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Pneumonia

Pneumonia (inflammation of the lungs) is inflammation in the alveoli, bronchioles, and interstitial connective tissue that are different in etiology and pathogenesis; often involved in the inflammatory process and blood vessels of the lung.

Pneumonia occurs as an independent disease or complicates the course of other diseases.

There are acute and chronic pneumonia. There are a number of clinical and morphological types of acute pneumonia, but focal and lobar pneumonia are considered the main ones. This separation gives an idea of ​​the nature of the anatomical changes, the prevalence of the process and the severity of the disease. In case of focal and croupous pneumonia, inflammation is localized in the lung tissue and bronchi (parenchymal pneumonia). Interstitial pneumonia is also isolated, in which predominantly the connective tissue of the lung is affected.

Etiology and pathogenesis . Pneumonia refers to infectious diseases, because in its occurrence the bacterial microflora (pneumococci, staphylococci , streptococci ), viruses (influenza, adenoviruses), mycoplasmas of pneumonia, etc. are important. The penetration of pathogens into the lungs occurs mainly by bronchial route. Hematogenous and lymphogenous routes of infection are also possible. The oral cavity and nasopharynx are the main sources of microbes entering the trachea and bronchi. Along with infectious agents for the occurrence of the disease, factors predisposing to the disease that affect the reactivity of the organism and lower its resistance are also important.

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Such factors include certain meteorological effects on the body, primarily hypothermia in combination with high humidity, disruption of normal working and living conditions, physical and mental fatigue, past lung diseases, chronic intoxication, bad habits (smoking, alcoholism), malnutrition.

Various forms of pneumonia are associated with features of the body’s response to pathogens. Croupous pneumonia usually occurs with increased reactivity, focal - with normal or reduced body reactivity.

Pathological anatomy. With pneumonia in areas affected by the inflammatory process of the lung at the beginning of the disease, intensive blood circulation begins. The alveoli are filled with inflammatory effusions containing fibrin , rejected cell epithelium , red and white blood cells, as a result of which the air from the inflamed part of the lung is forced out. The lung loses airiness, becomes dense and heavy. Inflammatory changes are observed not only in the alveoli, but also in the smallest bronchi. The epithelium lining the bronchi is loosened, the lumen of the bronchi is filled with effusion. Alveoli overflowing with inflammatory contents press on capillaries, as a result of which they are poorly filled with blood up to a complete cessation of blood flow in a number of areas of inflamed tissue; then comes the gradual softening of the inflammatory effusion. Leukocytes, which contain enzymes that dissolve effusion coagulated in the alveoli, are of great importance. The contents of the alveoli after its dilution is partially absorbed, and partially removed when coughing.

Anatomical changes do not always occur in a strictly defined sequence. In croupous pneumonia, there are several stages (hyperemia, red and gray hepatization, and resolution stage). The morphological picture of focal pneumonia is quite variegated: along with the resolution sites, there are foci of intense hyperemia, etc. Lymph nodes located near the inflammatory sites increase in size and remain swollen even for some time after the inflammatory process has been eliminated.

As recovery occurs, the normal anatomical structure of the lung is restored, and the alveoli again begin to perform the function of gas exchange .

Definition

Pneumonia (pneumonia; from Greek. Pneumon - lung) is an inflammation of the lung. Under the name pneumonia, inflammatory processes of various etiology and pathogenesis are found, localized in the bronchioles, alveolar tissue, interstitial connective tissue; often the inflammatory process extends to the vascular system of the lungs. Soviet clinicians distinguish acute and chronic pneumonia by the nature of the clinical course and originality of morphological changes.

Usually the term "pneumonia" indicates inflammation, mainly acute, pulmonary parenchyma. The term “pneumonitis” is a synonym for the first concept, it is more often used to define mild segmental pneumonia, and its use is best avoided. Clinically, the diagnosis of pneumonia is established either in the presence of certain physical signs, or radiographically, in the presence of areas of compaction of the lung tissue.

