Multilocus sequence typing (MLST) methods for the emerging Campylobacter species C. hyointestinalis, C. lanienae, C. sputorum, C. concisus and C. curvus

Authors: Miller, William - Bill; Chapman, Mary; YEE, EMMA; ON, STEPHEN - INSTITUTE OF ENVIRONMENTAL SCIENCE AND RESEARCH; MCNULTY, DESMOND - CHERRY ORCHARD HOSPITAL; LASTOVICA, ALBERT - UNIVERSITY OF THE WESTERN CAPE; CARROLL, ANNE - CHERRY ORCHARD HOSPITAL; MCNAMARA, ELEANOR - CHERRY ORCHARD HOSPITAL; DUFFY, GERALDINE - TEAGASC (AGRICULTURE AND FOOD DEVELOPMENT AUTHORITY); MANDRELL, ROBERT

Submitted to: Frontiers in Cellular and Infection Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2012
Publication Date: 4/2/2012
Citation: Miller, W.G., Chapman, M.H., Yee, E., On, S.L., Mcnulty, D.K., Lastovica, A.J., Carroll, A.M., Mcnamara, E.B., Duffy, G., Mandrell, R.E. 2012. Multilocus sequence typing (MLST) methods for the emerging Campylobacter species C. hyointestinalis, C. lanienae, C. sputorum, C. concisus and C. curvus.. Frontiers in Cellular and Infection Microbiology. 10:3389/fcimb.2012.00045.

Interpretive Summary: Campylobacter have been isolated from a wide variety of environments, warm-blooded animals (birds, mammals). Campylobacters cause disease in both livestock and humans; human disease is primarily gastroenteritis, however other clinical outcomes, such as septicemia, can occur. Several Campylobacter species, predominantly C. jejuni, have been isolated from food, milk and water; thus, several campylobacters are considered food-borne pathogens. Although the primary pathogen within Campylobacter is C. jejuni, other Campylobacter species have been associated with clinical human disease. One such organism is C. concisus, in which a strong association has been demonstrated recently with Crohn’s disease and ulcerative colitis. Thus, other campylobacters, previously thought of as non-pathogenic or organisms with a minor impact on human health, are now considered to be emerging human pathogens. Little is known about these organisms and no typing method has been developed that could be used to identify and distinguish emerging Campylobacter strains. This study describes four new typing methods that can distinguish five Campylobacter species, including C. concisus, to the strain level. These methods were used to type 213 strains: multiple strain types of each species were identified. A great deal of variation was observed among C. concisus strains and this species was determined to possess two major types: those associated with the human oral environment and those associated with the human GI tract. These methods identified also potentially new Campylobacter species isolated from livestock.

Technical Abstract: Multilocus sequence typing (MLST) systems have been reported previously for multiple food- and food animal-associated Campylobacter species (e.g. C. jejuni, C. coli, C. lari and C. fetus) to both differentiate strains and identify clonal lineages. These MLST methods focused primarily on campylobacters of human clinical (e.g. C. jejuni) or veterinary (e.g. C. fetus) relevance. However, other, emerging, Campylobacter species have been isolated increasingly from environmental, food animal or human clinical samples. We describe herein MLST methods for five emerging Campylobacter species: C. hyointestinalis, C. lanienae, C. sputorum, C. concisus and C. curvus. The concisus/curvus method uses the loci aspA, atpA, glnA, gltA, glyA, ilvD and pgm, whereas the other methods use the seven loci defined for C. jejuni (i.e., aspA, atpA, glnA, gltA, glyA, pgm, and tkt). Multiple food animal and human clinical C. hyointestinalis (n=48), C. lanienae (n=34) and C. sputorum (n=24) isolates were typed, along with 86 human clinical C. concisus and C. curvus isolates. A large number of sequence types (STs) were identified using all four MLST methods. Similar to Campylobacter MLST methods described previously, these novel MLST methods identified mixed isolates containing two or more strains of the same species. Additionally, these methods speciated unequivocally isolates that had been typed ambiguously using other molecular-based speciation methods, such as 16S rDNA sequencing. Finally, the design of degenerate primer pairs for some methods permitted the typing of related species; for example, the C. hyointestinalis primer pairs could be used to type C. fetus strains. Therefore, these novel Campylobacter MLST methods will prove useful in speciating and differentiating strains of multiple, emerging Campylobacter species.