INTRODUCTION Slender rods branching Liquid culture pellicle Resist

INTRODUCTION: - • • • Slender rods, branching Liquid culture – pellicle Resist decolourisation Aerobic Growth – slow

MYCOBACTERIA �Three groups �obligate parasites �opportunistic pathogens �saprophytes

OBLIGATE PARASITES: Mycobacterium tuberculosis complex � M. tuberculosis � M. bovis � M. africanum � M. microti Mycobacterium leprae

OPPORTUNISTIC PATHOGENS: � Non-tuberculous �Photochromogens �Scotochromogens mycobacterium (NTM) �Non-photochromogens �Rapid growers

SAPROPHYTES: - M. phlei • M. smegmatis •

M. TUBERCULOSIS Morphology • M. tuberculosis – straight, slightly curved rod; 3 × 0. 3 µm in size • Ziehl – Neelsen – acid fast • Fluorescent dyes – auramine O, rhodamine

CULTURAL CHARACTERISTICS: Generation time – 14 – 15 hours • Optimum temperature – 37°C • M. tuberculosis – obligate aerobe • M. bovis – microaerophilic • M. tuberculosis – eugonic • M. bovis – dysgonic •

CULTURE • Solid media – Lowenstein–Jensen, dry, rough, raised, irregular, buff coloured • Liquid media – Dubo’s , Middlebrook’s, sensitivity test, preparation of antigen, vaccine

RESISTANCE • Killed – 60°C – 15– 20 minutes • Cultures killed – exposure to direct sunlight; room temperature 6– 8 months • Sputum – 20– 30 hours • Droplet nuclei 8– 10 days • Resistant to disinfectants • Sensitive to formaldehyde, glutaraldehyde

BIOCHEMICAL REACTIONS Niacin test – positive • Aryl sulphatase – positive – atypical • Nitrate reduction – positive • Amidase – positive • Pyrazinamide – positive • Tween 80 hydrolysis – positive •

TYPING METHODS • Phenotypic – epidemiology • Molecular typing �bacteriophage typing �bacteriocin typing �IS 6110 RFLP typing �spoligotyping

TUBERCULOSIS • Koch’s phenomenon – response to reinfection • Three components – local reaction, focal response, response • Tuberculin test – purified protein derivative – (PPD) – 50, 000 tuberculin units

PATHOLOGY • Tubercle – avascular granuloma – central zone of giant cells, with or without caseation, and peripheral zone of lymphocytes and fibroblasts Tubercle or granuloma with caseation

PATHOLOGY • Exudative type – acute inflammatory reaction with accumulation of edema fluid and polymorphonuclear leucocytes • Productive type – predominantly cellular

CLASSIFICATION • Primary tuberculosis – Ghon focus, primary complex • Post-primary tuberculosis

LABORATORY DIAGNOSIS Pulmonary tuberculosis • Specimen – sputum • Bronchoalveolar lavage • Gastric lavage

DECONTAMINATION • Decontamination and concentration of specimen �Petroff’s method �NALC Na. OH method

MICROSCOPY • Ziehl–Neelsen method Mycobacterium tuberculosis (AFB) Auramine rhodamine • Kinyoun’s method •

CULTURE • Solid media – LJ medium – two sets • Confirmation – biochemical tests • Liquid media – Middlebrook 7 H 11 • Automated system – BACTEC 460

ANIMAL INOCULATION • Guinea pigs – intramuscular • Progressive loss of weight • Positive tuberculin test • Autopsy

MOLECULAR METHODS PCR • LCR • RFLP • IS fingerprinting •

IMMUNODIAGNOSIS • Demonstration of hypersensitivity to tuberculoprotein • Mantoux test – induration of 10 mm or more – positive • Heaf test

EXTRAPULMONARY TUBERCULOSIS • Specimen �CSF �Joint fluid �Biopsy specimen �Body fluid

EXTRAPULMONARY TUBERCULOSIS CSF – tuberculous meningitis • Bone marrow • Pus – tuberculous abscess • Pleural effusion • Urine – renal tuberculosis •

PROPHYLAXIS • General measures – nutrition, health education, good housing • Immunoprophylaxis – BCG – live attenuated vaccine

TREATMENT • Bactericidal – rifampicin, pyrazinamide, isoniazid, streptomycin • Bacteristatic – ethambutol • Regimen – HRZE – 4 months; HR – 2 months

DRUG RESISTANCE • Primary resistance • Acquired resistance • Multidrug resistant tuberculosis (MDR-TB) • XDR strains – extensively resistant strains

RNTCP • Revised National Tuberculosis Control Programme – standardised treatment and proper diagnosis • DOTS – directly observed treatment short course; important component of RNTCP