Detailed Notes on Inflammation and Infection

Sterile Inflammation

  • Definition: An immune system response to injuries and irritations without the involvement of a pathogen.
  • It is a non-infectious inflammation that can develop into an infectious one.
    • Example: Arthritis is typically non-infectious but can become infectious if bacteria colonize the affected joint. This infection can be caused by bacteria, viruses, or fungi.

Etiology

  1. Autoimmune Conditions: The immune system reacts against the body's own cells.
  2. Physical Damage: Traumatic injuries (crushing, puncture, cut), radiation, high heat, burns.
  3. Chemical Damage: Excessive production of substances in the body, like uric acid, depositing in joints.

Symptoms

  • Inflammation can be acute or chronic.
  • Signs can be external (visible) or internal.
  • Includes redness, swelling, heat, and pain in the affected tissue.
  • Impairs the normal function of the organ.

Pathophysiology

When inflammation occurs in an organ:

  • Swelling and edema are noticeable.
  • Redness, heat to the touch, and pain are present.

Explanation of these phenomena:

  • Increased Blood Flow: Blood flow to the affected area increases due to cytokines secreted by immune cells called leukocytes. These cytokines initiate the inflammatory process.
  • Endothelial Gaps: In response to leukocyte-secreted cytokines, gaps between endothelial cells lining blood vessels widen, and fluids leak from the blood vessels into the interstitial fluid. This leads to blood congestion and local heat.
  • Blood congestion also causes swelling and edema, which put pressure on local nerve endings, causing pain.
  • The result is swelling and edema, pain, redness, and local heat.

Healing Process

  • Leukocytes (macrophages) ingest and remove dead cells, sometimes forming pus, initiating healing.
  • In some cases, healing does not occur, leading to chronic inflammation from a prolonged overreaction of leukocytes, resulting in disease instead of protection.

Diagnosis

  1. CRP (C-Reactive Protein) Blood Test: Identifies inflammatory processes in the body by measuring CRP levels. Normal values are 3-5 mg/L, but no more than 10 mg/L. Levels increase in inflammatory conditions.
  2. Elevated ESR (Erythrocyte Sedimentation Rate) and Leukocyte Count: Normal leukocyte count is 4,500-11,000 per cubic millimeter.

Treatment

Treatment depends on the cause:

  • Anti-inflammatory drugs: Prevent the production of prostaglandins (e.g., aspirin) and steroids.
  • Cytotoxic drugs: Harm cell division, affecting the division of inflammatory cells.
  • Pain relievers: such as Optalgin; cooling or heating the area can also alleviate pain.
  • Rest: Increased body temperature and pain are intended to make the patient rest and avoid strenuous physical activity, thereby accelerating the recovery process.

Types of Inflammation

  • Acute Inflammation: A desirable response of the body's immune cells to cope with damage, typically resolving within a few days.
  • Chronic Inflammation: Inflammation that lasts for an extended period because immune cells cannot overcome the cause. It often results in fibrosis (connective tissue formation) in the affected organ or tissue, damaging the tissue and impairing its function. Chronic pain, depression, anxiety, sleep disorders, and avoidance of physical activity leading to obesity can also accompany it.

Prevention

  1. Maintaining proper hygiene to prevent pathogenic infiltration that can cause sterile inflammation to develop into infectious inflammation.
  2. Strengthening the immune system by maintaining a healthy lifestyle: eating a varied diet (vegetables of all colors, two to three fruits a day, whole grains, legumes, avoiding fatty red meat and saturated and trans fats), drinking enough water and avoiding sugary drinks, engaging in consistent physical activity, and avoiding smoking.
  3. Avoiding contact with allergenic and polluting agents.

Infectious Inflammation

Definition

Infectious inflammation is caused by the entry of microorganisms into the body.

Etiology

The infectious agents can be bacteria, viruses, and various parasites. Some potential contaminants live in the body all the time, coexist in equilibrium with the body's cells, and are harmless when the immune system is working correctly. However, if the immune system is impaired due to immunosuppression or a poor physical condition such as poor nutritional status or after injury, trauma, or surgery, infectious inflammation will appear.

