01635nas a2200241   4500000000100000008004100001260001700042653003100059653001600090653002500106653001800131653001400149653002600163653001700189100001700206700001400223700001300237245006300250300001100313490000700324520104800331022001401379       1975                            d  c1975 Oct-Dec10aBacteriological Techniques10aFatty Acids10aMycobacterium leprae10aPhospholipids10aPyridines10aStaining and Labeling10aTime Factors1 aSkinsnes O K1 aChang P H1 aMatsuo E00aAcid-fast properties and pyridine extraction of M. leprae.  a339-470 v433 a<p>The reportedly unique pyridine extractability of acid-fastness as an identifying characteristic for M. leprae was examined in the leprosy bacilli and in eight other strains of mycobacteria. The initial findings were, in general, in accord with previous reports except that M. smegmatis and M. phlei likewise demonstrated two hour pyridine extractability of acid-fastness. Perhaps, more significantly, it was found that this characteristic in M. leprae is related to aged, probably nonviable bacilli. Some other strains of mycobacteria when tested in aged cultures showed the same phenomenon while M. leprae cultivated in vitro in a recently developed medium resisted pyridine extraction up to three weeks of growth, but thereafter as the culture aged pyridine extractability became characteristic. It is concluded that this pyridine extractability of acid-fastness is a characteristic of aging or nonviable bacilli. As such it is not definitive in the determination of whether or not in vitro cultivation of M. leprae has been achieved.</p>  a0148-916X