Tuberculosis (TB) Facts, Signs, Symptoms, Treatment

Tuberculosis (TB) Facts, Signs, Symptoms, Treatment

It is a chronic granulomatous inflammatory infectious bacterial disease caused by mycobacterium tuberculosis which most commonly affects the lungs.

 Facts of Tuberculosis

  • 7 positions of leading causes of deaths
  • 1/3 of the world’s population could be infected
  • >80% can be cured
  • Prevention can be >90% affectively

Etiology of TB (Tuberculosis)

Most common cause other than tuberculosis include

  1. Avium intracellulare
  2. M.kansari
  3. M.scrofulaceum
  4. M.ulcerans
  5. M.marinum
  6. M.fortuitum
  7. M.chelonei

Characteristics of m. tuberculosis

  • Rod-shaped
  • 0.2 – 0.5 micro in diameter
  • 2-4 micro in length
  • Mycolic a¯ present in its cell wall makes it a fast
  • So it resists against a & alcohol
  • Aerobic and non-motile
  • Multiplies slowly
  • Can remain dormant for decades

Clinical features of tuberculosis

•Malaise, anorexia, weight loss & fever

•The fever is usually low grade & remittent (appearing late each afternoon & then subsiding)

•With progressive pulmonary involvement increase amount of sputum, which is at 1st mucoid & later purulent (containing pus) may appear

•Haemoptysis

•Pleuritic pain (inflammation of the pleura of the lungs)

PATHOGENESIS

•Inhalation of air droplet contains m. tuberculosis

•Once inhaled the infections droplets settle throughout the airways

•The majority of the bacilli are trapped in the upper parts of the airways where the mucus-secreting goblet cells exist

•The mucus produced catches foreign substances & the cilia on the surface of the cells constantly beat the mucus & its entrapped particles upward for removal

•Bacteria in droplets that bypass this system & reach the alveoli are quickly surrounded and engulfed by alveolar macrophages

•The subsequent phagocytosis by macrophages initiates a cascade of events that result in either successful control of the infection, followed by latent tuberculosis, or progressive to an active disease called primary progressive tuberculosis

•The outcome is essentially determined by the quantity of the host defences & the balance that occurs between host defences & the invading mycobacteria

•After being ingested by macrophages, the mycobacteria continue to multiply slowly, c- bacterial cell division occurring every 25 to 32 hours

•Regardless of whether the infection becomes controlled or progressive initial development involves the production of proteolytic enzyme.

•Released cytokines attract T lymphocytes to the site of the cells that constitute cell-mediated immunity.

•This initial immune process continues for 2 to 12 weeks.

•The micro-org continue to grow until they reach sufficient numbers to fully elicit the cells mediated immune response which can be detected by a skin test.

•For persons c- intact cell-mediated immunity the next defensive step I formation of granulomas

•Around the M. Tuberculosis organism

•These nodular type lesion form from an accumulation of activated T lymphocytes & macrophages which creates a micro-environment

•By 2 or 3 weeks, the necrotic environment resembles soft cheese, often referred to as caseous necrosis & is characterized by low oxygen levels, low Ph & limited nutrients.

•This condition restricts further growth & establishes latency.

•Lesions in person c- an adequate immune system generally undergo fibrosis & calcification successfully controlling the infection so that the bacilli are contained in the dormant, healed lesions.

•Lesions in persons with less effective immune systems progress to primary progressive tuberculosis

•For less immunocompetent persons, granuloma formation is initiated yet ultimately is unsuccessful in containing the bacilli

•The necrotic tissue undergoes liquefaction & the fibrous wall loses structural integrity

•The semi-liquid necrotic material can then drain into a bronchus or nearby blood vessel, leaving on air-filled cavity at the original site

•In patients infected with M. tuberculosis droplets can be coughed up from the bronchus

The natural cause of M. tuberculosis infection

clinical manifestation

As the cellular processes occur, tuberculosis may develop differently in each patient, according to the status of the patient’s immune system stages include

  • Latency
  • Primary disease
  • Primary progressive disease
  • Extrapulmonary disease

latent tuberculosis

mycobacterium tuberculosis organisms can be enclosed as previously described but are difficult to completely eliminate

persons with latent tuberculosis have no signs or symptoms of the disease, do not feel sick are not infectious

however viable bacilli can persist in the narcotic material for years or even a lifetime & if the immune system later becomes compromised as it does in many critically ill patients, the disease can be reactivated.

