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At least 19 recordsLinked to original sources
PubMed1955

Studies on susceptibility to infection following ionizing radiation. IV. The pathogenesis of the endogenous bacteremias in mice.

In half of the normal mice examined, cultures of mesenteric lymph nodes were positive for enteric bacteria. When a non-pathogenic microorganism, Serratia marcescens, was established in the intestinal tract by administering it to mice in their drinking water, it, too, was recovered from the mesenteric lymph nodes of almost half of the normal mice examined. From these findings it was concluded that bacteria in small numbers were able to pass from the lumen of the unirradiated gut as far as the regional lymph glands. Such bacteria, except the pathogen, Salmonella, were rarely found in liver or spleen, never in the blood of the normal mice. After x-irradiation with 700 r, the incidence of positive cultures showed the liver or spleen became infected with enteric microorganisms before the blood stream was invaded. It appears, therefore, that these elements of the reticulo-endothelial system were able for a time to maintain the sterility of the blood after failure of the more immediate defenses against bacterial invasion from the intestinal tract. It is concluded that if any increased migration of bacteria through the intestinal mucosa resulted from the radiation injury, the increase must have occurred very soon after irradiation.

Animals↗
PubMed1956

Studies on bacteriemia. I. Mechanisms relating to the persistence of bacteriemia in rabbits following the intravenous injection of staphylococci.

During the course of studies on the characteristics of experimental bacteriemia, staphylococci were swiftly cleared from the blood stream of rabbits during the initial 10 to 15 minutes following intravenous injection of microorganisms. A subsequent abrupt decline in the rate of clearance ensued, resulting in a low grade bacteriemia which was demonstrable for many hours. The experiments reported have indicated that this strain of staphylococcus is rapidly phagocyted within the vascular system of rabbits, and that viable staphylococci circulate within the cytoplasm of polymorphonuclear leukocytes. The removal mechanisms contained within the liver and spleen appear to preferentially trap circulating extracellular staphylococci. When most of the circulating staphylococci are contained within leukocytes, splanchnic removal declines or virtually ceases. These observations suggest that viable, intracellular microorganisms are responsible for the persistence of staphylococcal bacteriemia in rabbits following the phase of rapid removal from the blood stream.

Animals↗
PubMed1957

Studies on bacteriemia. III. The blood stream clearance of Escherichia coli in rabbits.

Large numbers of E. coli were rapidly removed from the blood stream of rabbits at rates which initially paralleled the removal of similar numbers of staphylococci. Splanchnic tissues removed approximately two-thirds of the circulating bacilli in transit through the liver and spleen. In contrast to the cessation of splanchnic trapping noted 20 to 40 minutes following the injection of staphylococci, splanchnic trapping of E. coli continued unchanged for 3 to 5 hours unless the splanchnic tissues were dearly reseeding the blood stream. This resulted in the continued disappearance of E. coli over a 60 to 90 minute period, and differed from the constant bacteriemia maintained beyond 20 minutes after the injection of staphylococci. Some of the differences in the initial clearance of these two microorganisms appeared to relate to differences in host leukocyte-bacterium relationships. In vitro studies indicated that E. coli were rapidly killed following ingestion by rabbit polymorphonuclear leukocytes. Staphylococci survive such ingestion. The injection of E. coli was followed by a prolonged granulocytopenia with evidence of sequestration of granulocytes within the pulmonary vascular bed. The injection of staphylococci was followed by a transient leukopenia, with rapid return of granulocytes to the circulation (15). It appears probable that E. coli ingested by sequestered leukocytes are destroyed within the cell, and that leukocytes do not reenter the circulation containing living E. coli. Such intraleukocytic residence in the blood stream has been shown to be of possible importance in the maintenance of staphylococcal bacteriemia (14). An increasing E. coli bacteriemia occurred rapidly after the initial clearance period, indicating that many sequestered bacilli remained viable. Increasing bacteriemia also occurs 3 to 5 hours after the injection of staphylococci. The bacterial or host cell mechanisms which allow this secondary resurgence of bacterial populations are currently under investigation.

Animals↗
PubMed1957

Studies on bacteriemia. II. Further observations on the granulocytopenia induced by the intravenous injection of Staphylococci.

Intravenous injection of staphylococci produced a marked, transient granulocytopenia inrabbits. Leukopenia was rapidly followed by return of polymorphonuclear leukocytes to the peripheral blood, and normal circulating granulocyte levels were reestablished within 20 to 40 minutes. Differential arterio-venous leukocyte studies showed that polymorphonuclear leukocytes were trapped within the pulmonary vascular bed and, less constantly, in the splanchnic viscera during the initial 10 to 20 minutes following the injection of staphylococci. Granulocytes were subsequently found in larger numbers in blood leaving the lungs and splanchnic tissues, suggesting that entrapped polymorphonuclear leukocytes rapidly reentered the blood stream. This sequence of changes in circulating granulocytes was not significantly altered by splenectomy or the administration of cortisone. It has previously been shown that virtually all staphylococci in the blood stream are found within circulating polymorphonuclear leukocytes 10 to 40 minutes after the injection of culture (9). It is during this period that granulocytes return to the blood stream in large numbers. These observations suggest that staphylococci are phagocyted by polymorphonuclear leucocytes temporarily sequestered in the lungs and splanchnic viscera. It appears probable that some sequestered granulocytes containing living staphylococci subsequently return to the circulation. Such intraleukocytic staphylococci are believed to play a role in the maintenance of bacteriemia.

