Transcriptional responses of cytokines, immunoglobulin A, and nitric oxide genes in 1-day-old chicks post Salmonella typhimurium infection: An experimental study.

Background: Salmonella has become one of the hazards prevalent foodborne pathogens causing different diseases in chickens. However, Salmonella typhimurium (ST), a nonhost-specific serovar, is a major avian agent that causes severe disturbance in young chicken wellness. Aim: The occurrence of Salmonella in chickens and their antimicrobial resistance were explored in this study. In addition, the immune response of 1-day-old broiler chicks, against multidrug resistant (MDR) ST infection, was also assessed at 4 and 24 hours post infection (pi) in the cecum and spleen, representing their mucosal and systemic immune responses, respectively. Methods: A total of 375 samples from 130 diseased and apparently healthy broiler and layer chickens were randomly collected for Salmonella isolation, identification, and resistance profile evaluation, from farms and different clinical laboratories. The immune response of 1-day-old broiler chicks, Ross 308, against in-vivo ST infection was ascertained through the evaluation of heterophile phagocytosis and s expression of cytokines, immunoglobulin A and other immune-regulating genes in the cecum and spleen. Twenty-four, 1-day-old nonvaccinated broiler chicks were used and divided into two groups. The chicks in the infected group were orally inoculated with 0.5 ml of 2 × 108 colony forming units (CFU)/ml of MDR ST suspension, while those in the control group were taken nutrient broth. Results: Seven out of 130 (5.38%) examined chickens were positive for Salmonella. All isolates (100%) were resistant to amoxicillin-clavulanic acid (AMC), cefazolin (CZ), cefoxitin (FOX), ciprofloxacin (CIP), nalidixic acid (NA), tetracycline (TE), fosfomycin (FOS), and colistin (CT) with multiple antimicrobial resistances (MARs) index range of 0.72-0.83, where none of them was resistant to meropenem (MEM). The results of immune response revealed that chicks infected with ST showed significantly different phagocytosis percentages and index values compared to controls. According to the real-time quantitative polymerase chain reaction (RT-qPCR) results, the transcription of IL-8, iNOS, IL-18, IgA, and IFN-γ for chicks infected by ST showed a significantly increased trend (p < 0.01) with increasing chicken age and was higher in the cecum than spleen compared to controls (p < 0.05) during 24 hours after infection. Conclusion: The findings indicated a strong mucosal immune response in the chicks after the ST challenge, which reflects humoral and cellular responses. Our insight recommended the occurrence of a natural immune response stimulator at 1 day age to face the infection, and this can prevent the resistance transfer, with efficient control measures.

Apple cider vinegar exhibits promising antibiofilm activity against multidrug-resistant Bacillus cereus isolated from meat and their products.

Background: Bacillus cereus (B. cereus) biofilm is grown not only on medical devices but also on different substrata and is considered a potential hazard in the food industry. Quorum sensing plays a serious role in the synthesis of biofilm with its surrounding extracellular matrix enabling irreversible connection of the bacteria. Aim: The goal of the current investigation was to ascertain the prevalence, patterns of antimicrobial resistance, and capacity for B. cereus biofilm formation in meat and meat products in Egypt. Methods: In all, 150 meat and meat product samples were used in this study. For additional bacteriological analysis, the samples were moved to the Bacteriology Laboratory. Thereafter, the antimicrobial, antiquorum sensing, and antibiofilm potential of apple cider vinegar (ACV) on B. cereus were evaluated. Results: Out of 150 samples, 34 (22.67%) tested positive for B. cereus. According to tests for antimicrobial susceptibility, every B. cereus isolates tested positive for colistin and ampicillin but negative for ciprofloxacin and imipenem. The ability to form biofilms was present in all 12 multidrug-resistant B. cereus isolates (n = 12); of these, 6 (50%), 3 (25%), and 3 (25%) isolates were weak, moderate, and strong biofilm producers, respectively. It is noteworthy that the ACV demonstrated significant inhibitory effects on B. cereus isolates, with minimum inhibitory concentrations varying between 2 and 8 µg/ml. Furthermore, after exposing biofilm-producing B. cereus isolates to the minimum biofilm inhibitory concentrations 50 of 4 µg/ml, it demonstrated good antibiofilm activity (>50% reduction of biofilm formation). Strong biofilm producers had down-regulated biofilm genes (tasA and sipW) and their regulator (plcR) compared to the control group, according to reverse transcriptase quantitative polymerase chain reaction analysis. Conclusion: Our study is the first report, that spotlights the ACV activity against B. cereus biofilm and its consequence as a strong antibacterial and antibiofilm agent in the food industry and human health risk.

Nigella sativa oil extract: A natural novel specific conjugal transfer inhibitor of vancomycin resistance from vanA/B-resistant Enterococcus faecium to Staphylococcus aureus.

