Heterogeneity WithinCorynebacterium minutissimumStrains Is Explained by MisidentifiedCorynebacterium amycolatumStrains

Abstract

Korty-eight clinical strains that were tentatively identified as Corynebacterium minutissimum on the basis of standard biochemical reactions (Hollis-Weaver tables) as well as by the use of the API (RAPID) Coryne system were examined further. Two different groups of strains were observed. The first group (including the type strain of C minutissimum) contained 27 strains showing creamy colonies. These strains grew homogeneously in 6.5% NaCl broth, exhibited DNase activity, were susceptible to the vibriocidal compound O/l 29, produced succinic acid, and contained mycolic acids. The second group comprised 21 strains with dry colonies. They grew in clumps at the surface of 6.5% NaCl broth, DNase activity was not detected, they were resistant It is generally believed that the identification of coryneform bacteria (ie, asporogenous, irregular gram-positive rods) is one of the most difficult tasks for the clinical microbiologist. The reason for this is two-fold: (1) the group of coryneform bacteria is extremely heterogeneous; 1 and (2) there are very few identification systems for coryneform bacteria, and their databases cover only a certain proportion of this large group of bacteria. " 4Corynebacterium minutissimum is considered to be one of the more frequently encountered true Corynebacterium species in clinical specimens. Originally, it was thought that C minutissimum caused erythrasma, but later studies questioned this disease association and revealed that erythrasma is probably a polymicrobial process. ' Since 1990, the Department of Medical Microbiology at the University of Zurich (DMMZ) has isolated or received many clinically significant strains tentatively identified as C minutissimum. As a cursory review of these strains indicated that they were rather heterogeneous we decided to characterize them further. Heterogeneity within C minutisssimum strains was also reported by Hollis and Weaver who divided C minutissimum isolates into two groups corresponding to strains NCTC 10288 (ATCC 23348) (sucrose fermenting) and ATCC 23346 (sucrose nonfermenting).5 By applying phenotypical, chemotaxonomical and molecular methods, we could demonstrate that a large proportion of strains identified as C minutissimum actually correspond to C amycolatum. MATERIALS AND METHODS StrainsThe clinical strains used in this study were cultured from clinical materials using standard procedures or were referred to the DMMZ for identification between 1990 and 1995. Some strains were also received from 378 Downloaded from https://academic.oup.

Corynebacterium singulare sp. nov., a New Species for Urease-Positive Strains Related to Corynebacterium minutissimum

“…Our two previously undescribed strains possess mycolic acids, unlike C. amycolaturn, and using the findings of Wauters et al (22), we found that they differ from C. amycolatum by not producing propionic acid. In addition, we found the following differences in the biochemical and morphological properties of the previously undescribed strains and C. amycolatum: the two previously undescribed strains are positive for leucine aminopeptidase activity and degradation of tyrosine and produce colonies with a glistening and creamy appearance, whereas C. amycolatum is negative for leucine aminopeptidase activity and degradation of tyrosine and produces dry colonies (13,22,23). Finally, the results of this study indicate that the two previously undescribed strains should belong to a new species distinct from C. minutissimum and other Corynebacterium species, particularly because of their urease activity, which is one of the key reactions in the identification of corynebacteria.…”

“…As determined with the API biotype 100 gallery, the two previously unrecognized strains utilized D-turanose and 3-hydroxybutyrate but not N-acetyl-D-glucosamine, whereas none of 19 C. minutissimum strains exhibited this pattern. In two recent studies of the taxonomy of the genus Corynebacterium, workers reinvestigated the status and identification of C. minutissimum in more detail by using biochemical characteristics and DNA-DNA hybridization since it was demonstrated that there could be confusion with strains of Corynebacterium amycolatum (22,23). As a result, accurate identification of C. minutissimum should be based on a lack of urease, nitrate reductase, a-glucosidase, and P-glucuronidase and the presence of leucine aminopeptidase and tyrosine clearing.…”

“…In addition, 18 C. minutissimum wild strains were obtained from the Institute of Bacteriology of Strasbourg or from the personal collection of F. Renaud, University Institute of Technology, Villeurbanne, France. These strains were identified as C. minutissirnurn strains by using recently published schemes (13,22,23). Bacteria were grown aerobically at 37°C on Trypticase soy agar (bioMCrieux, Marcy-l'Etoile, France) and on Trypticase soy agar supplemented with 5% (vol/vol) sheep blood.…”

Characteristics of Rare or Recently Described Corynebacterium Species Recovered from Human Clinical Material in Canada

“…Products of glucose fermentation for the taxa shown in Table 2 were analyzed here as described previously (1) or as described in other publications. Vibriostatic disk O129 was applied to most of these taxa for at least one strain, and a zone of 11 to 36 mm was considered to show sensitivity while one of 0 to 10 mm was considered to show resistance (34).…”

Endocarditis due to Corynebacterium amycolatum

“…C. amycolatum has recently been included in the updated API Coryne database 2.0 (Wauters et al, 1998). The presence of only two reports of C. amycolatum causing endocarditis in the literature may be due to its misidentification, as other non-lipophilic fermentative Corynebacterium species, including Corynebacterium xerosis and Corynebacterium minutissimum, are associated with human disease (Funke et al, 1996a;Zinkernagel et al, 1996). Letek et al (2006) described a molecular method for rapid identification of C. amycolatum from the closely related Corynebacterium striatum, C. minutissimum and C. xerosis, without the requirement for further molecular analysis, based on the use of different primers for amplification of the cell-division divIVA gene using conventional or real-time PCR (Letek et al, 2006).…”