Mycobacterium novocastrense sp. nov., a Rapidly Growing Photochromogenic Mycobacterium

Abstract

A strain isolated from a biopsy sample taken from a slowly spreading skin granulation on a child's hand was found to have properties consistent with its classification in the genus Mycobacterium. An almost complete gene sequence of the 16s rRNA of the strain was determined following the cloning and sequencing of the amplified gene. The sequence was aligned with those available for mycobacteria, and phylogenetic trees were inferred with four tree-making algorithms. The organism, which formed a distinct phyletic line within the evolutionary radiation occupied by rapidly growing mycobacteria, was readily distinguished from members of validly described species of rapidly growing mycobacteria on the basis of its mycolic acid pattern and a number of other phenotypic features, notably its ability to form yellow pigmented colonies when incubated in the light. The name proposed for this new species is Mycobacterium novocastrense. The type strain is DSM 44203.A relatively rapidly growing, weakly acid-alcohol-fast organism was isolated from biopsy tissue of a patient who had received six weeks of antituberculosis therapy. The strain had phenotypic properties consistent with its classification in the genus Mycobacterium, and these set it apart from other rapidly growing mycobacteria. In the present investigation, the organism was the subject of a polyphasic taxonomic study designed to clarify its taxonomic position. The results indicate that the organism represents a new species, for which the name Mycobacterium novocastrense is proposed. MATERIALS AND METHODSOrganism and culture conditions. The organism (strain 73), which was isolated on Lowenstein-Jensen medium (9) after 9 weeks of growth at 36T, was obtained from a biopsy sample taken from a slowly spreading skin granulation on the hand of a six-year-old child. It was then cultivated on Columbia blood agar (4), Lowenstein-Jensen medium (9), MacConkey agar (IS), Middlebrook 7H10 agar (17), and 5% (wt/vol) sodium chloride agar (13) for between 3 and 10 days at 25°C and 36°C. The strain, which was maintained on Middlebrook 7H10 agar (17), was grown at 36°C in all of the remaining tests.Phenotypic characterization. The growth, temperature, and sensitivity studies were carried out on Middlebrook 7H10 agar (17). The Gram (16) and ZiehlNeelsen (20) stains were performed on cells grown for 5 days at 36°C on this medium. Catalase (14) and niacin (12) activity were examined after 10 days, and the production of arylsulfatase (29) was examined after 3 and 14 days. Similarly, iron uptake (27) and Tween hydrolysis (28) were detected after 10 days at 36°C.Extraction and analysis of mycolic acids. Lyophilized biomass from 10-day-old Middlebrook 7H10 agar plates was degraded by alkaline methanolysis (23) and two-dimensional thin-layer chromatography of the methanolysates carried out as described previously (19).Sequencing of genes coding for 16s rRNA (16s rDNA). The biomass of the test strain needed for sequencing was obtained from a 5-day-old Liiwenstein-Jensen (9) slant incubated at 36...

Assessment of Partial Sequencing of the 65-Kilodalton Heat Shock Protein Gene ( hsp65 ) for Routine Identification of Mycobacterium Species Isolated from Clinical Sources

“…Many of the discrepancies were attributed to isolates submitted as M. chelonae (33), M. fortuitum (17), M. gordonae (42), M. avium-M. intracellulare complex (10), M. scrofulaceum (8), and M. terrae (9). Reexamination of data and further testing of isolates indicated that 23 isolates previously identified as M. chelonae were probably M. abscessus, and another 4 were M. mucogenicum.…”

“…The inability of hsp65 sequencing to confirm the identification of some isolates was VOL. 42, 2004 IDENTIFICATION OF MYCOBACTERIA BY hsp65 SEQUENCING 3007 compounded since the majority of the isolates were identified by using biochemical techniques or commercial probes, both of which incorrectly identify some clinical isolates (8,12,30,39,41,42,43,44,45,46,47,59,71). We estimated that 85 isolates had been misidentified by using the latter techniques (Table 3).…”

Impact of Genotypic Studies on Mycobacterial Taxonomy: the New Mycobacteria of the 1990s

“…The only strain of M. novocastrense isolated to date was reported in 1997 and was obtained from a slowly spreading skin granuloma on a child's hand (124).…”

Mycobacterium barrassiae sp. nov., a Mycobacterium moriokaense Group Species Associated with Chronic Pneumonia

“…Among the rapidly growing mycobacteria (RGM), the species most commonly recovered from patients belong to the Mycobacterium chelonae-Mycobacterium abscessus, Mycobacterium mucogenicum, Mycobacterium fortuitum, Mycobacterium mageritense, Mycobacterium wolinskyi, and Mycobacterium smegmatis groups (1,2,3,4,5,6,7,10,11,31,43,44). Rarely encountered species include Mycobacterium novocastrense, which is responsible for cutaneous infections (33); Mycobacterium hodleri, which causes opportunistic infections in the course of rheumatoid arthritis (40); Mycobacterium neoaurum, which was isolated from a patient with catheter-related bacteremia (46); Mycobacterium flavescens, which caused a disseminated infection in a probable case of chronic granulomatous disease (8); and Mycobacterium thermoresistible, which was responsible for an infection following kneereplacement surgery (20). Other species were isolated from human samples, such as Mycobacterium hassiacum from urine (32); Mycobacterium elephantis from the sputum and granulomatous tissue of an axillary lymph node (26,37,39); Mycobacterium doricum from cerebrospinal fluid (38); Mycobacterium brumae from sputum and a case of catheter-related bacteremia (21,22); Mycobacterium brisbanense from the antral sinus (31); Mycobacterium confluentis from sputum (17); Mycobacterium holsaticum from sputum, urine, and gastric fluid (28); Mycobacterium cosmeticum from a footbath drain and a granulomatous subdermal lesion in a female patient who was undergoing mesotherapy (12); and Mycobacterium canariasense from the blood of a patient with febrile syndrome (15).…”