Virulence characteristics of Escherichia coli strains causing asymptomatic bacteriuria.
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.


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 ABU-associated 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 (chi2 = 9.97, p < 0.01), whereas the adherence and hemolytic abilities did not differ between the two ABU groups.


CONCLUSIONS
A further prospective study is needed to determine whether the HA ability is the predictor of subsequent symptomatic UTI.
Vranes
J
J
Dept. of Microbiology and Parasitology, Andrija Stampar School of Public Health, Zagreb University Medical School, Rockefeller Str. 4, HR-10000 Zagreb, Croatia. jvranes@snz.hr
Kruzić
V
V
Sterk-Kuzmanović
N
N
Schönwald
S
S
D018829:Adhesins, Bacterial / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001437:Bacteriuria / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D004926:Escherichia coli / Q000145:classification* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D011336:Probability; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012703:Serotyping; D012720:Severity of Illness Index; D014552:Urinary Tract Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D014774:Virulence
D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents