Virulence Characteristics of Escherichia coli Strains Causing Asymptomatic Bacteriuria

Abstract

Background:The objective of this study was to examine the expression of Escherichia coli virulence-associated factors among the strains isolated from a group of women with a history of recurrent urinary tract infections (UTIs), in whom asymptomatic bacteriuria (ABU) was detected at follow-up, and from a group of children without a history of previous UTI, in whom ABU was detected during the screening. Possible differences between the virulence potential of these strains were investigated. Materials and Methods: Hemolysin production, the ability to adhere to Buffalo green monkey cell line and hemagglutination (HA) ability of the ABU-associated E. coli strains were tested. E. coli strains isolated from patients with acute recurrent UTIs served as a comparison. Results: The well-known low virulence of strains isolated from patients with ABU was demonstrated. In contrast to strains isolated from recurrent uncomplicated UTIs, the ABUassociated strains were mostly nonhemolytic (75%), nonadherent (70%) and lacked HA ability (61%). HA ability was significantly more common among the strains isolated from children without a history of UTI than among the strains isolated from women with recurrent UTIs ( 2 = 9.97, p < 0.01), whereas the adherence and hemolytic abilities did not differ between the two ABU groups.

Specific selection for virulent urinary tract infectiousEscherichia colistrains during catheter-associated biofilm formation

“…Colonization of urinary catheters by pathogens is a main problem among hospitalized patients, often resulting in recurrent infections. The problem is accentuated by the rise of antibiotic resistance in UTI infectious bacteria due to the spread of resistance genes (Manges et al , 2001; Vranes et al , 2003). Furthermore, when a biofilm has established in a catheter, the inherent tolerance/resistance of biofilm‐dwelling bacteria towards antibiotics often make such infections extremely recalcitrant and hard to eradicate.…”

Transcriptomics and adaptive genomics of the asymptomatic bacteriuria Escherichia coli strain 83972

“…Several studies have investigated the virulence characteristics of uropathogenic E. coli (UPEC) isolates and ABU isolates, in order to get better understanding of how some UTI strains can cause severe disease, while others can be used prophylactically to prevent the same (Blanco et al 1996 ; Dobrindt et al 2003 ; Vranes et al 2003 ; Johnson et al 2005 ; Marrs et al 2005 ). ABU strains have been shown to lack many of the virulence-associated phenotypes; many of them are nonhaemolytic, nonadherent and lack haemagglutination ability (Vranes et al 2003 ). Strain 83972 lacks many of the virulence-associated phenotypes but has been shown to carry many of the virulence-associated genes, such as kps , iutA , fyuA and malX (Dobrindt et al 2003 ).…”

Asymptomatic bacteriuria prevalence and its relationship with urinary tract infections in the elderly

“…Although all similarities are known, there have not been any reliable studies that demonstrate the direct relationship yet. [6][7][8][9][10][11][12] Most of the studies conducted are studies including a short-term follow-up in few patient series. However, besides, there are also studies which followed for a long period of time like 14 years and concluded that it was not a risk factor for UTI.…”