Mycobacterium Tuberculosis pathogensis and it’s spread

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Mycobacterium tuberculosis

Mycobacterium tuberculosis is rod-shaped bacilli, which have waxy cell walls and RNA in their genome. This wax or lipid in the cell wall makes the bacteria to survive and multiply in human cells. This bacteria causes tuberculosis in humans which is an extremely serious disease but can be cured with antibiotics. It can affect infants, children, adults, and older people but mostly affects the compromised immune system or debilitated people like AIDS, immunosuppressive therapies, non-vaccinated people.

First, it starts with mild or no symptoms, but after 3 to 4 weeks, flu-like symptoms like upper respiratory tract infection, cough, fever, weight loss or night sweats begin to appear. It is curable. Nine-month proper medication intake can cure this disease completely. If it is undiagnosed or untreated, it’s mortality rate is 80 percent in the population. It mostly provoked by poverty, small area of living, large people in a small home, smoking, and poor hygiene.

TRANSMISSION OF TUBERCULOSIS

Tuberculosis spreads from person to person through the respiratory droplets. Infected people are the source of transmission of this disease. It is highly contagious. This can also occur via meat of infected animals or milk. It can also spread via respiratory aerosols of infected feces.

TYPES OT MYCOBACTERIUM TUBERCULOSIS

There are two types of tuberculosis that are:

  1. Primary tuberculosis

Initial exposure of tuberculosis bacteria in an uninfected person

2. Secondary tuberculosis

Re-exposure of the bacteria after the recovery of initial tuberculosis

PRIMARY TUBERCULOSIS

Primary tuberculosis occurs, when a mycobacterium enters through the respiratory tract of an uninfected person and it is a very initial phase. Sometimes it is symptomatic or some time is asymptomatic. Most commonly seen symptoms are

  • High-grade fever
  • Anorexia
  • Weight loss
  • Fatigue
  • Restlessness
  • Night Sweats
  • Cough
  • Upper respiratory tract infections

On radiography, cavitation is seen mostly in the lower lobe of the lung.

How Mycobacterium Tuberculosis Affects The Body?

Bacteria enter via respiratory droplets of a deceased person into the normal individual. Inflammatory proteins and plasma cells of blood transmit this bacteria into the circulation. Mostly this bacteria enters the lungs. In the lungs, these bacteria attach with the non-activated macrophages and make the complex. This area is called Gohn focus. Bacilli multiply in this macrophage and affected the nearby lymph nodes and cause lymphangitis. This lymph node and Gohn focus collectively called as GOHN’s COMPLEX. Now inflammatory mediators like lymphokines, cytokines accumulate around this Gohn complex, and fibrosis occurs. This fibrosis is seen on x-rays. Now tubercle bacteria have large numbers and it can affect any part of the body if left untreated. It can affect

1- Tb In Bones

If it infects the bones, known as Skeletal Tuberculosis. In primary infection, it spreads via blood or lymphatics to the bones or joints. It mostly affects the metaphysis part of bones, because it is rich in blood supply. Their cells have died, necrosis occurs, bones destruction takes place by the direct infection of tubercle. The body has many joints but mostly vertebrae are affected by this bacteria. Among vertebrae, T12 is more likely to be affected. Vertebrae have body, processes, and space, but the body is mostly destructed. Therefore on Xrays, the body of vertebrae is widened and disc space appeared narrow.

Clinical Features

Patients having skeletal Tb presented with the complaints of

  • Restlessness
  • Fatigue
  • Postural disturbance
  • Abnormal gait
  • Low-grade fever
  • Pain

2- Tb In Lungs

Mycobacterium can spread to many parts of the body but mostly it affects the lung because it is a site of its primary lesion. In the lungs, mostly the upper lobe of the lung is prone to get an infection because it is a more oxygenated part of the lung. It spreads via lymph nodes or blood vessels. It causes Bronchopneumonia. Most of the lunch tuberculosis are subclinical or latent. They don’t show any symptoms on radiographic or as well as inpatients, but a tuberculin skin test is a tool of diagnosis.

Clinical Features

Children with bronchopneumonia or pulmonary pneumonia mostly manifest the

  • High-grade fever
  • Anorexia
  • Weight loss
  • Cough
  • Upper respiratory tract infection
  • Night Sweats
  • Fatigue
  • Irritability
  • Malaise

On radiography, lungs show lymphadenopathy, infiltration of lymphocytes or neutrophils. Mostly hilar lymph nodes are inflamed. If these lymph nodes are involved, lobar pneumonia is seen. The patient presents with high-grade fever, cough, respiratory distress, high breath sounds, dullness on percussion, and rales.

3- Tb In Systemic circulation

From the early lesion, Gohn Complex, tubercle bacteria begin to multiply and released via the vascular system. When this mycobacterium enters the systemic circulation, it causes Systemic Miliary Tuberculosis. It spreads by lympho-hematogenous. Miliary Tuberculosis is defined as, the release of multiple numbers of tubercles into the bloodstream and affects simultaneously one or two organs of the body. It mostly appeared at 3 to 6 months of the primary gohn complex.

Clinical Features

Miliary Tuberculosis is manifested by the following symptoms:

  • Low-grade fever
  • Anorexia
  • Weight loss
  • Malaise
  • Generalized lymphadenopathy
  • Hepatosplenomegaly
  • If it infects the brain, then headache is the complaint of meningitis.

If it infects the abdomen, abdominal pain and tenderness are the signs of peritoneal tuberculosis.

On radiographic, pleural effusion is seen. Lungs are filled with bacteria, wheezing, rales, pneumothorax, and pneumomediastinum are the positive findings on X-Rays.

4- Tb In Kidney

It is rare in children because it takes many years to develop. If tubercle spreads through the lympho-hematogenous dissemination, it causes Renal Tuberculosis. Actually, these bacteria reach the kidney and multiple within the renal parenchyma. Infections may spread to the ureter, urethra, prostate, and epididymis.

Clinical Features

No symptoms are seen over here. Some signs are characterized like

  • Sterile pyuria
  • Hematuria
  • Flank pain
  • Dysuria

It is diagnosed by a positive urine culture.

DIAGNOSIS OF MYCOBACTERIUM TUBERCULOSIS

Following tests are done to diagnose tuberculosis effectively

  • Contact History
  • Tuberculin Skin Test
  • Radiological findings
  • AFB smear or blood culture
  • Biopsy