Pneumonia in adults

Pneumonia is an acute pneumonia caused by an infection. The initial diagnosis is usually based on chest X-ray.

The causes, symptoms, treatment, prophylaxis and prognosis depend on whether the infection is bacterial, viral, fungal or parasitic; community hospital, hospital, or originated in a nursing home; develops in an immunocompetent patient or against the background of a weakened immunity.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]

Epidemiology

Pneumonia is among the most common infectious diseases. In Europe, the annual number of patients with this diagnosis ranges from 2 to 15 per 1000 population. In Russia, the incidence of community-acquired pneumonia reaches 10-15 per 1000 population, and in the older age groups (over 60 years) - 25-44 cases per 1000 people per year. Approximately 2-3 million people in the United States suffer from pneumonia every year, about 45,000 of them die. This is the most common nosocomial infection with a fatal outcome and the most common cause of death in developing countries.

Despite significant progress in diagnosis and treatment, the mortality rate for this disease is increasing. Community-acquired pneumonia is the most common cause of death among all infectious diseases. In the overall structure of the causes of death, this disease is the fifth after of cardiovascular, oncological, cerebrovascular diseases and COPD, and in the older age group, mortality reaches 10-33%, and among children under 5 years old - 25%. Even higher mortality (up to 50%) is characterized by the so-called nosocomial (hospital or nosocomial) and some “atypical” and aspiration pneumonia, which is explained by the highly virulent flora that causes these forms of the disease, as well as the rapidly developing resistance to traditional antibacterial drugs.

The presence of a significant proportion of patients with severe concomitant diseases and some risk factors, including primary and secondary immunodeficiency, has a significant impact on the course and prognosis of pneumonia.

[11], [12], [13], [14], [15], [16]

Causes of the pneumonia

In adults older than 30 years old, the most frequent pathogens of pneumonia are bacteria, and in all age groups, under all socio-economic conditions and in all geographical areas, Streptococcus pneumoniae dominates. However, pneumonia can cause any disease-causing organisms, from viruses to parasites.

The respiratory tract and lungs are constantly exposed to disease-causing organisms in the environment; the upper respiratory tract and oropharynx are especially colonized by the so-called normal flora, which is safe thanks to the body’s immune defenses. If disease-causing organisms overcome numerous protective barriers, infection develops.

See also: Inflammation of the lungs

Protective factors of the upper respiratory tract include salivary IgA, proteolytic enzymes and lysozyme, as well as growth inhibitors produced by normal flora and fibronectin, which covers the mucosa and inhibits adhesion. Nonspecific protection of the lower respiratory tract includes coughing, clearance of ciliated epithelium and the angular structure of the respiratory tract, which prevents airspace infection. Specific protection of the lower respiratory tract is provided by pathogen-specific immune mechanisms, including opsonization of IgA and IgG, anti-inflammatory effects of surfactant, phagocytosis by alveolar macrophages and T-cell immune responses. These mechanisms protect most people from infection. But in many conditions (for example, in case of systemic diseases, malnutrition, hospitalization or stay in a nursing home, antibiotic therapy), the normal flora changes, its virulence increases (for example, when exposed to antibiotics) or the protective mechanisms are violated (for example, when smoking cigarettes, nasogastric or endotracheal intubation). Pathogens that in these cases reach the alveolar spaces by inhalation, due to contact or hematogenous spread or aspiration, can multiply and cause inflammation of the lung tissue.

Specific pathogens that cause inflammation of the lung tissue are not released in more than half of the patients, even with a comprehensive diagnostic study. But, since under similar conditions and risk factors there are certain tendencies in the nature of the pathogen and the outcome of the disease, pneumonia is classified into community-acquired (acquired outside the hospital), hospital-acquired (including postoperative and associated with artificial ventilation of the lungs), acquired in nursing homes, and in immunocompromised persons; This allows you to prescribe empirical treatment.

The term “interstitial pneumonia” refers to a variety of conditions with an unknown etiology characterized by inflammation and fibrosis of the pulmonary interstitium.

Community-acquired pneumonia develops in people with limited or no contact with medical institutions. Usually identified Streptococcus pneumoniae, Haemophilus influenzae and atypical microorganisms (ie. E. Chlamydia pneumoniae, Mycoplasma Legionella sp pneumoniae ). Symptoms - fever, cough, shortness of breath, tachypnea and tachycardia. The diagnosis is based on clinical manifestations and chest X-ray. Treatment is carried out empirically selected antibiotics. The prognosis is favorable for relatively young and / or healthy patients, but many pneumonia, especially caused by S. Pneumoniae and the influenza virus, are fatal in the elderly and debilitated patients.

Many microorganisms cause community-acquired pneumonia, including bacteria, viruses, and fungi. Different pathogens prevail in the etiological structure depending on the patient's age and other factors, but the relative importance of each as a cause of community-acquired pneumonia is doubtful, since most patients do not undergo a complete examination, but even with the examination specific agents are detected in less than 50% of cases.

