DETECTION OF LAWSONIA-INTRACELLULARIS, SERPULINA-HYODYSENTERIAE, WEAKLY BETA-HEMOLYTIC INTESTINAL SPIROCHETES, SALMONELLA-ENTERICA, AND HEMOLYTIC ESCHERICHIA-COLI FROM SWINE HERDS WITH AND WITHOUT DIARRHEA AMONG GROWING PIGS

A polymerase chain reaction (PCR) was optimized to detect Lawsonia int racellularis in faeces from naturally infected pigs. By combining a bo iling procedure to extract DNA and a nested PCR procedure, a detection limit at 2x10(2) bacterial cells per gram of faeces was achieved. The optimized PCR was used together with conventional culture techniques to detect Serpulina hyodysenteriae, weakly beta-haemolytic intestinal spirochaetes (WBHIS), Salmonella enterica, and haemolytic Escherichia coli, in a case control study to examine selected risk factors for the development of diarrhoea in growing pigs. Herds with diarrhoea were s elected as cases and randomly chosen herds without diarrhoea were chos en as controls. Infection with L. intracellularis significantly enhanc ed the chance of diarrhoea. S. hyodysenteriae, WBHIS group IV (Serpuli na pilosicoli), and S. enterica were isolated only from case herds whi ch indicate that these species may influence the development of diarrh oea. In addition, herd-type had a significant impact, that is specific pathogen-free herds showed an odds ratio at 0.2 relative to conventio nal herds for the development of diarrhoea. (C) 1998 Elsevier Science B.V. All rights reserved.