Prevalence and characteristics of necrotoxigenic Escherichia coli (NTEC) strains isolated from diarrhoeic dairy calves

• Published in: Veterinary microbiology Vol. 66; no. 4; pp. 265 - 273
• Main Authors: Orden, J.A, Ruiz-Santa-Quiteria, J.A, Cid, D, Garcı́a, S, de la Fuente, R
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.1999; Elsevier Science
• Subjects: Agglutination Tests - veterinary; Animal bacterial diseases; Animals; Antigens, Bacterial - chemistry; Bacterial diseases; Bacterial Toxins - chemistry; Bacterial Toxins - genetics; Bacteriology; Biological and medical sciences; Biological Assay - veterinary; CALVES; Cattle; Cattle Diseases - microbiology; Cattle-bacteria; Cercopithecus aethiops; Cytotoxins - chemistry; Cytotoxins - genetics; Diarrhea - veterinary; DNA Primers - chemistry; DNA, Bacterial - chemistry; Epidemiology; ESCHERICHIA COLI; Escherichia coli - chemistry; Escherichia coli - classification; Escherichia coli - genetics; Escherichia coli Infections - microbiology; Escherichia coli Infections - veterinary; Escherichia coli Proteins; F17; Feces - microbiology; Female; Fimbriae, Bacterial - chemistry; Fundamental and applied biological sciences. Psychology; HeLa Cells; Humans; Infectious diseases; Medical sciences; Microbiology; NTEC; PCR; Polymerase Chain Reaction - veterinary; Prevalence; Serotyping; TERNERO; TOXICIDAD; TOXICITE; TOXICITY; TOXINAS; TOXINE; TOXINS; VEAU; Vero Cells; Southern Europe; Europe; Spain; NTEC; Cattle-bacteria; F17; Escherichia coli; Cytotoxic factor; Prevalence; Dairy cattle; Diarrhea; Pilus; Epidemiology; Necrosis; Infection; Vertebrata; Mammalia; Animal; Bacteriosis; Digestive diseases; Bacteria; Intestinal disease; Artiodactyla; Diagnosis; Veterinary; Detection; Ungulata; Enterobacteriaceae
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/S0378-1135(99)00012-7

Fecal samples from 246, 1–90-days old diarrhoeic dairy calves in 72 herds were screened for the presence of cytotoxic necrotizing factors (CNF)-producing Escherichia coli (NTEC). NTEC were detected by tissue culture assays and PCR in 39 (15.8%) of the diarrheic calves, and the majority of these animals (34 of 39, ca. 87.2%) were infected by NTEC producing CNF2. Calves were grouped according to their age (1–7 days, 8–14 days, 15–21 days, 22–30 days and 31–90 days) and analyses of prevalence were done by the Mantel-Haenzsel χ 2-test for trend. A significant age-associated increase in the prevalence of NTEC producing CNF2 ( p < 0.0001) was found. Eighty-one (8.4%) of the 958 E. coli isolates from the 246 diarrheic calves were positive for CNF in the tissue culture assays. These strains were analyzed by PCR and this technique showed that three (3.7%) strains were CNF1-positive and 75 (92.6%) were CNF2-positive. Moreover, three of the strains positive in the tissue culture assays were negative by PCR. These strains were subsequently assayed in several biological tests (rabbit skin test, mouse intraperitoneal test and mouse footpad test) which showed that they were really NTEC, probably producing CNF2, but with some different properties to classical strains producing CNF2. NTEC strains producing CNF2 belonged to different serogroups (O2, O7, O9, O14, O15, O41, O43, O45, O55, O76, O86, O88, O109, O115, O123, O128, O153 and O159) than strains producing CNF1 (O11 and O32) or PCR-negative strains (O111). Moreover, a strong association between CNF2 and F17 fimbriae was found (78.6% of CNF2-positive strains were F17-positive, whereas only 22.9% of CNF2-negative strains were F17-positive).