The Immediate Fate of Staphylococci after Phagocytosis

Abstract

SUMMARYFour methods were employed to study the immediate fate of staphylococci within leucocytes after phagocytosis. These were : ( a ) The met hod of Cohn & Morse where leucocytes and staphylococci were mixed in tubes and kept agitated. Periodically samples were removed and lightly centrifuged to sediment the leucocytes. Plate counts were made on the lysed leucocytes to measure the intracellular organisms, the supernatant to measure the extracellular population, and a non-centrifuged saniple to determine the total number of viable cocci present, (b) Concentrated suspensions of leucocytes and staphylococci were packed together by brief centrifugation to permit rapid phagocytosis without antibodies then diluted in cold Hanks solution to stop further phagocytosis. The suspension was then rapidly passed through a Servall centrifuge with the continuous flow attachment to remove excess extracellular organisms. The infected leucocytes were placed in suspension and samples removed and treated as in the previous procedure. (c) Leucocytes and staphylococci were placed in plastic chambers containing a number of small coverslips. The cells were allowed to sediment and adhere to the coverslips, then washed to remove most of the extracellular organisms. Coverslips were removed at intervals and attached leucocytes lysed to liberate intracellular cocci which were enumerated by plate counts. Companion coverslips were washed, fixed, and stained in order to count the number of leucocytes present. The extracellular staphylococcal population was estimated by making plate counts on the tissue culture medium in the chambers. ( d ) Suspensions of infected leucocytes were diluted and placed in a series of Petri dishes. The cells were permitted to settle and attach to the glass. Periodically the plates were washed and melted trypticase soy agar was added, After incubation the plate counts afforded an estimation of the viable cocci remaining within the leucocytes at each sampling.The results obtained with these procedures were in fairly good agreement with each other. It was found that Staphylococcus aureus (IS-z and Smith strains) survived in significant numbers within monocytes and polymorphonuclear leucocytes of normal rabbits for several hours. Little destruction of this organism during the first hour after phagocytosis could be demonstrated.

Staphylococcus aureus Protein A Promotes Immune Suppression

“…Whether antibody is required for phagocytosis of S. aureus has also been brought into question in past studies. For example, early work by Shayegani and Kapral demonstrated that S. aureus can be ingested by leukocytes in the absence of antibodies under conditions now known to prime neutrophils for enhanced phagocytosis (17). Notably, adherence primes neutrophils for enhanced functions, such as phagocytosis, and the vast majority of community-associated S. aureus infections are those of skin and soft tissue—conditions under which phagocytes are adherent.…”

Nonspecific resistance to Escherichia coli in mice

“…Administration of the antigens alone seemed to have no effect on host resistance. Since S. aureus do not multiply within the cells (13,14) and are therefore eventually eliminated, the presence of homologous antigens is needed for stimulation of cellular resistance. This finding confirms a previous report (12) describing the need for elicitation in which cell-mediated immunity was tested at the cellular level, using peritoneal macrophages from infected and elicited animals in order to study the intracellular destruction of S. aureus.…”

Role of Serum in the Intracellular Killing of Staphylococci in Rabbit Monocytes

“…The tubes were placed in a roller drum (about 30 rev/min) in a 37 C incubator. The counts of viable total, and cell-associated staphylococci, staphylococci in the centrifugal supernatant fluid, and leukocytes were determined by methods described previously (3,13).…”

“…Coagulase-positive Staphylococcus aureus cells, after ingestion by both polymorphonuclear and mononuclear phagocytes, are more slowly and less completely rendered noncultivable than are other pyogenic cocci (1- 3,6,8,9,[11][12][13][14][15][16][17][18]). This relative refractoriness to intracellular killing in all probability is a significant factor in the tendency of staphylococcal infections to become chronic and recurrent.…”