Effect of p-aminosalycyclic acid (PAS) on the loss of acid-fastness produced in tubercle bacilli by isoniazid.
Varma, K.G.
Indian Journal of Medical Research; 1961; 49; 194-195.
The microbiological assay method for estimating free isoniazid in serum described by Mandel et al ., (1956) used as the assay end-point the dilution producing loss of acid-fastness in 50 per cent of bacilli. The advantage of this end-point is that loss of acid-fastness is produced specifically by isoniazid, and not by either PAS (Mandel et al ., loc.cit.) or streptomycin Middlebrook, 1952). Mandel et al . (loc. cit.) claimed that the addition of as much as 1,000 µg./c.c of PAS to undiluted human sera did not interfere with the assay of isoniazid in the serum using loss of acid-fastness as the end-point. Since Mandel et al . (loc. cit.) did not, however, describe their results fully, it remained a possibility that PAS in concentrations near that necessary to inhibit the growth of tubercle bacilli could act synergestically or antagonistically with isoniazid in producing loss of acid-fastness. This was investigated in the following experiments.
Back to List of publications / Home |