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Classification and etiology of pneumonia

Although lobar consolidation is most often caused by pneumococcus, any anatomical type of pneumonia can, on occasion, be caused by any established etiological agent. The diagnosis must therefore be both etiological and anatomical. For example, we can talk about pneumococcal or staphylococcal lobar pneumonia; segmental pneumonia caused by the virus of psittacosis, or staphylococcal lobular pneumonia, which has complicated the viral infection.

Anatomical classification . It is convenient to divide pneumonia into lobar, segmental and lobular, which, when bilateral localized, are often called bronchopneumonia.

Etiological classification . Determination of etiological agents. Most pneumonia is infectious, although chemical or allergic pneumonia can occur. Isolation of certain viruses or bacteria from the patient’s sputum does not necessarily mean that this agent is the cause of pneumonia. This is particularly true of influenza bacilli or Escherichia coli in adults or enterovirus in children. It is not clear whether normal saprophytes of the upper respiratory tract can, if necessary, cause pneumonia. The suppuration phase of a common cold is probably associated with the activation of common saprophytes, especially N. catarrhalis and greening streptococcus [65].

In some elderly people, in persons with weakened or with previous diseases, such as chronic bronchitis, pneumonia occurs clinically and therapeutically as bacterial, although it is not possible to isolate any pathological agent. It is possible that the deterioration of the protective properties of the organism allows the saprophytes of the upper respiratory tract to penetrate into the lower parts of the respiratory tract, multiply there and become pathogenic. It was with certainty proven by blood cultures, pleural exudates or areas of the lungs obtained by autopsy that green streptococcus can cause the development of pneumonia [70]. When applying the best methods in patients who have not undergone prior antibiotic therapy, only in rare cases can the etiological factor not be determined. Bath et al. found that the inability to isolate a bacterial agent was most often associated with previous antibacterial therapy [8]. The presence of a viral infection or some kind of technical error can explain other failures. Only in 10% of all negative results there was no objective explanation.

If the patient has already received antibacterial drugs, then determining the etiological factor may be difficult. In particular, pneumococci very quickly disappear from sputum and blood, they can sometimes be detected with conventional smear smear, although they already do not give growth. It must be remembered that if the patient has already received antibacterial drugs, it is likely that only microorganisms that are resistant to this drug survive, but they may have nothing to do with the observed pneumonia. For example, the isolation of penicillin-resistant E. coli from a patient who has already received penicillin for 2 days does not indicate that this microorganism has etiological significance. In addition, if several colonies of stable staphylococcus grow in the course of sowing sputum of a patient who has already received antibiotic therapy, then these cocci should be considered as pollution rather than as microorganisms causing pneumonia.

Special care is required when isolating viruses. In the past, material from patients often remained at low temperatures before the study, and this, as shown now, contributes to the inactivation of the respiratory syncytial virus and, perhaps, other viruses. Currently, the exact etiological diagnosis for viral pneumonia is usually established retrospectively, because the time required to isolate the virus is long, and a fourfold increase in serological titers, which is believed to be diagnostically reliable, can only be obtained by the time of the patient's final recovery. Other, faster methods are being developed, and perhaps the immunofluorescence method will soon provide direct and immediate identification of the virus in sputum or other material [6]. Doane et al. described the immediate identification of the parainfluenza virus in a secret from the nasopharynx both by electron microscopy and by the hemagglutination method [18].

The cause of pneumonia is usually multiple agents. Quite often, excretion of influenzae streptococcus as well as influenza bacilli occurs in the same patient [8]. In patients in need of inpatient treatment, it is often possible to find evidence of both viral and bacterial infections. Quite often, more than one virus can be isolated in the presence of bacterial agents [20]. In such cases, it is difficult to resolve the issue of primary infection, but since in most cases viruses infect the upper respiratory tract, a viral infection is likely primary, which prepares the ground for bacterial pneumonia, as has long been known in cases of influenza and measles.

