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Table 8 Likelihood of identifying resistance among NTSEC isolates recovered from individuals that were culture-positive for M haemolytica to those that were culture-negative, stratified by sample time1,2

From: Methodological comparisons for antimicrobial resistance surveillance in feedlot cattle

Resistance outcome in fecal E. coli3 Sample Time M. haemolyticaCulture Status4 OR5 95% CI6 P-value
Ampicillin First Positive 1.2 0.3 – 4.8 0.78
   Negative ref   
  Second Positive 3.3 0.4 – 26.8 0.19
   Negative ref   
Streptomycin First Positive 0.4 0.2 – 0.9 0.04
   Negative ref   
  Second Positive 0.5 0.1 – 2.3 0.46
   Negative ref   
Sulfisoxazole First Positive 0.8 0.4 – 1.7 0.56
   Negative ref   
  Second Positive 1.5 0.5 – 4.4 0.50
   Negative ref   
Teteracyline First Positive 1.1 0.5 – 2.5 0.82
   Negative ref   
  Second Positive 0.9 0.4 – 2.2 0.90
   Negative ref   
  1. 1n=377 isolates recovered from 186 individuals that were culture-positive for MH, and n=225 isolates recovered from 77 individuals that were culture-negative for MH.
  2. 2Susceptibility testing was performed using broth microdilution.
  3. 3Other drugs could not be analyzed because of low resistance prevalence (amikacin, amoxicillin-clavulanate, cefoxitin, ceftiofur, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, trimethoprim-sulfamethoxazole).
  4. 4Culture status regarding recovery of M. haemolytica from nasopharyngeal swabs.
  5. 5Analyses controlled for repeated measures and hierarchical data structure using generalized estimating equations (GEE), and fixed effects for feedlot, sample time, M. haemolytica culture-status, and a single interaction term for sample time*M. haemolytica culture-status.
  6. 695% confidence intervals.
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