Impact of "Raised Without Antibiotics" Beef Cattle Production Practices On Occurrences of Antimicrobial Resistance.

Impact of "Raised Without Antibiotics" Beef Cattle Production Practices On Occurrences of Antimicrobial Resistance. Appl Environ Microbiol. 2017 Sep 08;: Authors: Vikram A, Rovira P, Agga GE, Arthur TM, Bosilevac JM, Wheeler TL, Morley PS, Belk KE, Schmidt JW Abstract The specific antimicrobial resistance (AMR) decreases that can be expected from reducing antimicrobial (AM) use in United States (US) beef production have not been defined. To address this data gap, feces were recovered from 36 lots of "raised without antibiotics" (RWA) and 36 lots of "conventional" (CONV) beef cattle. Samples (N = 719) were collected during harvest and distributed over a year. AMR was assessed by: i) culture of six AM-resistant bacteria (ARB); ii) qPCR for 10 AMR genes (ARGs); iii) an qPCR array of 84 ARGs; and iv) metagenomic sequencing. Generally, AMR levels were similar, but some were higher in CONV. The prevalence of third-generation cephalosporin-resistant (3GC(r)) Escherichia coli was marginally different between production systems (47.5 % CONV, 34.8% RWA, P = 0.04), but the seasonal effect (92.8% summer, 48.3% winter, P < 0.01) was greater. Erythromycin-resistant (ERY(r)) Enterococcus spp. concentrations significantly differed between production systems (CONV = 1.91 log10 CFU/g, RWA = 0.73 log10 CFU/g, P < 0.01). Levels of aadA1, ant(6)-I, blaACI, erm(A), erm(B), erm(C), erm(F), erm(Q), tet(A), tet(B), tet(M), and tet(X) ARGs were higher (...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research