Production of Shiga toxin by Shiga toxin-expressing Escherichia coli (STEC) in broth media: from divergence to definition

Author(s)

Rocha, L. B. ; Piazza, R. M. F.

• Document type: Journal article
• Source: Letters in Applied Microbiology; v. 45, n. 4, p. 411-417, Oct. 2007.
• Field of knowledge: Biological Sciences - Microbiology

Abstract

To determine the suitability of eight different commercial broth media for Shiga toxin (Stx) production. Shiga toxin-producing Escherichia coli (STEC) strains producing Stx1 or Stx2 were grown at 37°C (250 rev min-1) for 24 h in brain heart infusion broth, E. coli broth, Evans medium, Luria-Bertani broth, Penassay broth, buffered-peptone water, syncase broth and trypticase soy broth. Toxin production was measured by enzyme-linked immunosorbent assay (ELISA) in polymyxin-treated cell pellets and/or supernatants of cultures, ELISA optical densities reached 1 when isolates were grown for 2-4 h in E. coli broth in the presence of antibiotic. Besides, a collection of STEC-expressing Stx strains was evaluated and the Stx production was assayed in the supernatants and in polymyxin-treated pellets of bacterial growth after 4 h of cultivation in E. coli broth in the presence of antibiotic. The most suitable medium for Stx production was E. coli broth when the bacterial isolates were grown for 4 h in the presence of ciprofloxacin and the Stx production is detected in the supernatant. This study presents the first comprehensive comparison of different broth media with regard to Stx production to establish optimal culture conditions for STEC detection in routine diagnostic laboratories. (AU)

• FAPESP's process: 04/12136-5 - Atypical enteropathogenetic Escherichia coli (atypical EPEC)
• Grantee: Waldir Pereira Elias Junior
• Support Opportunities: Research Projects - Thematic Grants