TABLE 2.
Factors associated with methicillin-resistant Staphylococcus aureus in nursery herds
| Parameter | Mean or proportion of parameter for: |
P valuea | |
|---|---|---|---|
| MRSA-positive cohorts (n = 8) | MRSA-negative cohorts (n = 14) | ||
| Herd size (no. of sows, SD) | 698 (433) | 425 (427) | 0.076 |
| Nursery was off site (%) | 25 | 14.3 | 0.602 |
| Continuous nursery flow (%) | 25 | 57.1 | 0.204 |
| Avg weaning age (days, SD) | 22.4 (2.6) | 24.5 (4.8) | 0.351 |
| No. of pigs weaned per month (SD) | 1,224 (696) | 795 (711) | 0.088 |
| Nursery stocking density (no. of pigs/m2, SD) | 3.22 (1.23) | 2.47 (1.17) | 0.048 |
| Direct pig-to-pig contact between pens (%) | 50 | 42.9 | 0.999 |
| Exposure to wooden surfaces (%) | 25 | 21.4 | 0.999 |
| Temp upon entrance to nursery (°C, SD) | 27.6 (1.23) | 26.7 (2.79) | 0.273 |
| No outside breeding stock replacements (%) | 62.5 | 71.4 | 0.999 |
| Danish entry (%) | 37.5 | 42.9 | 0.999 |
| Bootbath (%) | 0 | 28.6 | 0.254 |
| Shower-in/shower-out required (%) | 62.5 | 28.6 | 0.187 |
| Danish entry, bootbath, or shower (%) | 75 | 71.4 | 0.999 |
| Older pigs sometimes mixed with new pigs coming into the nursery (%) | 25 | 35.7 | 0.999 |
| Nursery pens disinfected for incoming pigs every time (%) | 100 | 50 | 0.022 |
| Corridors are disinfected on a weekly to monthly basis (%) | 87.5 | 42.9 | 0.074 |
| Cat(s) and/or dog(s) on the property (%) | 37.5 | 92.9 | 0.011 |
| Pets allowed into the barn (%) | 0 | 71.4 | 0.115 |
| Live rodents observed in barn at sampling (%) | 12.5 | 7.1 | 0.999 |
| Wild birds observed in barn in past year (%) | 12.5 | 42.9 | 0.193 |
| Antibiotic administration (%) | |||
| Feed | 87.5 | 78.6 | 0.999 |
| Water | 37.5 | 42.9 | 0.999 |
| Injection | 87.5 | 71.4 | 0.613 |
| Antimicrobial treatment (%)b | |||
| Tetracycline (in-feed) | 62.5 | 85.7 | 0.309 |
| Tiamulin (in-feed) | 25 | 42.9 | 0.649 |
| Penicillin (in-feed/injection) | 50 | 50 | 0.999 |
| Sulfamethazine (in-feed/in-water) | 25 | 21.4 | 0.999 |
| Zinc therapy (≥2,000 ppm in-feed) | 100 | 50 | 0.022 |
| No. of different antibiotics administered at the group-level (SD) | 1.88 (1.13) | 2.43 (1.09) | 0.345 |
a
Univariate statistics (Fisher's exact or Wilcoxon rank sum).
b
Group-level exposure to antimicrobial between birth and 3 weeks postweaning.