Bacterial Adhesins and Host Factors: Role in the Development and Outcome of Escherichia coli Bacteremia

Abstract

To assess the contributions of bacterial virulence factors and defects in host defense to Escherichia coli bacteremia, we examined isolates and available medical records from 169 episodes at two hospitals. Adhesins and hemolysin virulence factors were documented in 84% of bacteremia-associated isolates originating from the urinary and respiratory tracts and in 50% of such isolates originating from other extraurinary foci. Of the evaluable episodes of bacteremia involving 35 adhesin-negative isolates, 21 (60%) were in patients who had mucocutaneous defects at the primary site of infection, and another 13 (37%) were in patients who had comorbid systemic diseases (i.e., chronic renal failure or alcoholism) associated with impaired leukocyte function. In contrast, of 93 evaluable episodes with adhesin-positive isolates, 22 (24%) were in patients who had none of these host conditions (P = .008). Overall, of evaluable episodes of bacteremia involving 128 isolates, 71 (55%) had both bacterial virulence-associated and host-related risk factors. Mortality was related to the severity of comorbid illnesses and was not affected by the presence of the bacterial virulence factors assessed.

Colonization with Extraintestinal Pathogenic Escherichia coli among Nursing Home Residents and Its Relationship to Fluoroquinolone Resistance

“…In contrast, adhesins and hemolysin, virulence factors classically associated with bacteremia and pyelonephritis (10), were detected in a minority of isolates (15%) from 22.4% subjects, a result similar to those from prior studies of normal fecal flora (1,6,13), which suggests that carriage of adhesin-positive strains was not spread within the NH population.…”

“…The increased prevalence of iutA-and kpsII-positive (and adhesin-negative) strains has unknown clinical ramifications, primarily since isolates of E. coli causing UTIs and bloodstream infections typically express adhesins and/or hemolysin (10). An unanswered question is whether the presence of iutAand kpsII-positive strains may increase the risk for future infectious events.…”

Ongoing Horizontal and Vertical Transmission of Virulence Genes and papA Alleles among Escherichia coli Blood Isolates from Patients with Diverse-Source Bacteremia

“…It accounted for ϳ7% of isolates overall, and its isolates outnumbered even those of the prominent O6:K2:H1 clonal group (ϳ4%). The associated primary sources of bacteremia for these O6:Kϩ;F48/F536 strains included UTI, pneumonitis, and intra-abdominal infections (49). The evident pathogenetic versatility of this clone with respect to host species, clinical syndrome, and anatomical site of infection illustrates the inappropriateness of the traditional designation of uropathogenic E. coli and supports instead a more inclusive rubric such as ExPEC (65).…”

Host Factors and Portal of Entry Outweigh Bacterial Determinants To Predict the Severity of Escherichia coli Bacteremia

“…Relatively few studies have jointly examined the roles of host and bacterial factors in the severity and outcome of this infection (14, 17, 25, 30-32, 36, 50). The discrepancies among the conclusions of those studies might reflect the retrospective (14,31,36,50) and/or monocenter (14,30,32,36,50) nature of most of them, the small number (30 to 185) of patients included (14, 17, 30-32, 36, 50), the small number of bacterial factors examined (14, 17, 25, 30-32, 36, 50), and the diversity of the disease's pathophysiological mechanisms.…”