title: Colonization antigens, antibiotic resistance and plasmid content of enterotoxigenic Escherichia coli isolated from piglets with diarrhoea in Galicia (north-western Spain).
abstract: Escherichia coli colonies isolated from 50 diarrhoeic and 29 healthy piglets were investigated for several properties related to pathogenicity, such as production of heat-labile (LT) and heat-stable (STa) enterotoxins, presence of K88 and K99 colonization antigens, mannose-resistant haemagglutinating activity (MRHA), beta-haemolysis and antibiotic resistance. The objective was to establish the toxic and adhesive abilities of E. coli strains that cause porcine diarrhoea in Galician farms. Fifty-seven colonies from 14 diarrhoeic piglets formed STa, while no STa+ colony was detected from healthy piglets. Thirty-four of the 57 STa+ colonies were resistant to gentamicin. Sixteen representative STa+ strains isolated from the 14 infected piglets were serotyped, investigated for plasmid content and examined by electron microscopy. Of these STa+ strains, 15 belonged to serotype 0141:K85ab and carried on their surface the fimbrial antigen P987. The remaining representative STa+ strain belonged to serotype 0101:K30 and was K99+, being the only STa+ strain with MRHA activity. All 15 STa+ P987+ strains possessed a similar plasmid pattern, with three plasmids ranging in molecular weight from 33 X 10(6) to 74 X 10(6); nine of the gentamicin-resistant strains possessed an additional plasmid of molecular weight 16 X 10(6), which was absent in the six gentamicin-sensitive strains. Strains producing LT or K88 antigen were not detected. Forty-one MRHA+ colonies were isolated at similar rates from both diarrhoeic and healthy piglets. Twelve of the 19 non-enterotoxigenic MRHA+ strains of which the O-group was established, belonged to serogroups (01, 02, 07, 08, 09 and 075) typical of the human E. coli strains that cause extraintestinal infections. Finally, a statistically significant association between haemolytic and MRHA activities in porcine E. coli was found. In conclusion, it was found that STa+ E. coli strains belonging to serotype 0141:K85ab:P987 are associated with porcine diarrhoea in Galicia. Additionally, no correlation between the isolation of non-ETEC MRHA+ strains and diarrhoea was observed.
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000942:Antigens, Bacterial / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis; D001427:Bacterial Toxins / Q000096:biosynthesis; D003967:Diarrhea / Q000382:microbiology / Q000662:veterinary*; D004352:Drug Resistance, Microbial; D004768:Enterotoxins / Q000096:biosynthesis; D004926:Escherichia coli / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D029968:Escherichia coli Proteins; D005243:Feces / Q000382:microbiology; D005839:Gentamicins / Q000494:pharmacology; D006384:Hemagglutination; D008854:Microscopy, Electron; D010957:Plasmids; D012703:Serotyping; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D005839:Gentamicins; C030659:K antigens; C034151:heat stable toxin (E coli)