Detección de antígenos de adhesión en Escherichia coli enterotoxigénica. Estudio de la expresión en diferentes medios de cultivo / [Detection of enterotoxigenic Escherichia coli adhesion antigens. Study of their expression in different culture media]

ABSTRACT

Polyclonal antibodies were raised in rabbits against the adherence antigens K88ab, ac, ad K99 and F41 of enterotoxigenic Escherichia coli (ETEC). Their specificity for the antigen was tested by using homologous and heterologous E. coli strains, which had been grown under permissive and nonpermissive conditions for pili expression and also confronted to a purified extract of each fimbrial adhesin. Optimal conditions for agglutinating bacterial suspensions were established for both antisera and antigens. Expression of adhesins was studied in several culture media, which are being commonly used in clinical bacteriology. K99, K88ab and K88ad were satisfactorily expressed in both Minca broth and solid media on T.S.I. Mac Conkey and E.M.B. K88ac was not expressed on G1253 strain when grown on T.S.I. or in Mac Conkey when the inoculum was obtained from E.M.B. However, Mac Conkey allowed K88ac expression when inoculum had been grown on Luria-Bertani. On the other hand, F41 was only satisfactorily expressed in Minca broth, failing in being detected by agglutination in the remaining culture media. These results allow to use alternative media, beyond the recommended Minca broth, to detect adhesins K99, K88ab, and K88ad on ETEC isolates.