorganisms, alkaline reaction of the urine are basic factors for local urine crystallization, formation of the base of the nephroliths and its rigid fixation to the pelvic mucosa. Mechanic trauma of the pelvic tissues by the concrement results in destruction of the pelvic mucosa epithelium at the site of the nephrolith. Subsequent inflammation in the underlying connective tissue contributes to formation of connective tissue commissures fixing the conrement in the kidney. It is shown that bacteria as a part of a biofilm are capable to persist in nephroliths for a long time. Destruction of the stones during operation or lithotripsy can trigger activation of growth of bacteria integrated in the biofilm and cause septic complications. Preservation of commissures with elements of the destroyed stone after lithotripsy or surgical removal is one of the leading causes of recurrent nephrolithiasis.