ABSTRACT
Little is known about bacteria associated with asymptomatic bacteriuria (ABU) with regard to urinary tract colonization mechanisms. In this study, virulence properties of Escherichia coli 83972, a strain that was isolated from a clinical ABU episode, were examined. The genetic potential for expression of P and type 1 pili was demonstrated, and DNA sequences related to type 1C and G (UCA) pilus genes were also detected. However, E. coli 83972 did not express D-mannose-resistant or D-mannose-sensitive hemagglutination after growth under standard conditions in vitro or upon isolation from the urine of colonized test subjects. Limited uroepithelial cell adherence was observed in vivo, and weak D-mannose-sensitive hemagglutination was detected after extended growth in urine in vitro.
Subject(s)
Bacteriuria/microbiology , Escherichia coli Infections/microbiology , Escherichia coli/genetics , Escherichia coli/pathogenicity , Fimbriae Proteins , Adhesins, Escherichia coli/genetics , Alleles , Base Sequence , Cloning, Molecular , Escherichia coli/isolation & purification , Female , Fimbriae, Bacterial/genetics , Genes, Bacterial , Humans , Male , Molecular Sequence Data , Phenotype , Sequence Analysis, DNA , Urinary Bladder, Neurogenic/microbiology , VirulenceABSTRACT
Chronic bacteriuria is a common occurrence among spinal-cord injury patients and others with neuropathic bladders. If bacteria are present in the urinary tract, the patient may develop symptoms of infection or remain asymptomatic. We have compared virulence properties of 28 Escherichia coli isolates from patients with symptomatic urinary tract infections (UTI) and 29 E. coli isolates from patients with asymptomatic bacteriuria (ABU). Bacteria from patients with symptomatic UTI were more likely to be hemolytic than isolates from patients with ABU (P = 0.05) or fecal isolates obtained from healthy volunteers (P < 0.001). Bacteria from patients with symptomatic UTI were also more likely than strains isolated from patients with ABU (P = 0.08) or fecal strains (P < 0.001) to exhibit D-mannose-resistant hemagglutination of human erythrocytes. The results suggest that E. coli isolates from nonimmunocompromised patients who require intermittent catheterization and who develop symptomatic UTI may be distinguished from bacteria recovered from patients who remain asymptomatic and possibly from normal fecal E. coli.
