Molecular Typing of Campylobacter jejuni and Campylobacter coli Isolated from Various Retail Meats by MLST and PFGE

Abstract

<i>Campylobacter</i> species are one of the leading causes of foodborne disease in the United States. <i>Campylobacter jejuni</i> and <i>Campylobacter coli</i> are the two main species of concern to human health and cause approximately 95% of human infections. Molecular typing methods, such as pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) are often used to source track foodborne bacterial pathogens. The aim of the present study was to compare PFGE and MLST in typing strains of <i>C. jejuni</i> and <i>C. coli</i> that were isolated from different Oklahoma retail meat sources. A total of 47 <i>Campylobacter</i> isolates (28 <i>C. jejuni</i> and 19 <i>C. coli</i>) isolated from various retail meat samples (beef, beef livers, pork, chicken, turkey, chicken livers, and chicken gizzards) were subjected to pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). PFGE was able to group the 47 <i>Campylobacter</i> isolates into two major clusters (one for <i>C. jejuni</i> and one for <i>C. coli</i>) but failed to differentiate the isolates according to their source. MLST revealed 21 different sequence types (STs) that belonged to eight different clonal complexes. Twelve of the screened <i>Campylobacter</i> isolates (8 <i>C. jejuni</i> and 4 <i>C. coli</i>) did not show any defined STs. All the defined STs of <i>C. coli</i> isolates belonged to ST-828 complex. The majority of <i>C. jejuni</i> isolates belonged to ST-353, ST-607, ST-52, ST-61, and ST-21 complexes. It is worthy to mention that, while the majority of <i>Campylobacter</i> isolates in this study showed STs that are commonly associated with human infections along with other sources, most of the STs from chicken livers were solely reported in human cases. In conclusion, retail meat <i>Campylobacter</i> isolates tested in this study particularly those from chicken livers showed relatedness to STs commonly associated with humans. Molecular typing, particularly MLST, proved to be a helpful tool in suggesting this relatedness to <i>Campylobacter</i> human isolates.