Mushrooms can sometimes also cause pneumonia. Changes considered pneumonic can occur in certain allergic and collagen diseases. Less commonly, aspiration or inhalation of certain fluids, fumes, or toxic gases can cause pneumonia or, more accurately, pulmonary edema with its secondary infection. Pneumonia can also develop with x-ray irradiation.

Infectious agents causing the development of pneumonia. The main bacterial agents that cause pneumonia are the following: pneumonic streptococcus, pyogenic staphylococcus, Friedlender's wand, whooping cough bacteria and mycobacterium tuberculosis. Respiratory syncytial virus is the most common cause of viral pneumonia in children. Secondary bacterial flora often leads to the development of pneumonia in patients with measles and influenza, and sometimes in patients with other types of viral infections of the upper respiratory tract, especially with para-influenza. These viruses can sometimes cause pneumonia themselves, which is relatively common in the group of psittacosis (ornithosis). Mycoplasma pneumonia can cause epidemics, especially among isolated groups of young people, such as in barracks, but can also occur in the form of endemia. Q fever (V. burneti) causes the development of pneumonia in some parts of England and other countries of the world. Actinomycetes israelii and other fungi give the development of pneumonia relatively rarely.

This is followed by a detailed list of agents that may cause pneumonia. Less important are enclosed in brackets.

Bacterial pneumonia

Frequent
Streptococcus pneumonia: pneumococcus
Pyogenic staphylococcus
Mycobacterium tuberculosis

Rare
Friedlander's Wand
Influenza Wand
E. coli
Pseudomonas aeruginosa
Bacteroids
Pus Streptococcus
Green Streptococcus

Pneumonia as a manifestation of a specific bacterial disease
Frequent
Whooping cough: whooping cough
GIF - paratyphoid: Salmonella typhoid and paratyphoid
Brucellosis: Brucella cattle and small cattle
Rare
Plague: Pasteurella Plague
Tularemia: Tularemia Bacterium
Anthrax: anthrax bacillus
Leptospirosis: leptospira icter-hemorrhagic and silt

Viral pneumonia
Pneumonia, usually complicating the infection:
Psittacosis-ornithosis group
Respiratory syncytial virus
Influenza: pneumonia is usually bacterial
Measles: pneumonia is usually bacterial
Cytomegalovirus
Pneumonia, occasionally complicating infections:
Most viral infections of the upper respiratory tract include:
Frequent
Adenoviruses
Parainfluenza viruses
Rhinoviruses
Rare
Chickenpox: varicella virus
Shingles
Smallpox
Lymphocytic choriomeningitis
Infectious mononucleosis

Rickettsial pneumonia
(complicating epidemic and endemic typhus)
Q fever: Burnet’s rickettsia

Mycoplasma pneumonia
Mycoplasma pneumonia
Erythema polymorphic exudative: Stevens-Johnson syndrome.

Pneumonia associated with yeast, fungi and protozoa
Frequent
Actipomycosis: Actinomyces israelii
(Nocardiosis: Nocardia asteroides)
(Aspergillosis: Aspergillus fumigatus)
Rare
(Coccidioidomycosis: Coccidioides immitis)
(Histoplasmosis: Histoplasma capsulatum)
(Pneumocystis carinii) (Toxoplasma gondii)

Allergic pneumonia and pneumonia complicating collagen diseases
Pulmonary eosinophilia (including polyarteritis nodosa and Wegener syndrome)
(Rheumatism)
(Rheumatoid disease)
(Disseminated lupus erythematosus)

Chemical pneumonia
Frequent
Aspiration of vomit
(Dysphagic pneumonia)
(Toxic gases and smokes)
(Oil pneumonia)
Rare
Manganese
Beryllium
Aspiration of volatile hydrocarbons, such as gasoline
Radiation pneumonia