Evaluation of antibacterial and therapeutic effects of egg-white lysozyme against Salmonella Typhimurium in ICR mice infected with Salmonella Typhimurium

Salmonellosis is a major bacterial zoonosis that causes self-limited enteritis in animals and foodborne disease and typhoid fever in humans. Recently, multi-drug-resistant strains of Salmonella spp. have increased and caused more serious problems in public health. The present study investigated the antibacterial effects of egg-white lysozyme (EWL) against Salmonella (S.) Typhimurium and the therapeutic effects of EWL for murine salmonellosis. Evaluation of the antibacterial effects of EWL against S. Typhimurium revealed a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of EWL of 6.25 and 300 µg/mL, respectively. In the bacterial growth inhibition test, EWL at 300 (p < 0.05) and 600 µg/mL (p < 0.01) significantly inhibited the growth of S. Typhimurium at 4 h postincubation. EWL administration at MIC (LYS-1), MBC (LYS-2) and 2× MBC (LYS-3) for 14 days resulted in mortality of mice infected with S. Typhimurium of 70, 40 and 10%, respectively, while that of control mice (CON) was 90%. Counts of S. Typhimurium in murine spleens were significantly lower in LYS-2 and LYS-3 than CON (p < 0.05). The results of this study indicate that EWL has the potential for treatment of ICR mice infected with S. Typhimurium.

Effect of a mixture of Galla rhois and Cinnamomum cassia extracts on susceptibility to the colonization of Campylobacter jejuni in broiler chickens

The present study evaluated the effects of a mixture of Galla rhois and Cinnamomum cassia extracts (GCE) (1 : 1, w/w) on susceptibility to the colonization of Campylobacter (C.) jejuni in broilers. Eighty two-week-old broilers (n = 20 per group) were used to estimate the efficacy of GCE against C. jejuni infection via drinking water. Antibacterial activity testing revealed that the minimum bactericidal concentration of GCE against C. jejuni was 2.5 mg/mL. Broilers challenged with C. jejuni were administered 0.0 (Non-GCE), 2.5 (GCE-2.5), 5.0 (GCE-5.0) and 10.0 g/L (GCE-10) GCE for 7 days, and the cecal contents were collected from five broilers per group on the 1st, 3rd, 5th, and 7th day post-treatment. On day 3 post-administration, the number of C. jejuni in GCE-5.0 (p < 0.05) and GCE-10 (p < 0.01) was significantly decreased relative to Non-GCE, while on day 7 those in all GCE-treated groups were significantly decreased compared to the Non-GCE group (p < 0.001). Hematological and blood biochemical analysis revealed no significant differences in parameters between the Non-GCE and GCE-treated groups. Based on the results of the present study, GCE was identified as a safe and alternative candidate to suppress C. jejuni colonization in broilers.

Therapeutic effect of oregano essential oil on subclinical bovine mastitis caused by Staphylococcus aureus and Escherichia coli / 대한수의학회지

Oregano (Origanum vulgare) is an aromatic herb belonging to the Lamiaceae family. This study evaluated the therapeutic effect of oregano essential oil (OEO) on clinical bovine mastitis caused by Staphylococcus (S.) aureus and/or Escherichia (E.) coli. Thirty-two quarters from 18 lactating cows with subclinical mastitis were selected from a dairy farm and were divided into 4 groups (8 quarters/group): negative control (CON), positive control (GEN) and two OEO-treated groups (OEO-1 and OEO-2). Each group was intramammarily treated with saline, 10 g/tube of gentamicin ointment, and single and double doses of 0.9 mL OEO ointment twice a day for three days, respectively. After the treatments, physical udder conditions were greatly improved in GEN and OEO groups. In CON group, somatic cell counts (SCCs), number of white blood cells (WBC) and bacteria were increased. However, in OEO groups, SCCs and number of WBC were significantly decreased and S. aureus and E. coli were not detected in milk as compared with those before the treatments as well as GEN group. These results suggest that OEO may be a useful alternative to antibiotics for the control of subclinical bovine mastitis caused by S. aureus and/or E. coli.

Antibacterial and therapeutic effects of a combination of Coptidis rhizoma and Galla rhois extracts in piglets challenged with Campylobacter coli / 대한수의학회지

The antibacterial effects of a combination of Coptidis rhizoma and Galla rhois extracts (CGE) were evaluated in piglets. The minimum bactericidal concentration of CGE was 2.0 mg/mL. Thirty 5-week-old piglets were challenged with Campylobacter (C.) coli after allocation to three different groups, a control and two treatment groups fed with CGE at 2.0 or 4.0 g/kg feed for 7 days. On day 7, C. coli in the feces of the CGE-treated groups were significantly lower than in the control (p < 0.01). These results suggest that CGE can be used to control C. coli in piglets.

Influence of various photoperiods on stress hormone production, immune function, and hematological parameters in ICR mice / 대한수의학회지

In the present study, the effects of different photoperiods on stress, immunity, and hematological parameters in ICR mice were evaluated. Fifty male ICR mice 7 weeks old (body weight, 27.3 +/- 2.5 g) were divided into five groups: DP-0 (0/24-h light/dark cycle), DP-6 (6/18-h light/dark cycle), DP-12 (12/12-h light/dark cycle), DP-18 (18/ 6-h light/dark cycle), and DP-24 (24/0-h light/dark cycle). During the experimental period, no significant differences in body weight or feed intake were observed between the groups. Hematological analysis revealed that white blood cell, red blood cell, and hemoglobin values for the DP-0 group were significantly different compared to those of the other groups. After 28 days, no significant difference in serum cortisol concentration was observed among the groups, but serum cortisol levels increased in a light exposure-dependent manner. Total serum immunoglobulin G (IgG) concentrations of the DP-0 and PD-6 groups were significantly increased compared to those of the other groups (P < 0.05), and serum total IgG levels decreased in a light exposure-dependent manner. Results of the present study indicated that various photoperiods affect hematological parameters and total serum IgG levels in ICR mice while having no significant effects on body weight, feed intake, or cortisol levels.