AIM: The emergence of vancomycin-resistant Staphylococcus aureus (VRSA) has been identified as one of the most challenging problems in healthcare settings worldwide. Specific conjugation inhibitors' development is critical in the fight against the spread of emerging VRSA. The impact of Nigella sativa oil on VR genes conjugal transfer from Enterococcus faecium (VREtfm) to vancomycin-sensitive S. aureus (VSSA) was investigated in this study. METHODS AND RESULTS: Enterococciwere isolated from retail broilers, fish, cows' milk, and human urine. VR E. faecalis and VREtfm VanA phenotypes were prevalent in retail broiler samples. The VREtfm isolates were dominant, exhibiting high levels of resistance to gentamycin and ciprofloxacin antibiotics, as well as the existence of both vanA and vanB genes and virulence traits (ESP+ , asa1+ ) as determined by PCR. Transconjugant VREtfm strains containing vanA/vabB and 20 kb plasmids (transfer frequency around 103 ) and carrying the Tn1546 transposon were identified. Tn1546 transposon transfer with its VR markers to VSSA was effectively inhibited in treated VREtfm donor strains with a sub-minimum inhibitory concentration of N. sativa oil. THE SIGNIFICANCE AND IMPACT OF THE STUDY: This work offers new insights for overcoming VR conjugal transfer utilizing natural N. sativa oil, as well as a suggestion for a novel specialized conjugation inhibitor that could effectively facilitate the difficulty of eliminating VR bacteria from healthcare settings.

Anti-Inflammatory and Immunomodulatory Role of Bone Marrow-Derived MSCs in Mice with Acute Lung Injury.

Recently, studies suggested that the mesenchymal stem cells (MSCs) have anti-inflammatory and immune-modulatory roles in the induced acute lung injury in mice via controlling innate, humoral, and cell-mediated immunity. Sixty adult male mice were divided equally into three groups. Group A (control group) received an intraperitoneal (IP) phosphate-buffered saline. Group B was injected IP with lipopolysaccharide (LPS). Group C was injected IP with LPS, followed after 2 h by intravenous labeled bone marrow-derived MSCs (BM-MSCs). The plasma and bronchioalveolar lavage (BAL) fluid were collected at 12, 24, and 72 h postinjection. Estimation of total cell and neutrophils count and immunoglobulin M (IgM) in BAL fluid was performed. Enzyme-linked immunosorbent assay (ELISA) was used to analyze tumor necrosis factor-α (TNF-α) that is a proinflammatory cytokine and interleukin-10 (IL-10), which is an anti-inflammatory cytokine, in plasma. Lung samples were collected for histopathological examination at 12, 24, 72 h, and 1 week postinjection. Decreased TNF-α and increased IL-10 levels in the plasma of MSC-treated group compared to the LPS-infected group were observed. Also, decreased IgM level in BAL fluid of the MSC-treated group after 72 h compared to the LPS-infected group was detected with a resolution of inflammation and improvement in lung injury. Moreover, MSC-treated group showed a reduction in total leukocyte count and neutrophil percentage in comparison to control and LPS-infected groups. Histopathological improvement was detected in MSC-treated group as well. In conclusion, systemic MSCs injection has an anti-inflammatory and immune-modulatory effect in LPS-induced acute lung injury in mice.

Mutations of domain V in 23S ribosomal RNA of macrolide-resistant Mycoplasma gallisepticum isolates in Egypt.

INTRODUCTION: Avian mycoplasmas impose a significant economic burden to the poultry industry. In recent years, macrolide-resistant Mycoplasma gallisepticum have occasionally been encountered in Egypt. METHODOLOGY: This study was designed to document the involvement of macrolide-resistant M. gallisepticum in respiratory organs of chickens suffering respiratory problems. Concurrently, an exhaustive molecular characterization of the intrinsic resistance of recovered isolates to macrolides was done. RESULTS: Of 120 chickens showing respiratory problems, 14 (11.67%) M. gallisepticum were isolated and genetically identified; 8 of them were recovered from air sacs, 4 from lungs, and 2 from tracheas. Broth microdilution of all M. gallisepticum isolates showed various degrees of minimum inhibitory concentrations (MICs) against macrolides: erythromycin (0.25-32 µg/mL), tylosin (0.0625-4 µg/mL), and tiamulin (0.031-2 µg/mL). Nucleotide sequencing of domain V (peptidyl transferase region) of the 23S rRNA gene of macrolide-resistant M. gallisepticum isolates revealed transition mutations at positions 2068 and 2069 (corresponding to 2058 and 2059 in Escherichia coli numbering) in an isolate and at position 2067 (corresponding to 2057 in E. coli numbering) in three isolates as hot spots for macrolide resistance. Surprisingly, a transversion mutation at position 2621 (corresponding to 2611 in E. coli numbering) was reported in one of the recovered isolates as a first report. CONCLUSION: Generation of new mutations is evidence for persistence of M. gallisepticum despite macrolide treatment. Periodic surveys to monitor for the possible appearance of resistant strains are recommended.