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The association of Escherichia coli virulence and pulmonary microvascular damage
R A Barke1, D L Dunn, A P Dalmasso
1Department of Surgery, University of Minnesota, Minneapolis.
Abstract:
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.
Insights
Bacterial virulence, not just bacterial numbers, significantly increases lung microvascular damage. This study shows virulent Escherichia coli strains cause greater lung injury in sheep models.
Area of Science:
- Microbiology
- Pathophysiology
- Pulmonary Medicine
Background:
- Bacterial virulence quantifies a microbe's pathogenicity for a specific host.
- Understanding the impact of bacterial virulence on host physiology is crucial for infection control.
Purpose of the Study:
- To investigate the effect of Escherichia coli virulence on lung microvascular permeability in a sheep model.
- To determine if increased bacterial numbers or virulence itself is the primary driver of lung injury.
Main Methods:
- Sheep with chronic pulmonary lymph fistulas were used.
- Four groups were established: wild-type E. coli (WT), virulent E. coli (PV), nonvirulent E. coli (PNV), and high-inoculum WT E. coli (HIWT).
- Lung lymph flow, pulmonary artery pressure, pulmonary wedge pressure, and albumin lymph/plasma ratio were measured.
Main Results:
- The virulent E. coli (PV) group exhibited a significantly greater increase in lung lymph flow compared to WT, PNV, and HIWT groups in the late period (2-6 hours).
- No significant differences were observed among groups in pulmonary artery pressure, pulmonary wedge pressure, or albumin lymph/plasma ratio.
- Lung lymph flow increase correlated with E. coli virulence.
Conclusions:
- Increased virulence of Escherichia coli directly leads to enhanced lung microvascular damage.
- The observed lung microvascular damage is influenced by bacterial virulence, not solely by the quantity of bacteria over time.