Antiphagocytic Effect of Slime from a Mucoid Strain of Pseudomonas aeruginosa

Area of Science:

• Microbiology
• Immunology
• Bacterial Pathogenesis

Background:

• Mucoid strains of Pseudomonas aeruginosa are implicated in persistent tracheobronchial tree colonization in cystic fibrosis patients.
• This persistent colonization may be facilitated by the organism's secreted slime, potentially inhibiting phagocytosis.
• The antiphagocytic properties of this slime require direct investigation.

Purpose of the Study:

• To determine if slime produced by mucoid Pseudomonas aeruginosa exhibits antiphagocytic activity in vitro.
• To assess the inhibitory effect of the slime on the phagocytosis of various bacterial species by polymorphonuclear leukocytes.

Main Methods:

• Separation of slime from a mucoid Pseudomonas aeruginosa strain.
• Incubation of bacterial cells (P. aeruginosa, Escherichia coli, Staphylococcus aureus) with rabbit polymorphonuclear leukocytes in the presence and absence of slime.
• Measurement of phagocytosis by assessing the killing of bacteria after incubation.

Main Results:

• Phagocytosis of P. aeruginosa, E. coli, and S. aureus by leukocytes occurred efficiently in the absence of slime.
• The addition of slime significantly inhibited phagocytosis, as evidenced by reduced bacterial killing.
• The most pronounced inhibition of phagocytosis was observed with P. aeruginosa.

Conclusions:

• The slime produced by mucoid Pseudomonas aeruginosa possesses significant antiphagocytic activity in vitro.
• This antiphagocytic property of the slime is a potential mechanism contributing to the persistent colonization of the respiratory tract in cystic fibrosis.
• Further research into the composition and mechanism of action of the slime is warranted.