A Time Limit for Using Bacteriophages

Sin,?Various laboratories in Calcutta are nowadays manufacturing bacteriophages for use in bowel diseases especially. Some foreign made are also available. The time limit for their use is very puzzling. Majority put two years as their time limit for use whereas two do not put any date at all, with the idea that their products can be used with benefit, after any length of time. Considering the mean average temperature of India, and also the manner in which they are stocked (they are not stocked in refrigerators), I think in some cases the bacteriophages are liable to deteriorate and lose their potency, before the time limit of two years. An independent test done by me entirely corroborates the report, published by Major Pasricha and others on this subject, that some preparations lose their potency before the time limit (/. M. G., November 1937). I think, to the interest of the medical profession, the dates should be put in such a way as to maintain the maximum potency up to that time, and, moreover, it is wholly unscientific to declare that bacteriophages remain active and potent for years together, whatever may be the condition in which they are kept. Colonel Morrison was of opinion that 12 months should be the maximum length of time up to which the phages remain potent, if kept in cold storage. I shall be highly obliged if research workers on this line can throw light as to what should be the maximum time limit for use of bacteriophages in India; also whether it is scientific at all to believe that bacteriophages may be used after any length of time.