Medical bacteriology,Mycobacterium leprae

Medical bacteriology

1. VIVEKANANDHA ARTS AND SCIENCE COLLEGE FOR WOMEN VEERACHIPALAYM,SANKAGIRI,SALEM DT. TAMIL NADU, INDIA. DEPARTMENT OF MICROBIOLOGY SUBJECT : MEDICAL BACTERIOLOGY TOPIC : MEDICAL BACTERIOLGY SUBJECT INCHARGE : PRODUCED BY: Dr. R. MYTHILY , DIVYADHARSHINI NAGARAJAN, ASSAISTANT PROFESSOR, III B.Sc., MICROBIOLOGY , DEPARTMENT OF MICROBIOLOGY. DEPARTMENT OF MICROBIOLOGY .

2. Synopsis History Introduction Morphology Culture characteristics Biochemical Reaction Resistance Virulence factor Pathogenesis Lab Diagnosis Treatment

3. Mycobacterium leprae History In 1873 G. H. Armaver Hansen in Norway discovered the causative agent of leprosy, Mycobacterium leprae . This was the first bacterium to be identified as causing disease in humanas . From the 19 th century, European nations adopted some practices of India and China, administering naturally occurring.

4. Mycobacterium leprae Introduction Mycobacterium leprae , otherwise known as Hansen’s disease, is primarily a tropical, mycobacterial infection which most often affects skin, nerves, and nasal mucosa. Mycobacterium leprae is an obligate intracellular gram positive, partially acid fast bacillus.

5. Mycobacterium leprae Morphology The acid – fast bacilli arranged singly, in parallel bundles ( like rolls of cigarettes in a packet ) or in globular masses. The bacilli are slender, slightly curved or straight rods, 1-8 um to 0.2-0.5 um in size. They are Gram positive and acid fast but to lesser extant than tubercle bacilli. They are aerobic rod shaped.

6. Mycobacterium leprae Cultural characteristics These organisms are unable to cultivate in other medias

7. Mycobacterium leprae Biochemical reaction Biochemical studies have revealed that M. Leprae contains an unusual form of the enzyme diphenoloxidase which has not been detected in other mycobacteria. The presence of a specific glutamic acid decarboxylase in the organism has been demonstrated.

8. Mycobacterium leprae Resistance Emergence of drug resistance has been reported in several countries, with the highest burden of drug-resistant Mycobacterium leprae reported in Brazil and India. Dapsone -resistant and rifampicin-resistant M leprae is transmitted in Guinea and the Philippines.

9. Mycobacterium leprae Virulence factor The virulence mechanism of mycobacteria is very complex. Broadly, the virulence factors can be classified as secretion factors, cell surface components, enzymes involved in cellular metabolism, and transcriptional regulators. The mycobacterium has evolved several mechanisms to secrete its protein.

10. Mycobacterium leprae Pathogenesis Infection occurs by inhalation of bacteria into the respiratory system along with that , the organisms also enters into the from small abrasion in present on the skin . Most of the damage done is by entering the nerves , mainly spinal nevers and cause damage to them . It leads to the loss of sensation of touch, pain , temperature.

11. Mycobacterium leprae Clinically 4 types of leprosy are 1 Lepromatous leprosy 2 Tuberculiod type 3 Dimorphic leprosy 4 Inditerminate leprosy

12. Mycobacterium leprae Lepromatous leprosy Lepromatous leprosy is a skin condition Consisting of place macules The macules will appear or face, hand, feet, ear lobes, and less commonly on the trunk. In the macules a large number of bacilli will be present

13. Mycobacterium leprae Tuberculoid type In the Tuberculoid form of the disease the skin lesions appear as light red or purplish sports. Tuberculoid leprosy is the more benign type, even through it is accompanied by nerve involvement, which leads to numbness (usually of the extremities ), contractures, and ulceration

14. Mycobacterium leprae Dimorphic leprosy /Border line Borderline is a cutaneous skin condition with numerous skin lesions that are red irregularly shaped plaques. In this type lesions produced possess characteristics of both Lepromatous and tuberculoid lesions.

15. Mycobacterium leprae Indeterminate leprosy In this type, the lesions produced often resemble maculo-anesthetic patches which are neither characteristic of Lepromatous or tuberculoid type.

16. Mycobacterium leprae Lab diagnosis Specimens Acid fast staining Skin and nerve biopsy Animal inoculation Lepromin test

17. Mycobacterium leprae 1.Specimens Nasal mucosa, skin lesions, ear lobules. Skin and nerve 2.Acid fast staining Ziehl-Neelson method Decolourising agent=5% Sulphuric acid Leprae cells confirm the diagnosis of Lepromatous leprosy

18. Mycobacterium leprae 3. Skin and nerve biopsy For histological confirmation of tuberculoid bacilli (as they cannot be demonstrated in direct smear) Skin biopsy is also useful in diagnosis and accurate classification of leprosy

19. Mycobacterium leprae 4. Animal inoculation Nine banded armadillo Injection of ground tissue from Lepromatous nodules or nasal scrapings from leprosy patient into the foot pad of armadillo Typical granuloma at the site of inoculation within 6 months

20. Mycobacterium leprae 5. Lepronim test Delayed type of hypersensitivite reaction First described by mitsuda in 1919 Leprominus used as antigen

21. Mycobacterium leprae Treatment Multi drug therapy is based on dapsone , rifiampicin and clifazimine by WHO Leprosy is a curable disease. The currently recommended treatment regimen consists of three drugs: dapsone , rifampicin and clofazimine . The combination is referred to as multi-drug therapy (MDT).

22. Reference Medical Microbiology. ( S.Rajan )

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