Variation and adaptation of Pseudomonas aeruginosa toxicity to HeLa cells and fibroblasts

Abstract

The toxic components of supernatants from Pseudomonas aeruginosa cultures directed against HeLa cells and Staphylococcus aureus were evaluated with the aim of discovering interactions. Supernatants of eight different strains of P. aeruginosa were assayed for cytotoxic activity. All were active against HeLa cells; seven were toxic for S. aureus. On repeated suspension of P. aeruginosa in 0.9% sodium chloride solution, a shift from HeLa cell toxicity to staphylococcal lytic activity occurred along with a change of toxic activity from a high (50,000 + 5,000) to a low (8,000 + 400) molecular weight (MW) range on gel filtration. Addition of protein to the minimal medium of cultures producing material toxic only for S. aureus reactivated the generation of HeLa cell-toxic material. Cultivation of P. aeruginosa in the presence of HeLa cells and a chloramphenicol supplement produced suppression of the generation of material toxic for S. aureus but facilitated that of HeLa-toxic material of high MW. Adaptation of toxicity against fibroblasts developed only on cocultivation of P. aeruginosa together with S. aureus and in the presence of fibroblasts. Under these conditions a strong lytic activity for S. aureus appeared, even in the presence of chloramphenicol. Chloramphenicol caused the material toxic for fibroblasts to elute at a low MW well separated from that toxic for HeLa cells. In contrast to the high-MW toxic substances, the low-MW material did not induce antibodies after injection into rabbits. This may explain failures of vaccination against P. aeruginosa infection and of serum therapy of homologous sepsis in humans.

Prospective study of serum antibodies to Pseudomonas aeruginosa exoproteins in cystic fibrosis

“…Also, in the patients (n = 8) with extremely high titers (>3), no significant difference could be found in clinical or X-ray score, lung function (FEVI.0), age, length or type of colonization (P or SP), or type of strain (mucoid or nonmucoid) compared to patients with normal titers. This is not in agreement with the afore-mentioned studies (3,4,13,17,18) and might reflect differences in co-colonization, properties of the Pseudornonas strains (20,23,31), or biochemical or immunological factors.…”

In situ survival of plasmid-bearing and plasmidless Pseudomonas aeruginosa in pristine tropical waters

“…2). The density of serotype 5 increased significantly over time (t = 2.5, df = 6, P < 0.05), while no significant change in density was observed for serotype 15. Although incorporation of [3H]thymidine appeared to be quite low (Fig.…”

“…A plasmid-bearing strain of Pseudomonas aeruginosa was used as a model for genetically engineered strains. The plasmids in the wild-type strain are nonessential for the survival of this strain (15). Since they are not required for survival, these exogenous pieces of DNA could generate a growth stress in their host cells; this may give other bacteria a competitive disadvantage.…”