Volume 21, Number 6—June 2015
Dose-Response Relationship between Antimicrobial Drugs and Livestock-Associated MRSA in Pig Farming1
|Characteristic||No.†||OR (95% CI)||p value|
|0 mo||262||0.83 (0.48–1.43)||<0.001|
|6 mo||290||2.05 (1.25–3.37)|
|12 mo||259||1.96 (1.20–3.20)|
|Suckling piglets||212||3.87 (2.34–6.39)|
|Weaned piglets||280||9.89 (5.96–16.39)|
|External supply of gilts‡|
|Delivery room for materials|
|Sows housed in stable groups|
|Antimicrobial drug use, per 2-fold increase, log2 DDDA/Y
|Use of cephalosporins|
*Model fit: −2 log RSPL estimation = 5331.7. Multivariable final model after backward elimination of non-significant variables from a full model (online Technical Appendix Table 3, http://wwwnc.cdc.gov/EID/article/21/6/14-0706-Techapp1.pdf) containing the significant associations (p<0.05) presented in Table 5 (http://wwwnc.cdc.gov/EID/article/21/6/14-0706-T5.htm) for all farms, together with antimicrobial drug use, use of cephalosporins, sampling time, and age group of the pool. MRSA, methicillin-resistant Staphylococcus aureus; OR, odds ratio; DDDA/Y, defined daily dosages animal per year; Ref, reference category; RSPL, residual pseudo-likelihood.
†Multiple variables had missing values in the full model reducing the number of observations in the final model.
‡Farms were defined as open when they received external supplies of gilts ≥1 time per year from at least 1 supplier and as closed when they received no external supply of gilts.
1Preliminary results from this study were presented at the 3rd American Society for Microbiology–European Society of Clinical Microbiology and Infectious Diseases (ASM-ESCMID) Conference on Methicillin-resistant Staphylococci in Animals: Veterinary Public Health Implications, 2013 November 4–7, Copenhagen, Denmark (oral presentation, speaker abstract S7:3); and at the Society for Veterinary Epidemiology and Preventive Medicine annual meeting, 2014 March 26–28, Dublin, Ireland (poster presentation).