Description of Wautersiella falsenii gen. nov., sp. nov., to accommodate clinical isolates phenotypically resembling members of the genera Chryseobacterium and Empedobacter.

A total of 26 isolates of non-fermenting, Gram-negative rods, obtained between 1980 and 2004 by various clinical laboratories in Belgium, with phenotypic characteristics resembling those of members of the genera Chryseobacterium and Empedobacter (indole-positive) and a biochemical profile resembling that of CDC group II-h, but urease-positive, were collected at the Université Catholique de Louvain Microbiology Laboratory, Belgium. The 16S rRNA gene sequences were determined for most of the isolates and showed 94-95 % similarity with the type strain of Empedobacter brevis as the closest relative, indicating that these isolates might belong to a separate genus. Furthermore, the 16S rRNA gene sequences of the isolates were similar, but two clusters (genomovars) could be distinguished. The sequence similarities were 99.5-100 % for the 14 isolates of genomovar 1 and 99.4-100 % for the 12 isolates of genomovar 2. The similarity between the two clusters was 98.3-99.5 %. The presence of two clearly different groups was corroborated by using tRNA intergenic length polymorphism analysis, which also enabled differentiation of the novel species from all other species studied thus far using this technique. DNA-DNA hybridization results excluded a close relatedness to Empedobacter brevis. The DNA G+C contents of the reference strains of genomovars 1 and 2 were 33.8+/-0.4 and 34.4+/-0.2 mol%, respectively. The name Wautersiella falsenii gen. nov., sp. nov., is proposed for this group, comprising two closely related genomovars. The type strain of the species and reference strain for genomovar 1 is NF 993(T) (=CCUG 51536(T)=CIP 108861(T)), which was isolated from a surgical wound. The reference strain for genomovar 2 is NF 770 (=CCUG 51537=CIP 108860), which was isolated from blood.

Distribution of nocardia species in clinical samples and their routine rapid identification in the laboratory.

Eighty-six Nocardia strains isolated from clinical samples in Belgium were identified by 16S rRNA gene sequencing. Eighty-three (96%) strains belonged to only six Nocardia species: N. farcinica (38 [44%]), N. nova (19 [22%]), N. cyriacigeorgica (13 [15%]), N. brasiliensis (6 [6.9%]), N. abscessus (5 [5.8%]), and N. paucivorans (2 [2.3%]). A gallery of nine conventional and enzymatic tests was developed for the rapid identification of the most common species isolated during this survey. Pyrrolidonyl aminopeptidase, gamma-glutamyl aminopeptidase, alpha-mannosidase, and alpha-glucosidase were found to be highly discriminating and could be used to develop an identification scheme.

Histidine decarboxylase in Enterobacteriaceae revisited.

With a modification of Taylor's decarboxylation broth, histidine decarboxylase was detected in Enterobacter aerogenes, Morganella morganii, Raoultella ornithinolytica, and some strains of Citrobacter youngae and Raoultella planticola. This method provides a useful confirmatory test for identification of E. aerogenes strains.

Identification of a novel Brevibacterium species isolated from humans and description of Brevibacterium sanguinis sp. nov.

Six coryneforms isolated from blood and dialysate fluid were phenotypically similar to Brevibacterium casei, but 16S rRNA gene sequencing and DNA-DNA hybridization indicate that they belong to a new species for which the name Brevibacterium sanguinis is proposed.

Brevibacterium lutescens sp. nov., from human and environmental samples.

Three strains of coryneform rods isolated from clinical samples and one of environmental origin exhibited phenotypic and chemotaxonomic properties characteristic of the genus Brevibacterium and their 16S rRNA gene sequences were closely related (98.5-99.0 %) to that of Brevibacterium otitidis. However, DNA-DNA hybridization of one strain (CF87(T)) showed only 59.6 % relatedness to the type strain of B. otitidis, DSM 10718(T), and 75-82 % relatedness to the three other strains. The four strains could be differentiated from B. otitidis by cellular fatty acid composition and some phenotypic characteristics. These findings suggest that the four strains belong to a novel species, for which the name Brevibacterium lutescens sp. nov. is proposed. The type strain of B. lutescens is CF87(T) (=DSM 15022(T)=CCUG 46604(T)).

Bacteremia due to a novel Microbacterium species in a patient with leukemia and description of Microbacterium paraoxydans sp. nov.

A yellow-pigmented coryneform rod was isolated from the blood of a child with acute lymphoblastic leukemia who was perfused with a central venous catheter. The culture bottles were positive twice, at a 2-month interval. The isolate was identified as a Microbacterium sp. and studied along with five other similar strains. Phenotypic, chemotaxonomic, and genetic characteristics indicated that they are closely related to Microbacterium oxydans but that they belong to a distinct species, for which the name Microbacterium paraoxydans sp. nov. is proposed. The type strain of M. paraoxydans is CF36(T) = DSM 15019(T). The G+C content of its DNA is 69.9 mol%.

Biochemical and susceptibility tests useful for identification of nonfermenting gram-negative rods.

Six hundred nineteen strains of nonfermenting gram-negative rods were tested for alkaline phosphatase, benzyl-arginine arylamidase, pyrrolidonyl arylamidase, ethylene glycol acidification, and susceptibility to desferrioxamine and colistin. The results were highly discriminant. Therefore, the proposed tests may be helpful for the identification of this group of organisms.