title: Comparison of some decontamination methods and growth media for isolation of mycobacteria from northern brook waters.
abstract: Two decontamination methods and five media were compared for the isolation of mycobacteria from brook waters of different physical, chemical and bacteriological characteristics. The decontaminants used were: 0.7 mol l-1 NaOH followed by 50 g l-1 oxalic acid and 0.9 mol l-1 H2SO4 combined with 0.5 g l-1 cycloheximide. The media compared were: Mycobacteria 7H11 agar with OADC enrichment (pH 6.6), glycerol egg (pH 6.5 and 5.5), and pyruvate egg (pH 6.5 and 5.5). All media contained cycloheximide, 0.5 g l-1. The NaOH-oxalic acid method generally resulted in lower contamination and higher isolation of mycobacteria than the H2SO4-cycloheximide method. With the NaOH-oxalic acid method, all five media were equal in positivity rates but contamination was a problem on Mycobacteria 7H11 agar. Of the four egg media tested, the highest positivity rate (92% of the samples) was obtained on the pyruvate modification (pH 6.5), and the highest mean colony count of mycobacteria (900 cfu l-1) on the glycerol modification (pH 6.5). Characteristics of water and sampling site had similar effects on the isolation frequencies of mycobacteria obtained by different combinations.
authors.affiliation: Laboratory of Environmental Microbiology, National Public Health Institute, Kuopio, Finland.
authors.forename: E
authors.initials: E
authors.lastname: Iivanainen
authors.forename: P J
authors.initials: PJ
authors.lastname: Martikainen
authors.forename: M L
authors.initials: ML
authors.lastname: Katila
mesh_terms: D003470:Culture Media / Q000494:pharmacology; D004202:Disinfectants / Q000494:pharmacology; D006862:Hydrogen Sulfide / Q000494:pharmacology; D008828:Microbiological Techniques; D009161:Mycobacterium / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification*; D012972:Sodium Hydroxide / Q000494:pharmacology; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D003470:Culture Media; D004202:Disinfectants; D012972:Sodium Hydroxide; D006862:Hydrogen Sulfide