Infection by the distribution of biotypes of enterobacteriacease species in leukaemic patients treated under ward conditions and in units for protective isolation in seven hospitals in Europe.

In a cooperative study on the efficiency of isolation and decontamination in patients with acute leukaemia performed in seven hospitals in Europe, faecal samples and oral washings were collected twice weekly and shipped for culturing to a Central Bacteriological Laboratory. In this laboratory the Enterobacteriaceae species isolated from these samples were biotyped as well as those isolated from infections that occurred in these patients during treatment. Enterobacteriaceae biotypes isolated for the first time during the isolation phase of the patient indicated a leak in the isolation system. The "colonizing" (newly resident) biotypes of Enterobacteriaceae species were found to be more often involved in infections and to be more commonly distributed among the patients in the participating hospitals than the "contaminating" (transient) Enterobacteriaceae biotypes. Furthermore, a linear correlation was found between the incidence of gram-negative infections and the number of cases in which these Enterobacteriaceae biotypes colonized the gastro-intestinal tract of patients. The majority of the infections was caused by Enterobacteriaceae biotypes that had settled in the gastro-intestinal tract during treatment and consequently were of nosocomial origin.