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We investigated antimicrobial resistance trends and characteristics of ESBL-producing Escherichia coli isolates from pets and whether this correlates with antibiotic usage in the clinic. Clinical samples containing E. coli from diseased cats and dogs were screened for antibiotic sensitivity and associated genotypic features. We identified 127 E. coli isolates from 1886 samples from dogs (n = 1565) and cats (n = 321) with the majority from urinary tract infections (n = 108, 85%). High rates of resistance were observed for β-lactams and fluoroquinolones and resistance to > 3 antibiotic classes (MDR) increased from 67% in 2012 to 75% in 2017 (P < 0.0001). This was especially true for strains resistant to 6-9 antibiotics that increased from 26.67 to 60.71%. Increased rates in β-lactam use for clinical treatment accompanied these increasing resistance rates. Accordingly, the most frequently encountered subtypes were bla CTX-M (n = 44, 34.65%), bla CTX-M-65 (n = 19) and bla CTX-M-15 (n = 18) and qnrB (n = 119, 93.70%). The bla CTX-M-isolates possessed 36 unique pulsed field electrophoretic types (PFGEs) and 28 different sequence types (STs) in ST405 (7, 15.9%), ST131 (3, 6.8%), ST73, ST101, ST372, and ST827 (2, 4.5% each) were the most prevalent. This data demonstrated a high level of diversity for the bla CTX-M-positive E. coli isolates. Additionally, bla NDM-5 was detected in three isolates (n = 3, 2.36%), comprised of two ST101 and one ST405 isolates, and mcr-1 was also observed in three colistin-resistant E. coli with three different STs (ST6316, ST405, and ST46). Our study demonstrates an increasing trend in MDR and ESBL-producing E. coli and this correlated with β-lactam antibiotic usage for treatment of these animals. This data indicates that there is significant risk for the spread of resistant bacteria from pets to humans and antibiotic use for pets should be more strictly regulated.

The effects of Enterococcus faecium on growth, intestinal barrier function, and immune response in Escherichia coli O78-challenged broiler chickens were investigated. Three hundred eight 1-day-old Ross male chickens were randomly assigned into three treatment groups: negative control (C), E. coli O78-infected positive (EP), and E. coli O78-infected with 200 mg/kg E. faecium dietary supplementation (EF). E. faecium significantly increased the body weight on day 10 (P < 0.05) and day 15. Furthermore, these birds had a greater average daily gain compared with the other groups during days 1-10 (P < 0.05). The death rate of the EF chickens dramatically declined. E. faecium supplementation improved the jejunal villus height and the ratio of villus height to crypt depth (P < 0.05) 3 and 7 days post-infection. The mRNA expression of claudin-1 significantly increased by E. faecium (P < 0.05) 3 and 7 days post-infection, and Mucin2 was markedly enhanced (P < 0.05) 3 days post-infection. E. faecium upregulated the mRNA expression of PPAR-γ and IL-10 (P < 0.05) and downregulated that of NF-κB, TLR4, and IL-1β (P < 0.05) in the spleen 3 and 7 days post-infection. Lipopolysaccharide stimulation index was markedly enhanced in the EF group (P < 0.05) 3 days post-infection. The increased liver E. coli number caused by the E. coli O78 challenge was significantly reversed by E. faecium (P < 0.05). E. faecium improved growth and reduced the death rate by regulating the immune response and maintaining the intestinal integrity in E. coli O78-challenged broiler chickens.

The aim of this study was to investigate the effects of Clostridium butyricum (C. butyricum) on the performance, serum lipid metabolism, muscle morphology, meat quality, and fatty acid profiles of Peking ducks. A total of 1,500 Peking ducks were randomly divided into five groups with five replicates and were fed a non-antibiotic basal diet (Control) or a basal diet supplemented with either 200, 400, or 600 mg/kg of C. butyricum (2.0 × 109 CFU/g) or 150 mg of aureomycin/kg for 42 d. Compared with the control group, supplementation with C. butyricum increased the average daily weight gain but reduced the feed/gain ratio from 1 to 42 d of age. Similarly, dietary C. butyricum increased the activities of antioxidant enzymes but decreased the malondialdehyde (MDA) and lipid metabolites concentration. C. butyricum supplementation increased the muscle pH value at 45 min postmortem, the redness of the meat, and the contents of inosine acid (IMP) and intramuscular fat (IMF) in Peking ducks. By contrast, C. butyricum supplementation lowered the lightness, drip loss, and the shear force of breast meat. Supplementation with C. butyricum increased the concentrations of essential amino acids and flavor amino acids, as well as arachidonic acid (AA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and total polyunsaturated fatty acids (PUFA) in breast muscle. Dietary C. butyricum could positively improve performance, lipid metabolism, meat quality, and the amino acid and fatty acid composition in a dose-dependent manner. Therefore, C. butyricum is proposed as a feasible alternative feed additive for the production of healthier Peking duck meat with favorable properties.