|On, Stephen - DANISH VETERINARY INST.|
|Lastovica, Albert - UNIV. CAPE TOWN, S.AFRICA|
Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 2005
Publication Date: May 3, 2005
Citation: Miller, W.G., On, S., Wang, G., Fontanoz, S., Lastovica, A., Mandrell, R.E. 2005. Extended multilocus sequence typing system for campylobacter coli, c. lari, c. upsaliensis, and c. helveticus. Journal of Clinical Microbiology. 43(5).2315-2329. Interpretive Summary: A multilocus sequence typing (MLST) system has been described for Campylobacter jejuni. This system has been shown to be efficient in both differentiating C. jejuni strains and identifying clonal lineages in this species. However, sequence variation at the MLST loci prevents the use of this method in related, yet clinically relevant, Campylobacter species. Therefore, to increase the utility of MLST in Campylobacter, an expanded MLST method was developed to include Campylobacter coli, Campylobacter lari, Campylobacter upsaliensis, and Campylobacter helveticus. The C. coli and C. helveticus methods use the same seven C. jejuni loci (aspA, atpA, glnA, gltA, glyA, pgm, and tkt); however, adk and pgi were substituted for aspA and gltA in C. lari and for gltA and pgm in C. upsaliensis. Multiple C. coli, C. lari, C. upsaliensis, and C. helveticus isolates, representing both clinical and environmental sources, were typed. All four species were genetically diverse: the majority (>80%) of the isolates had unique sequence types (STs). Using this method, mixed C. lari, C. upsaliensis and C. helveticus isolates were identified; upon separation, each isolate was shown to contain two strains of the same species with distinct STs. Additionally, the expanded MLST method was able to detect potential lateral transfer events between C. jejuni and either C. coli or C. lari, and between C. upsaliensis and C. helveticus. Thus, the expanded MLST method will prove useful in differentiating strains of five Campylobacter species, identifying mixed Campylobacter cultures, and detecting genetic exchange within the genus.
Technical Abstract: Campylobacter is a major cause of human bacterial gastrointestinal illness worldwide. The majority of these illnesses are caused by one species of Campylobacter, C. jejuni. However, other Campylobacter species have been implicated in human illness. These species include: C. coli, C. lari, and C. upsaliensis. To characterize the epidemiology of these infections and investigate Campylobacter outbreaks, a DNA sequence-based typing system was developed in the UK for C. jejuni. However, as described above, the increasing role of other Campylobacter species in human illness required an expanded typing method. This manuscript reports the development and characterization of an expanded typing method for C. coli, C. lari, C. upsaliensis, and a related species, C. helveticus. Development of this method was possible only through the availability of chromosome sequences for C. coli, C. lari, C. upsaliensis, obtained through a recent USDA collaboration. This method demonstrates a high degree of diversity and genetic exchange within Campylobacter. It also permits identification of cultures composed of two or more strains, which had been designated previously as 'pure'.