Anthrax lethal and edema toxins produce different patterns of cardiovascular and renal dysfunction and synergistically decrease survival in canines.
BACKGROUND
High mortality in the 2001 US and recent European anthrax outbreaks suggests that better understanding of the effects of the toxins produced by this bacterium is needed to improve treatment.


RESULTS
Here, 24-h edema (ETx) and lethal (LeTx) toxin infusions were investigated for 96 hin sedated canines receiving mechanical ventilation. The initial study compared similarly lethal doses of ETx (n=8) or LeTx (n=15) alone. ETx was 24 times less lethal than LeTx, and the median time to death in nonsurvivors (n=6 and n=9, respectively) was shorter with ETx (42 vs 67 h; P=.04). Compared with controls(n=9), both toxins decreased arterial and central venous pressures and systemic vascular resistance and increased heart rate, cardiac index, blood urea nitrogen (BUN) level, creatinine (Cr) concentration, BUN:Cr ratio, and hepatic transaminase levels (P ≤ .05 for toxin effect or time interaction). However, ETx stimulated early diuresis,reduced serum sodium levels, and had more pronounced vasodilatory effects, compared with LeTx, as reflected by greater or earlier central venous pressures, systemic vascular resistance, and changes in the BUN:Cr ratio(P ≤ .01). LeTx progressively decreased the left ventricular ejection fraction (P ≤ .002). In a subsequent study, a lethal dose of LeTx with an equimolar nonlethal ETx dose (n=8) increased mortality, compared with LeTx alone (n=8; P= .05).


CONCLUSIONS
Shock with ETx or LeTx may require differing supportive therapies, whereas toxin antagonists should likely target both toxins.
Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
Daniel A
DA
Sweeney
Xizhong
X
Cui
Steven B
SB
Solomon
David A
DA
Vitberg
Thi S
TS
Migone
Dara
D
Scher
Robert L
RL
Danner
Charles
C
Natanson
G Mani
GM
Subramanian
Peter Q
PQ
Eichacker
D000818:Animals; D000942:Antigens, Bacterial / Q000633:toxicity*; D001427:Bacterial Toxins / Q000633:toxicity*; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D003404:Creatinine / Q000097:blood; D004195:Disease Models, Animal; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D007668:Kidney / Q000187:drug effects*; D011041:Poisoning / Q000473:pathology* / Q000503:physiopathology*; D016019:Survival Analysis; D000637:Transaminases / Q000097:blood; D014508:Urea / Q000097:blood; D014655:Vascular Resistance / Q000187:drug effects
D000942:Antigens, Bacterial; D001427:Bacterial Toxins; C030325:anthrax toxin; D014508:Urea; D003404:Creatinine; D000637:Transaminases