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Title: Bacteria in post-antimicrobial enteritis in weaned pigs
Author: Pradal-Roa, Pedro Juan Bautista de la Salle Fernando
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1994
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This research was undertaken to determine whether or not diarrhoea and enteritis occurred following the withdrawal of antimicrobials used for growth promotion or therapy in the pig. Cases of post-antimicrobial enteritis were investigated on 6 farms. Post-antimicrobial enteritis could not be confirmed in any instance but was suspected in one unit, Farm 1 on one visit. Inadequate or inappropriate therapy was found to be the main reason for the reappearance of disease following antimicrobial withdrawal. Swine dysentery was responsible on Farms 2 and 3, antimicrobial resistance of Salmonella kedougou to trimethoprim- sulphadiazine used for treatment was responsible on Farm 5 and inappropriate treatment was being given on Farm 1. On two farms (4 and 6) disease had disappeared or was being treated successfully. Experimental studies were carried out using pigs free from major pathogens and feeding or treating them with antimicrobials reported to cause post-antimicrobial enteritis. The initial study with avoparcin at 80 ppm for 10 days proved inconclusive. Rotavirus and Cryptosporidium spp. (both insensitive to antimicrobials) were identified. Two controlled studies were carried out using lincomycin at 13.3 ppm for 11 days and 20 days (Experiments 2 and 3). Antimicrobial withdrawal was found to affect levels of total coliforms, lactobacilli, campylobacters, Clostridium perfringens type A and Bacteroides spp. in individual pigs but the changes were not statistically significant on a group basis. A further study was carried out using chiortetracycline in the feed at 300 ppm for 21 days. Weight gains in the treated pigs were higher than those in controls during adaptation to treatment 346g/d compared with 254g/d. A fall in the rate of gain occurred in the treated group following antimicrobial withdrawal. This change provided evidence of a post-antimicrobial effect, but it could not be attributed to any clinical disease, to pathogens in other body systems or to the bacterial species monitored. It was concluded that a post-antimicrobial effect occurred and that it was not associated with the bacteria being monitored. It was not associated with pathogens such as Clostridium difficile, Serpulina hyodysenteriae. Salmonella spp. or Ileal symbiont intracellularis which have all been implicated in previously reported cases.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available