Characterization of a haemolytic phospholipase A2 activity in clinical isolates of Campylobacter concisus

Abstract

A membrane-bound, haemolytic phospholipase A 2 (PLA 2 ) activity was detected in clinical strains of Campylobacter concisus isolated from children with gastroenteritis. The clinical strains were assigned into two molecular groups (genomospecies) based on PCR amplification of their 23S rDNA. This calcium-dependent, heat-stable, haemolytic PLA 2 activity was detected in strains from both genomospecies. A crude haemolysin extract (CHE) was initially prepared from cellular outermembrane proteins of these isolates and was further fractionated by ultrafiltration. The haemolytic activity of the extracted fraction (R30) was retained by ultrafiltration using a 30 kDa molecular mass cut-off filter, and was designated haemolysin extract (HE). Both CHE and HE had PLA 2 activity and caused stable vacuolating and cytolytic effects on Chinese hamster ovary cells in tissue culture. Primers for the conserved region of pldA gene (phospholipase A gene) from Campylobacter coli amplified a gene region of 460 bp in all tested isolates, confirming the presence of a homologous PLA gene sequence in C. concisus. The detection of haemolytic PLA 2 activity in C. concisus indicates the presence of a potential virulence factor in this species and supports the hypothesis that C. concisus is a possible opportunistic pathogen.

Detection and Isolation of Campylobacter Species Other than C. jejuni from Children with Crohn's Disease

“…Although the exact clinical relevance of C. concisus remains undetermined, a recent review by Newell reported this bacterium to be an emerging human pathogen of intestinal infectious diseases (10). The facts that C. concisus has been shown to have the potential to damage epithelial integrity (3,6) and that the immune response detected in this study to C. concisus in CD children was greater than in controls suggest that C. concisus may contribute to CD pathogenesis.…”

Delineation of Campylobacter concisus Genomospecies by Amplified Fragment Length Polymorphism Analysis and Correlation of Results with Clinical Data

“…Moreover, colonization of the intestines of mice by C. concisus is transiently achieved (R. Aabenhus, unpublished data), whereby infected mice exhibited a significant loss of body weight compared with uninfected mice. Istivan and colleagues (12) have identified a membranebound hemolytic phospholipase in C. concisus strains, and many C. concisus strains show cytotoxic activity (9). However, the prevalence of C. concisus in 4 to 15% of asymptomatic patients (9,10,30) has been used by some to suggest that C. concisus should be regarded as at best an opportunistic pathogen, most relevant to immunocompromised patients and those at the extremes of age.…”

The Family Campylobacteraceae

“…S-layer RTX proteins and their genes were detected in both oral and enteric C. concisus strains (Kaakoush et al 2010;Kalischuk and Inglis 2011;Mahendran et al 2011). C. concisus strains revealed hemolytic activities (Istivan et al 2004;Kalischuk and Inglis 2011).…”