Symptoms

The symptoms of sterile and infectious inflammation can be identical, making it difficult to distinguish between them. They manifest as redness, swelling, heat, and pain in the affected tissue. In infectious inflammation, an increase in body temperature is also expected due to substances secreted by leukocytes that reach the hypothalamus (the area that regulates body temperature) via the bloodstream, raising it.

Pathophysiology

Pathogenic agents cause inflammation by secreting toxins that damage adjacent tissues. Immune cells are attracted to the site due to the toxins and respond by secreting cytokines, initiating the process described in sterile inflammation: enlarging the gaps between endothelial cells of blood capillaries and leakage of blood fluid into the interstitial spaces. In infectious inflammation, the process is initiated by a pathogenic agent, whereas in sterile inflammation, the cause is a traumatic or autoimmune factor. When an infection develops, inflammation will always occur, manifesting as swelling, redness, heat, and pain. Leukocytes exit the blood through the enlarged gaps between endothelial cells, enter the tissue, and ingest bacteria and other foreign particles. The exit of leukocytes in the inflammatory area allows a larger number of them to ingest pathogenic agents. They die in the process, resulting in accumulated pus.

Diagnosis

  1. Bacterial Infection: The number of leukocytes in a blood count will greatly increase, especially the percentage of neutrophils (normal range is 40%-75% of total leukocytes).
  2. Viral Infection: The total blood count will increase less and will mainly manifest in an increase in the number of lymphocytes (normal range is 20%-45% of total white blood cells) and monocytes (normal range is 2%-9% of total white blood cells).
  3. Parasitic Infection: The number of eosinophils will increase (normal range is 1%-7% of total white blood cells).

Tests

  1. Blood Tests: ESR and CRP (see details in sterile inflammation).
  2. Blood Count: For white blood cells of all types.
  3. Smears and Cultures: From inflammatory areas and blood (throat swab, urine culture, sputum culture, blood culture) to check for the presence of a pathogen.
  4. Serological Tests: To find antibodies in the serum against microorganisms, usually in viral diseases.

Routes of Infection

  1. Direct contact with the patient through kissing, sexual contact, droplets emitted in speech, coughing, or sneezing.
  2. Via a disease carrier such as an animal or insect.
  3. Eating or drinking contaminated food.
  4. Transfer from mother to fetus or infant.
  5. Organisms that entered the body through wounds or mucous membranes.

Primary Prevention

  1. Strengthening the immune system by maintaining a healthy lifestyle: varied diet, sufficient drinking, physical activity, avoiding smoking (see details in sterile inflammation).
  2. Vaccinations given in childhood and adulthood, as well as in cases of injury (against tetanus).

Treatment

  1. Supportive treatment with rest, hydration, and pain management.
  2. Antibiotic treatment against bacteria, fungi, or parasites.
  3. Viral Infection: Treatment with antiviral drugs (provided that treatment begins immediately upon onset of infection). In most cases, there is no drug treatment for viral infection, and it resolves on its own. Anti-inflammatory or cytotoxic drugs that impair the body's ability to cope with the infectious agent should be avoided as much as possible.

