Identification of Vibrio hollisae sp. nov. from patients with diarrhea

Abstract

The name Vibrio hollisae (synonym = Special Bacteriology group EF-13) is proposed for a new group of 16 strains that occurred in stool cultures of patients with diarrhea. V. hollisae is a small gram-negative rod, which is motile with a single polar flagellum. No lateral or peritrichous flagella were observed, even when it was grown on a solid medium. Sodium chloride is required for growth, so V. hollisae is a halophilic vibrio. Strains were positive (36°C, 24 or 48 h) for oxidase (Kovacs), indole production, nitrate reduction to nitrite, and fermentation of D-glucose (acid, no gas), L-arabinose, D-galactose, and D-mannose. Strains were negative for the following tests often used in enteric bacteriology: lipase (corn oil); deoxyribonuclease; gelatinase; methyl red; Voges-Proskauer; utilization of citrate, acetate, and malonate; L-lysine decarboxylase (Mollers); L-ornithine decarboxylase (Mollers); L-arginine dihydrolase (Mollers); growth in KCN medium; and acid production from D-adonitol, D-arabitol, cellobiose, dulcitol, erythritol, glycerol (25% delayed positive at 7 days), i-(myo)-inositol, lactose, maltose, D-mannitol, melibiose, α-methyl-D-glucoside, mucate, raffinose, L-rhamnose, salicin, D-sorbitol, sucrose, trehalose, and D-xylose. None of the strains were motile (semisolid medium) at 36°C at 48 h, but by 7 days 88% were motile. The strains did not grow within 2 days when plated on thiosulfate-citrate-bile salts-sucrose (TCBS) agar on MacConkey agar, but they grew on sheep blood agar and marine agar. By DNA-DNA hybridization (75°C, hydroxyapatite with 32P), V. hollisae was only 0 to 4% related to 21 named species in Vibrio and Photobacterium. The type strain is designated ATCC 33564, which has a mean guanine-plus-cytosine content in DNA of 50 mol%. With the disk diffusion method V. hollisae had relatively large zones of inhibition around penicillin, ampicillin, carbenicillin, cephalothin, colistin, polymyxin B, streptomycin, kanamycin, gentamicin, tetracycline, chloramphenicol, and sulfadiazine. Future studies should focus on the isolation of this new vibrio and its ecology and relationship to human diseases.