Table 3. Environmental contamination with MRSA in veal calf stables during the first production cycle of an intervention study performed in 51 farms to reduce MRSA carriage, the Netherlands 2010–2012.
| RAB farms | RAB-CD farms | Control farms | P-value | ||
|---|---|---|---|---|---|
| No. MRSA-positive EDCs/ total EDCs (%): | Complete cycle | 21/114 (18.4) | 44/130 (33.9) | 29/118 (24.6) | 0.02 a |
| Time 0 | 0/60 (0) | 7/66 (10.6) | 2/64 (3.1) | 0.01 a | |
| Week 12 | 21/54 (38.9) | 37/64 (57.8) | 27/54 (50.0) | 0.12 a | |
| Mean MRSA CFU/EDC (SD b ): | Complete cycle | 17.2 (43.3) | 61.8 (155.4) | 24.1 (51.4) | <0.01 c |
| Time 0 | 0 (0) | 28.6 (82.8) | 7.9 (43.0) | 0.01 c | |
| Week 12 | 35.4 (56.9) | 93.9 (197.9) | 42.2 (54.3) | 0.03 c | |
| GM d MRSA CFU/EDC (p-value e ): | Complete cycle | 2.9 (0.24) | 9.1 (0.04) | 4.6 (Ref.) | 0.01 f |
| Time 0 | 0 (0.19) | 0.44 (0.07) | 0.06 (Ref.) | 0.01 f | |
| Week 12 | 14.5 (0.31) | 30.8 (0.18) | 20.4 (Ref.) | 0.06 f |
P-values <0.05 are in boldface. MRSA, methicillin resistant Staphylococcus aureus; RAB, farms reducing antimicrobials by protocol; RAB-CD, farms reducing antimicrobials by protocol and applying a cleaning and disinfection program; Control, farms without interventions; CFU, colony-forming units; EDC, electrostatic dust collector; Ref., reference category of the variable.
a p-values among proportions are calculated with Chi-squared / Fisher’s exact tests.
b Standard deviation.
c p-values for the difference in means obtained from ANOVA.
d Geometric mean (antilogged results from tobit regression).
e p-values in brackets indicate the difference with the reference category (control farms).
f overall p-values from tobit regression.