Summary – Inflammation and Infection

Inflammation

  • Definition: A protective response of the immune system against many events of stress. There are inflammations due to autoimmune reasons, traumatic reasons such as crushing, cutting and stabbing, chemical injury or heat injury, and as a reaction to infection.
  • Causes: Overexertion in a tendon causing inflammation in that tendon. Deposition of uric acid in a joint can cause body cells to react in inflammation of that joint. Injury, sting, penetration of microorganisms, thorn or other foreign body.
  • Mode of Transmission: Overexertion, deposition of various substances in the body, injury, sting, allergy and penetration of organisms such as in infection.
  • Diagnosis: Various components of the immune system participate in the inflammatory response. There is an increase in inflammatory markers (ESR and CRP) as well as an increase in leukocyte count. Sometimes it is also possible to find specific antibodies indicating certain types of autoimmune diseases (e.g., in inflammation of blood vessels, arthritis, etc.).
  • Signs: Redness, swelling and local heat only in the area of inflammation or systemic throughout the body and pain in the affected tissue.
  • Pathophysiology:
    1. Blood vessels in the affected area dilate, the distance between endothelial cells increases, and blood flow is increased.
    2. Blood vessel permeability increases and edema appears.
    3. White blood cells leave the blood, enter the tissue and attack the cause that created the inflammation.
    4. Other cells remove the dead cells, sometimes forming pus, thus beginning the healing process.
    5. Heat and a feeling of pain, as in the case of infectious inflammation. In some circumstances, healing does not occur, and chronic inflammation develops – a condition of illness rather than protection.
  • Tests:
    1. Blood test for ESR and CRP.
    2. Blood count to check the number of leukocytes and their rate.
    3. Tests for specific antibodies of autoimmune diseases.
    4. Various smears to detect the infectious agent if present.
  • Primary Prevention:
    1. Strengthening the immune system with a healthy lifestyle: varied diet, sufficient drinking, physical activity, avoiding smoking.
    2. Avoiding contact with allergenic and polluting agents.
  • Secondary Prevention - Treatment:
    1. Treatment according to the cause, such as preventing contact with the substances that created the inflammation. Treatment for infection.
    2. Anti-inflammatory drugs such as aspirin that work to prevent the production of prostaglandins.
    3. Anti-inflammatory drugs of the steroid type.
    4. Cytotoxic drugs that impair cell division in general and the division of inflammatory cells in particular.
    5. Pain relievers such as paracetamol and optalgin.
    6. Relief with cooling or heating of the place.

Infection

  • Definition: Invasion of disease-causing organisms into the body.
  • Causes: Bacteria, viruses, parasites, fungi.
  • Mode of Transmission: Direct contact with a patient through kissing, sexual contact, droplets emitted in coughing or sneezing, through a disease carrier such as an animal or insect, by eating or drinking contaminated food, by transfer from mother to fetus or baby. Organisms can enter the body through wounds or mucous membranes.
  • Diagnosis:
    1. In most cases of bacterial, fungal or viral infection, inflammation develops due to the presence of intracellular or extracellular toxins and damage to adjacent tissues, and the immune system responds in the same mechanism as in inflammation.
    2. The blood count will increase greatly in bacterial infection and will mainly manifest in an increase in the percentage of neutrophils. The total blood count in a viral infection will increase less and will mainly manifest in an increase in lymphocytes. There will be an increase in eosinophils in parasitic infection and monocytes.
    3. Cultures (blood, urine, throat, sputum, etc.) that confirm and identify the infectious agent.
  • Signs: In most cases, the response is very similar to the inflammatory response and it is difficult to distinguish between them: redness, swelling, local heat and pain in the affected tissue.
  • Pathophysiology:
    1. At the beginning of the infectious process, the immune system activates white blood cells that try to ingest and destroy the pathogen. At the same time, they secrete substances that attract other white blood cells to the site of the invasion. The blood vessels in the area of infection dilate to allow a large number of white blood cells to reach there, and the blood vessels that leave it contract.
    2. As a result, additional phenomena accompanying inflammation are swelling, redness, an increase in body temperature and pain. The increase in body temperature stems from the flow of substances secreted from white blood cells to the hypothalamus, the area in the brain that regulates body temperature. The feeling of pain originates in the contraction of the blood vessels leaving the site of injury, which causes an increase in fluid pressure and swelling that puts pressure on the pain sensors.
  • Tests:
    1. Blood test for ESR and CRP.
    2. Blood count to check for the presence of inflammatory cells.
    3. Smears and cultures from the areas of inflammation and from the blood (throat swab, urine culture, etc.).
    4. Serological tests to find antibodies against the microorganism, usually in the case of viral diseases.
  • Primary Prevention:
    1. Strengthening the immune system with a healthy lifestyle: varied diet, sufficient drinking, physical activity, avoiding smoking.
    2. Vaccinations given in childhood and in cases of injury.
  • Secondary Prevention - Treatment:
    1. Antibiotic treatment against the bacteria.
    2. Treatment against fungi.
    3. Drug treatment against parasites.
    4. Viral Infection: Treatment with antiviral drugs. In most cases, there is no drug treatment and the infection goes away on its own. Sometimes antibiotics are given to prevent secondary infection by bacteria and treatment against the virus (e.g. in cases of herpes).
    5. Supportive treatment of rest, drinking and painkillers.
    6. Anti-inflammatory or cytotoxic drugs that impair the body's ability to cope with the infectious agent should be avoided.