Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

Mycobacterium leprae (Leprosy)- "Hansen's disease"

•
•

Mycobacterium leprae is the causative agent of leprosy. It is an acid-fast, non-motile bacillus that can be identified microscopically in skin and nerve smears stained with Ziehl-Neelsen stain. Leprosy exists as a spectrum depending on host immunity, ranging from tuberculoid leprosy where host immunity is high to lepromatous leprosy where host immunity is low. Diagnosis involves identification of bacilli in smears as well as serological and molecular tests. Treatment involves multidrug therapy with dapsone, rifampicin, and clofazimine depending on whether the patient has the paucib

1 of 20
Mycobacterium leprae By R.Rakshni II.M.SC MICROBIOLOGY Medical Microbiology UNDER THE GUIDANCE Mrs.S.Selvajeyanthi Asst.Professor, Dept.of Microbiology, Tiruppur Kumaran College For Women,Tirupur CONTENT: Taxonomy, Introduction Pathogenesis Morphology Cultural Characteristics Clinical symptoms Diagnosis Treatment Reference Image courtesy: https://microbenotes.com/
TAXONOMY: CLASS : Actinobacteria ORDER : Actinomycetales FAMILY : Mycobacteriaceae GENUS : Mycobacterium SPECIES : Mycobacterium leprae the small brick-red rods in cluster The name “Mycobacterium” was given to this genus by LEIFMANN AND NEUMANN in 1896 on account of the mould like pellicle’s produced by these bacteria when grown in liquid media.
LEPRAE:  M.leprae is a causative agent of LEPROSY , which disease of great anti quality.  Hansen first observed leprosy bacillus in 1868.  It was first human BACTERIAL PATHOGEN to be described.
MORPHOLOGY: STRUCTURE OF M.LEPRAE  Straight/curved slender  capsulated  non-motile  nonsporing  acid fast, but resistant to only 5% sulphuric acid.  Rod-1to 8u in length -0.2 to 0.5u in width  appear fragmented or beaded  cell stain homogenously; divides by binary fission.  live and dead bacilli are differentiated by ZIEHL- NEELSEN method.  live bacilli appear solid, stain brightly and uniformly, granular and stain weekly.  it can easily be stained by gram’s method and gram positive.  the bacilli are seen in parallel rows and give the appearance of Cigar bundles.
CULTURAL CHARACTERISTICS: India cancer research center has isolated an acid-fast bacillus from leprosy patients using human fetal spinal ganglion cell culture and has been adapted for growth on LJ medium. Nine-banded aramdilo is more susceptible to infection with lepra bacillus. Average generation time is 12-13 days. Remains unaffected in warm humid environment for 9-16 days moist soil-46 days, direct sunlight-2 hours, uv-light -a few minutes. The organisms has been successfully grown on artificial cell culture medium. It can be used as diagnostic test for presence of bacilli in body lesions of suspected leprosy patients. The difficulty in culturing the organism appears to be because it is an obligate intracellular parasite that lacks many necessary genes for independent survival.
ANTIGENIC STRUCTURE: M.LEPRAE CELLWALL CONSISTS OF FOUR LAYER:- An intermost layer of peptidoglycan, that give shape and rigidity to the cell. Attached to this lipoarabinomannan-B[LAM-B], which is highly immunogenic and used in sero diagnosis of of leprosy. Adjacent to this is mycolic acid layer. The outermost layer is made up of a phenolic glycolipid-1 [PGL-1], which suppresses host cell immunity. It is also used in the serodiagnosis of leprosy.
PATHOGENESIS: o Leprosy is generally a disease of skin, peripheral nerves and nasal and mucosa. o Other tissue [or] organs may also be affected. o Leprosy is a strictly a parasite man. o Sources of infection are nasal discharge and skin lesions. o Leprosy is a chronic granulomatous diseases. o Incubation period is long varies from 3-15 years. o Prolonged close contact with infective patient is necessary for transmission of the diseases. o The principle target cell of lepra bacilli are Schwann cell and the resulting nerve damage causes manifestation of leprosy, which include anesthesia and muscle paralysis. o A non-specific or indeterminate skin lesion is the FIRST SIGN OF DISEASES.
