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Previous Volume 328:1457-1460 May 20, 1993 Number 20 Next

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Endotoxin, a lipopolysaccharide component of the outer membrane of gram-negative bacteria, is involved in the pathogenesis of septic shock, but it is unclear whether endotoxin alone is capable of causing all the manifestations of the septic shock syndrome. In animals, endotoxin causes many of the clinical features¹ but produces a low-cardiac-output form of shock that is unlike the hyperdynamic cardiovascular profile of septic shock in humans^2,3. In humans, the administration of endotoxin (4 ng per kilogram of body weight) triggers the release of cytokines,⁴ activates the coagulation and fibrinolytic systems,^5,6 and causes a decrease in systemic vascular resistance and an increase in cardiac output⁷. At these low doses, however, endotoxin does not cause shock, disseminated intravascular coagulation, or clinically important organ dysfunction. A septic shock-like syndrome occurred in patients treated for cancer with crude preparations of endotoxin⁸ and in patients who received transfusions of blood products contaminated with gram-negative bacteria⁹. These reports, however, did not include detailed hemodynamic data, and other bacterial products may have contributed to the clinical signs and symptoms. We describe a patient who self-administered a single large dose of endotoxin and in whom the full clinical manifestations of septic shock syndrome developed.

Case Report

A middle-aged laboratory worker was brought to the emergency department because of malaise, headaches, nausea, and vomiting. The patient was awake but listless with a pulse of 114 per minute, a blood pressure of 42/20 mm Hg, and an oral temperature of 40 °C. The patient was treated with intravenous fluids, and a dopamine infusion was started at a dose of 5 µg per kilogram per minute. Blood cultures were obtained, and vancomycin and gentamicin were administered intravenously. The results of a urinalysis, chest roentgenography, and electrocardiography were normal. The patient was admitted to the medical intensive care unit with a presumptive diagnosis of septic shock.

A norepinephrine infusion was begun for persistent hypotension and titrated to maintain a mean arterial pressure of more than 60 mm Hg. Right ventricular catheterization revealed a form of shock in which there was low systemic vascular resistance (Table 1). Eleven hours after admission, it was discovered that 2.5 hours before arriving at the emergency department, the patient had administered 1 mg of Salmonella minnesota endotoxin (Sigma, St. Louis), dissolved in sterile water, intravenously in an attempt to treat a recently diagnosed tumor. Consequently, a 100-mg dose of HA-1A antibody (Centoxin, Centocor, Malvern, Pa.) was administered 23 hours after the injection of endotoxin.

View this table: [in this window] [in a new window]   Table 1. Hemodynamic Measurements and Vasopressor Administration after the Injection of S. minnesota Endotoxin.

 
Forty-four hours after the injection of endotoxin, the patient was alert, oriented, and afebrile. The respiratory rate was 30 per minute, and rales were audible bilaterally. A chest roentgenogram showed bilateral interstitial infiltrates consistent with the presence of pulmonary edema. Furosemide was administered, and a brisk diuresis followed. The norepinephrine infusion was discontinued 50 hours after the injection of endotoxin. All cultures (blood, urine, and stool) were negative for pathogens. The patient was sent home on the eighth hospital day.

Methods

Informed consent was obtained from the patient to transcribe relevant clinical data and draw blood specimens. Serum specimens were frozen at -20 °C until assayed. Before the specimens arrived at the research laboratory, no special precautions were taken to keep them free of pyrogens, with the exception of the use of sterile techniques. The specimens were thawed and kept at 4 °C before testing was conducted. Aliquots were assayed for endotoxin with a chromogenic limulus amebocyte lysate method (Whittaker M.A. Bioproducts, Walkersville, Md.) as previously described,¹¹ but with the kinetic modification recommended by the manufacturer¹². This assay was sensitive to a concentration of U.S. Standard Reference Endotoxin of 5 pg per milliliter (0.05 endotoxin units [EU] per milliliter).

Tumor necrosis factor- (TNF-) was measured at Centocor by enzyme-linked immunosorbent assay (ELISA) (Genzyme, Cambridge, Mass.) and by a bioassay method based on TNF--induced cytotoxicity in WEHI cells¹³. Interleukin-6 and granulocyte colony-stimulating factor concentrations were determined with double-ligand immunoassays (R & D Systems, Minneapolis) performed according to the manufacturer's instructions. Interleukin-8 concentrations were determined with a modified ELISA⁴.

