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| Year : 1985 | Volume
: 31
| Issue : 3 | Page : 161-3 |
Experimental mycoplasma infection in albino rats.
Deodhar LP
How to cite this article:
Deodhar L P. Experimental mycoplasma infection in albino rats. J Postgrad Med 1985;31:161 |
The occurrence of mycoplasmas in the urethra has attracted a great deal of interest and Ureaplasma urealyticum (T-mycoplasma) has been suspected as an etiological agent of non-gonococcal urethritis. The role of genital mycoplasmas in extra-genital disease has been reviewed recently. Thomsen[5] has reported the occurrence of mycoplasmas in urinary tracts of patients with acute pyelonephritis. Earlier, Thomsen and Rosendal[6] have reported experimental pyelonephritis in rats by using M. arthritidis (a strain known to produce arthritis in rats) along with E. coli. In the present work, results of experimental studies in rats injected with strains of Mycoplasma hominis (M. hominis) and U. urealyticum are reported.
A batch of 6 Wistar albino rats (100-150 gm each) obtained from Haffkine Institute, Bombay, were used for each strain. The following strains were used. Standard strains of M. hominis PG 21 and U. urealyticum Vancouver serotype 9, and a strain of M. hominis isolated from a patient suffering from pelvic inflammatory disease. All the strains were reconstituted in PPLO broth. 0.2 ml of the culture containing 10[6] colony forming units/ml of M. hominis and 0.2 ml of the culture containing 10[6] colour changing units/ml of U. urealyticum were injected intrarenally in each rat as per procedure described by Miller et al,[3] except that the culture was injected only at one place in the kidney by tuberculin syringe and needle (no. 26) instead of a capillary tube.
The cultures were injected in the left kidney roughly in the centre from the outer margin. For control, 0.2 ml of PPLO broth was injected in the right kidney of all animals (control kidneys).
Animals were sacrificed after 5 days and both kidneys were removed under sterile conditions. From each kidney a small piece was cultured and the remaining kidney tissue was processed for histopathological examination. All the cultures were processed in the laboratory by standard techniques of isolation and identification.[2]
In all, 18 animals were used. Antibody studies were not done.
All the animals challenged with M. hominis showed histologic and bacteriologic evidence of renal infection.
Histopathological examination of kidney sections showed focal inflammatory lesions in the cortex and in the papilla. The lesions were characterised by infiltrations mainly consisting of mononuclear cells [Fig. 1] and a few neutrophils.
No organisms were grown from control kidneys and histopathological examination of these kidneys did not show any evidence of inflammation.
None of the animals challenged with U. urealyticum showed any change suggestive of nephritis grossly or microscopically, though kidney cultures grew U. urealyticum. No abnormality was detected in lower urinary tract of the animals under study.
In the present study, direct inoculation of M. hominis into the rat kidney resulted in a consistent and reproducible infection in the renal parenchyma of all animals. Thomsen et al,[7] by using M. arthritidis strain, have reported experimental production of acute pyelonephritis lesions in rat kidneys with complete obstruction of the ureter as opposed to the absence of any lesion in the non-obstructed kidney. In their study, the M. arthritidis culture was injected intra-cardially. In the present study, ureters were not ligated. In another study by Thomsen and Rosendal,[6] a synergistic effect between M. arthritidis and E. coli during the development of pyelonephritis has also been shown.
Injection of U. urealyticum in animals, in the present study, did not produce any gross or microscopic lesion. Taylor-Robinson et al(as quoted by Moller and Freundt[4]) described intraurethral inoculation of ureaplasmas into male Chimpanzees and they successfully reisolated the organisms from the urethra but found no clinical signs of urethritis, during the observation period.
Friedlander and Braude[1] demonstrated production of bladder stones by injecting human T. mycoplasmas in renal medulla of male rats. Animals were killed 6 weeks after injection; 78% of the male animals showed bladder calculi and the stone formation was observed as early as one week. Inoculation of M. hominis cultures into the bladder lumen of rats did not produce vesical calculi. In the present study, animals were killed after 5 days and hence possibly these lesions, described with T-mycoplasmas were not observed.
| 1. | Friedlander, A. H. and Braude, A. I.: Production of bladder stones by human T. mycoplasmas. Nature, 247: 67-69, 1974.  |
| 2. | Kenny, G. E.: Mycoplasma. In "Gradwohl's Clinical Laboratory Methods and Diagnosis." Editors: A. C. Sonnenworth and L. Jarret, The C. V. Mosby and Co.. Saint Louis, Toronto and London, 1980, pp. 1870-1875. |
| 3. | Miller, J. E. and Robinson, K. B.: Experimental pyelonephritis-a new method for developing pyelonephritis in the rat. J. Inf. Dis., 127: 307-310, 1973. |
| 4. | Moller, B. R.. and Freundt, E. A.: Monkey animal model for study of mycoplasmal infections of the urogenital tract. Sex. Transm. Dis., 10: 359-362, 1983. |
| 5. | Thomsen, A. C.: Occurrence of mycoplasmas in urinary tracts of patients with acute pyelonephritis. J. Clin. Microbiol., 8: 84-88, 1978. |
| 6. | Thomsen, A. C. and Rosendal, S.: Mycoplasmosis: Experimental pyelonephritis in rats. The effect of secondary infection with Escherichi coli. Acta. Pathol. & Microbiol. Scandinav., 82B: 94-98, 1974. |
| 7. | Thomsen, A. C., Rosendal, S. and Thomsen, O. F.: Mycoplasmosis: Experimental pyelonephritis in rats. Acta. Pathol. & Microbiol. Scandinav., 81A: 379-380, 1973. |
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