Yersinia HPI in septicemic Escherichia coli strains isolated from diverse hosts.

High pathogenicity islands (HPIs), first identified in various Yersinia species, encode an iron uptake system. We have studied the occurrence of HPIs in septicemic strains of Escherichia coli isolated from a variety of hosts. The results presented in this communication indicate that most septicemic strains tested contained HPI sequences even though they already have the aerobactin encoding genes. We have also observed two types of HPI deletions, suggesting genetic instability of this element. Notable exceptions are several strains isolated from septicemia in sheep that lacked both iron acquisition systems.