Results

Initial measurements (Table 1)¹⁰ revealed hypotension with an elevated cardiac index and a low index of systemic vascular resistance. The pulmonary-capillary wedge pressure was low, and it rose slowly with fluid resuscitation to a peak of 21 mm Hg. While hypotensive, the patient received 14.9 liters of fluid in excess of the measured output and had clinical symptoms consistent with a generalized capillary-leak syndrome.

The patient's temperature and heart rate (Figure 1) did not return to normal until approximately 60 hours after the injection of endotoxin. The initial white-cell count of 1600 per cubic millimeter (Figure 1) was followed by progressive leukocytosis with increased band forms (up to 45 percent of the total count) that peaked at a count of 37,000 per cubic millimeter 24 hours after the injection of endotoxin. On admission, the patient had a normal platelet count, prothrombin time, and partial-thromboplastin time. The platelet count subsequently fell, reaching a nadir of 64,000 per cubic millimeter 74.5 hours after the injection (Figure 1). The prothrombin time and the partial-thromboplastin time (Figure 1) became prolonged and reached maximal values (14.6 and 59.6 seconds, respectively) 36 hours after the injection of endotoxin. The levels of fibrin split products were elevated at 44 hours to 64 µg per milliliter (normal, <10). Blood cultures were negative.

View larger version (60K): [in this window] [in a new window]   Figure 1. Serial Changes in Body Temperature and Heart Rate, Total White-Cell Count and Platelet Count, and Prothrombin Time (PT) and Partial-Thromboplastin Time (PTT) after the Intravenous Injection of Endotoxin. The arrows denote the time at which HA-1A antibody was administered.

 
Other abnormal findings included increased serum lactate dehydrogenase and aspartate aminotransferase values of 385 and 70 IU per liter, respectively. The serum creatinine concentration was 1.6 mg per deciliter (141.4 µmol per liter) 3.7 hours after the injection of endotoxin, and it returned to normal 24 hours later (0.9 mg per deciliter [79.5 µmol per liter]). A mild metabolic acidosis with an anion gap of 16 mmol per liter was present on admission, but the serum lactate concentration, measured 10 hours later, was only 2.0 mmol per liter. On admission, the patient had a partial pressure of arterial oxygen of 130 mm Hg while breathing room air. Forty-eight hours later, however, this value had decreased to 87 mm Hg while the patient received 4 liters of nasally administered oxygen per minute, and there was clinical and roentgenologic evidence of pulmonary edema.

The results of serial determinations of endotoxin, TNF-, interleukin-6, interleukin-8, and granulocyte colony-stimulating factor are shown in Table 2¹⁴. Since blood samples were not collected in a pyrogen-free manner, the possibility of exogenous contamination with endotoxin cannot be excluded. Although a positive endotoxin test is difficult to interpret in such a situation, the finding of an undetectable level suggests clearance of endotoxin from the circulation. The first serum sample without detectable endotoxin was obtained 11.5 hours after the endotoxin injection. The endotoxin level in an earlier sample, obtained 6.8 hours after the injection, was only 38 pg of U.S. Standard Reference Endotoxin per milliliter (0.38 EU per milliliter). The cytokine concentrations were highest at the first measurement and decreased thereafter.

View this table: [in this window] [in a new window]   Table 2. Serial Serum Concentrations of Endotoxin and Cytokines after the Injection of S. minnesota Endotoxin.

 
Discussion

The experience with this patient demonstrates that a single large intravenous dose of endotoxin reproduces all the manifestations of septic shock syndrome, including a high-cardiac-output form of hypotension, disseminated intravascular coagulation, abnormalities of hepatic and renal function, and noncardiogenic pulmonary edema. To maintain the blood pressure, the patient required therapy with norepinephrine for 50 hours after the injection of endotoxin. The coagulopathy and thrombocytopenia persisted for two and five days, respectively. Thus, endotoxin alone, in the absence of an ongoing infection, produced an inflammatory response that continued for days.

The precise role of endotoxin as a causative factor in septic shock remains controversial. Tolerance to endotoxin does not protect animals from lethal gram-negative bacillary infection,¹⁵ nor does it protect humans from experimental typhoid fever and tularemia¹⁶. Studies in animals¹⁷ and clinical studies¹⁸ have shown that microorganisms devoid of endotoxin can cause septic shock and that bacterial products other than endotoxin may contribute to mortality from gram-negative infections¹⁹. Finally, frequent serial determinations of endotoxin in 100 patients with septic shock revealed that 57 percent never had detectable endotoxemia¹¹. The case reported here, however, shows that endotoxin alone is sufficient to trigger the endogenous inflammatory response that leads to septic shock in humans.

