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Recent work describing six named species and two unnamed genomospecies within Citrobacter has enlarged the genus to 11 species. DNA relatedness and phenotypic tests were used to determine how well these species can be identified. One hundred thirty-six strains were identified to species level by DNA relatedness and then identified phenotypically in a blinded fashion. By using conventional tests, 119 of the 136 strains (88%) were correctly identified to species level. Three additional strains (2%) were identified as citrobacteria but were not identified to species level, and 14 strains (10%) were misidentified as other Citrobacter species. Carbon source utilization tests were used to identify 86 of the strains. Eighty-four strains (98%) were correctly identified, and two strains (2%) were misidentified as other Citrobacterspecies. Additional strains of Citrobacter genomospecies 10 and Citrobacter genomospecies 11 were identified, allowing these species to be formally named as Citrobacter gilleniisp. nov. and Citrobacter murliniae sp. nov., respectively.

The structure of the O-specific side chain of the lipopolysaccharide (LPS) of Plesiomonas shigelloides, strain CNCTC 113/92 has been investigated by NMR spectroscopy, matrix-assisted laser desorption/ionization time of flight mass spectrometry and sugar and methylation analysis. It was concluded that the polysaccharide is composed of a hexasaccharide repeating unit with the following structure:This structure represents a novel hexasaccharide repeating unit of bacterial O-antigen that is characteristic and unique to the Plesiomonas shigelloides strain. Using the high-resolution magic angle spinning technique, 1 H-NMR spectra were also obtained for the O-polysaccharide components of isolated LPS and in their original form directly on the surface of bacterial cells.Keywords: high-resolution magic angle spinning (HR-MAS); lipopolysaccharide; matrix-assisted laser desorption/ionization time of flight (MALDI-TOF); O-antigen; Plesiomonas shigelloides.Plesiomonas shigelloides (previously Aeromonas shigelloides) is a ubiquitous, facultatively anaerobic, flagellated, Gramnegative, rod-shaped bacterium which has been isolated from a variety of sources such as freshwater, surface water and many wild and domestic animals, and is particularly common in tropical and subtropical habitats [1]. DNA±DNA hybridization tests [1] showed that all P. shigelloides strains are closely related to each other thus constituting a separate well defined genus within the family Vibrionaceae. P. shigelloides shares biochemical and antigenic properties with Enterobacteriaceae and Vibrionaceae; however, genetically it shows only 8% and 7% similarity, respectively [1].Infections with P. shigelloides have been strongly associated with drinking untreated water [2,3], eating uncooked shellfish or with travel to developing countries [4,5]. Recent studies have suggested that P. shigelloides is an opportunistic pathogen in immunocompromised hosts [6] especially neonates [6±10]. It has been associated with diarrhoeal illness [11] and other diseases in normal hosts as well. P. shigelloides has been isolated from a variety of clinical specimens including cerebrospinal fluid, wounds and the respiratory tract. Reported cases of meningitis and bacteraemia [10] caused by P. shigelloides are of special interest because of their seriousness. P. shigelloides causes both localised infections originating from infected wounds and gastrointestinal infections, which can disseminate to other parts of the body [12].The serotyping scheme of P. shigelloides proposed by Shimada and Sakazaki [13], and Aldova et al.[14±17] includes 102 O-serotypes, some O-antigens showing cross-reactivity with antisera directed against lipopolysaccharides (LPS) of Shigella sonnei, Shigella dysenteriae strains 1, 7 and 8, Shigella boydi strains 2, 9 and 13, and Shigella flexneri strain 6 [13,18]. Two P. shigelloides strains were found to share the structure of O-antigens with those of S. flexneri and S. dysenteriae [19].Although the antigenic schemes of P. shigelloides have been extensively st...

Pragia is proposed as a new genus in the family Enterobacteriaceae. Pragia fontium is proposed for the single Pragia species, in which 18 strains are known, all of which were isolated in Czechoslovakia. P. fontium strains give positive tests for Simmons citrate, H,S production, motility, acid production from D-glucose and D-galactose, and gluconate oxidation. The majority of strains are positive in tests for methyl red and esculin. Acid production from glycerol, salicin, and ~-xylose varies among strains, whereas all strains are negative in Voges-Proskauer tests and tests for indole production, urea hydrolysis, phenylalanine deaminase, lysine and ornithine decarboxylases, arginine dihydrolase, gelatin hydrolysis, growth in KCN, malonate utilization, gas production from D-glucose, lipase, deoxyribonuclease, tyrosine clearing, and acid production from carbohydrates other than those noted above. The levels of deoxyribonucleic acid (DNA) relatedness of seven P . fontium strains to labeled DNA from the type strain ranged from 85 to 94% (hydroxyapatite method at 60 and 75°C); the levels of DNA relatedness of P . fontium to other members of the Enterobacteriuceae were 17% or less except for biochemically atypical Budvicia aquatica DRL 23575 (37%). Seventeen P. fontium strains were isolated from wells or water pipes, and one strain was isolated from the stool of a healthy woman. The type strain of P . fontium is strain CNCTC Eb11182 (= CDC 963-84 = DRL 20125).

Deoxyribonucleic acid relatedness studies (S1 nuclease method) showed that 60 strains proposed as Budvicia aquatica form a homogeneous deoxyribonucleic acid hybridization group. Three strains labeled Budvicia-like were 9 to 22% related to B. aquatica. A total of 74 strains representing known species and genera in the Enterobacteriaceae were 0 to 8% related to B. aquatica. These findings support designation of Budvicia aquatica as a new genus and new species. This new species in the family Enterobacteriaceae is composed of strains which produce H2S; hydrolyze urea and o-nitrophenyl-P-D-galactopyranoside; do not produce acid from trehalose, D-mannose, glycerol, sucrose, maltose, and D-melibiose; do not decarboxylate lysine, ornithine, or arginine; do not produce phenylalanine deaminase; and have complex growth factor requirements. The guanine-plus-cytosine content of the deoxyribonucleic acid is 46 mol%. The type strain is strain 20186HG01 (= ATCC 25567).