Effects of dietary XXXX on the antimicrobial resistance of porcine faecal streptococcaceae.

@entity1707 @entity114 @entity36965 @entity797 @entity7914 @entity6375 @entity803
Breeding @entity1707 and one-half of their progeny were fed antimicrobial-free rations; the other half of the progeny received rations supplemented with 100 g of @entity7914 (Ctc)/ton. Effects of dietary Ctc with respect to the distribution of species and biotypes of faecal Gram-positive cocci and their relative resistance to 12 antimicrobial agents were studied. Diversity of antimicrobial resistance (AMR) patterns and modal AMR patterns were determined for bacterial species common to all three groups. Numerical taxonomic analysis placed 1140 of 1150 isolates (99%) into 10 groups. Three of these were biotypes of @entity6375 and contained the largest number of isolates (n = 934, 81%). @entity797 , Strep. morbillorum, @entity36965 and Gemella haemolysans also were isolated. Generally, the proportion of @entity803 -resistant strains for a species or biotype was greater from @entity1707 fed Ctc, although differences were not significant (P greater than 0.05). There was a significant difference (P less than 0.05) among all the groups for the percentage of @entity114 -resistant strains in a biotype of Strep. faecium. Overall, 57 and 43 different AMR patterns, including 2 to 11 and 1 to 11 resistance determinants, were demonstrated in isolates from control @entity1707 and @entity1707 fed Ctc, respectively. Modal AMR patterns in species and biotypes were the same from both progeny groups, except for Strep. faecium. AMR pattern diversity was decreased for strains from @entity1707 fed Ctc. Similar proportions of resistant strains from each group of progeny @entity1707 were accompanied by decreased AMR pattern diversity in strains from @entity1707 fed Ctc. These results indicated a change in distribution of AMR phenotypical patterns, rather than a change in overall frequency of individual resistant phenotypes.