This patient injected 1 mg of purified endotoxin and survived. This dose, which is equal to 15,000 ng per kilogram, is 3750 times the dose of 4 ng per kilogram given to normal volunteers in experimental studies⁷. The apparently rapid clearance of endotoxin from the circulation in this patient is consistent with previous studies in animals^20,21 and humans¹⁶. However, the detection of endotoxemia in this patient may have been hampered because only serum was available for testing²². Although some investigators have found that endotoxin is not trapped by clotted blood,²³ others have reported the loss of endotoxin from serum after coagulation²². The serum TNF- concentration was 9157 pg per milliliter by a cytotoxicity assay (14,630 pg per milliliter by ELISA) 3.6 hours after the injection of endotoxin, a concentration much higher than those measured in volunteers challenged with smaller doses of endotoxin^4,7 or in patients with septic shock²⁴. The level measured in this patient is in the range of the highest TNF- levels reported among patients with fatal meningococcemia^25,26.

The successful outcome and mild organ dysfunction observed in this patient, despite the occurrence of profound shock, may have been due to the limited nature of the insult, the absence of an active infection with the production of other microbial toxins, early intervention with fluid resuscitation and cardiovascular support, and the overall health of the patient. However, the role of other host-related factors, such as naturally occurring anti-endotoxin antibodies, cannot be excluded. It is possible that the administration of the HA-1A antibody affected the outcome in this patient, but it appears that endotoxin had already been cleared from the circulation before the dose was given. In conclusion, a single injection of endotoxin in the absence of infection can cause a syndrome of shock and organ injury that evolves over days and is similar to septic shock.

We are indebted to Patricia Madara, Renee Miller, and Jeanette M. Hosseini for their technical assistance, to Drs. Peter Daddona, Scott Siegal, and Richard McCloskey (all of Centocor) for performing the TNF- assays, and to Dr. Ronald J. Elin for guidance and advice.

Source Information

From the Division of Pulmonary and Critical Care Medicine (A.M.T.S., F.S.C.) and the Department of Medicine (H.C.K., D.R.L.), Georgetown University, Washington, D.C., and the Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Md. (A.F.S., R.L.D.).

Address reprint requests to Dr. Taveira da Silva at the Division of Pulmonary and Critical Care Medicine, Georgetown University Hospital, 3800 Reservoir Rd., NW, Washington, DC 20007.

