LONGITUDINAL STUDY ON METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) NASAL COLONISATION IN A FARROW TO FINISH PIG HERD

Objectives - To contribute to better understanding of age-related changes in MRSA nasal colonization (n.c.) in pigs. Materials and methods - Thirty sows were submitted to nasal swabbing (n.s.) at d 80 of gestation. At d 3 post partum mammal skin was swabbed. Sixty pigs were submitted to n.s. at d3 of life, one day before weaning (wean.) (d27); last day of wean. (d75); first day of fattening (d120); approx. half of fattening (d180); slaughtering (approx. d270). Dust samples were collected with dry sterile gauzes. Gestation facilities were tested only once (30 samples). Farrowing (farr.) crates, weaning boxes, growing and fattening pens were tested twice: in the presence of animals (10 samples) and in cleaned and sanitized (C&S) rooms (10 samples). Results - N. c. was recorded in 1/30 sows. No MRSA were detected from mammal skin swabs. At d3 of life 1/30 pig resulted colonized (1,7%): At d 27 all pigs tested negative. At d75 and at d120 all pigs (30/30) resulted MRSA colonized. At approximately d180 the number of colonized pigs decreased at 11/60 (18,3%) and at slaughter 14/59 tested positive (23,7%). MRSA environmental contamination was not detected in gestation pens and in farr. crates. Five out of ten dust samples were identified as MRSA positive in populated weaning boxes. After C&S, MRSA were detected in 4/10 weaning boxes. In growing boxes the rate of positive samples (p.s.) was 5/10 in populated boxes and 2/10 after C&S. In fattening boxes the rate of p. s. was 1/10 before and after C&S. Conclusions - MRSA n. c. rate appeared age-related. A clear increase was registered during wean., with the rate reaching 100%, persisting in growers and decreasing in fatteners to approx. 20%. A similar trend was observed in environmental samples. The rapid colonization of all pigs followed their introduction in contaminated wean. boxes.