Genotypical and phenotypical characterization of potential virulence of bovine Escherichia coli strains isolated in Algeria

• Published in: Annales de médecine vétérinaire Vol. 142; no. 3
• Main Authors: Mellata, M. (Universite de Mouloud Mammeri, Tizi-Ouzou (Algeria)), Bakour, R, Mohamed ou Said, A, Jacquemin, E, Mainil, J
• Format: Journal Article
• Language: French
• Published: 01.05.1998
• Subjects: ALGERIA; ALGERIE; ARGELIA; BOVINAE; ESCHERICHIA COLI; FENOTIPOS; GENOTIPOS; GENOTYPE; GENOTYPES; PATHOGENICITY; PATOGENICIDAD; PHENOTYPE; PHENOTYPES; POUVOIR PATHOGENE
• ISSN: 0003-4118

In order to characterize pathogenic potential of Escherichia coli strains isolated from diarrhoeic calves in Algeria, a large range of virulence factors and markers were researched in 51 strains via DNA-DNA hybridation on colonies and via phenotypical tests. The sequence researched were those coding for adhesins F5, F41, Fl 7, PapA, PapG, AFA and SFA, proteins involved in the effacement of the enterocyte microvilli EaeA and EaeB, and toxins STAP, STb, LTp, SLT1, SLT2, CNF1 and CNF2. The phenotypes explored were the colicins, aerobactin, haemolysins, and haemagglutinin production and the serum resistance. The reaction of the strains to these different tests allows to distinguish three groups of strains: - Strains with intestinal tropism sub-divided into 2 strains STAP+F5+F41 + (ETEC), 2 strains EaeA+EaeB+SLT1+ (EHEC-Iike) and 5 strains EaeA+ (EPEC). The strains had a negative reaction to aerobactin, serum resistance, and haemolysins tests. Only EPEC and EHEC-Iike strains were colicinogenic. - Potentially invading strains subdivided into 3 strains NTEC2 (CNF2+, CNF2+AFA+ and CNF2+F17A+PapA+), 17 strains positive to AFA and/or F 17 and/or Pap adhesins probes, and 13 strains negative to genetic probes. Except for one Pap+F 17+ strain, all the others were positive to aerobactin production and/or serum resistance; furthermore, some were colicinogenic. Nine strains with negative reaction to genotypical and phenotypical tests (except for hemagglutination) can be considered as commensals or belonging to pathotypes not detected in this study. Mannose-resistant hemagglutination test was positive for 13 strains out of 19 positive with at least one gene probe of adhesins and for 8 strains out of 13 negative to gene probes of adhesins. A pathotype diversity exists in bovine E. coli isolated in Algeria. These pathotypes are similar to those met in Europe and America, but their relative importance is to be determined.