Comprehensive Study of Corynebacterium freneyi Strains and Extended and Emended Description of Corynebacterium freneyi Renaud, Aubel, Riegel, Meugnier, and Bollet 2001

Abstract

In 2001, Corynebacterium freneyi was described as a new fermentative, ␣-glucosidase-positive Corynebacterium species related to C. xerosis based on data from three strains. During a review of our extensive culture collection we encountered 18 additional C. freneyi strains and further characterized them in detail. Thirteen of the 18 strains were isolated from female genital tract specimens without any obvious disease association. Phenotypically, C. freneyi can be easily differentiated from C. xerosis by its distinct wrinkled colonies whereas nearly all other routinely applied phenotypic tests do not allow a unanimous separation of C. freneyi from C. xerosis. Restriction length polymorphism analysis using CfoI of the 16S-23S rRNA gene intragenic spacer definitively allows differentiation between the two species. Surprisingly, comparative 16S rRNA gene analysis does not discriminate between C. freneyi and C. xerosis because the designated type strain of C. freneyi is not the most representative strain for this species. The present report also includes detailed data on the antimicrobial susceptibility pattern of C. freneyi presented here for the first time. Based on the large number of additional C. freneyi strains from our culture collection, we provide an extended and emended species description of C. freneyi.

Characterization of Some Bacterial Strains Isolated from Animal Clinical Materials and Identified as Corynebacterium xerosis by Molecular Biological Techniques

“…These last characteristics had not been reported for this species before. The macroscopic characteristics of the colonies obtained with C. freneyi, C. amycolatum, and C. hansenii strains were in agreement with those previously described for these species (7,20,26). Therefore, the colonies formed by C. xerosis were very similar to those formed by C. freneyi, C. amycolatum, and C. hansenii and the macroscopic characteristics of colonies do not seem to be very useful for the presumptive differentiation of clinical strains of C. xerosis.…”

“…xerosis is rarely isolated from clinical samples, and most of the previously identified isolates were subsequently recognized as C. amycolatum (9). Thus, most of the studies that have analyzed the phenotypic or genetic characteristics of C. xerosis have included a very limited number of strains (7,20). In the present work, most (n ϭ 17; Table 1) of the animal clinical strains suspected to be C. xerosis belonged to this species.…”

“…Moreover, we describe the first Table 1). Previously, C. freneyi had only been isolated from human clinical samples (3,7,19). Macroscopically, C. xerosis gave dry, rough, and yellowish pigmented colonies that are considered typical for this microorganism (7); however, colonies of C. xerosis also had a wrinkled surface (100% of the strains; Table 1) and were whitish-grayish (50% of the strains; Table 1).…”

“…C. xerosis is phylogenetically closely related to Corynebacterium freneyi, Corynebacterium amycolatum, and Corynebacterium hansenii (19,20,26), but DNA-DNA hybridization experiments have demonstrated that they represent different species (19,20). The unambiguous discrimination of these species based on phenotypic characteristics and comparative 16S rRNA gene analysis is problematic (7,9,20). Molecular-genetic methods, such as sequencing of the RNA polymerase beta subunit-encoding gene (rpoB), have been proposed as alternative or complementary molecular methods to 16S rRNA gene analysis for discerning phylogenetically closely related Corynebacterium species (13,14).…”

“…Molecular-genetic methods, such as sequencing of the RNA polymerase beta subunit-encoding gene (rpoB), have been proposed as alternative or complementary molecular methods to 16S rRNA gene analysis for discerning phylogenetically closely related Corynebacterium species (13,14). Also, restriction fragment length polymorphism (RFLP) analysis of the 16S-23S rRNA gene intergenic spacer region (IGS) has been proposed for the accurate differentiation of some of these species (7,19,20). However, these studies included a very limited number of C. xerosis strains because most of the strains previously classified as C. xerosis had been misidentified (9).…”