The survival of microorganisms of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) complex was evaluated after various soil and water decontamination regimens. Survival was reduced by growing cells in natural waters compared with laboratory media and by inclusion of malachite green in media as an antifungal agent. Decontamination with benzalkonium chloride, while reducing survival significantly less than 1% NaOH, failed to eliminate many fungi. Recovery from soil was further reduced by transfer losses and by irreversible cell adsorption onto particulates.

To obtain information on the epidemiology of mycobacteriosis, water and air samples collected along the East Coast of the United States were examined for mycobacteria. Mycobacterium avium-intracellulare-scrofulaceum (MAIS) were isolated from 25%7o of the water, samples, mostly those from South Carolina, Georgia, and the Gulf states. Mycobacterium kansasii and Mycobacterium marinum were not found, probably because of the detrimental effects of the NaOH used to decontaminate the samples. MAIS strains were found more often in estuaries than in fresh or ocean waters. The frequency of Mycobacterium intracellulare was relatively uniform along the entire coast, while Mycobacterium scrofulaceum predominated in the South. Only M. intracellulare was found in aerosol specimens, although both M. intracellulare and M. scrofulaceum were found in waters collected at the same sites.

Between October 15 and November 18, 1985, 5 patients on a medical ward of the Albany VA Medical Center (Ward 8A) became colonized with Mycobacterium fortuitum. Because other patients in Ward 8A were at risk of developing disease with M. fortuitum, microbiologic surveillance to identify colonization in sputum was begun. By February 15, 1986, 30 colonized patients had been identified in this ward but none in another ward with a comparable patient population, which suggests a source unique to Ward 8A. Because water has been recognized as a source of opportunistic mycobacterial pathogens, we conducted a retrospective case-control study using a telephone survey questionnaire to examine a number of water exposures in 10 patients and 20 control subjects. Exposure to ice from the Ward 8A ice machine, but not to potable water, was associated with colonization with M. fortuitum. Large-volume water samples from a variety of sources were cultured for acid-fast bacilli. M. fortuitum was isolated only from the ice machine in Ward 8A. The ice machine was disconnected, and no additional patients became colonized. Although ice machines are infrequently implicated in nosocomial outbreaks, they represent a potential source for pathogens that survive or replicate in water.

Because of the widespread distribution of Mycobacterium intracellulare and M. scrofulaceum in southeastern U.S. waters, the susceptibility of members of these species to heavy-metal salts and oxyanions was investigated. Isolates with abnormally high tolerance to mercuric chloride or cadmium chloride were identified.The Mycobacterium avium, M. intracellulare, and M. scrofulaceum group includes pathogens whose source for human infection appears to be environmental (18). In fact, the great abundance of these mycobacteria in water (5,6) correlates with the high proportioq of residents in counties of the southeastern states who show evidence of prior infection (3,4).Because of the widespread distribution of M. intracellulare and M. scrofulaceum (M. avium is rarely found) in southeastern U.S. waters (5, 6), including the heavy-metalpolluted Chesapeake and Delaware Bays (8, 15), we investigated the susceptibility of members of these species to heavy-metal salts and oxyanions, to identify highly resistant strains that will serve as subjects for studies .of the genetic and physiological basis for resistance. The rationale of the work was based on the observation of Nelson and Colwell (10) who inferred a "possible causal relationship between ambient mercury levels and numbers of mercury-resistant bacteria" in the Chesapeake Bay. Further, resistance in a variety of bacteria to high concentrations of mercury salts (11,12,14), as well as to other heavy metals such as cadmium (16), is due to plasmid-encoded gene functions. Though plasmid DNA in M. avium and M. intracellulare has been shown to be involved in restriction and modification (2) and in colonial variation (9), none of these characteristics are useful genetic markers, unlike metal resistance. Previous studies of the influence of heavy-metal salts on mycobacteria have used only very high concentrations of salts, and these studies have either focused on the effect of these concentrations on colonial characteristics such as pigmentation (13) waters of the eastern United States (5). The basal medium was Middlebrook and Cohn 7H10 agar medium (BBL Microbiology Systems, Cockeysville, Md.) containing 0.5% (vol/vol) glycerol (M7H10), to which was added HgCl2, NiSO4 * 6H20, Co(NO3)2 * 6H20, CdC12 * 21/2H20, AgNO3, CuSO4 5H20, K2CrO4, Na2SeO3, Na2SeO4, K2TeO3, or K2TeO4 to achieve final metal salt concentrations of 10-6 to 10-3 M. Basal medium was prepared and sterilized by autoclaving, and appropriate amounts of filter-sterilized stock solutions of the metal salts were added before pouring plates, with the pH adjusted to that of M7H10 (pH 6.6) if necessary. For susceptibility tests, the isolates were grown to the mid-log phase (ca. 2 x 108 cells per ml) in Middlebrook and Cohn liquid medium 7H9 (BBL) containing 0.5% (vol/ vol) glycerol and 10% (vol/vol) OADC enrichment (BBL) in screw-capped tubes. A loop containing 0.01 ml of each culture was streaked on the surface of the metal-containing and metal-free (control) 7H10 agar medium. The plates were incubated at 30°C in candl...

The properties of an unusual catalase isolated from Aspergillus niger are reported. The enzyme, which has a molecular weight of 323,000, consists of four subunits and is highly resistant to sodium azide.