Depending on the immune status of the host, the diseases is classified into Four Types:
LEPROMATUS LEPROSY : HOST RESISTANCE IS LOW. LEPROMIN TEST NEGATIVE, PROGNOSIS IS POOR. NODULER SKIN LESIONS APPEAR ON FACE,EAR LOBES, HANDS, FEET ETC… HIGHLY INFECTION. BORDERLINE (OR) DIMORPHOUS TYPE LEPROSY: LESIONS RESEMBLE BOTH LEPROMATOUS AND TUBERCULOID TYPE.
TUBERCULOID TYPE LEPROSY: HOST RESISTANCE IS VERY HIGH. LEPROMIN TEST POSTIVE. PROGONSIS IS GOOD. SKIN LESIONS ARE FEW. NON-INFECTIOUS. INDETERMINATE TYPE LEPROSY: IT IS EARLY UNSTABLE TISSUE REACTION WHICH NEITHER RESEMBLES LEPROMATOUS NOR TUBERCULOID TYPE. THE LESIONS EITHER HEAL SPONTANEOUSLY (OR) PROGRESS TO TUBERCULIOD (OR) LEPROMATOUS TYPE. PAUCIBACILLARY-ALL LEPROMATOUS AND FEWBORDERLINE TYPES. MULTIBACILLARY-ALL LEPROMATOUS AND FEWBORDERLINE TYPES.
EPIDERMOLOGY: Leprosy is an exclusively human disease and is not highly communicable. Sources of infection are nasal secretions and discharges from skin lesions. Route of entry may be through the respiratory tract (or) skin. India has one-third of global burden of leprosy with BIHAR AND ORISSA having the highest prevalence . Nasal droplets, contact with infected soil,& even insect vectors. 95% population has innate immunity against it.
LABORATORY DIAGNOSIS: Skin biopsies, nasal discharges, scrapings from the nasal mucosa and slit-skin smears which are prepared by making superficial incisions in the skin, scraping out some tissue fluid and cells. Skin smears: The skin smears are collected from the leprous lesions, such as nodules, thick papules, and areas of infiltration. In cases of patches, the samples are obtained from the edge of the lesion rather than from the center. The skin smears from these sites are collected by slit and scrap method.
Nasal smears: Smears from the nasal patches are collected by scraping material from the mucous membrane of the internal nasal septum, particularly from inferior turbinate folds of the nasal septum. Skin and nerve biopsy: Skin biopsy is collected from active edge of the patches and nerve biopsy from thickened nerve for histological confirmation of tuberculoid leprosy.
Microscopy: The slit-skin smears, nasal smears, or smears from other specimen on the slide are stained by Ziehl- Neelsen technique by using 5% sulfuric acid for decolorizarion. Under oil immersion objective, red acid fast bacilli are seen, arranged singly or in groups (cigar like bundles), bound together by lipid-like substance, the glia to form The globi are present inside the foamy macrophages called Virchow’s lepra cells or foamy cells. Bacillary index: The bacillary index or BI is an expression of the extent of bacterial load. It is calculated by counting six to eight stained smears under the oil immersion lens. This index is obtained by totaling the number of pluses.
Morphological index: The uniformity of the bacilli is used as a criterion to differentiate live bacilli from dead bacilli in stained smears. The lepra bacilli that stain uniformly with carbol fuchsin as solid acid- fast rods are believed to be viable, and the bacilli that stain irregularly are considered dead and degenerated. The percentage of uniformly stained bacilli in the tissues is known as morphological index (MI).
Lepromin test: The lepromin test is used to study host immunity to M. leprae. The test is an intradermal skin test performed by using lepromin antigen, which is a suspension of killed M. leprae obtained from infected human or armadillo tissue. The lepromin test is not used to confirm the diagnosis of leprosy. It is also not useful to indicate prior contact of the person with leprae bacilli. Leprosins, which are ultrasonicates of tissue-free bacilli extracted from lesions (the suffixes -H and -A are used to denote human and armadillo origins, respectively). These reagents elicit two types of reaction:  The Fernandez reaction is analogous to tuberculin reactivity and appears in sensitized subjects 48 hours after skin testing. Positive reaction is characterized by the appearance of a localized area of inflammation with congestion and edema measuring 10 mm and more in diameter during 24–48 hours of injection. These lesions disappear within 3–4 days. Positive reaction suggests that the patient has been infected by leprae bacilli during sometime in the past.  The Mitsuda reaction is characterized by development of a nodule at the site of inoculation after 3–4 weeks after testing with lepromin. The nodule subsequently may undergo necrosis followed by ulceration. This reaction is indicative of the host’s ability to give a granulomatous response to antigens of M. leprae, and is positive at or near the TT pole.
