High-dose recombinant endotoxin neutralizing protein improves survival in rabbits, with Escherichia coli sepsis.
OBJECTIVE
To assess the benefit of a recombinant endotoxin neutralizing protein from Limulus polyphemus in treating Gram-negative bacterial sepsis in rabbits.


METHODS
Prospective, blinded, controlled, laboratory trial.


METHODS
Animal research laboratory.


METHODS
New Zealand White rabbits.


METHODS
We established a rabbit model of Escherichia coli peritonitis and bacteremia, with high mortality rate, despite treatment with gentamicin and ceftriaxone. Twenty-five pairs of male New Zealand White rabbits were challenged intraperitoneally with E. coli O18ac K1 in 5% porcine mucin (mean 7 x 10(1) colony-forming units). All animals were treated with intravenous gentamicin (2.5 mg/kg) and ceftriaxone (100 mg/kg), and with either intravenous endotoxin neutralizing protein (50 mg/kg) or saline 1 hr after E. coli challenge.


RESULTS
All animals were bacteremic 1 hr after challenge (mean 3.6 x 10(5) colony-forming units/mL). Animals in both groups developed tachycardia, hypotension, and acidosis (NS). Geometric mean serum endotoxin and tumor necrosis factor (TNF) concentrations were significantly ( p < .001) higher 1 hr after challenge compared with baseline prechallenge concentrations in both groups. From 1 to 2 hrs after challenge, endotoxin concentrations increased 2.5-fold in control animals (95% confidence interval = 13.1 to 32.9 endotoxin units/mL, p = .024), whereas endotoxin concentrations increased only 1.2-fold in endotoxin neutralizing protein-treated animals (95% confidence interval = 20.4 to 23.6 endotoxin units/mL, NS). TNF concentrations increased significantly (p < .001) in both groups from 1 to 2 hrs after challenge. Eighteen (72%) of 25 endotoxin neutralizing protein-treated animals vs. 11 (44%) of 25 controls survived 24 hrs (p = .032).


CONCLUSIONS
Treatment with endotoxin neutralizing protein had the following effects: a) the increase in serum endotoxin was blunted, but not TNF concentrations measured 1 hr after antibiotic treatment; and b) survival in rabbits with E. Coli sepsis was improved.
Saladino
R A
RA
Department of Medicine, Children's Hospital, Boston, MA 02115, USA.
Stack
A M
AM
Thompson
C
C
Sattler
F
F
Novitsky
T J
TJ
Siber
G R
GR
Fleisher
G R
GR
D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage*; D023181:Antimicrobial Cationic Peptides; D060829:Arthropod Proteins; D004731:Endotoxins / Q000097:blood; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000401:mortality; D006737:Horseshoe Crabs; D007447:Invertebrate Hormones / Q000008:administration & dosage*; D008070:Lipopolysaccharides / Q000097:blood; D008297:Male; D011817:Rabbits; D011994:Recombinant Proteins / Q000008:administration & dosage; D018805:Sepsis / Q000188:drug therapy* / Q000401:mortality; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D060829:Arthropod Proteins; D004731:Endotoxins; D007447:Invertebrate Hormones; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; C034705:antilipopolysaccharide factor (Limulus); C044101:endotoxin, Escherichia coli