Effect of lysozyme or antibiotics on fecal zoonotic pathogens in nursery pigs

Abstract Text: Lysozyme is a 1,4-β-N-acetylmuramidase that has antimicrobial properties.  The objective of this study was to determine the effect of lysozyme and antibiotics on zoonotic pathogen shedding in feces in nursery pigs housed without and with an indirect disease challenge.  Two replicates of 600 pigs each were weaned from the sow at 26 d of age (d 0), blocked by litter and gender, and then randomly assigned to one of 24 pens in either a nursery room that had been fully disinfected or a nursery room left unclean after the previous group of pigs.  Within a room, pigs were randomly assigned to control diets (C; 2-phase nursery regime), control diets + antibiotics (C + A; chlortetracycline and Denegard), or control diets + lysozyme (C + Lyso; 100 mg/kg diet).  Rectal swab samples were collected on d 0 and 28 of treatment, and enriched and cultured for Campylobacter spp. and shigatoxigenic Escherichia coli (STEC) O26, O45, O103, O111, O121, O145 and O157.  Enrichments from rectal swab samples were also analyzed for presence of enterohemorrhagic E. coli (EHEC) virulence genes (hlyA, eae, stx1, and stx2).  Overall, the percentage of samples positive for Campylobacter spp., hlyA, eae, and stx1/stx2 on d 0 were 43.8, 27.4, 25.3, and 14.3%, respectively, and all were different on d 28 (70.6, 17.4, 78.7, and 3.0%, respectively; P<0.05).  Room hygiene on d 0 had little effect on d 28 results, except the percentage positives for hlyA was greater (21.6 vs 13.4%; P<0.02) and for eae was less (74.7 vs 82.6%; P<0.02) in unclean compared to clean rooms, respectively.  Percentage of samples culture positive for Campylobacter spp. was lowest for C + Lyso diet, but similar for C and C + A diets (43.2, 83.7, and 84.8.respectively; P<0.01).  Diet had little effect on the EHEC virulence genes hlyA or eae (P>0.1), but there was a tendency for lower percentage of samples positive for stx1/stx2 in C + A or C + Lyso diet groups compared to C diet (5.8, 1.2, and 2.1%, respectively; P<0.07).  The STEC types tested were rarely detected and not affected by time, hygiene or treatment (P>0.1).  Thus, lysozyme in the diet can reduce fecal shedding of Campylobacter spp. from nursery swine.  USDA is an equal opportunity provider and employer.

Keywords: Antibiotics, Lysozyme, Swine