THE end-result of direct bacterial infection of the human kidney has only recently been fully appreciated. It is therefore essential that the evolution of the chronic pyelonephritic kidney should be traced experimentally, and notable amongst the attempts to do this have been those of Mallory et al. (1940) and De Navasquez (1950). The present paper describes experiments performed along similar lines, but with certain modifications, t o confirm or otherwise the findings of these workers. Because of the relationship which exists between chronic pyelonephritis and raised blood pressure in man, we studied the blood pressure in our experimental rabbits during the evolution of the inflammatory process.
MATERIALS AND METEODSThe animals were divided up into 2 groups depending on the infecting organism used. I n group 1, 16 Chinchilla and Rex rabbits of both sexes and aged approximately 9 months were injected intravenously with a coagulaaepositive, mannitol-fermenting Staphylowccus aureua. This organism was isolated from a human boil, and a number of samples from the original culture were freeze-dried in ampoules. One of these waa opened the day before the experiment and cultivated overnight in broth. It waa then ,diluted in buffer so that 1 mi. contained 200 million organisms, and either 1.0 or 0.5 ml. was injected into the marginal vein of the rabbit's ear. I n order to reduce the consequent initial mortality, a course of intramuscular procaine penicillin was commenced 2 days after the infection waa induced, the amount ranging from 600,000 to 4 million units. Animals which survived were killed at fixed time intervals up to 4 months.In group 2, 36 rabbits of similar strain, sex and age to those in the first, group were infected with a highly virulent coliform organiam, designated 1-2, isolated from human faeces. Its biochemical properties were as follows :c;lucose +, lactose -, dulcitol +, maltose -, sucrose -, citrate -, V.P. -. indole +, M.R. +. It would grow freely on minimal amounts of medium.The stock culture was prepared by injecting 1 ml. of a broth culture of the organism into a rabbit, and at death, which occurred in 3 days, a pure culture of the organism was obtained from the kidneys and kept on Dorset egg slopes at 4 O C. On the day of the experiment the organism waa grown in broth with gent.le shaking for 4 hours at 37°C. It was then growing in the log. phtwe and was centrifuged and re-suspended in cold buffer so that the viable count ww 4-5 x 108 organisms per ml.I n this group one kidney only was infected, so that the effects of removing