Agranulocytosis↗
PubMed1958

Studies on bacteriemia. IV. Alterations in rabbit mortality associated with aging of a culture of Escherichia coli.

Rabbits given an intravenous injection of an 18 to 24 hour broth culture of E. coli commonly died within 28 hours. The injection of a 4 hour broth culture of the same strain of E. coli containing equal numbers of living bacilli produced only an occasional death. Initial clearance rates and subsequent bacteriemias were similar in animals receiving either culture. Study of changes in circulating leukocytes or the temperature response to washed bacterial cells or culture filtrates failed to reveal obvious differences in host response to young or old cultures. It was found that both living bacterial cells and some substance or substances present in culture filtrates were required to produce subsequent death. The injection of whole old cultures containing both these factors produced hypothermia instead of the endotoxin type fever response which followed the injection of whole young cultures. Subsequent experiments revealed that this hypothermia appeared to be secondary to a period of transient but profound shock which occurred soon after the injection in rabbits receiving old cultures. No significant alterations in arterial pressure accompanied injections of young cultures. Evidence is presented which suggests that this period of hypotension rendered animals more likely to die with a persisting bacteriemia tolerated without event by non-shocked animals. The mechanisms which operate to increase mortality during the post shock period are as yet unclarified.

Aging↗
PubMed1959

A quantitative study of the kinetics of blood clearance of P32-labelled Escherichia coli and Staphylococci by the reticuloendothelial system.

1. The clearance of P(32)-labelled heat-killed E. coli and staphylococci from the blood follows an exponential function of the time, and the bacteria are phagocytized principally by the RES of the liver and spleen. 2. The rates of clearance of equivalent number of E. coli from the blood is rapid in rabbits and slow in mice and appears to be related to the level of antibodies in the serum of these animals. 3. Unlike E. coli, staphylococci are cleared rapidly and efficiently by the RES from the blood of mice which have a sufficient level of serum antibody against these bacteria. 4. The numbers of bacteria, phagocytized by the liver or the spleen respectively, depend upon the rate of clearance and the extent of opsonization of the bacteria. Rapidly cleared, well opsonized E. coli are removed almost exclusively by the liver, while less efficiently phagocytized bacteria are also cleared by the spleen in large numbers. 5. The rate of clearance of E. coli and the efficiency with which they are phagocyted by the RES in mice have been shown to be directly related to the level of antibody in the serum. 6. Treatment of mice with S. typhi or Serratia marcescens endotoxins increases the rate of clearance of E. coli from the blood and the level of antibody against E. coli in the serum. The enhanced clearance of E. coli can be transferred to normal mice by the serum of endotoxin-treated mice.

Animals↗
PubMed1951

Studies on the cellular immunology of acute bacteremia. I. Intravascular leucocytic reaction and surface phagocytosis.

Evidence has been presented that the introduction of large numbers of bacteria into the blood stream causes a widespread intravascular reaction, characterized by the sticking of leucocytes to the endothelium of capillaries, arterioles, and venules. The adherent granulocytes promptly become motile and thus potentially phagocytic. This intravascular leucocytic response affords a rapid and efficient mobilization of a vast number of active phagocytes within the blood stream. In some of the smaller vessels of both the systemic and pulmonary circulation the reaction is accompanied by the deposition of what appears to be intravascular fibrin. Direct observation by the rabbit ear chamber technique has revealed that leucocytes thus mobilized in small peripheral vessels are capable of phagocyting fully encapsulated Friedländer's bacilli in the absence of antibody. Ingestion of the encapsulated blood-borne bacteria results from surface phagocytosis and occurs primarily in those vessels in which the flow of blood is either slowed or has temporarily stopped altogether. Leucocytes can be seen to phagocyte the organisms by first trapping them against the walls of the vessels or against adjacent leucocytes. Bacteria caught in the interstices of the intravascular "fibrin" may likewise be immobilized and readily phagocyted. Thus granulocytes, without the aid of opsonins, are able to ingest and destroy encapsulated blood-borne bacteria by the same mechanisms that operate in extravascular tissues. It is concluded from these studies that intravascular surface phagocytosis by polymorphonuclear leucocytes supplements the well known phagocytic activities of the reticulo-endothelial cells and therefore serves as an important defense of the host in acute infections caused by encapsulated bacteria and complicated by bacteriemia.

Antibodies↗
PubMed1954

Studies on susceptibility to infection following ionizing radiation. I. The time of onset and duration of the endogenous bacteremias in mice.

Daily cultures of blood obtained from the tail were made on mice from the 7th day to the 17th or 22nd days after exposure to 550 r total body x-irradiation. Seven mice with negative blood cultures survived to the 27th day when they were sacrificed and found to have negative heart's blood cultures. Every mouse with bacteremia died. Heart's blood cultures post mortem always confirmed the bacteriological findings in the serial cultures. Most of the bacteremias occurred between the 7th and 15th days. The duration of the bacteremia varied with the microorganism which caused it. Pseudomonas bacteremia was always rapidly fatal. Those caused by Proteus and E. coli continued for a maximum of 72 and 48 hours. Of longest duration was bacteremia caused by Paracolobactrum which was tolerated for as long as 5 days.

Animals↗