Pneumonia of the lungs caused by bacterial pneumonia and other pathogens

Bacterial pneumonia

1. Streptococcus pneumoniae pneumonia

Streptococcal pneumoniae pneumonia is pneumonia caused by the bacterium Streptococcus pneumoniae (SP), which usually has a rapid onset and is characterized by high fever, chills, cough, bloody sputum, and chest pain.

【Etiology and Pathogenesis】

SP is a Gram-positive cocci with a capsule, and its virulence is related to the structure and content of polysaccharides in the capsule. Type 3 is the most virulent and is a normal flora that resides in the oral cavity and nasopharynx, does not produce toxins, does not cause tissue necrosis or the formation of cavities. The pathogenicity is due to the invasive effect of the capsule of the polymer polysaccharide on tissues.

【Pathology】

After the lesion dissipates, the lung tissue structure is mostly undamaged, and there is no fibrous scarring.

【Clinical manifestations】

1. Symptoms: history of cold, rain, fatigue, drunkenness, viral infection, sudden onset, high fever, chills, muscle aches all over the body, body temperature rises to 39~40 °C within a few hours, and the sputum is rusty.

2. Signs: acute fever, crimson cheeks, nasal wings, burning and dry skin, herpes simplex at the corners of the mouth and around the nose; In patients with sepsis, hemorrhages of the skin and mucous membranes and jaanthosis of the sclera may occur. Severe patients have intestinal flatulence.

【Complications】Patients with severe sepsis or toxemia are prone to septic shock.

[Laboratory and other tests]

1. Blood culture should be done for severe pneumonia.

2. If pleural effusion is combined, the effusion should be actively extracted for bacterial culture.

3. Chest imaging examination: in the dissipation period, the inflammatory infiltration is gradually absorbed, and there may be patchy areas with rapid absorption and "pseudocavitation" signs. Pneumonia in the elderly is prone to incomplete absorption, forming organizing pneumonia.

【Diagnosis】Pathogen detection is the main basis for confirming the diagnosis of this disease.

【Treatment】

1. Antibacterial drug treatment: penicillin is preferred, patients who are allergic to penicillin, or infected with penicillin-resistant strains, use respiratory fluoroquinolones, cefotaxime or ceftriaxone and other drugs, and those infected with MDR strains can use vancomycin, teicoplanin or linezolid.

2. Supportive therapy.

3. Treatment of complications: After antimicrobial treatment, high fever often subsides within 24 hours, or gradually decreases within a few days. If the body temperature drops and rises again or does not decrease after 3 days, extrapulmonary infection of SP, such as empyema, pericarditis, or arthritis, should be considered.

2. Staphylococcal pneumonia

Staphylococcal pneumonia is an acute purulent inflammation of the lungs caused by staphylococcal bacteria. It usually occurs in patients with underlying medical conditions, with sudden onset, high fever, chills, chest pain, purulent sputum, and early circulatory failure. complicated by lung abscess, empyema, etc.

【Etiology and Pathogenesis】

Staphylococci are gram-positive cocci, which can be divided into coagulase-positive staphylococci (mainly Staphylococcus aureus) and coagulase-negative staphylococci (such as Staphylococcus epidermidis) The causative substances are mainly toxins and enzymes, and Staphylococcus aureus is positive for coagulase, which is the main cause of purulent infection.

【Pathology】Tension pulmonary air cyst is produced. Superficial pulmonary cysts can ulcerate to form pneumothorax or pneumothorax if the tension is too high.

【Clinical manifestations】

1. Symptoms: sudden onset, chills, high fever, chest pain, thick phlegm, body temperature as high as 39~40 °C, obvious symptoms of poisonous blood, and peripheral circulatory failure can occur early in severe cases. Elderly patients are atypical.

2. Signs: early morning is optional, often not parallel to severe poisoning symptoms and respiratory symptoms. Other corresponding signs (empyema, pneumothorax, consolidation, wet and dry rales).

[Laboratory and other tests]

1. Chest X-ray examination: cavity is formed, and the liquid air sac cavity is formed. Another feature is the variability of the radiographic opacities, which manifest as the loss of inflammatory infiltrates in one place and the appearance of new lesions in another, or the development of large opacities in a small single lesion.

【Diagnosis】Bacteriological examination is the basis for confirming the diagnosis.

【Treatment】

The resistance rate of Staphylococcus aureus to penicillin has been as high as about 90%, and penicillinase-resistant semisynthetic penicillin or cephalosporins, oxacillin sodium, cefuroxime, combined with aminoglycosides such as amikacin.For MRSA, vancomycin, teicoplanin, and linezolid should be used.

Lung infections caused by other pathogens

1. Mycoplasma pneumoniae pneumonia

Mycoplasma pneumoniae pneumonia is an acute inflammatory change in the respiratory tract and lungs caused by Mycoplasma pneumoniae (MP), often with pharyngitis, bronchitis, and pneumonia. It occurs mainly in children and adolescents.

【Etiology and Pathogenesis】

Interstitium, alveolar wall, etc. can be involved. IgE response is also enhanced after MP infection, and IgE-mediated hypersensitivity reactions may occur, prompting acute exacerbations in asthma patients.

【Pathology】

Bronchopneumonia, interstitial pneumonia, and bronchiolitis.

【Clinical manifestations】

There is an incubation period, slow onset, fatigue, headache, sore throat, muscle aches, can be accompanied by nasopharyngeal, ear pain, lymphadenopathy, obvious cough, mostly episodic dry cough, severe at night, persistent paroxysmal cough is a typical manifestation of mycoplasma pneumonia, and some people have maculopapular rash and erythema.

[Laboratory and other tests]

1. White blood cells: mainly neutrophils.

2. 2/3 of the patients have a positive condensation test, a titer of ≥1:32, an IgM antibody ≥ 1:64, or a 4-fold increase in the convalescent antibody titer, which can further confirm the diagnosis.

3. X-ray examination: it is segmental distribution, and the lower field of the lungs is more common.

【Treatment】

Macrolide antibiotics are preferred, with erythromycin, roxithromycin, and azithromycin. Patients who are insensitive to macrolides may be treated with a respiratory fluoroquinolone, such as levofloxacin. Mycoplasma do not have a cell wall, and antibiotics such as penicillin or cephalosporins are ineffective.

2. Chlamydia pneumoniae pneumonia

[Clinical manifestations] early stage: symptoms of upper respiratory tract infection, quite similar to mycoplasma pneumonia.

【Treatment】Macrolide antibiotics are the first choice

3. Viral pneumonia

【Pathology】Bronchiolitis. It is usually interstitial pneumonia with a large number of monocytic infiltration. A transparent membrane is formed, and viral inclusion bodies are visible.

【Clinical manifestations】The symptoms are similar to those of mycoplasma pneumonia.However, the onset is more acute, and systemic symptoms such as fever, headache, body aches, and fatigue are more prominent.

[Laboratory and other tests]

1. The white blood cells are mostly monocytes.

2. Chest X-ray examination: increased lung textures, ground-glass shadows, small flake infiltrates or extensive infiltrates, consolidation, severe cases show diffuse nodular infiltrates in both lungs, but lobar consolidation and pleural effusion are rare.

【Treatment】Ribavirin, acyclovir, ganciclovir, oseltamivir, cytarabine, amantadine.