A 28-d experiment evaluated the growth performance, acute-phase response, and bacterial shedding patterns in pigs (n = 108; initially, 38.7 ± 6.7 kg) fed 6 treatment diets, including a control diet with no antimicrobial agents (CON), a positive control diet containing chlortetracycline, 100 mg/kg (CT), a diet containing anti-Salmonella Typhimurium bacteriophage, 3 × 10⁹ plaque-forming units/kg of feed (ASB), Lactobacillus plantarum CJLP56, 6.5 × 10⁸ cfu/kg of feed (LP), 0.2% microencapsulated organic acids (MOA), or 5% fermented soybean meal (FSM). Pigs were fed the diets for 2 wk before and 2 wk after challenging orally with Salmonella enterica serotype Typhimurium (SalT). Before bacterial challenge, ADFI was similar in all groups. After SalT challenge, ADFI of CON pigs was less (P < 0.05) than all other groups. Before challenge, pigs on MOA, FSM, and CT diets had greater (P < 0.05) ADG and G:F than CON pigs. After challenge (wk 3 to 4) and during the overall experimental period (wk 1 to 4), ADG of all treatment groups and G:F of all treatment groups except the LP group were greater (P < 0.05) than those of CON pigs. Relative to all other treatments, CON and LP pigs had greater (P < 0.05) bacterial shedding scores on d 7 after SalT challenge. At d 14 postchallenge, shedding scores declined (P < 0.05) in all treatment groups compared with CON pigs. Serum haptoglobin for all treatment groups increased from d 0 concentrations on d 6 postchallenge and declined to prechallenge concentrations on d 13 (P < 0.05). Circulating IGF-I concentrations declined from 2 to 6 d postchallenge and increased again by d 13 in ASB and LP groups, did not decline in FSM and CT groups, and continuously declined through d 13 in CON and LP groups (P < 0.05). However, in MOA group, IGF-I concentrations declined from preinfection concentrations on d 2, increased on d 4, and declined again until d 13 (P < 0.05). The serum concentrations of the cytokines IL-6 and IL-1β were not generally affected by SalT challenge. In conclusion, acute infection of growing pigs with SalT was associated with short-term febrile responses in most pigs and reductions in ADFI and ADG of CON pigs. Compared with the CON diet, ASB, FSM, and MOA diets had a similar benefit to the antibiotic-supplemented diet in improving the performance of growing pigs, especially after bacterial challenge. However, further work needs to be done to better understand their mode of action in this class of pigs. Copyright © 2010. American Society of Animal Science .

Jo WS, et al. Mycobiology. 2014 Sep;42(3):215-220. http://dx.doi.org/10.5941/MYCO.2014.42.3.215

Quorum sensing (QS) is a cell density-dependent regulation of virulent bacterial gene expression by autoinducers that potentially pertains in the epidemic of bacterial virulence. This study was initially designed to evaluate the effect of 5 phenolic compounds in the modulation of QS and virulence factors of Chromobacterium violaceum and Pseudomonas aeruginosa, and to determine the mechanisms of their effects. Biosensor strains were used to assess antibacterial and anti-QS effect of these compounds. Only methyl gallate (MG) among these compounds demonstrated profound anti-QS effect in the preliminary study, and thus only MG was utilized further to evaluate the effects on the synthesis and activity of acyl homoserine lactone (AHL) in C. violaceum and on the modulation of biofilm, motility, proteolytic, elastase, pyocyanin, and rhamnolipid activity in P. aeruginosa. Finally, the effect of MG on the expression of QS-regulated genes of P. aeruginosa was verified. MG suppressed both the synthesis and activity of AHL in C. violaceum. It also restricted the biofilm formation and other QS-associated virulence factor of P. aeruginosa. MG concentration-dependently suppressed the expression of lasI/R, rhlI/R, and pqsA of P. aeruginosa and was non-toxic in in vitro study. This is the first report of the anti-QS mechanism of MG.

Probiotics are being used as feed/food supplements as an alternative to antibiotics. It has been demonstrated that probiotics provide several health benefits, including preventing diarrhea, irritable bowel syndrome, and immunomodulation. Alongside probiotic bacteria-fermented foods, the different structural components, such as lipoteichoic acids, teichoic acids, peptidoglycans, and surface-layer proteins, offer several advantages. Probiotics can produce different antimicrobial components, enzymes, peptides, vitamins, and exopolysaccharides. Besides live probiotics, there has been growing interest in consuming inactivated probiotics in farm animals, including pigs. Several reports have shown that live and killed probiotics can boost immunity, modulate intestinal microbiota, improve feed efficiency and growth performance, and decrease the incidence of diarrhea, positioning them as an interesting strategy as a potential feed supplement for pigs. Therefore, effective selection and approach to the use of probiotics might provide essential features of using probiotics as an important functional feed for pigs. This review aimed to systematically investigate the potential effects of lactic acid bacteria in their live and inactivated forms on pigs.