Although co-infection with human immunodeficiency virus is the most notable cause for progression to active disease other factors such as uncontrolled

Primary disease

Primary pulmonary Tb is often asymptomatic so that the results of diagnostic tests are the only evidence of the disease

Associated paratracheal lymphadenopathy may occur because the bacilli spread from the lungs through the lymphatic system

If the primary lesion enlarges pleural effusion is a distinguishing finding

The effusion may remain small and resolve spontaneously or it may become large enough to induce symptoms such as fever

Primary progressive TB

Active TB develops in only 5% to 10% of persons exposed to M. tuberculosis

When a patient progresses to active TB,  early signs & symptoms are often non-specific

Manifestation often include progressive fatigue, malaise, weight loss & a low-grade fever accompanied by chills & night sweats

Wasting a classic features of tuberculosis it involves the loss of both fat & lean tissue the decreased muscle mass contributes to the fatigue

A cough eventually develops in most patients

The sputum may also be streaked with blood hemoptysis can be due to the destruction of a patent vessel located in the wall of the cavity the rupture of a dilated vessel in a cavity

The inflamed parenchyma may cause pleuritic chest pain

The extensive disease may lead to dyspnea or orthopnea because the increased interstitial volume to leads to a decrease in lung diffusion capacity

Although many patients with active disease have few physical finding rates may be detected over-involved areas during inspiration, particularly after cough

leukocytosis may also occur because of the large increase in the number of leucocytes

Extrapulmonary tuberculosis

Although the pulmonary system is the most common location for Tb extrapulmonary disease occurs in more than 20% of immune-competent patients & the risk for extrapulmonary disease increase with immunosuppression

The most serious location is the central nervous system where infection may result in meningitis or space-occupying tuberculomas

Headaches & change in mental status often possible exposure to Tb or in high-risk groups should prompt consideration of this

Another fatal form of extrapulmonary Tb is an infection of the bloodstream by mycobacteria, the form of the disease is called disseminated or military tuberculosis. The bacilli can then spread throughout the body, leading to multi-organ involvement

Military Tb progresses rapidly & can be difficult to diagnose because of its systemic & non-specific signs & symptoms such as fever, weight loss & weakness

Lymphatic Tb is the most common extrapulmonary Tb

Diagnosis of Tb (Tuberculosis)

  • Clinical features are not confirmatory
  • Zell nelson stain
  • Adenosine deaminase test
  • Culture most sensitive & specific  test
  • Conventional Lowenstein Jensen media 3-6 weeks
  • Automated techniques within 9-16 days
  • PCR is available but should only be performed by experienced laboratories
  • Mantoux test

Mantoux test

Infection with mycobacterium Tb leads delayed hypersensitivity reaction which can be detected by the Mantoux test

About 2 to 4 weeks after infection intracutaneous injection of purified protein derivative (PPD) of M. tuberculosis induces a visible & palpable induration that peaks in 48 to 72 hours

PPD tuberculin testing

  • Sub-cutaneous
  • Weal formation
  • Itching no scratch
  • Read after 72 hours
  • Induration size
  • 5-10-15 mm

1)induration less than 5mm- no exposure to tubercular bacilli

2)induration between 5-9 mm -this can be due to typical mycobacteria or BCG vaccination.it may suggest infection in immune-compromised children such as HIV infection or other immune suppression

3)induction 10mm or more an induction of 10 mm or more at 45-72 hours in a child with symptoms of Tb should be  interpreted as tubercular disease

The chest X-ray examination

It is the most important test the most common diagnostic test that leads to the suspicion of infection is a chest x-ray

In primary TB an x ray will show on abnormality in the mild & lower lung field & lymph nodes may be enlarged

Reactivated TB bacteria usually in filtrate the upper lobes of the lungs

Therapeutic management of TB

DOTS REGIMENS OF RNTCP

 

Urinary Tract Infection