An Improved Enrichment Broth for Isolation of Escherichia coli O157, with Specific Reference to Starved Cells, from Radish Sprouts

An enrichment broth was developed for the efficient isolation of Escherichia coli O157 from radish sprouts. The broth was buffered peptone water containing 0.5% sodium thioglycolate (STG-BPW), which was designed to allow growth of E. coli O157 in starved and unstarved states. However, this medium suppressed the growth of non-carbohydrate-fermenting obligate aerobes whose colonial appearance on sorbitol MacConkey agar containing cefixime and tellurite (CT-SMAC) resembled that of E. coli O157. Both starved and unstarved cells of E. coli O157 experimentally inoculated into radish sprouts were successfully recovered with STG-BPW enrichment in all cases, most of which showed marked disappearance of E. coli O157-like colonies on CT-SMAC

Isolation from a Healthy Carrier and Characterization of a Neisseria meningitidis Strain That Is Deficient in γ-Glutamyl Aminopeptidase Activity

γ-Glutamyl aminopeptidase (GGT) activity is used as a specific marker for the identification of Neisseria meningitidis. We isolated from a healthy carrier and characterized an N. meningitidis isolate which lacked the activity due to the insertional mutation of the ggt gene, suggesting that naturally occurring N. meningitidis isolates do not always possess GGT activity

Two strains of Vibrio cholerae non-O1 possessing somatic (O) antigen factors in common with V. cholerae serogroup O139 synonym "Bengal"

Two strains (O22 reference strain, 169-68, and strain 490-93 isolated from a patient with diarrhea in Thailand) ofVibrio cholerae non-O1 possessing somatic (O) antigen factors in common withV. cholerae O139 synonym Bengal are described. The O antigens of these two strains were closely related to that ofV. cholerae O139 in an a,b-a,c type of relationship, but were not completely identical with serogroup O139. Therefore, both these strains are not classified into the O139 serogroup ofV. cholerae, because they have their own major antigens. As the strain 490-93 could not be placed into any of the 154 established O serogroups ofV. cholerae, this strain was assigned to a new serogroup, O155. For practical use, the diagnostic antiserum prepared against the O139 reference strain (MO45, ATCC 51394) ofV. cholerae must be absorbed with reference strains 169-68 and 490-93 representing serogroups O22 and O155 ofV. cholerae to remove cross-reacting agglutinins of the O22 and O155 strains, respectively