Phylogenetic Analysis Reveals Common Antimicrobial Resistant <em>Campylobacter coli</em> Population in Antimicrobial-Free (ABF) and Commercial Swine Systems

<div><p>The objective of this study was to compare the population biology of antimicrobial resistant (AR) <em>Campylobacter coli</em> isolated from swine reared in the conventional and antimicrobial-free (ABF) swine production systems at farm, slaughter and environment. A total of 200 <em>C. coli</em> isolates selected from fecal, environmental, and carcass samples of ABF (<em>n</em> = 100) and conventional (<em>n</em> = 100) swine production systems were typed by multilocus sequence typing (MLST). Sequence data from seven housekeeping genes was analyzed for the identification of allelic profiles, sequence types (STs) and clonal complex determination. Phylogenetic trees were generated to establish the relationships between the genotyped isolates. A total of 51 STs were detected including two novel alleles (<em>glnA</em> 424 and <em>glyA</em> 464) and 14 novel STs reported for the first time. The majority of the <em>C. coli</em> isolates belonged to ST-854 (ABF: 31, conventional: 17), and were grouped in clonal complex ST-828 (ABF: 68%, conventional: 66%). The mean genetic diversity (<em>H</em>) for the ABF (0.3963+/−0.0806) and conventional (0.4655+/−0.0714) systems were similar. The index of association () for the ABF ( = 0.1513) and conventional ( = 0.0991) <em>C. coli</em> populations were close to linkage equilibrium, indicative of a freely recombining population. Identical STs were detected between the pigs and their environment both at farm and slaughter. A minimum spanning tree revealed the close clustering of <em>C. coli</em> STs that originated from swine and carcass with those from the environment. In conclusion, our study reveals a genotypic diverse <em>C. coli</em> population that shares a common ancestry in the conventional and ABF swine production systems. This could potentially explain the high prevalence of antimicrobial resistant <em>C. coli</em> in the ABF system in the absence of antimicrobial selection pressure.</p> </div

Radial neighbor-joining tree of the unique ABF and conventional <i>C. coli</i> STs.

<p>ABF and conventional STs are represented by red and blue circles, respectively.</p

Genetic diversity of <i>C. coli</i> from ABF and conventional production systems.

a<p>Non-synonymous to synonymous ratio.</p>b<p>Mean genetic diversity.</p><p>Standardized index of association.</p

Minimum spanning tree (MST) of <i>C. coli</i> isolates from ABF and conventional production systems.

<p>Each ST is represented by a node. The size of each node is proportional to the number of strains that comprise that ST. Pie charts with differential colors represent <i>C. coli</i> sources: ABF pigs and carcass (purple), ABF environment at farm and slaughter (yellow), conventional pigs and carcass (red), and conventional environment at farm and slaughter (green). Allele differences are represented by thick bold branch lines (single locus variants), thin continuous lines (double locus variants), and dashed lines (three allele differences). Unique STs of the pigs, carcass, and environment at farm and slaughter from ABF and conventional systems were distinguished by single colored nodes.</p

Common STs between ABF and conventional <i>C. coli</i> isolates.

a<p>No. of isolates (%).</p>b<p>Environment.</p

<i>Brachyspira hyodysenteriae</i> Infection Regulates Mucin Glycosylation Synthesis Inducing an Increased Expression of Core‑2 <i>O</i>‑Glycans in Porcine Colon

<i>Brachyspira hyodysenteriae</i> causes swine dysentery (SD), leading to global financial losses to the pig industry. Infection with this pathogen results in an increase in <i>B. hyodysenteriae</i> binding sites on mucins, along with increased colonic mucin secretion. We predict that <i>B. hyodysenteriae</i> modifies the glycosylation pattern of the porcine intestinal mucus layer to optimize its host niche. We characterized the swine colonic mucin <i>O</i>-glycome and identified the differences in glycosylation between <i>B. hyodysenteriae</i>-infected and noninfected pigs. <i>O-</i>Glycans were chemically released from soluble and insoluble mucins isolated from five infected and five healthy colon tissues and analyzed using porous graphitized carbon liquid chromatography tandem mass spectrometry. In total, 94 <i>O</i>-glycans were identified, with healthy pigs having higher interindividual variation, although a larger array of glycan structures was present in infected pigs. This implied that infection induced loss of individual variation and that specific infection-related glycans were induced. The dominating structures shifted from core-4-type <i>O</i>-glycans in noninfected pigs toward core-2-type <i>O</i>-glycans in infected animals, which correlated with increased levels of the C2GnT glycosyl transferase. Overall, glycan chains from infected pigs were shorter and had a higher abundance of structures that were neutral or predominantly contained NeuGc instead of NeuAc, whereas they had a lower abundance of structures that were fucosylated, acidic, or sulfated than those from noninfected pigs. Therefore, we conclude that <i>B. hyodysenteriae</i> plays a major role in regulating colonic mucin glycosylation in pigs during SD. The changes in mucin <i>O</i>-glycosylation thus resulted in a glycan fingerprint in porcine colonic mucus that may provide increased exposure of epitopes important for host–pathogen interactions. The results from this study provide potential therapeutic targets and a platform for investigations of <i>B. hyodysenteriae</i> interactions with the host via mucin glycans