Immunological study of rabbits experimentally injected with Klebsiella pneumoniae isolated from human urinary tract infections


This study aimed to isolate Klebsiella pneumoniae bacteria from urinary tract infections in humans and studyof the immune response of rabbits after being experimentally injected with this bacteria. After that, one of theactive isolates from urine samples in human was chosen, so that were used 45 local rabbits of both sexes , in twoexperiments. In the first experiment, 20 rabbits (It was divided into five groups, each group containing four rabbits,and the first four groups were injected with 1 ml of each concentration in the intraperitoneal area, and the fifthgroup was treated as a control group and injected with 1 ml of PBS solution.) were used to estimate the infectivedose of Klebsiella pneumoniae bacteria which characterized by the appearance of signs of disease but without fatalities . The remaining rabbits (25 rabbits) were randomly divided into two groups. The first group (A) consisted of15 rabbits. They were injected with the estimated infective dose (5 ×108) CFU/ml) in the peritoneal area, while groupB, which consisted of 10 rabbits, were injected with phosphate-buffered saline (PBS) solution also in the peritonealarea and was considered as a control group. Where an immunological study was conducted to determine the effectiveness of the cellular and humoral immune response. On the 21st day after the injection, cellular immunoassayswere conducted. The results of the delayed sensitivity test (skin examination) showed a significant increase in thethickness of the right side of the abdomen of the injected rabbits from group (A).Compared with the control group(B), where it reached the highest mean of thickness after 48 hours of injection and then started to decline after 72hours. As for the examination of the phagocytosis index, it increased clearly in the affected group (A), which gave apercentage (35.20 ± 1.9) compared to the control group (B) which gave a ratio (14.60 ± 1.4.) As for the examinationof the humoral immune response, in which the proportion of immunoglobulin (G) IgG was measured by the enzymelinked immunosorbent assay (ELASA) test after experimental infection in rabbits. The results of this examinationshowed a significant increase in the rate of measuring IgG antibodies in group (A), reaching its maximum in thefourth week after the injection. Where it was (7.5 ± 0.51) and then this percentage began to decrease in the sixthweek where it was (5.68 ± 0.15), while the rate of measuring IgG antibodies in the control group (B) did not show anysignificant increase in its readings over the four weeks where it was ( 4.02 ± 0.10), (3.98 ± 0.07), (3.93 ± 0.11), (3.99± 0.07) and (3.96 ± 0.09) at the time of zero, the second, third, fourth and sixth weeks, respectively.