References

1. Danner RL, Suffredini AF, Natanson C, Parrillo JE. Microbial toxins: role in the pathogenesis of septic shock and multiple organ failure. In: Bihari DJ, Cerra FB, eds. Multiple organ failure. Fullerton, Calif.: Society of Critical Care Medicine, 1989:151-91. 
2. Wichterman KA, Baue AE, Chaudry IH. Sepsis and septic shock -- a review of laboratory models and a proposal. J Surg Res 1980;29:189-201. [CrossRef][Medline]
3. Hess ML, Hastillo A, Greenfield LJ. Spectrum of cardiovascular function during gram-negative sepsis. Prog Cardiovasc Dis 1989;23:279-298. 
4. Martich GD, Danner RL, Ceska M, Suffredini AF. Detection of interleukin 8 and tumor necrosis factor in normal humans after intravenous endotoxin: the effect of antiinflammatory agents. J Exp Med 1991;173:1021-1024. [Free Full Text]
5. van Deventer SJH, Buller HR, ten Cate JW, Aarden LA, Hack CE, Sturk A. Experimental endotoxemia in humans: analysis of cytokine release and coagulation, fibrinolytic, and complement pathways. Blood 1990;76:2520-2526. [Free Full Text]
6. Suffredini AF, Harpel PC, Parrillo JE. Promotion and subsequent inhibition of plasminogen activation after administration of intravenous endotoxin to normal subjects. N Engl J Med 1989;320:1165-1172. [Abstract]
7. Suffredini AF, Fromm RE, Parker MM, et al. The cardiovascular response of normal humans to the administration of endotoxin. N Engl J Med 1989;321:280-287. [Abstract]
8. Brues AM, Shear MJ. Chemical treatment of tumors. X. Reactions of four patients with advanced malignant tumors to injection of a polysaccharide from Serratia marcescens culture filtrate. J Natl Cancer Inst 1944;5:195-208. 
9. Stevens AR Jr, Legg JS, Henry BS, Dille JM, Kirby WMM, Finch CA. Fatal transfusion reactions from contamination of stored blood by cold growing bacteria. Ann Intern Med 1953;39:1228-1239. [Medline]
10. Appendix: normal values. In: Grossman W, ed. Cardiac catheterization and angiography. 3rd ed. Philadelphia: Lea & Febiger, 1986:545-6.
11. Danner RL, Elin RJ, Hosseini JM, Wesley RA, Reilly JM, Parrillo JE. Endotoxemia in human septic shock. Chest 1991;99:169-175. [Free Full Text]
12. Donovan MA, Berzofsky RN. Kinetic-QCL and validation of blood collection tubes for endotoxemia detection. J Cell Biochem 1992;16:170-170.abstract 
13. Espevik T, Nissen-Meyer J. A highly sensitive cell line, WEHI 164 clone 13, for measuring cytotoxic factor/tumor necrosis factor from human monocytes. J Immunol Methods 1986;95:99-105. [CrossRef][Medline]
14. Boujoukos AJ, Martich GD, Supinski E, Suffredini AF. Compartmentalization of the acute cytokine response in humans following intravenous endotoxin administration. J Appl Physiol (in press).
15. McCabe WR, Olans RN. Shock in gram-negative bacteremia: predisposing factors, pathophysiology, and treatment. In: Remington JS, Swartz MN, eds. Current clinical topics in infectious diseases. Vol. 2. New York: McGraw-Hill, 1981:121-50.
16. Greisman SE, Hornick RB, Wagner HN Jr, Woodward WE, Woodward TE. The role of endotoxin during typhoid fever and tularemia in man. IV. The integrity of the endotoxin tolerance mechanisms during infection. J Clin Invest 1969;48:613-629.
17. Natanson C, Danner RL, Elin RJ, et al. Role of endotoxemia in cardiovascular dysfunction and mortality: Escherichia coli and Staphylococcus aureus challenges in a canine model of human septic shock. J Clin Invest 1989;83:243-251.
18. Parker MM, Shelhamer JH, Natanson C, Alling DW, Parrillo JE. Serial cardiovascular variables in survivors and nonsurvivors of human septic shock: heart rate as an early predictor of prognosis. Crit Care Med 1987;15:923-929. [Medline]
19. Danner RL, Natanson C, Elin RJ, et al. Pseudomonas aeruginosa compared with Escherichia coli produces less endotoxemia but more cardiovascular dysfunction and mortality in a canine model of septic shock. Chest 1990;98:1480-1487. [Free Full Text]
20. Herring WB, Herion JC, Walker RI, Palmer JG. Distribution and clearance of circulating endotoxin. J Clin Invest 1963;42:79-87.
21. Braude AI, Carey FJ, Zalesky M. Studies with radioactive endotoxin. II. Correlation of physiologic effects with distribution of radioactivity in rabbits injected with lethal doses of E. coli endotoxin labelled with radioactive sodium chromate. J Clin Invest 1955;34:858-866.
22. Levin J, Tomasulo PA, Oser RS. Detection of endotoxin in human blood and demonstration of an inhibitor. J Lab Clin Med 1970;75:903-911. [Medline]
23. Webster CJ. Principles of a quantitative assay for bacterial endotoxins in blood that uses Limulus lysate and a chromogenic substrate. J Clin Microbiol 1980;12:644-650. [Free Full Text]
24. Marks JD, Marks CB, Luce JM, et al. Plasma tumor necrosis factor in patients with septic shock: mortality rate, incidence of adult respiratory distress syndrome, and effects of methylprednisolone administration. Am Rev Respir Dis 1990;141:94-97. [Medline]
25. Girardin E, Grau GE, Dayer J-M, Roux-Lombard P, J5 Study Group, Lambert P-H. Tumor necrosis factor and interleukin-1 in the serum of children with severe infectious purpura. N Engl J Med 1988;319:397-400. [Abstract]
26. Waage A, Brandtzaeg P, Halstensen A, Kierulf P, Espevik T. The complex pattern of cytokines in serum from patients with meningococcal septic shock: association between interleukin 6, interleukin 1, and fatal outcome. J Exp Med 1989;169:333-338. [Free Full Text]

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