The Addition of Putative Virulence Markers to an Established P-BIT Typing Scheme Enables Campylobacter coli, but not Campylobacter jejuni, to be Separated into Country of Origin

Introduction:  Campylobacter is the leading cause of foodborne bacterial gastroenteritis in many industrialised countries. Standardized protocols for Multi Locus Sequence Typing exist to facilitate the epidemiological study of these organisms. A PCR binary typing system (P-BIT) recently developed in New Zealand provides a less expensive, rapid and highly portable typing system.

Purpose:  The purpose of this study was to determine if the P-BIT system with or without additional data can differentiate Campylobacterfrom three countries.

Methods:  A total of 58 Campylobacter isolates from Australia (15 C. jejuni, 5 C. coli), Poland (16 C. jejuni, 6 C. coli), and Malaysia (9 C. jejuni, 7 C. coli), isolated from chicken carcasses at the end of processing or at retail, were examined for the presence of the 18 P-BIT genes and eight putative virulence markers. P-BIT and gene presence were analysed using Bionumerics with simple matching and UPGMA. Clusters were separated at the 75% level.

Results:  Across countries only a single pair of isolates from Australia and Poland had the same P-BIT code. Within countries four pairs of Australian and a single pair of Malaysian isolates had the same P-BIT code. Including a further eight genes involved in various aspects of pathogenicity in analysis of P-BIT data allowed separation of C. coli from C. jejuni and allowed further separation by country. Australian isolates had a significantly higher prevalence of ciaB while Polish isolates had a significantly higher presence of the cdtgene cluster. 

Significance:  The P-BIT method in conjunction with other putative virulence genes may be able to differentiate C. coli but not C. jejuni based on geographic origin.