A new genus Gordona has been proposed for slightly acid-fast organisms which occur in sputa of patients with pulmonary disease and in soil. This genus is considered to contain ' Mycobacterium ' rhodochrous-like organisms. The genera Mycobacterium and Gordona are characterized by absence of mycelium and slight or strong acid-fastness. The genus Gordona shows characters intermediate between the genera Mycobacterium and Nocardia. It is distinguished from rapidgrowing mycobacteria by its slight acid-fastness (weaker than Mycobacterium), absence of arylsulphatase activity at 2 weeks, ability to utilize sucrose as a sole carbon source and inability to utilize trimethylene diamine as a simultaneous nitrogen and carbon source. The genus is distinguished from nocardias by the absence of mycelium, ability to form acid from mannose, positive nitrate reduction and ability to utilize sucrose as a sole carbon source. It can be isolated from sputa of patients with lung cavities or bronchiectasis and from soil by prior treatment with alkali. The organisms are Gram-positive or variable ; slightly acid-fast, that is, stained light pink or light violet by the Ziehl-Neelsen method; mycelium not formed ; spores not formed ; non-motile ; aerobic ; catalase-positive ; oxidase-negative; acid formed from glucose by oxidation; growth occurs at 2 8 O and 37O but not at 45"; growth at 2 to 3 days forming rough, reddish or pinkish colonies in air; occur as short rods; non-pathogenic for mice, rabbits, guinea pigs and chickens. Type species is Gordona bronchialis. I N T R O D U C T I O NDuring the course of studies on 'atypical' mycobacteria from clinical specimens, a number of organisms forming rough pinkish or reddish colonies on egg media as isolated from sputa of patients with pulmonary disease. Similar organisms were isolated from soils. These organisms showed intermediate characters between the genus Mycobacterium and the genus Nocardia but were distinguished from these genera by several common characters.The organisms most resembled 'Mycobacterium ' rhodochrous, an organism whose taxonomyis not yet clarified (Gordon & Mihm, 1957Gordon, 1966). A new genus Gordona is proposed for these organisms. M E T H O D SIsolation. Sputum specimens from patients with pulmonary disease (cavitary pulmonary tuberculosis and/or bronchiectasis) were added to an equal volume of 4 % (wlv) NaOH solution and liquefied by incubation at 37O for 30 min. or by shaking vigorously at room temperature for 15 to 30 min. The sputum specimen was then inoculated on Ogawa egg 2-2

Mycobacterium smegmatis is a rapidly growing environmental species not considered a human pathogen. We identified 22 human isolates of M. smegmatis from Australia and the southern United States: 19 were from skin or soft-tissue infections, and none were from urine or the male genital tract. These isolates closely resembled Mycobacterium fortuitum, except for a negative three-day arylsulfatase test; growth at 43-45 C; a low semiquantitative catalase test; and, in 50% of isolates, a late-developing, yellow-to-orange pigment. The isolates were biochemically identical to four reference strains and the type strain of M. smegmatis. Isolates were resistant to isoniazid and rifampin but susceptible to ethambutol, doxycycline, sulfamethoxazole, ciprofloxacin, imipenem, and amikacin. Eleven patients treated on the basis of in vitro susceptibility tests responded well to therapy. The similarity of M. smegmatis to M. fortuitum and the failure to recognize that the former is an environmental species may have contributed to previous failures to recognize it as a human pathogen.

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SUMMARYAn Rdaiisonian classification of mycobacteria has been done by using 94 characters. Fifty-nine strains of slowly growing mycobacteria. were classified into five groups: (1) Mycobacterium tuberculosis and M . bovis (2) M . kansasii; (3) M . avium, 16 strains of non-photochromogens from human sources, 6 strains of non-photochromogenic mycobacteria from soil sources, and scotochromogens from human sources ( M . aquae) ; (4) 2 strains of non-photochromogens from human sources; ( 5 ) 1 strain of non-photochromogen from human source.The third group seemed to consist of three subgroups: (3, i) nonchromogens from soil sources; (3, ii) Mycobacterium avium and some non-photochromogens, which were inseparable from M , avium; (3, iii) some non-photochromogens from human sources resembling M . avium (but separable from it) and scotochromogens from human sources.Slowly growing non-photochromogenic mycobacteria from soil sources (subgroup 3, i) were considered to form a new species, M . terrae. A description of this species is given.Seventy-eight strains of rapidly growing mycobacteria were classified into seven groups : (6) 6 strains of miscellaneous species, Mycobacterium marinum, M . balnei, M . platypoecilus, M . ranae and M . piscium; (7) M . thermoresistibile (sp.nov.); (8) M . phlei; (9) M . aurum (sp.nov.); (10) M . fortuitum and group IV rapid growers; (11) 1M. parafortuitum; (12) M .smegmatis. These groups seemed to form independent species. Mycobacterium thermoresistibile is a new species capable of growing at 52'. Mycobacterium aurum is a new species consisting of rapidly growing scotochromogenic mycobacteria with urease, nicotinamidase and pyrazinamidase and some strains also with acetarnidase and allantoinase.

Previous studies of Mycobacterium fortuitum identified isolates that did not fit its two recognized biovariants. Eighty-five clinical isolates of this group, the "third biovariant complex", were evaluated. They represented 16% of 410 isolates of M. fortuitum submitted to a Texas laboratory and 22% of 45 isolates in Queensland, Australia. Most infections (76%) involved skin, soft tissue, or bone and occurred after metal puncture wounds or open fractures. Isolates differed from biovar fortuitum in resistance to pipemidic acid and use of mannitol and inositol as carbon sources. Two subgroups were present, and examples were deposited in the American Type Culture Collection. Isolates were resistant to doxycycline and one-third were resistant to cefoxitin. All were susceptible to amikacin, ciprofloxacin, sulfamethoxazole, and imipenem. Surgical debridement combined with drug therapy based on in vitro susceptibilities resulted in cures of cutaneous disease or osteomyelitis. DNA homology studies are needed to determine the taxonomic status of these organisms.