Correlation analysis of Shiga toxin-producing Escherichia coli shedding and faecal bacterial composition in beef cattle

Aims: The objectives of this study were to investigate the correlations between Shiga toxin-producing Escherichia coli (STEC) shedding and faecal microflora in beef cattle and to identify functional species that might be used for STEC control. Methods and Results: Faecal samples were collected from 110 calves and 92 dams. The number and prevalence of STEC were determined using CHROMagar (TM) STEC; denaturing gradient gel electrophoresis (DGGE) was employed to analyse faecal bacterial composition. Six-month-old calves had the highest STEC shedding levels (3.03 +/- 1.41 Log CFU g(-1)) and prevalence (95.5%). Both the number and prevalence decreased significantly as the calf age increased (P < 0.05). The DGGE analysis showed that faecal bacterial diversity increased, while cattle ages increased and STEC shedding levels decreased. Significant correlations between STEC shedding, cattle age and bacterial compositions were observed by redundancy analysis (P < 0.05). T-value biplots and sequencing results indicated that butyrate-producing bacteria (BPB) negatively correlated with STEC shedding. Conclusions: Higher STEC shedding levels and prevalence were associated with younger cattle age, lower faecal bacterial diversity and lower BPB levels. Significance and Impact of the Study: Butyrate-producing bacteria in GI tract might serve as an option for the future development of STEC shedding control strategy.