Serodiagnosis: Serodiagnosis of leprosy is based on demonstration of antibodies to M. leprae, specific PGL-1 antigens. Enzyme linked immunosorbent assay (ELISA) and latex agglutination test are used to detect serum antibodies. The serology is useful primarily in patients with untreated lepromatous leprosy, as most of patients have higher levels of serum antibodies. The serology, however, is less useful for diagnosis of paucibacillary disease, because serum antibodies are present in only 40–60% of such patients. FLA-ABS (Fluorescent leprosy antibody absorption test) is widely used to identify subclinical cases. It detects M. leprae specific antibodies irrespective of duration and stage of the disease.
Molecular Diagnosis: Polymerase chain reaction (PCR) for identifying DNA that encodes 65 kDa and 18 kDa M. leprae proteins and repetitive sequences of M. leprae is being used to detect and identify M. leprae in clinical specimens. PCR is used to monitor treatment, diagnose relapses, or determine the need for chemotherapy. The technique is most useful in cases of leprosy showing atypical clinical or histopathological features but positive for acid-fast bacilli. It is not useful for diagnosis of cases when acid-fast bacilli are not detected by light microscopy.
Prophylaxis: Early detection and regular treatment. Health education. No effective vaccine is available. TREATMENT: Dapsone monotherapy (H,H’-diamino diphenyl sulphone, DDS) was standard treatment for all types of leprosy. Currently, multiple drug therapy i.e. in practice. paucibacillary- rifampicin 600mg once a month and dapsone 100mg daily for six months. multibacillary- rifampicin 600mg once a month, dapsone 100mg daily and dot azamine 50mg daily for 2 years (or) still smear become negative.
Reference: www.sciencedirect.com www.microbiologysociety.org www.wikipedia.com

More Related Content

Mycobacterium leprae (Leprosy)- "Hansen's disease"

  • 1. Mycobacterium leprae By R.Rakshni II.M.SC MICROBIOLOGY Medical Microbiology UNDER THE GUIDANCE Mrs.S.Selvajeyanthi Asst.Professor, Dept.of Microbiology, Tiruppur Kumaran College For Women,Tirupur CONTENT: Taxonomy, Introduction Pathogenesis Morphology Cultural Characteristics Clinical symptoms Diagnosis Treatment Reference Image courtesy: https://microbenotes.com/
  • 2. TAXONOMY: CLASS : Actinobacteria ORDER : Actinomycetales FAMILY : Mycobacteriaceae GENUS : Mycobacterium SPECIES : Mycobacterium leprae the small brick-red rods in cluster The name “Mycobacterium” was given to this genus by LEIFMANN AND NEUMANN in 1896 on account of the mould like pellicle’s produced by these bacteria when grown in liquid media.
  • 3. LEPRAE:  M.leprae is a causative agent of LEPROSY , which disease of great anti quality.  Hansen first observed leprosy bacillus in 1868.  It was first human BACTERIAL PATHOGEN to be described.
  • 4. MORPHOLOGY: STRUCTURE OF M.LEPRAE  Straight/curved slender  capsulated  non-motile  nonsporing  acid fast, but resistant to only 5% sulphuric acid.  Rod-1to 8u in length -0.2 to 0.5u in width  appear fragmented or beaded  cell stain homogenously; divides by binary fission.  live and dead bacilli are differentiated by ZIEHL- NEELSEN method.  live bacilli appear solid, stain brightly and uniformly, granular and stain weekly.  it can easily be stained by gram’s method and gram positive.  the bacilli are seen in parallel rows and give the appearance of Cigar bundles.