The purpose of the present study was to evaluate the effect of diets containing Lactobacillus plantarum CJLP243 on the growth and cytokine response of weaning pigs (Sus scrofa) challenged with enterotoxigenic Escherichia coli (ETEC). In a 28-d experiment (14 d before and 14 d after challenge), a total of 108 pigs at 20 ± 1 d of age were allotted to 1 of 6 diets. These were a control diet without ETEC challenge (CON) and 5 treatment diets with ETEC challenge, including a control diet with ETEC challenge (negative control, NC); a positive control diet containing antibiotics (PC); control diet plus (10⁸, 10⁹, or 10¹⁰) cfu/kg L. plantarum CJLP243 (T1, T2, and T3, respectively). After challenge, NC showed the least ADFI, whereas PC and T3 had the greatest ADFI (P = 0.002). The ADG of PC, T2, and T3 were greater (P = 0.001) than that of CON, NC, and T1 during wk 1 to wk 2. During wk 3 to wk 4, a marked decline was seen in NC (P = 0.001) compared with CON, whereas PC and T3 showed increased ADG (P = 0.001). The overall ADG of PC and T3 were greater (P < 0.001) than the remaining groups. The PC and T3 had the greatest G:F during the second 2 wk (P = 0.002), and the overall 4-wk experimental period (P = 0.003). At 3 h after challenge, all groups except CON had greater rectal temperatures (RT; P < 0.05). The RT decreased to prechallenge temperatures at 9 h (PC and T3), 24 h (T1 and T2), and remained increased until d 7 in NC. At 7 and 14 d postinfection, the number of animals detected positive for ETEC by PCR assay was the greatest in NC; however, the PC group had the fewest ETEC-positive animals (P < 0.05), which was similar to T3. All challenged pigs, except T2, had greater concentrations of serum haptoglobin compared with CON, with the greatest concentration observed in NC (P < 0.001). Challenged pigs had increased serum concentrations of tumor necrosis factor alpha (TNF-α) 3 to 48 h postinfection, with the greatest concentration of TNF-α at 48 h observed in NC (P < 0.05). Similarly, greater (P < 0.05) serum concentrations of interferon-γ were observed for 9 h (T1 and T3), 24 h (T2 and PC), and 48 h (NC) postinfection. The serum concentration of IL-6 increased (P < 0.05) for 3 h in T3 and 24 h in NC. In conclusion, our findings suggest that L. plantarum CJLP243, at a concentration of 10¹⁰ cfu/kg, may serve as a potential alternative to antibiotic supplementation to improve the growth and health performance of weaning pigs, especially during acute inflammation of the gut after bacterial infections. Copyright © 2012. American Society of Animal Science .

Salmonella enterica serovar Typhimurium infects intestinal epithelia and macrophages, which is prevented by inhibiting adhesion and cell invasion. This study aimed to investigate the role of methyl gallate (MG) in adhesion, invasion, and intracellular survival of Salmonella Typhimurium in Caco-2 and RAW 264.7 cells via a gentamicin protection assay, confocal microscopy, and quantitative reverse-transcription polymerase chain reaction. MG (30 µg/mL) inhibited adhesion and invasion of Salmonella Typhimurium by 54.01% and 60.5% in RAW 264.7 cells, respectively. The combination of MG with sub-minimum inhibitory concentration (MIC) of marbofloxacin (MRB) inhibited the adhesion, invasion, and intracellular survival by 70.49%, 67.36%, and 74%, respectively. Confocal microscopy further revealed reductions in bacterial count in Caco-2 cells treated with MG alone or with sub-MIC of MRB. Furthermore, MG alone or in combination with sub-MIC of MRB decreased the motility of Salmonella Typhimurium. Quorum sensing genes including sdiA, srgE, and rck were downregulated by 52.8%, 61.7%, and 22.2%, respectively. Moreover, rac-1 was downregulated by 56.9% and 71.9% for MG alone and combined with sub-MIC of MRB, respectively, in mammalian cells. Furthermore, MG downregulated virulence genes of Salmonella Typhimurium including cheY, ompD, sipB, lexA, and ompF by 59.6%, 60.2%, 20.5%, 31.4%, and 16.2%, respectively. Together, the present results indicate that MG alone or in combination with a sub-MIC of MRB effectively inhibited the adhesion, invasion, and intracellular survival of Salmonella Typhimurium in vitro by downregulating quorum sensing and virulence genes.