Effect of enterocins against methicillin-resistant animal-derived staphylococci

Susceptibility to postbiotics - enterocins of methicillin-resistant Staphylococcus aureus strains isolated from rabbits

There is a major problem with the rising occurrence of highly virulent and multiply-resistant strains, including methicillin-resistant Staphylococcus aureus (MRSA), because of their difficult treatment. This study aimed to evaluate the antibacterial and antibiofilm effect of new enterocins (Ent) against potential pathogenic MRSA strains isolated from rabbits. Staphylococci were identified with PCR and screened for methicillin/oxacillin/cefoxitin resistance (MR) using the disk diffusion method and the PBP2' Latex Agglutination Test Kit. Enzyme production, hemolysis, DNase activity, slime production, and biofilm formation were tested in MRSA strains. The susceptibility of MRSA to eight partially-purified enterocins (Ent) produced by E. faecium and E. durans strains was checked using agar spot tests. The antibiofilm activity of Ents was tested using a quantitative plate assay. Out of 14 MRSA, PBP testing confirmed MR in 8 strains. The majority of MRSA showed DNase activity and β-hemolysis. Slime production and moderate biofilm formation were observed in all strains. MRSA were susceptible to tested Ents (100-12,800 AU/mL; except Ent4231). The antibiofilm effect of Ents (except Ent4231) was noted in the high range (64.9-97.0%). These results indicate that enterocins offer a promising option for the prevention and treatment of bacterial infections caused by biofilm-forming MRSA.

The effect of enterocin A/P dipeptide on growth performance, glutathione-peroxidase activity, IgA secretion and jejunal morphology in rabbits after experimental methicillin-resistant Staphylococcus epidermidis P3Tr2a Infection

The increasing frequency of methicillin-resistant (MR) staphylococci in humans and animals need special attention for their difficult treatment and zoonotic character, therefore novel antimicrobial compounds on a natural base against antibiotic-resistant bacteria are requested. Currently, bacteriocins/enterocins present a new promising way to overcome this problem, both in prevention and treatment. Therefore, the preventive and medicinal effect of dipeptide enterocin EntA/P was evaluated against MR Staphylococcus epidermidis SEP3/Tr2a strain in a rabbit model, testing their influence on growth performance, glutathione-peroxidase (GPx) enzyme activity, phagocytic activity (PA), secretory (s)IgA, and jejunal morphometry (JM). Eighty-eight rabbits (aged 35 days, meat line M91, both sexes) were divided into experimental groups S (SEP3/Tr2a strain; 1.0 × 105 CFU/mL; dose 500µL/animal/day for 7 days, between days 14 and 21 to simulate the pathogen attack), E (EntA/P; 50 µL/animal/day, 25,600 AU/mL in two intervals, for preventive effect between days 0 and 14; for medicinal effect between days 28 and 42), E + S (EntA/P + SEP3/Tr2a; preventive effect; SEP3/Tr2a + EntA/P; medicinal effect) and control group (C; without additives). Higher body weight was recorded in all experimental groups (p < 0.001) compared to control data. The negative influence/attack of the SEP3Tra2 strain on the intestinal immunity and environment was reflected as decreased GPx activity, worse JM parameters and higher sIgA concentration in infected rabbits. These results suggest the promising preventive use of EntA/P to improve the immunity and growth of rabbits, as well as its therapeutic potential and protective role against staphylococcal infections in rabbit breeding.

Preventive Potential of Dipeptide Enterocin A/P on Rabbit Health and Its Effect on Growth, Microbiota, and Immune Response

Simple Summary

Rabbits are animals sensitive to alimentary disturbances and various spoilage agents, mostly during the weaning period. For this reason, the use of natural feed additives has become an area of research in rabbit nutrition, mainly with a focus on prevention. The “in vivo” administration of bacteriocins/enterocins shows an increasing potential in the prevention/treatment of animals’ diseases. Therefore, our study focused on the preventive potential of the dipeptide enterocin (Ent) A/P against the methicillin-resistant (MR) Staphylococcus epidermidis SE P3/Tr2a strain in rabbit model, determining its effect on the growth performance, phagocytic activity, secretory (s) IgA, and gut microbial composition of rabbits. Ent A/P increased the weight gain of rabbits and its antibacterial effect showed a tendency to stabilize and improve gut microbiota due to reduction of MR staphylococci, total bacteria, and coliforms. The immune-stimulatory effect of Ent A/P was noted due to increased phagocytic activity. Achieved results showed the great potential of Ent A/P application as a feed additive in rabbit nutrition to improve the health and productivity of animals.

Abstract

The present study investigated the effect of the dipeptide enterocin (Ent) A/P on growth, immune response, and intestinal microbiota in rabbits. Eighty-eight rabbits (aged five weeks, M91 meat line, both sexes) were divided into three experimental groups: E (Ent A/P; 50 µL/animal/day for 14 days; between 0–14 days); S (methicillin-resistant Staphylococcus epidermidis SE P3/Tr2a strain; 500 µL/animal/day for 7 days starting at day 14 to day 21); and E + S (Ent A/P between 0–14 days and SE P3/Tr2a strain between 14–21 days) groups, and the control group (C). The additives were administered in drinking water. Administration of Ent A/P lead to an increase in weight gain, reduction of feed conversion; phagocytic activity was stimulated and gut microbiota were optimized due to reduction of coliforms, total bacterial count, and methicillin-resistant staphylococci. Good health and increased weight gain also showed that methicillin-resistant S. epidermidis SE P3/Tr2a strain did not have any pathogenic effect on rabbits’ health status.