Bettiol S S, Hunt A L, Goldsmid J M
Department of Pathology, University of Tasmania, Hobart, Australia.
Isr J Med Sci. 1993 Dec;29(12):777-82.
An investigation in 1989 of human fecal specimens revealed that of 111 diarrheal samples examined Escherichia coli Alkalescens-Dispar (A-D) were found in 9 (8.1%), but none were isolated from normal stool samples. Further studies have shown that although these isolates may be potential pathogens, they seem to remain unrecognized by routine laboratories due to their biochemical similarity to shigellae, a problem further exacerbated by their extensive sharing of O antigens. All the isolates were screened with an invasive DNA probe and all but three isolates were found to have a common plasmid. They were also confirmed to be invasive in HEp-2 monolayers. No isolates were shown to produce heat-labile or heat-stable toxin but electronmicroscopy revealed the presence of pili. The A-D isolates were biotyped using the two-tier schema of Crichton and Old and were categorized into biotypes 11, 12 and 16. These data confirm the importance of introducing an awareness of this intermediate strain into routine laboratories.
