Pseudo-outbreak of Aeromonas hydrophila isolates related to endoscopy

Over a two-month period there was a sudden increase in Aeromonas hydrophila isolated from colon i.e., biopsies from patients without related symptoms. Strains were studied by biotyping (API 20 NE, bioMerieux), antibiotyping, plasmid analysis,SDS-PAGE of whole cell proteins and toxicity for cell cult ures. All strains gave identical results. In particular SDS-PAGE of whole c ell proteins showed an identical electrophoretic pattern for all the strain s, and so all were considered to be of the same clone. During the study per iod, endoscopic materials were disinfected with quaternary ammonia and glut araldehyde phenate. After these disinfectants were changed to glutaraldehyd e 2%, there were no more isolates of A. hydrophila from the biopsies. We co nclude that SDS-PAGE can be a useful technique for epidemiological characte rization of A. hydrophila.