Intracellular Survival of Staphylococci

Abstract

These studies on the intracellular survival of staphylococci were begun with the idea of investigating possible mechanisms of "cellular immunity" in staphylococcal infections. At that time the reports of Rogers and Tompsett (1) and Baker (2) had stated that virulent staphylococci would not only survive, but actually multiply within human and rat leucocytes. These reports prompted the present authors to see whether staphylococci could multiply within rabbit leucocytes and if this were the case whether rabbits "immunized" with staphylococci would exhibit an increase in cellular immunity such as has been reported to occur in tuberculosis and Brucella infections (3-5), in which cells from immune animals seem to suppress intracellular multiplication of the organisms. However, it soon became evident that "normal" rabbit and human leucocytes did not permit virulent staphylococci to multiply intracellularly. This suggested that the so called normal individual possessed a considerable degree of resistance to the organism without additional immunization. This report presents data to support the conclusion that virulent staphylococci only survive, but do not multiply within normal leucocytes of human and rabbit origin, while the organisms are actually destroyed by rat monocytes. These studies were performed both in the presence of varying amounts of streptomycin and in its absence. Materials and MethodsThe tissue culture procedure about to be described was developed as a means of following in a completely quantitative manner the intracellular survival of an organism. With this procedure it was possible to determine simultaneously both the extracellular and intracellular bacterial concentration as well as the leucocyte population. Streptomycin was employed to prevent extraeellular multiplication, thereby ruling out the complication of continual phagocytosis. The use of special tissue culture chambers not only facilitated the use of coverslip cultures, but also permitted an entire test condition to be performed within one vessel, thereby minimizing effects due to variations in experimental conditions.Tissue Culture Chambers.--These chambers were fabricated from plexiglas with the dimensions as shown in Fig. 1. The base is of ~ inch stock, 19 mm. wide and 116 ram. long.

The Eventual Intracellular Destruction of Staphylococci by Mononuclear Cells

“…In a previous study (Kapral & Shayegani, 1959) it was reported that Staphylococcus a u r w could survive for several hours within rabbit mononuclear leucocytes. No multiplication or destruction of staphylococci was observed during this interval with the methods used.…”

“…This tissue-culture procedure was the same as previously described (Kapral & Shayegani, 1959) with the exception that 0.2 ml. of 10% sodium bicarbonate solution was incorporated into the tissue-culture medium and the chambers placed under 5 % CO, to stabilize the pH at 7.4 during the long incubation period, Fifty pg.…”

The Immediate Fate of Staphylococci after Phagocytosis

“…S . aureus strain 18-Z; the characteristics of this strain were described previously (Kapral & Shayegani, 1959). From this strain two mutants were derived : (i) 18-Z, ad--an adenine-requiring mutant, which grew slowly without added adenine, and had a lag phase of about 7-10 hr.…”

“…Monocytes and polymorphonuclear leucocytes were obtained from rabbits as described previously (Kapral & Shayegani, 1959 …”

“…In previous publications (Kapral & Shayegani, 1959;Shayegani & Kapral, 1962) the authors reported that Staphylococcus aureus usually survived for several hours within polymorphonuclear leucocytes and monocytes of normal rabbits, but were eventually slowly destroyed within the monocytes. S. albus, however, was rapidly destroyed by these cells under the same conditions.…”