  • 5. CULTURAL CHARACTERISTICS: India cancer research center has isolated an acid-fast bacillus from leprosy patients using human fetal spinal ganglion cell culture and has been adapted for growth on LJ medium. Nine-banded aramdilo is more susceptible to infection with lepra bacillus. Average generation time is 12-13 days. Remains unaffected in warm humid environment for 9-16 days moist soil-46 days, direct sunlight-2 hours, uv-light -a few minutes. The organisms has been successfully grown on artificial cell culture medium. It can be used as diagnostic test for presence of bacilli in body lesions of suspected leprosy patients. The difficulty in culturing the organism appears to be because it is an obligate intracellular parasite that lacks many necessary genes for independent survival.
  • 6. ANTIGENIC STRUCTURE: M.LEPRAE CELLWALL CONSISTS OF FOUR LAYER:- An intermost layer of peptidoglycan, that give shape and rigidity to the cell. Attached to this lipoarabinomannan-B[LAM-B], which is highly immunogenic and used in sero diagnosis of of leprosy. Adjacent to this is mycolic acid layer. The outermost layer is made up of a phenolic glycolipid-1 [PGL-1], which suppresses host cell immunity. It is also used in the serodiagnosis of leprosy.
  • 7. PATHOGENESIS: o Leprosy is generally a disease of skin, peripheral nerves and nasal and mucosa. o Other tissue [or] organs may also be affected. o Leprosy is a strictly a parasite man. o Sources of infection are nasal discharge and skin lesions. o Leprosy is a chronic granulomatous diseases. o Incubation period is long varies from 3-15 years. o Prolonged close contact with infective patient is necessary for transmission of the diseases. o The principle target cell of lepra bacilli are Schwann cell and the resulting nerve damage causes manifestation of leprosy, which include anesthesia and muscle paralysis. o A non-specific or indeterminate skin lesion is the FIRST SIGN OF DISEASES.
  • 8. Depending on the immune status of the host, the diseases is classified into Four Types:
  • 9. LEPROMATUS LEPROSY : HOST RESISTANCE IS LOW. LEPROMIN TEST NEGATIVE, PROGNOSIS IS POOR. NODULER SKIN LESIONS APPEAR ON FACE,EAR LOBES, HANDS, FEET ETC… HIGHLY INFECTION. BORDERLINE (OR) DIMORPHOUS TYPE LEPROSY: LESIONS RESEMBLE BOTH LEPROMATOUS AND TUBERCULOID TYPE.
  • 10. TUBERCULOID TYPE LEPROSY: HOST RESISTANCE IS VERY HIGH. LEPROMIN TEST POSTIVE. PROGONSIS IS GOOD. SKIN LESIONS ARE FEW. NON-INFECTIOUS. INDETERMINATE TYPE LEPROSY: IT IS EARLY UNSTABLE TISSUE REACTION WHICH NEITHER RESEMBLES LEPROMATOUS NOR TUBERCULOID TYPE. THE LESIONS EITHER HEAL SPONTANEOUSLY (OR) PROGRESS TO TUBERCULIOD (OR) LEPROMATOUS TYPE. PAUCIBACILLARY-ALL LEPROMATOUS AND FEWBORDERLINE TYPES. MULTIBACILLARY-ALL LEPROMATOUS AND FEWBORDERLINE TYPES.
  • 11. EPIDERMOLOGY: Leprosy is an exclusively human disease and is not highly communicable. Sources of infection are nasal secretions and discharges from skin lesions. Route of entry may be through the respiratory tract (or) skin. India has one-third of global burden of leprosy with BIHAR AND ORISSA having the highest prevalence . Nasal droplets, contact with infected soil,& even insect vectors. 95% population has innate immunity against it.
  • 12. LABORATORY DIAGNOSIS: Skin biopsies, nasal discharges, scrapings from the nasal mucosa and slit-skin smears which are prepared by making superficial incisions in the skin, scraping out some tissue fluid and cells. Skin smears: The skin smears are collected from the leprous lesions, such as nodules, thick papules, and areas of infiltration. In cases of patches, the samples are obtained from the edge of the lesion rather than from the center. The skin smears from these sites are collected by slit and scrap method.
