Characteristics of Massilia timonae and Massilia timonae-like isolates from human patients, with an emended description of the species.

The description of Massilia timonae, a nonfermentative aerobic gram-negative rod, was based on a single strain. A subsequent report of a second isolate has been recently published. Phenotypic descriptions of these two strains were based primarily on commercial test kit results. We have identified three additional strains as M. timonae by 16S rRNA sequence analysis and have characterized them phenotypically in parallel with the type strain of M. timonae, CIP 105350, by conventional test methods. A fourth strain, designated M. timonae-like, was also characterized. All four strains were isolated from human patients: two were blood isolates, one was isolated from cerebrospinal fluid, and one was isolated from bone. The four strains and the type strain were quite similar phenotypically. However, in contrast to the original description, the strains were found to be oxidase positive and arginine dihydrolase negative and to have lateral flagella as well as a single polar flagellum. Additionally the strains produced acid oxidatively from some carbohydrates. Other phenotypic characteristics, including cellular fatty acids, agreed with the original description. Based on our emended description, M. timonae and M. timonae-like strains can be differentiated from other aerobic nonfermentative gram-negative rods by conventional biochemical tests combined with cellular fatty acid analysis.