Generation times of Proteus mirabilis and Escherichia coli in experimental kidney infections have been determined using radio-isotope techniques. During the first 7 hours following infection, generation times of 2.3 and 0.9 h were determined for P. mirabilis and E. coli, respectively. Both pathogens showed greatly increased generation times in the subsequent 41-hour period. The significance of these findings is that once the kidney infection is well established, very little multiplication of the pathogen occurs. Some implications of these results in the chemotherapy of urinary tract and kidney infections are discussed.
A lipase which hydrolyzes triglycerides (tricaprylin and trilaurin) and naphthyl laurate was obtained from the broth of Corynebacterium acnes cultures by ammonium sulfate fractionation. Ca2+ and sodium taurocholate stimulated activity of the enzyme. Ethylenediaminetetraacetic acid (EDTA) did not inhibit activity of the Ca2+-activated enzyme, but lipolytic activity was inhibited by EDTA in the absence of Ca2+. Tetracycline (10-4M) produced a slight inhibition of the lipase activity with 5 X 10-5 M or less showing no effect on the lipase activity. However, complete inhibition by tetracycline at 104 M was observed for Ca2+-activated enzyme. Tetracycline inhibition of the C. acnes lipase could be demonstrated at concentrations as low as 10-6 M.
In animals developing experimentally induced unilateral pyelonephritis, both the infected kidney (IK) and the contralateral noninfected kidney (NIK) showed an immediate increase in renal lysozyme activity of about 5 days' duration after the unilateral injection of viable Proteus mirabilis into the renal cortex. Lysozyme activities of the NIK were consistently higher than those of the IK. This initial increase was followed by a second increase which lasted throughout the period of observation (17 days), and enzyme activities of the NIK were consistently higher than those of the IK. In saline punctured kidneys of control animals, both the saline punctured kidney (SP) and the non-saline punctured kidney (NSP) showed only the immediate increase in renal lysozyme activity, which persisted until the SP was completely healed. These enzyme activities were less than those observed in the infected animals, but the response of the NSP was greater than that of the SP. Trauma not directed to the kidney does not produce a similar response of renal lysozyme. The elevated renal lysozyme of the NIK could not be shown to protect it from bacterial infection.
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