  • 13. Nasal smears: Smears from the nasal patches are collected by scraping material from the mucous membrane of the internal nasal septum, particularly from inferior turbinate folds of the nasal septum. Skin and nerve biopsy: Skin biopsy is collected from active edge of the patches and nerve biopsy from thickened nerve for histological confirmation of tuberculoid leprosy.
  • 14. Microscopy: The slit-skin smears, nasal smears, or smears from other specimen on the slide are stained by Ziehl- Neelsen technique by using 5% sulfuric acid for decolorizarion. Under oil immersion objective, red acid fast bacilli are seen, arranged singly or in groups (cigar like bundles), bound together by lipid-like substance, the glia to form The globi are present inside the foamy macrophages called Virchow’s lepra cells or foamy cells. Bacillary index: The bacillary index or BI is an expression of the extent of bacterial load. It is calculated by counting six to eight stained smears under the oil immersion lens. This index is obtained by totaling the number of pluses.
  • 15. Morphological index: The uniformity of the bacilli is used as a criterion to differentiate live bacilli from dead bacilli in stained smears. The lepra bacilli that stain uniformly with carbol fuchsin as solid acid- fast rods are believed to be viable, and the bacilli that stain irregularly are considered dead and degenerated. The percentage of uniformly stained bacilli in the tissues is known as morphological index (MI).
  • 16. Lepromin test: The lepromin test is used to study host immunity to M. leprae. The test is an intradermal skin test performed by using lepromin antigen, which is a suspension of killed M. leprae obtained from infected human or armadillo tissue. The lepromin test is not used to confirm the diagnosis of leprosy. It is also not useful to indicate prior contact of the person with leprae bacilli. Leprosins, which are ultrasonicates of tissue-free bacilli extracted from lesions (the suffixes -H and -A are used to denote human and armadillo origins, respectively). These reagents elicit two types of reaction:  The Fernandez reaction is analogous to tuberculin reactivity and appears in sensitized subjects 48 hours after skin testing. Positive reaction is characterized by the appearance of a localized area of inflammation with congestion and edema measuring 10 mm and more in diameter during 24–48 hours of injection. These lesions disappear within 3–4 days. Positive reaction suggests that the patient has been infected by leprae bacilli during sometime in the past.  The Mitsuda reaction is characterized by development of a nodule at the site of inoculation after 3–4 weeks after testing with lepromin. The nodule subsequently may undergo necrosis followed by ulceration. This reaction is indicative of the host’s ability to give a granulomatous response to antigens of M. leprae, and is positive at or near the TT pole.
  • 17. Serodiagnosis: Serodiagnosis of leprosy is based on demonstration of antibodies to M. leprae, specific PGL-1 antigens. Enzyme linked immunosorbent assay (ELISA) and latex agglutination test are used to detect serum antibodies. The serology is useful primarily in patients with untreated lepromatous leprosy, as most of patients have higher levels of serum antibodies. The serology, however, is less useful for diagnosis of paucibacillary disease, because serum antibodies are present in only 40–60% of such patients. FLA-ABS (Fluorescent leprosy antibody absorption test) is widely used to identify subclinical cases. It detects M. leprae specific antibodies irrespective of duration and stage of the disease.
  • 18. Molecular Diagnosis: Polymerase chain reaction (PCR) for identifying DNA that encodes 65 kDa and 18 kDa M. leprae proteins and repetitive sequences of M. leprae is being used to detect and identify M. leprae in clinical specimens. PCR is used to monitor treatment, diagnose relapses, or determine the need for chemotherapy. The technique is most useful in cases of leprosy showing atypical clinical or histopathological features but positive for acid-fast bacilli. It is not useful for diagnosis of cases when acid-fast bacilli are not detected by light microscopy.
  • 19. Prophylaxis: Early detection and regular treatment. Health education. No effective vaccine is available. TREATMENT: Dapsone monotherapy (H,H’-diamino diphenyl sulphone, DDS) was standard treatment for all types of leprosy. Currently, multiple drug therapy i.e. in practice. paucibacillary- rifampicin 600mg once a month and dapsone 100mg daily for six months. multibacillary- rifampicin 600mg once a month, dapsone 100mg daily and dot azamine 50mg daily for 2 years (or) still smear become negative.