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Title of Thesis

Syed Aley hasan Zaidi
Institute/University/Department Details
University of Karachi/ Department of Microbiology
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
listeriosis, listeria monocytogenes inoculum, mononuclear phagocytic system, monocytosis, l. monocytogenes

1. Experimental listeriosis was produced in healthy rabbits of either sex by inoculating various doses of live Listeria monocytogenes inoculum via three different routesx (oral, intravenous and intraperitoneal).

2. The experimental disease was established by several parameters such as clinical features, reisolation of L. monocytogenes from blood and different organs showing histopathological changes. The presence of L. monocytogenes was further confirmed by the immnofluorscence technique and also by the immunohistological (Peroxidase antiperoxidase) methods

3. It was observed that the disease was produced by all the three modes of inoculation. However, the intensity of clinical features was not similar

4. The lesions produced as a result of L. monocytogenes inoculation showed a dose dependent relationship, smaller doses either had no effect or little effect as compared to larger doses

5. The histopathological features in different organs were described in terms of intensity of lesions from 1+ to 4+ (1+ being minimal size of lesion and 4+ indicating a severe lesion). It was found that these hidtopathological features were also dose dependent

6. It was interesting to observe that all the organs did not show uniformity in the intensity of lesions. Further, it was noticed that lymphoid related organs such as liver, spleen etc. were mainly and prominently affected as compared to non lymphoid organs

7. Those organs which have the presence of mononuclear phagocytic system (MPS) cells such as liver, spleen, kidney, lung, adrenals, brain etc. were the main organs involved forming a lesion in the form of necrotic foci

8. No lesions were seen in testis, ovary and uterus (non-pregnant)

9. Histopathological lesions of variable degree were consistently observed in the liver and spleen of rabbits when inoculated with 4 different doses (1.2X103,1.2X105, 1.2X107, 1.2X109 per ml per animal) by three different routes (oral, intravenous, intraperitoneal).

10. No histopathological evidence of infection was observed in the intestine, ovary, testis and uterus by any route except that of stomach, which developed lesions after intravenous route

11. Hearts of rabbits infected orally did not show any lesion while inconsistent results were obtained with intravenous and intraperitoneal routes of inoculation

12. Smaller dose (1.2X103 per ml per animal) failed to produce signs of keratoconjunctivitis and mucopurulent discharge in the eyes while lung, kidney and brain exhibited variable histopathological evidence of infection

13. L. monocytogenes was isolated from the various organs of rabbits infected by different routes except after oral inoculation of 1.2X103/ml/animal

14. The hyper immunized rabbit showed variable histopathological lesions after challenge by the oral route, whereas after intravenous challenge the organs looked normal

15. Several time passaged culture of L. monocytogenes proved to be highly virulent as it is shown in the form of some aggressive lesions in organs such as liver

16. The phenomenon of monocytosis was also studied. It showed variation after different routes and doses

17. The monocyte count was high after intravenous inoculation specially with a higher dose followed by intraperitoneal and then oral inoculation

18. The normal unimmunized rabbit showed a raised monocyte count up to 15% in 72 hours post inoculation. The count then gradually decreased in 120 hours. The immunized rabbits with the heat killed cells showed a normal range of the monocyte count after challenge with the live cells

19. Several times mice pass aged culture of L. monocytogenes (LD50, 0.55X104) when injected into rabbits showed sever histopathological lesions in the liver

20. The present study using rabbit as a model for the study of the pathogenesis of listeriosis may be compared with that of mice used by earlier workers

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
216.24 KB
2 1 Summary 1
31.22 KB
3 2 Introduction 4
42.72 KB
4 3 Review Of Literature 8
662.82 KB
  3.1 Historical Background 8
  3.2 Nomenclature And Classification 9
  3.3 Isolation And Identification 11
  3.4 Products Of Biological Significance 19
  3.5 Antigenic And Serologic Characters 23
  3.6 Epidemiology 23
  3.7 Pathogenecity 29
  3.8 Morphological Changes And Clinical Manifestations 37
  3.9 Listeria Monocytogenes And Environment 55
  3.10 Disease Pattern 53
  3.11 Diagnostic Approach 60
  3.12 Rapid Tests-Molecular Biological Techniques 63
  3.13 Treatment Of Listeriosis 65
  3.14 Prevention/Control Of Listeriosis 66
  3.15 Issues For Various Personnel 67
5 4 Materials And Methods 70
262.89 KB
  4.1 Bacteriological Studies 70
  4.2 Histopathological Studies 71
  4.3 Determination Of Health Status Of Animalas Used 72
  4.4 Preparation Of Inoculum 73
  4.5 Production Of Experimental Listeriosis 74
  4.6 Determination Of Experimental Listeriosis 75
  4.7 Animal Dissection 77
  4.8 Histopathology Of Various Organs 77
  4.9 Histopathology Of Hyperimmunized Challenged Animals 81
  4.10 Preparation Of Antigen For Hyperimmunization And Antiserum Production 82
  4.11 Immunofluorescent Studies 87
  4.12 Pathogenecity 94
  4.13 Haematologoical Studies 94
  4.14 Immunohistological Studies 95
6 5 Results 98
1353.71 KB
  5.1 Bacteriological Studies 98
  5.2 Identification Of Organisms Used 98
  5.3 Histopathological Studies 100
  5.4 Health Status Of Animals 100
  5.5 Effect Of Inoculation Of L. Monocytogenes Nctc 7973 In Different Doses And By Various Routes 102
  5.6 Establishment Of Experimental Listeriosis 109
  5.7 Haematological Studies 158
  5.8 Histopathological Changes (Tissue Response) After Oral And Intravenous Challenge In Hyper Immunized Rabbits 158
  5.9 Pathogenecity 163
  5.10 Immunohistological Studies 163
  5.11 Immunofluorescent Studies 165
7 6 Discussion 171
170.05 KB
8 7 Suggestions For Future Research 188
11.32 KB
9 8 References 189
336.59 KB