The association of Escherichia coli virulence and pulmonary microvascular damage

R. A. Barke, D. L. Dunn, A. P. Dalmasso, M. O'Connor-Allen, R. L. Simmons and E. W. Humphrey
Department of Surgery, University of Minnesota, Minneapolis.

Bacterial virulence indicates the degree of pathogenicity of a given strain of microbe for a given host. The effect of Escherichia coli virulence on lung microvascular permeability was studied in sheep with chronic pulmonary lymph fistulas following peritoneal contamination. The study was divided into four groups: (1) wild-type E coli (WT group, 2.5 x 10(9) colony-forming units [CFUs]/kg); (2) virulent E coli (PV group, 2.3 x 10(9) CFUs/kg); (3) nonvirulent E coli (PNV group, 2.6 x 10(9) CFUs/kg); (4) high-inoculum wild-type E coli (HIWT group, 6.1 x 10(9) CFUs/kg). In the late period (two to six hours), the increase in lung lymph flow in the PV group was significantly greater than the WT, PNV, and HIWT groups, with no difference noted among groups with respect to the pulmonary artery pressure, pulmonary wedge pressure, or albumin lymph/plasma ratio. It was concluded that (1) increased E coli virulence results in increased lung microvascular damage and (2) increased lung microvascular damage as a function of E coli virulence may not be solely due to increased bacterial numbers as a function of time.