[Virulence factors in Proteus spp. bacteria isolated from urinary tract infections: their detection and importance]

Nosocomial infections associated with biofilm formation have been a serious problem in recent years. Up to 32 % of them are urinary tract infections in patients with long-dwelling catheters. Catheters represent an ideal surface for bacterial adhesion, facilitating easier colonization of the urinary tract. Important pathogens causing these infections are bacteria of the genus Proteus that colonize catheters not only by biofilm formation but also using other virulence factors. Those were developed for survival in the host organism and are also used by bacteria to infect the host or fight the defence mechanisms. The study focused on the following selected virulence factors: swimming, swarming and twitching motility, swarming motility across various types of urinary catheters, biofilm formation in various media, formation of biofilm on catheters, haemolysin and urease production. A total of 102 strains isolated from urinary catheters and 50 strains isolated from stools were analyzed. In twitching motility, a difference between strains isolated from catheters and stools was statistically significant (p = 0.012). In swimming and swarming motility, the difference was not significant (p = 0.074 and p = 0.809, respectively). In motility across various catheter types, a statistically significant difference was found in strains isolated from both catheters and stools (p « 0.01 in both cases). For biofilm formation analyses, BHI and BHI with 4 % glucose were used. In BHI, biofilm was produced by all strains, with 65% of catheter strains and 88 % of strains from stools being strong producers. Similarly, all strains produced biofilm in BHI with 4 % glucose, with strong producers in 94 % and 92 % of strains isolated from catheters and stools, respectively. In formation of biofilm on catheters, there was a statistical difference between strains from catheters and stools (p = 0.00008). All strains isolated from both catheters and stools produced urease; no difference in urease production was statistically significant (p = 0.653). On agar with washed sheep erythrocytes, haemolysin production was not detected in any of the isolated strains. The quantitative method using horse erythrocytes revealed haemolysis production in three strains isolated from catheters.