Staphylococcal alpha toxin: a study with chronically instrumented awake sheep

Abstract

The in vivo responses to staphylococcal alpha toxin are reported for 15 chronically instrumented awake yearling sheep. The data obtained from a total of 30 experiments are grouped into four categories of response: no response, noted in seven experiments done on 5 sheep; pressor response, obtained seven times in 4 sheep; fluid and solute exchange, noted on six occasions in 3 sheep; and acute heart failure and death, which occurred in 10 of the 15 sheep. "No response" denoted no change in any of the measured outcome variables. The group of sheep labeled as showing "pressor response" responded to alpha toxin infusion with an increase in pulmonary artery pressure, unaccompanied by changes either in lung lymph flow or in lung mechanics. "Changes in lung fluid and solute exchange" involve increases in lung lymph flow. The harbinger of the last category, acute left heart failure leading to death, was a marked elevation in left atrial pressure. The threshold response dose in sheep is approximately 21 ,ug/kg. A very steep dose-response curve is observed, with only a narrow window of doses, 15 to 25 ;g/kg, between the group showing no response and the group showing death 3489 Vol. 60, No. 9 on August 5, 2020 by guest http://iai.asm.org/ Downloaded from

Induction of muscle-relaxing factor by staphylococcal alpha-toxin

“…Staphylococcal alpha-toxin is a bacterial protein whose biological properties include selective cell hemolysis, smooth muscle paralysis, dermonecrosis, and lethality (8,11,20). Although the target organ(s) for the lethal activity is not known, cardiotoxicity (1,7,10) and neurologic involvement (4,11,12) are thought to be important elements.…”