Virulence factors of Escherichia coli causing bacteriuria during pregnancy in comparison with isolates from community- acquired cystitis

ABSTRACT

Escherichia coli [E. coli] isolates from women with bacteriuria of pregnancy establish significant bacteriuria without causing symptoms of urinary tract infection [UTI]. In this study Escherichia coli isolates from patients with bacteriuria of pregnancy were compared phenotypically with uropathogenic E. coli [UPEC] from patients with community-acquired cystitis for the presence of established virulence determinants. The asymptomatic bacteriuria [ABU] strains from pregnant women were less likely to express type 1 fimbriae [26, 66%], P-fimbriae [20%] and ?-haemolysin [6.6%] than the other group [66.66% , 40% , and 13.3% respectively]. PCR analysis of the gene producing type 1 fimbria showed that the gene is present in 93.33% among both groups. However, determination of the phase switch orientation by analysis of positive PCR isolates showed that 3 of 14 ABU isolates of pregnant women [21.4%] was detectable in the on orientation compared to [64.2%] in community acquired cystitis patients. These data indicate that type 1 fimbriae are not necessary to maintain the majority of E. coli bacteriuria in pregnant women since there appears to be selection against their expression in this particular group in contrast to the considered role of this adhesion in community-acquired symptomatic infections