Antimicrobial resistance: its emergence and transmission

Effect of dietary probiotic, Bacillus coagulans, on growth performance, chemical composition, and meat quality of Guangxi Yellow chicken

The effect of Bacillus coagulans ZJU0616 with different concentrations supplemented as probiotic was evaluated on growth performance, feed conversion ratio, survival rate, breast chemical composition, and meat quality of Guangxi Yellow chicken. Birds were randomly segregated into 12 groups so that 3 replicates were available for each of the 3 treatments (T-1, T-2, and T-3) and control groups. The control groups were fed a basal diet without any probiotic and other groups were fed the diets that consisted of 3 probiotic levels at initial concentrations of 1.0 x 10(6) cfu.g(-1) (T-1), 2.0 x 10(6) cfu.g(-1) (T-2), and 5.0 x 10(6) cfu.g(-1) (T-3). The lowest final weight and daily weight gain were found in control groups (P < 0.05) and there were no significant differences among probiotic-treated groups. Significantly lower feed conversion ratio and higher survival rate were observed in T-2 and T-3 than that of the control. There were no significant differences (P > 0.05) in contents of breast chemical composition including moisture, CP, crude fat, and crude ash among all groups. For the meat quality parameter assays, the pH, shear force, and drip loss were used as indicators. As for pH values of breasts, no significant difference was found across all treatments. Higher shear force was observed (P < 0.05) in T-2 compared with T-1 and the control. Similar significant difference was also observed in T-1 compared with the control. However, there was no significant difference in shear force between T-3 and the other probiotic treatment groups (T-1 and T-2). As for probiotic-treated groups, there was significant difference (P < 0.05) in breast drip loss compared with that of the control (6.22 +/- 0.18%), with the lowest drip loss found in T-3 (5.38 +/- 0.25%). However, no significant difference was observed in drip loss between T-2 and T-3.

Development and validation of a resistance and virulence gene microarray targeting Escherichia coli and Salmonella enterica

A microarray was developed to simultaneously screen Escherichia coli and Salmonella enterica for multiple genetic traits. The final array included 203 60-mer oligonucleotide probes, including 117 for resistance genes, 16 for virulence genes, 25 for replicon markers, and 45 other markers. Validity of the array was tested by assessing inter-laboratory agreement among four collaborating groups using a blinded study design. Internal validation indicated that the assay was reliable (area under the receiver-operator characteristic curve=0.97). Inter-laboratory agreement, however, was poor when estimated using the intraclass correlation coefficient, which ranged from 0.27 (95% confidence interval 0.24, 0.29) to 0.29 (0.23, 0.34). These findings suggest that extensive testing and procedure standardization will be needed before bacterial genotyping arrays can be readily shared between laboratories.