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Retrospective molecular genetic analysis of 166 Mycobacterium intracellulare isolates showed that 143 (86%) strains could be assigned to Mycobacterium chimaera sp. nov. Of 97 patients from whom M. chimaera sp. nov. was isolated, only 3.3% exhibited mycobacterial lung disease, whereas all M. intracellulare isolates caused severe pulmonary infections. B acteria of the Mycobacterium avium complex (MAC)play an important role among infections caused by nontuberculous mycobacteria (NTM). MAC consists of the 2 well-established species, M. avium (which has 4 subspecies) and M. intracellulare, as well as several other closely related mycobacteria (1). Recently, a new species derived from the group of unnamed members of the MAC has been defi ned. It combines features characteristic of different MAC members and has been named M. chimaera sp. nov. (2).Based on the sequence of the 16-23S internal transcribed spacer (ITS) region, this species genetically corresponds to sequevar MAC-A and differs from M. intracellulare type strain, sequevar MIN-A (DSMZ 43223) by 20 nt mismatches (2,3). In contrast, the 16S rRNA gene sequence is identical, except for 1 nt mismatch, with that of the M. intracellulare type strain. Because sequencing of the 16S rDNA still is considered the approved standard for the identifi cation of NTMs, M. chimaera sp. nov. usually has been misreported as M. intracellulare. Molecular genetic standard tools in clinical microbiologic laboratories do not differentiate MAC members. These tools merely provide a rough classifi cation in M. intracellulare and M. avium and/or the MAC group as a whole. Currently, a detailed genotyping of MAC is restricted to research laboratories. Nevertheless, several studies have shown that certain serotypes or genotypes were associated with different clinical manifestations of MAC infection concerning the patient groups affected, the localization and course of disease, and the antimicrobial drug resistance patterns (4,5). The StudySince available data on the epidemiology of M. chimaera sp. nov. are sparse, we performed a retrospective study to determine the frequency of its occurrence within the group of MAC-positive clinical specimens and its possible role in causing human disease in comparison to M. intracellulare. We reanalyzed mycobacterial isolates from 97 in-house patients of the Charité University Hospital that have been processed in our laboratory from 2002 through 2006. An additional 69 isolates were provided by the National Reference Center (NRC) for Mycobacteria in Borstel, Germany. All strains had previously been classifi ed as M. intracellulare by 16S rDNA-based methods. In addition to the partial 16S rRNA gene, we sequenced the 16S-23S ITS region to allow for unambiguous identifi cation. Amplifi cation of the partial 16S rRNA gene was performed according to a standard procedure (6). For the amplifi cation of the ITS, the following primers were used: Sp1 (5′-ACC TCC TTT CTA AGG AGC ACC-3′) and Mb23S.44n (5′-TCT CGA TGC CAA GGC ATC CAC C-3′) (7,8). PCR conditions and the ...

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A novel denaturing high-performance liquid chromatography (DHPLC)-based technique allows rapid highresolution analysis of PCR products. We used this technique for unequivocal molecular identification of seven Candida species. We show the application of this PCR/DHPLC approach for direct detection and identification of yeast species from blood cultures and for detection of Candida colonization in the gastrointestinal tract of allogeneic transplant patients.