Inhibition of Salmonella enterica serovar Dusseldorf by enterocin A in gnotobiotic Japanese quails

The protective (ENT1) and therapeutic (ENT2) effects of enterocin A (Ent), produced by Enterococcus faecium EK13, against Salmonella enterica serovar Dusseldorf SA31 was determined in a model of gnotobiotic Japanese quails. Twenty-one 3 days old birds were divided into 3 groups of equal size; (ENT1, ENT2 and control group - CG). They were experimentally infected with SA31 (107 cfu/ml) per os. For the group ENT1, Ent A (200 µl of 25 600 AU/ml) was administered 8 h before infection with SA31 strain and for the group ENT2, treatment with Ent A was administered 8 h after infection; CG was infected with SA31 and not treated with Ent A. Sampling of the feces was performed 8, 24, 48 and 168 h after infection. At the end of the experiment also the content of the caecum and ileum was analyzed. A log 1.37 reduction of SA31 colonization in feces of the group ENT1 was found after 8 h in comparison with CG. After 24 h, a significant difference in SA31 colonization was observed when comparing CG and ENT2. After 48 h, a lower colonization of SA31 was found in both groups which continued until the end of the experiment (168 h). At the same time, reduction of Salmonella enterica serovar Dusseldorf was detected in the content of the caecum (2.44 log) and ileum (3.16 log) in ENT2 but not in ENT 1 when compared with control group. These observations indicate stronger therapeutic effect of Ent A than prophylactic one in the digestive tract of gnotobiotic Japanese quails.