Rapid presumptive identification of entero-pathogenic Escherichia coli in faecal smears by means of fluorescent antibody. 1. Preparation and testing of reagents.

In outbreaks of infantile diarrhoea caused by enteropathogenic Escherichia coli, rapid detection of the etiological agent is essential for specific and adequate therapy. Fluorescent antibody techniques have proved advantageous for rapid identification of many microorganisms. The development of fluorescein-labelled antibodies specific for nine serogroups of E. coli and the testing of these reagents for specificity are described in this paper. Results of testing pure cultures of various Enterobacteriaceae as well as faecal specimens from cases of diarrhoea are reported. These data show excellent correlation between the fluorescent antibody technique and conventional serological methods for identifying enteropathogenic types of E. coli. The immunofluorescent technique is more rapid than the usual bacteriological and serological methods in that smears from faecal specimens can be stained directly with the labelled antibodies. Details of the procedures for carrying out the technique are given in annexes.