A Comparative Bacteriological Study of a Group of Non-lactose-fermenting Bacteria Isolated from Stools of Healthy Food-handlers

The bacterial strains reported in this paper were isolated during a routine carrier examination of the stools of a group of normal food-handlers. Though culturally a heterogeneous group, these bacteria are interesting chiefly because of their confusing resemblance to the pathogenic intestinal bacteria when first isolated on differential media. A detailed report of their reactions and possible taxonomic position is considered valuable. Though unclassified gram-negative bacteria, with slight or no ability to ferment lactose, are frequently encountered in stool examinations, they are, in the majority of cases, isolated from hospitalized groups, or from individuals concerned in outbreaks of intestinal disorders of various kinds. For example, Meinicke and Neuhaus (1909) and Burri and Duggeli (1919), found strains in human feces which were like B. coli, but did not ferment lactose, though they could be trained to do so. Many "atypical" cultures were isolated by the British during the last war from soldiers who had attacks of intestinal disease. Douglas (1917), Dobell, Gettings, Jepps and Stephens (1918), and Dean, Adamson, Giles and Williamson (1917) all examined dysentery convalescents who were free of symptoms, and found a total of 130 "unnamed" strains, none of which fermented lactose, and the majority of which produced indol. None agglutinated in paratyphoid sera. Fildes (1917) and Glyn and Robinson (1918) report a total of fifty-one "unknown" paratyphoid-like strains iso-