Chlamydial Disease of the Male Koala (Phascolarctos cinereus) Reproductive Tract

Hamdy Deif (2011). Chlamydial Disease of the Male Koala (Phascolarctos cinereus) Reproductive Tract MPhil Thesis, School of Agriculture and Food Sciences, The University of Queensland.

       
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Author Hamdy Deif
Thesis Title Chlamydial Disease of the Male Koala (Phascolarctos cinereus) Reproductive Tract
School, Centre or Institute School of Agriculture and Food Sciences
Institution The University of Queensland
Publication date 2011-08
Thesis type MPhil Thesis
Supervisor Dr Stephen Johnston
Total pages 115
Total colour pages 6
Total black and white pages 109
Language eng
Subjects 07 Agricultural and Veterinary Sciences
Abstract/Summary Abstract While chlamydial genital disease in female koalas has been extensively studied, there are only a few reports of male associated urethritis and or prostatitis. The scarcity of information of chlamydial genital disease in males compared to females appears to be a consistent feature across mammals generally. This thesis systematically reviewed the literature on chlamydial genital disease in non-human mammals, noting the pathology of the organism in the genital tract and semen of mammals. To date, there has been no report on whether chlamydia can infect the testis and or epididymis of the koala. The first experimental chapter of this thesis investigated the presence of chlamydia in the reproductive tract (testis, epididymis and prostate) of 18 koalas presented to koala hospitals with clinical signs of disease. The Clearview Chlamydia MF (CV) test was validated for fresh and frozen tissue and then used as a rapid screening test for the presence of chlamydia antigen. Immunohistochemistry (IHC), using a chlamydia specific antibody was used to locate chlamydial inclusions within positive testicular and epididymal tissues. Quantitative real time polymerase chain reaction (qPCR) test was also used to detect for the possibility of a low level of infection in apparently healthy tissues and to determine whether these were infected with either Chlamydia pecorum or Chlamydia pneumoniae. The results of these investigations revealed that chlamydia was detected in the testis of two animals and the epididymis of one animal by all three diagnostic tests. While chlamydia antigen was localised within the seminiferous tubules in the right testis of one animal by IHC, there was no evidence of the presence of chlamydia inclusions in the interstitium of this testis. Although the left testis of this animal showed negative results by IHC and CV, it showed positive results by qPCR. Chlamydia inclusions were also observed inside the mononuclear cell infiltrates which were organised as granulomas in the epididymis from the same animal. IHC also localised chlamydia inclusions in the granulomatous lesions, which obliterated the seminiferous tubules in the testis of another animal; the epididymis from this animal did not show any positive results. While CV has identified chlamydia in the prostate of 8 animals, the prostate of all animals was negative by IHC and qPCR. The discrepancy in the results of the former test and the latter two tests may be due to the method of collection and the type of specimen analysed. While swabs were taken from fresh tissues for the CV, IHC and qPCR were conducted using formalin fixed wax embedded tissue biopsies; consequently, there is a possibility that chlamydia may not be present in some thin sections. While C. pecorum could be detected by qPCR from the testes of one animal, C. pneumoniae was not detected in any reproductive tissue from the animals in this study. In the second experiment, histopathology resulting from chlamydia infection was described from two koala testes and one epididymis; this also included a transmission electron microscopic examination from one koala. In the same study, koalas showing clinical signs of chlamydia urogenital disease or which were being treated for chlamydia infection were also examined to explore any potential negative effect on semen quality; these animals were assessed for sperm motility and DNA fragmentation. Histopathological examination revealed that chlamydia appeared to cause chronic fibrosis in the testis of one koala and granulomatous orchitis in the testis of another koala. The epididymis of the former animal possessed focal granulomas, which obliterated epididymal tubular structure; the epididymis from the other animal had interstitial fibrosis but the tubules appeared histologically normal with no sperm in the lumen. In the testis with chronic fibrotic orchitis, the seminiferous epithelium was completely degenerated, yet the basement membrane was intact in most tubules. The interstitium had mild mononuclear cell infiltration, which was found to migrate into tubules without an intact basement membrane. Ultrastructural studies showed chlamydia-like bodies within the Sertoli cells in the seminiferous tubules but all spermatogenic cells were found to be degenerated. Although the histopathological findings suggest that the infection may develop from acute to chronic fibrosis or granulomatous inflammation, it is still unclear whether chlamydia can potentially infect the seminiferous epithelium in the early stages of infection and then subsequently affects sperm morphology. While progressive motility was affected by the presence of pathology of the urogenital tract in 3 out of 4 koalas destined for euthanasia, DNA fragmentation was in the normal range in all four koalas. All other koalas under treatment or before and after treatment also showed normal sperm DNA fragmentation. As there was a concern that the assay was not working optimally, further investigations in the impact of chlamydial genital infection on sperm motility and DNA are recommended. The results of this thesis have shown for the first time that chlamydia infection can cause sterility in the male koala and thereby highlights the potential adverse impact of this disease on male koala reproduction. In order to better establish the underlying incidence of this disease in the wild population, it is recommended that all males presenting to koala hospitals with clinical signs of cystitis be routinely screened for the presence of the organism and associated reproductive pathology. The thesis also proposes a diagnostic key that can be used by the koala hospitals in order to screen the koala gonads and semen for chlamydia. Further studies are required to confirm the route of testicular infection (ascending or haematogenous) and whether the presence of chlamydia has any negative impact on koala semen quality. The results of this thesis also indicate that semen recovery from diseased koalas, can potentially be used in a genome resource bank (GRB), but it will also be important to have a sensitive screening mechanism for chlamydia antigen in place to manage this activity.
Keyword Koala, Phascolarctos cinereus, chlamydiosis, Chlamydia pecorum, Chlamydia pneumoniae, Chlamydophila, orchitis, epididymitis, DNA fragmentation, Clearview Chlamydia MF, marsupial.
Additional Notes Page numbers that should be printed in color: 46, 49, 50, 61, 63, 64

 
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