Pseudomonas aeruginosa Compared with Escherichia coli Produces Less Endotoxemia: Methods (5)

Pseudomonas aeruginosa Compared with Escherichia coli Produces Less Endotoxemia: Methods (5)These data were collected to determine that early peaks or surges in endotoxemia were not missed by the chosen time points. The endotoxin contents of the E coli and P aeruginosa strains used in this study were determined on freshly grown and washed bacteria using serial dilutions. buy ampicillin

The patterns of hemodynamic response among dog groups were assessed with the Kendall coefficient for concordance. Time courses of a hemodynamic variable (eg, EF) were summarized at each of four time points (baseline and days 1, 2, and 10 after surgery) by assigning ranks to the corresponding mean values of the variable in question (Fig 2 and 3). A Kendall concordance coefficient of 1 would indicate complete agreement among the assigned ranks and a value of 0 would indicate maximal disagreement. The shaded areas in Figures 2 and 3 represent the mean value for 100 normal dogs; the respective standard error was adjusted to the size of the comparison group.
Endotoxin levels were adjusted to baseline timepoints (Table 2).

Median endotoxin concentrations on days 1 and 2 were compared nonparametrically (due to variability in E coli groups) with a Mann -Whitney U test; significance was adjusted with a modified Bonferoni.
Mean decreases in mean arterial pressure (MAP) and left ventricular ejection fraction (LVEF) were compared among groups using unpaired, two-tailed, t tests. These results were declared significant only if the resulting analysis of variance (ANOVA) was significant, the so-called Protected Significant Difference Test. Other comparisons of mean values were performed with the appropriate t test, as indicated. Relative frequencies of death among groups were compared using the Fisher exact test.


Figure 2. Each graph plots the time course (solid line) of a single hemodynamic parameter (MAP, Cl, or SVI) for different study groups designated by the type of clot that was implanted. For each graph, the horizontal shaded area is the mean ± SEM for 100 normal dogs, which is shown for comparison. The dashed line originating from the solid line is the response to volume infusion at each time point.


Figure 3. As described for Figure 2, except different hemodynamic parameters are shown (LVEF, EDVI, ESVI).

Table 2—Endotoxemia during Septic Shock: Median Values and Ranges

Study Group Median Endotoxin Concentrations During First 48 h After Clot Implantation* Interquartile Range of Endotoxin Concentrations No. of Dogs Tested
1. Sterile clott 0.5 0.2-0.9 6
2. E colit
7×10″ 58.9 16.9-123.6 6
14 x 10 55.0 20.1-99.8 10
14 X 10 (with radiation) 32.7 6.3-84.7 10
3. P aeruginosa 2.3 1.1-5.0 28

Category: Pseudomonas aeruginosa

Tags: aeruginosa, endotoxin, sepsis, septic shock