Pseudomonas aeruginosa isolates from patients with cystic fibrosis: a class of serum-sensitive, nontypable strains deficient in lipopolysaccharide O side chains

Abstract

Twenty-six Pseudomonas aeruginosa strains from patients with cystic fibrosis were typed by the Fisher immunotyping scheme. Only 6 strains were agglutinated by a single typing serum, whereas 15 strains were agglutinated with more than one serum and 5 were not agglutinated by any serum. Neither the polyagglutinable nor the nonagglutinable strains were typable by hemagglutination inhibition or immunodiffusion, suggesting that these polyagglutinable strains did not express multiple serotype antigens, but were instead being agglutinated by antibody to nonserotype determinants. Four typable isolates were resistant to pooled normal human serum, whereas the 12 polyagglutinable and nonagglutinable isolates studied were very sensitive to normal human serum. The outer membranes of 16 strains were isolated and characterized. The data suggested, in general, strong conservation of outer membrane protein patterns. Lipopolysaccharides (LPS) were purified by a new technique which allowed isolation of both rough and smooth LPS in high yields. Three of four typable, serum-resistant strains examined had amounts of smooth, O-antigen-containing LPS equivalent to our laboratory wild type, P. aeruginosa PAO1 strain H103. In contrast, 10 of 12 polyagglutinable or nonagglutinable, serum-sensitive strains had very little or no smooth, O-antigen-containing LPS, and the other two contained less smooth LPS than our wild-type strain H103. In agreement with this data, five independent, rough, LPS O-antigen-deficient mutants of strain H103 were nontypable and serum sensitive. We suggest that the LPS defects described here represent a significant new property of many P. aeruginosa strains associated with cystic fibrosis.

Synthesis of multiple Pseudomonas aeruginosa biofilm matrix exopolysaccharides is post‐transcriptionally regulated

“…A-band LPS is antigenically conserved, while B-band LPS is serologically variable (Knirel, 1990;Islam et al, 2011). Pseudomonas aeruginosa isolated from CF patients with chronic lung infection often exhibit LPS phenotypes with reduced amounts of long O-antigen side-chains (Hancock et al, 1983). At present, it is not clear whether loss of LPS O-side-chain is coordinately linked to the production of the other exopolysaccharides, such as alginate and Psl.…”

Production of N-acyl-?-homoserine lactones by P. aeruginosa isolates from chronic lung infections associated with cystic fibrosis

“…During chronic pulmonary infection of patients with CF P. aeruginosa undergoes phenotypic changes that are thought to represent speci¢c adaptations to the CF lung environment. Strains from chronically colonized patients synthesize vast amounts of the exopolysaccharide alginate, usually lack pili and £agella [7], are de¢cient in O-speci¢c lipopolysaccharides [8], and produce reduced amounts of extracellular virulence factors [9^11]. Since expression of many virulence determinants is quorum sensing controlled we hypothesized that the low amounts of virulence factors observed with isolates from chronically infected patients may be a consequence of reduced levels of AHL synthesis by the strains.…”

The rfb locus from Pseudomonas aeruginosa strain PA103 promotes the expression of O antigen by both LPS‐rough and LPS‐smooth isolates from cystic fibrosis patients

“…Chronic colonization of the CF lung by P. aeruginosa has been associated with the emergence of strains that produce large amounts of a mucoid exopolysaccharide called alginate (Doggett et al, 1964). Many mucoid CF isolates express little or no Iipopolysaccharide (LPS) O antigen; these strains do not agglutinate with O antigen type-specific sera, are sensitive to killing by serum, and are referred to as LPS-rough (Hancock et aL, 1983). Alterations in expression of O antigen and alginate by P. aeruginosa are thought to be important in the pathogenesis of chronic infection of the CF lung by this microorganism.…”