Tuberculosis (TB) Presentation PDF

Present by:
Dr. Mahdi Yadollahzadeh.
Pulmonologist (MD).
Assistant professor.
Department of Internal Medicine,
School of medicine,
TUBERCULOSIS Firoozgar General Hospital,
Iran University of Medica...

Present by:
Dr. Mahdi Yadollahzadeh.
Pulmonologist (MD).
Assistant professor.
Department of Internal Medicine,
School of medicine,
TUBERCULOSIS Firoozgar General Hospital,
Iran University of Medical Sciences. Ref: Harrison’s Principles of Internal Medicine, 21th edition, 2022.
 INTRODUCTION Mycobacterium tuberculosis complex.
One of the oldest diseases known to affect humans.
The top cause of infectious death worldwide.
~70,000 years ago in Africa.
Affects the lungs, although other organs are involved in up to one-third of cases.
If properly treated, TB caused by drug-susceptible strains is curable in the vast majority of cases.
If untreated, the disease may be fatal within 5 years in 50–65% of cases.
Transmission: the airborne spread of droplet nuclei produced by patients with infectious pulmonary TB.
 ETIOLOGIC AGENT Family Mycobacteriaceae and the order Actinomycetales.
Pathogenic species, M. tuberculosis complex, eight distinct subgroups, 1. M. tuberculosis: the most common and important. 2. M. africanum: in West, Central, and East Africa. 3. M. bovis & M. caprae : zoonotic members. (the bovine tubercle bacillus; characteristically: resistant to pyrazinamide, transmitted: unpasteurized milk). 4. M. pinnipedii: seals and sea lions in the Southern Hemisphere. 5. M. mungi: banded mongooses in southern Africa. 6. M. orygis: oryxes and other Bovidae in Africa. 7. M. microti: the “vole” bacillus, a less virulent organism. 8. M. canetti: rare, East African, unusual smooth colonies on solid media and is considered closely related to a supposed progenitor type.  ETIOLOGIC AGENT  M. tuberculosis: a rod-shaped, non-spore-forming, thin aerobic, 0.5 μm by 3 μm, neutral on Gram’s staining.  AFB: once stained, the bacilli cannot be decolorized by acid alcohol.  Acid fastness: high content of mycolic acids, long-chain cross- linked fatty acids, and other cell wall lipids.  Lipids are linked to underlying arabinogalactan and peptidoglycan; very low permeability; reducing the effectiveness of antibiotics.  lipoarabinomannan: host interaction and facilitates the survival of M. tuberculosis within macrophages.  AFBs: Mycobacteria, Nocardia, Rhodococcus, Legionella micdadei, the protozoa Isospora and Cryptosporidium.  ETIOLOGIC AGENT Acid-fast bacillus smear showing M. tuberculosis bacilli.  EPIDEMIOLOGY WHO: 7.1 million new cases of TB (2019) were reported; but estimated 10 million new cases of TB occurred. 97% of cases were reported from low & middle-income countries. Eight countries accounted for 2/3 of all new cases: India, Indonesia, China, the Philippines, Pakistan, Nigeria, Bangladesh, and South Africa. 1980s-90s: cases of TB increased in industrialized countries.  Immigration from high incidence of TB.  The spread of the HIV epidemic.  Social problems (urban poverty, homelessness, drug abuse).  Dismantling of TB services.  EPIDEMIOLOGY Estimated tuberculosis (TB) incidence rates (per 100,000 population) in  EPIDEMIOLOGY Estimated tuberculosis (TB) mortality rates in HIV-negative people in 2018  EPIDEMIOLOGY TB incidence: stable or falling; 2000s 1.7%. RR-TB: rifampin- (also called rifampicin) resistant TB. MDR-TB (multidrug-resistant TB): Resistant at least to isoniazid and rifampin. XDR-TB (extensively drug-resistant TB): Resistance to powerful second-line anti-TB drugs (fluoroquinolones and at least one of the injectable drugs amikacin, kanamycin, and capreomycin). Only 44% of these cases were diagnosed because of a lack of culture and drug susceptibility testing (DST) capacity in many settings worldwide.  EPIDEMIOLOGY WHO new definitions: (i) Pre-XDR-TB: That of MDR/RR-TB and also resistant to any fluoroquinolone. (ii) XDR-TB : That of M DR/RR-TB and also resist ant to any fluoroquinolone and at least one additional Group A drug including levofloxacin or moxifloxacin, bedaquiline, and linezolid.) ~ 6.2% of the MDR-TB  may be XDR-TB, but remain undiagnosed because of the lack of reliable methods for DST and limited capacity laboratory in low-income countries. A few cases were deemed resistant to all anti-TB drugs; however, information must be cautious because susceptibility testing for several second-line drugs is neither accurate nor reproducible.  EXPOSURE TO INFECTION Droplet nuclei: the most commonly; aerosolized by coughing, sneezing, or speaking. Through the skin or the placenta: uncommon & of no significance. The tiny droplets dry rapidly; the smallest (90% trapped in the upper airways expelled by ciliated mucosal cells. Droplet inhaled 50% (usually ~4–6 g/dL), a normal to low glucose, a pH of ~7.3 (occasionally