Prevalence of resistance in non-type-specific <i>E</i>. <i>coli</i> recovered from feedlot cattle, by sampling date.

<p>Marginal (adjusted) means estimates of the prevalence of resistance to various antimicrobial drugs among non-type specific <i>E</i>. <i>coli</i> isolates obtained from individual fecal samples at the first and second samplings. These estimates have been adjusted for isolate, individual, and pen effects. Due to a large variation in second sampling relative to days on feed, estimates have been categorized and presented at 33–75 days on feed, 75–120 days on feed, and >120 days on feed. Error bars represent 95% confidence intervals. Dashed lines differentiate which antimicrobial drugs were tested by one or both susceptibility testing methods. Number of isolates in legend indicate how many were tested by each susceptibility test (n = number tested by disk diffusion / number tested by both tests / number tested by broth microdilution). <i>P</i>-values relate to differences in adjusted prevalence among the 4 days-on-feed categories, and were not adjusted for multiple comparisons among AMDs. * = unadjusted prevalence with “plus four 95% confidence interval for a proportion".</p

Pen-level exposures to antimicrobial drugs for groups which housed cattle that were used (n = 215 pens).

<p>Pen-level exposures to antimicrobial drugs for groups which housed cattle that were used (n = 215 pens).</p

Multivariate correlation between resistance outcomes.

<p>Pairwise correlation between 2 antimicrobial resistance outcomes obtained from a multivariate regression model including resistances to tetracycline, streptomycin, sulfisoxazole, ampicillin, and chloramphenicol.</p

Selection of study pens, individuals and <i>E</i>. <i>coli</i> isolates at arrival and second sampling.

<p>Selection of study pens, individuals and <i>E</i>. <i>coli</i> isolates at arrival and second sampling.</p

Exposures to antimicrobial drugs in individual cattle from which NTSEC were recovered for this study (n = 923).

<p>Exposures to antimicrobial drugs in individual cattle from which NTSEC were recovered for this study (n = 923).</p

Number of antimicrobial drugs to which non-type specific <i>E</i>. <i>coli</i> isolates were resistant.

<p>Number of antimicrobial drugs to which non-type specific <i>E</i>. <i>coli</i> isolates were resistant.</p

Dependence at different levels of clustering for NTSEC isolates in the second sample set as estimated using alternating logistic regression^a.

<p>Dependence at different levels of clustering for NTSEC isolates in the second sample set as estimated using alternating logistic regression<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143995#t006fn001" target="_blank">^a</a>.</p

Resistance patterns for non-type specific <i>E</i>. <i>coli</i> isolates recovered from the arrival and second sample sets.

<p>Resistance patterns for non-type specific <i>E</i>. <i>coli</i> isolates recovered from the arrival and second sample sets.</p