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Avian pathogenic Escherichia coli ( APEC ) causes colibacillosis in poultry, which has been traditionally controlled by the prophylactic in-feed supplementation of antibiotics. However, antibiotics are being removed from poultry diets owing to the emergence of multidrug-resistant ( MDR ) bacteria. Therefore, alternatives to control APEC are required. This study aimed to evaluate the effects of in ovo inoculation of probiotics on the incidence of APEC in broilers and evaluate the virulence and antimicrobial resistance properties of the APEC isolates. On embryonic day 18, 4 in ovo treatments ( T ) were applied: T1 (Marek's vaccine [ MV ]), T2 (MV and Lactobacillus animalis ), T3 (MV and Lactobacillus reuteri ), and T4 (MV and Lactobacillus rhamnosus ). A total of 180 male broilers per treatment were randomly placed in 10 pens. The heart, liver, spleen, and yolk sac were collected on day 0, 14, 28, and 42. Presumptive E. coli isolates were confirmed by real-time PCR. The positive isolates were screened for the APEC-related genes ( iroN , ompT , hlyF , iss , and iutA ), and E. coli isolates containing one or more of these genes were identified as APEC-like strains. A total of 144 APEC-like isolates were isolated from 548 organ samples. No differences ( P > 0.05) among treatments were observed for the incidence of APEC-like strains in all organs when averaged over sampling days. However, when averaged over treatments, the incidence in the heart, liver, and yolk sac was different among sampling days; a significant increase was observed in these organs on day 14 compared with day 0. Twenty-five antimicrobial resistance genes were evaluated for all APEC-like isolates, and 92.4% of the isolates carried at least one antimicrobial resistance gene. Thirty-seven isolates were then selected for antimicrobial susceptibility testing; MDR strains accounted for 37.8% of the isolates. In conclusion, the in ovo inoculation of a single probiotic strain did not confer protection against APEC strains in broilers. The high prevalence of MDR isolates indicates that further research on antibiotic alternatives is required to prevent APEC infections in broilers.

Background MicroRNAs (miRs) are known to participate in sepsis; hence, we aim to discuss the protective effect of miR-499-5p targeting sex-determining region Y-related high-mobility-group box 6 (Sox6) on sepsis-induced lung injury in mice. Methods The sepsis-induced lung injury model was established by cecal ligation and puncture. The wet/dry weight (W/D) ratio, miR-499-5p, Sox6, Caspase-3 and Caspase-9 expression in lung tissues of mice were tested. Lung injury score, collagen fibers and the degree of pulmonary fibrosis in lung tissues were determined. Further, the cell apoptosis in lung tissues was measured. The inflammatory factors contents and oxidative stress indices in bronchoalveolar lavage fluid (BALF) and lung tissues were detected via loss- and gain-of-function assays. The targeting relation between miR-499-5p and Sox6 was verified. Results W/D ratio and Sox6 were increased while miR-499-5p was decreased in lung tissues of sepsis-induced lung injury mice. Restored miR-499-5p or depleted Sox6 alleviated lung tissues pathology, reduced lung injury score, collagen fibers, the degree of pulmonary fibrosis, TUNEL positive cells, Caspase-3 and Caspase-9 protein expression and inflammatory factors contents in BALF and lung tissues as well as oxidative stress response in lung tissues of sepsis-induced lung injury mice. miR-499-5p targeted Sox6. Conclusion High expression of miR-499-5p can attenuate cell apoptosis in lung tissues and inhibit inflammation of sepsis-induced lung injury mice via depleting Sox6, and it is a potential candidate marker and therapeutic target for sepsis-induced lung injury.