Multilocus sequence typing of Campylobacter jejuni isolates from New South Wales, Australia

Abstract

Aims: Multilocus sequence typing (MLST) was used to examine the diversity and population structure of Campylobacter jejuni isolates associated with sporadic cases of gastroenteritis in Australia, and to compare these isolates with those from elsewhere. Methods and Results: A total of 153 Camp. jejuni isolates were genotyped. Forty sequence types (STs) were found, 19 of which were previously undescribed and 21 identified in other countries. The 19 newly described STs accounted for 43% of isolates, 16 of which were assigned to known clonal complexes. Eighty‐eight percent of isolates were assigned to a total of 15 clonal complexes. Of these, four clonal complexes accounted for 60% of isolates. Three STs accounted for nearly 40% of all isolates and appeared to be endemic, while 21 STs were represented by more than one isolate. Seven infections were acquired during international travel, and the associated isolates all had different STs, three of which were exclusive to the travel‐acquired cases. Comparison of serotypes among isolates from clonal complexes revealed further diversity. Eight serotypes were identified among isolates from more than one clonal complex, while isolates from six clonal complexes displayed serotypes not previously associated with those clonal complexes. Conclusions: Multilocus sequence typing is a useful tool for the discrimination of subtypes and examination of the population structure of Camp. jejuni associated with sporadic infections. Significance and Impact of the Study: This study highlights the genotypic diversity of Camp. jejuni in Australia, demonstrating that STs causing disease have both a global and a local distribution evident from the typing of domestically and internationally acquired Camp. jejuni isolates.

Clonal Complexes of Campylobacter jejuni Identified by Multilocus Sequence Typing Are Reliably Predicted by Restriction Fragment Length Polymorphism Analyses of the flaA Gene

“…Of the 40 STs detected among 153 isolates, there were 19 that had not previously been described (STs 197, 523 to 538, and 567 to 569) (18). Of these, 10 were represented by more than a single isolate, 8 of which (80%) were represented by a single RFLP-flaA(s) type (STs 197, 524, 525, 531, 532, and 535).…”

“…The distribution of subtypes using each method is given in Table 1. Of the four methods, MLST was the most discriminatory, identifying 40 ST (Table 1) which could be grouped into 14 clonal complexes (18) and having a DI of 0.94. There were 25 isolates represented by five ST for which a clonal complex could not be assigned (18).…”

“…Of the four methods, MLST was the most discriminatory, identifying 40 ST (Table 1) which could be grouped into 14 clonal complexes (18) and having a DI of 0.94. There were 25 isolates represented by five ST for which a clonal complex could not be assigned (18). In an attempt to seek alternative methods to MLST, congruence (with MLST), ability to predict clonal complexes, and evidence of genetic stability were examined for RFLP-flaA(s), RFLPflaA(d), and SVR-fla. An expected high level of congruence was detected between RFLP-flaA(s) and RFLP-flaA(d) (V ϭ 0.84, P Ͻ 0.001); thus, RFLP-flaA(s) only was analyzed for congruence, ability to predict MLST CCs, and genetic stability.…”

“…MLST was performed according to the method of Dingle et al (7), with modified amplification conditions (denaturation at 94°C [1 min], annealing at 50°C [1 min], and extension at 72°C [1 min]) as described by Mickan et al (18). Sequences were assigned allele numbers and the isolates were assigned their sequence types by interrogation of the Campylobacter MLST database (http://campylobacter.mlst.net/).…”

Campylobacter sequence typing databases: applications and future prospects

“…Despite this diversity, there is remarkable similarity amongst isolate collections both on a national and international scale, even across different continents (Cody et al, 2012;Dingle et al, 2008;Kittl et al, 2011;Litrup et al, 2007;Mickan et al, 2007;Sopwith et al, 2006). For example, there was relatively little genetic differentiation evident amongst human disease isolates from two different areas of the UK, Canada and Australia; however, greater genetic variation was apparent comparing strains from Curaçao, an island in the Caribbean, with those from the more industrialized countries .…”