The Mycobacterium fortuitum third biovariant complex (sorbitol-negative and sorbitol-positive) contains unnamed taxa first characterized in 1991. These organisms can cause respiratory infections, a spectrum of soft tissue and skeletal infections, bacteraemia and disseminated disease. To evaluate this group of organisms, clinical reference isolates and the type strains of M. fortuitum third biovariant complex sorbitol-negative (n=21), M. fortuitum third biovariant complex sorbitol-positive (n=3), M. fortuitum (n=3), Mycobacterium peregrinum (pipemidic acid-susceptible) (n=1), Mycobacterium porcinum (n=1), Mycobacterium senegalense (n=2) and Mycobacterium septicum (n=1) were characterized by using conventional phenotypic (morphological, physiological and antimicrobial susceptibilities), chemotaxonomic (HPLC and cellular fatty acids) and genotypic [RFLP of the rRNA gene (ribotyping), PCR-RFLP of a 439 bp segment of the 65 kDa hsp gene (PCR restriction analysis) and 16S rRNA gene sequence] analysis, DNA G+C content and DNA–DNA relatedness analyses. The results of these studies indicated that the strains comprised M. porcinum (n=13), M. septicum (n=1) and four novel closely related genetic groups within the M. fortuitum third biovariant complex: Mycobacterium boenickei sp. nov. (n=6), Mycobacterium houstonense sp. nov. (n=2), Mycobacterium neworleansense sp. nov. (n=1) and Mycobacterium brisbanense sp. nov. (n=1), with type strains ATCC 49935T (=W5998T=DSM 44677T), ATCC 49403T (=W5198T=DSM 44676T) ATCC 49404T (=W6705T=DSM 44679T) and ATCC 49938T (=W6743T=DSM 44680T), respectively.

Four strains of novel, rapidly growing, acid–alcohol-fast-staining bacteria were characterized with a polyphasic approach. Isolates were received by the Centers for Disease Control and Prevention from domestic health department laboratories for reference testing as unidentifiable, clinical mycobacteria. Bacteria were rod-shaped and produced non-pigmented (white to beige), non-photochromogenic, smooth or wrinkled-rough colonies on Middlebrook 7H10 and 7H11 media at 33 °C. The smooth and wrinkled colony forms were representative of two species with 68·0 and 72·0 mol% DNA G+C content. The cell wall contained meso-diaminopimelic acid and mycolic acids. Species were characterized by cellular fatty acids of C10 : 0, C14 : 0, C16 : 1ω9t, C16 : 0, C18 : 1ω9c and 10-methyl C18 : 0 (tuberculostearic acid). HPLC analysis of mycolic acids produced a novel late-emerging, genus-specific mycolate pattern. TLC analysis demonstrated a novel α +-mycolate. Species were 98·9 % similar by comparison of 16S rRNA gene sequences; however, the DNA–DNA association was <28 %. Phylogenetic analysis of 16S rRNA gene sequences demonstrated an association with Rhodococcus equi, although a DNA–DNA relatedness value of 2 % did not support a close relationship. PCR analysis of a proposed, selected actinomycete-specific 439 bp fragment of the 65 kDa heat-shock protein was negative for three of the four isolates. The creation of Segniliparaceae fam. nov. is proposed to encompass the genus Segniliparus gen. nov., including two novel species, the type species Segniliparus rotundus sp. nov. and Segniliparus rugosus sp. nov., with the respective type strains CDC 1076T (=ATCC BAA-972T=CIP 108378T) and CDC 945T (=ATCC BAA-974T=CIP 108380T).

NoteMycobacterium shottsii sp. nov., a slowly growing species isolated from Chesapeake Bay striped bass (Morone saxatilis)

Mycobacterium abscessus and Mycobacterium chelonae are two closely related species that are often not distinguished by clinical laboratories despite the fact they cause diseases requiring different treatment regimens. Multilocus enzyme electrophoresis, PCR-restriction fragment length polymorphism analysis of the 65-kDa heat shock protein gene, biochemical tests, and high-performance liquid chromatography of mycolic acids were used to identify 75 isolates as either M. abscessus or M. chelonae that were originally submitted for drug susceptibility testing. Only 36 of these isolates were submitted with an identification at the species level. Using the above methods, 46 of the isolates were found to be M. abscessus and 29 were identified as M. chelonae. Eight isolates originally submitted as M. chelonae were identified as M. abscessus, and one isolate submitted as M. abscessus was found to be M. chelonae. The four identification methods were in agreement in identifying 74 of the 75 isolates. In drug susceptibility testing, all isolates of M. abscessus exhibited resistance to tobramycin (MIC of 8 to >16 g/ml), while all isolates of M. chelonae were susceptible to this drug (MIC of <4 g/ml). The results suggest that once an identification method is selected, clinical laboratories should be able to easily identify isolates of M. abscessus and M. chelonae.Mycobacterium abscessus and Mycobacterium chelonae are two species of rapidly growing mycobacteria frequently associated with nosocomial outbreaks and pseudo-outbreaks (1,11,24). Widespread outbreaks of postinjection abscesses have occurred due to medications contaminated with M. abscessus (6,22). Contamination of hospital equipment and medications can generally be traced to the ubiquitous presence of these organisms in tap water and their resistance to commonly used disinfectants (24).It is clinically important to correctly identify these organisms since they cause infections requiring different treatment regimens (R. J. Wallace, Jr., B. A. Brown, D. E. Griffith, Letter, Pediatr. Infect. Dis. J. 16:829, 1997). Prior to 1992, M. abscessus was considered a subspecies of M. chelonae. Though Kusunoki and Ezaki (10) firmly established through DNA hybridization that these organisms are separate species, they are nearly indistinguishable phenotypically. Only two biochemical tests, those for sodium chloride tolerance and utilization of citrate, are useful for identifying these organisms at the species level (17), but these tests may take up to 4 weeks to complete (5). Identification of rapidly growing species using high-performance liquid chromatography (HPLC) of mycolic acids has been limited with M. abscessus and M. chelonae because they produce very similar mycolic acid patterns (2). Recently, PCRbased methods targeting polymorphic regions of the 65-kDa heat shock protein (HSP) gene have been used successfully to identify isolates of M. abscessus and M. chelonae (8, 15; A. R. Lakshmy, N. Siddiqi, M. Shamim, M. Deb, G. Mehta, and S. E. Hasnain, Letter, Emerg. Infect. Dis. 6...