[Phagocytosis of Staphylococcus aureus and Pseudomonas aeruginosa by pulmonary macrophages and granulocytes]

Abstract

The elimination (by human alveolar macrophages and pulmonary granulocytes) of one laboratory strain and one wild-type strain each of Staphylococcus aureus and Pseudomonas aeruginosa has been investigated in vitro. Administering 10(6) alveolar macrophages to 5 x 10(6) staphylococci leads to a reduction of viable colony-forming units (CFU) to 5.8 x 10(5) (L] (laboratory strain (L) and 6.9 x 10(5) (wild-type strain (W)) after 60 minutes. The corresponding values of Ps. aeruginosa are 4.3 x 10(6) (L) and 4.4 x 10(6) (W). The peak chemiluminescence values are 9, 160 (L) and 12,300 (W) counts/10(5) cells for Staph. aureus and 7,670 (L) and 8,950 (W) for Ps. aeruginosa. The addition of heat-inactivated serum increases the number of staphylococci observed within alveolar macrophages from 1.57 to 3.18 (L) and from 1.32 to 2.79 (W). Fresh serum enhances ingestion to 8.15 (L) and 9.73 (W) staphylococci/macrophage. The number of phagocytized pseudomonads in pure culture medium is 0.51 (L) and 0.46 (W) bacteria/macrophage. An increase by the addition of serum is not possible. While staphylococci adhere to the membrane of the macrophage over a wide area, the pseudomonads adhere to it in a highly circumscribed manner. The following ingestion steps do not differ from one organism to the other. After 60 minutes, cultivation of 10(6) granulocytes with 5 x 10(6) staphylococci leads to a reduction of the viable CFU to 7.5 x 10(5) (L) and 9.4 x 10(5) (W). In the case of Ps. aeruginosa, the number of surviving CFU is 4.5 x 10(6) (L) and 3.8 x 10(6) (W). After the addition of Staph. aureus, peak values of 37,800 (L) and 35,500 (W) counts/10(5) cells are measured. The corresponding values for Ps. aeruginosa are 28,900 (L) and 33,100 counts/10(5) cells (W). The addition of heat-inactivated serum leads, in the case of Staphylococcus aureus, to an increase in the ingestion of the laboratory strain from 1.07 to 1.94 and of the wild-type strain from 0.94 to 2.41 bacteria/granulocyte. Fresh serum brings about a further increase to 5.52 (L) and 4.82 (W). In the case of Ps. aeruginosa. 0.75 (L) and 0.69 (W) ingested bacteria/granulocyte are observed; the addition of serum fails to bring about any increase. In contrast to the staphylococci, pseudomonads adhere to the granulocyte membrane in a punctate manner only. No differences of ingestion are seen.