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this is a series of lectures on microbiology useful for both under and postgraduate medical and paramedical students
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Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
Mycobacterium• Name from Myco and Bacteria, Fungus like bacteria
• Because it forms mould like growth on liquid cultures
Dr. Ashish V. Jawarkar
Mycobacteria that infect humans
• M. Tuberculosis – TB• M. Leprae – Leprosy• Non tuberculous mycobacteria / atypical
mycobacteria
Dr. Ashish V. Jawarkar
Mycobacterium Tuberculosis• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Morphology
• Neither gram positive, nor negative• Acid fast• They have mycolic acid in their cell wall
which makes them acid fast• Difficult to decolorise with organic acids
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
Slightly curved rods
Non motile
Non capsulated
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Growth characteristics
• Obligate aerobes• Grow slowly – generation time 15 hours• Colonies appear in two weeks• Optimum temperature is 37 deg• Solid media most commonly used – LJ
media
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Biochemical teststo differentiate MTB from atypical
mycobacteria• Niacin test –
– adding cyanogen bromide+aniline + ethanol = canary yellow color
• Paranitrobenzoic acid– MTB cannot grow in presence of this
• Catalase peroxidase test– MTB is weakly positive
• Aryl sulfatase test– Negative for MTB
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Treatment and Resistance
• DOTS – directly observed treatment shortcourse– HRZE for 4 months– HR for 2 months
• H – isoniazid R – rifampicin Z - Pyrazinamide• E - Ethambutol
Dr. Ashish V. Jawarkar
MDR-TB
• Resistant to isoniazid and rifampicin
XDR-TB• Resistant to all drugs
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Pathogenicity and virulence
• Its pathogenicity is due to complex lipids like mycolic acid in cell wall.. This makes it– Acid fast– Resistant to antibiotics– Resistant to disinfectants like acid and alkalis– Resistant to immune system– Resistant to destruction by macrophages
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Epidemiology
• Source – Humans with TB• Spread – droplet nuclei – inhaled• India – more than 40 percent population – that is
nearly half of us are infected• Only saved due to our immunity• To stop TB – RNTCP – revised national
tuberculosis control program has been started – offering DOTS to nearly 15 million patients daily – free of charge
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Tuberculosis
• Pulmonary• Extra pulmonary
Dr. Ashish V. Jawarkar
Pulmonary
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Lab diagnosis
• Sample – sputum for pulmonary, biopsy for extrapulmonary sites
• Stain – Zn stain• Culture – LJ media• Raised ESR• PCR – polymerase chain reaction
Dr. Ashish V. Jawarkar
Montoux test
• PPD/tuberculin is injected into skin• Look for induration of skin
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Treatment
• DOTS
Dr. Ashish V. Jawarkar
Mycobacterium leprae
Dr. Ashish V. Jawarkar
• Causes leprosy• Seen in developing countries like India only
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
• Slightly curved rods• Singly or in groups• Cigar bundle appearance• Lepra cells
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Growth characteristics
• Cannot be cultivated in vitro on any media• Grown in foot pad of armadillo
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Biochemical reactions
• Cannot be grown..• Cannot know biochemical reactions
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Resistance
• Not known
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
• ----
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Epidemiology
• Human disease only• Source – nasal secretions• Entry – respiratory tract / skin• Not highly communicable
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Diseases caused
• Leprosy• Affects skin and nerves• Hypoaesthetic patch, thickened nerves• Lion face, saddle nose, autoamputation• Two main types – tuberculoid leprosy,
lepromatous leprosy
Dr. Ashish V. Jawarkar
Tuberculoid leprosyaka paucibacillary leprosy
Dr. Ashish V. Jawarkar
Tuberculoid leprosy
Dr. Ashish V. Jawarkar
Multibacillary leprosy/lepromatous leprosy
Dr. Ashish V. Jawarkar
AUTO AMPUTATION
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
Lab Diagnosis• Sample – biopsy from nasal mucosa, skin
lesions, ear lobes• Stained with modified ZN stain – use 5%
H2SO4 instead of 20%• Cannot be cultured
Dr. Ashish V. Jawarkar
LEPROMIN TEST
• Method is similar to tuberculin test• Injected antigen is lepromin• Reaction is read at
– 48 hours – fernandez– 3-4 weeks - mitsuda
Dr. Ashish V. Jawarkar
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Dr. Ashish V. Jawarkar
• MDT
Dr. Ashish V. Jawarkar
Treatment• Multi drug therapy consisting of
– RIFAMPICIN– DAPSONE
Dr. Ashish V. Jawarkar
Dr. Ashish V. Jawarkar
NOT COVERED
• ATYPICAL MYOBACTERIA – Can be asked for short note – 5 marks
Dr. Ashish V. Jawarkar