Escherichia coli types isolated from porcine E. coli infections in Saxony from 1963 to 1990.

Between 1963 and 1990, 4221 Escherichia coli strains were isolated from 4221 cases of porcine neonatal colibacillosis and 16826 E. coli strains from 16064 cases of E. coli enterotoxicosis of weaned pigs. They belonged to serotypes which, due to their enterotoxigenicity or verotoxigenicity, are considered to be pathogenic for pigs. Nonhaemolytic enterotoxigenic strains characterized by one of the fimbrial antigens K99 (F5), 987p (F6), and F41 and one of at least 8 different A antigens were only found in suckling piglets. Haemolytic serotypes lacking the K88 (F4), K99, 987p, and F41 fimbrial antigens as well as A antigens were only isolated from pigs with E. coli enterotoxicosis of weaned pigs, which can occur already some days before weaning, while enterotoxigenic types carrying the fimbrial antigen K88 were found in both neonatal colibacillosis and E. coli enterotoxicosis of weaned pigs. In the 28 years considered, the type O149: (K91), K88 dominated in neonatal colibacillosis and, since 1972, in E. coli enterotoxicosis of weaned pigs, too. It was mainly nonhaemolytic during the first years and always haemolytic later. The emergence of type O147: (K89) coincided with a gradual disappearance of type O147: (K89), K88, both types differing in their biochemical behaviour.