S. Pneumoniae, H. Influenzae, S. Pneumoniae, and M. Pneumoniae are the most common bacterial pathogens. Chlamydia and mycoplasma are clinically indistinguishable from other causes. Frequent viral pathogens are respiratory syncytial virus (RSV)., Adenovirus., Influenza virus, metapneumovirus and parainfluenza virus in children and influenza in the elderly. Bacterial superinfection may complicate viral differentiation from bacterial infection.

C. Pneumoniae causes 5–10% of community-acquired pneumonia and is the second leading cause of lung infections in healthy people aged 5–35 years. C. Pneumoniae is usually responsible for outbreaks of respiratory tract infections in families, educational institutions and military training camps. It causes a relatively benign form that does not often require hospitalization. Pneumonia caused by Chlamydia psittaci (ornithosis) occurs in patients with birds.

The reproduction of other organisms causes an infection in the lungs in immunocompetent patients, although the term community-acquired pneumonia is commonly used for more frequent bacterial and viral etiologies.

Qu fever, tularemia, anthrax and plague are rare bacterial infections for which there may be marked pneumonia; The last three infectious diseases should raise suspicion of bioterrorism.

Adenovirus, Virus and virus is a widespread virus that rarely causes pneumonia. The varicella zoster virus and hantavirus cause lung infection in adults with chickenpox and gantavirus pulmonary syndrome; A new coronavirus causes severe acute respiratory syndrome.

The most common fungal pathogens are Histoplasma (histoplasmosis) and Coccidioides immitis (coccidioidomycosis). Blastomyces dermatitidis (blastomycosis) and Paracoccidioides braziliensis (paracoccidioidomycosis) are less common.

Parasites that cause lung damage in patients in developed countries include Plasmodium sp. (malaria) Tokhocara canis or catis (migration of larvae to internal organs), Dirofilaria immitis (dirofipariosis) and Paragonimus westermani (paragonimiaz).

[17], [18], [19], [20], [21], [22], [23], [24]

Symptoms of the pneumonia

Symptoms of pneumonia include malaise, cough, shortness of breath, and chest pain.

Cough is usually productive in older children and adults and dry in infants, small children and the elderly. Shortness of breath is usually mild and occurs during physical exertion and is rarely present at rest. Chest pain is pleural and localized near the affected area. Inflammation of the lung tissue may manifest as pain in the upper abdomen when infection of the lower lobe irritates the diaphragm. Symptoms vary in extreme age groups; infection in infants may manifest as indefinite irritability and restlessness; in the elderly - as a violation of orientation and consciousness.

Manifestations include fever, tachypnea, tachycardia, wheezing, bronchial breathing, egophony and dullness with percussion. Symptoms of pleural effusion may also be present. The swelling of the nostrils, the use of additional muscles and cyanosis are frequent in infants.

Signs of pneumonia, as previously thought, differ depending on the type of pathogen, but there are many common manifestations. In addition, none of the symptoms or signs are sensitive enough or specific so that it can be used to determine the etiology. Symptoms may even resemble non-infectious lung diseases, such as pulmonary embolism, neoplasms, and other inflammatory processes in the lungs.

[25], [26], [27], [28], [29]

Diagnostics of the pneumonia

The diagnosis is suspected based on the symptoms of the disease and is confirmed by chest X-ray. The most severe condition misdiagnosed as inflammation of the lung tissue is pulmonary embolism, which is more likely in patients with minimal sputum production, absence of concomitant ARVI or systemic symptoms and risk factors for thromboembolism.

Chest radiography almost always reveals infiltration of varying severity; rarely, infiltration is absent in the first 24–48 hours of the disease. In general, no specific study results distinguish one type of infection from another, although multi-part infiltrates suggest infection with S. Pneumoniae or Legionella pneumophila, and interstitial pneumonia suggests a viral etiology or mycoplasma.

Hospitalized should conduct a general analysis of blood and electrolytes, urea and creatinine to determine the degree of hydration and risk. Two blood cultures are performed to detect pneumococcal bacteremia and sepsis, since approximately 12% of all patients hospitalized with pneumonia have bacteremia; S. Pneumoniae accounts for two thirds of these cases.

Research is continuing to help determine if the results of blood cultures are so important for treatment as to justify the costs of conducting these tests. Pulse oximetry or arterial blood gas analysis should also be performed.

Usually there are no indications for research, including analysis of sputum analysis identifying the pathogen; exceptions can be made for critically severe patients who suspect a drug-resistant or unusual microorganism (for example, tuberculosis), and patients whose condition worsens or who do not respond to treatment within 72 hours. Expediency of Gram stain and bacteriological examination remains in question, since samples are often contaminated and in general their diagnostic efficacy is low. In patients without sputum, samples can be obtained non-invasively with a simple cough or after inhalation of a hypertonic saline solution, or a patient can undergo bronchoscopy or endotracheal suction that can be easily performed through an intubation tube in patients on a ventilator. In patients with a worsening condition and not responding to therapy with broad-spectrum antibiotics, the study should include staining for mycobacteria and for fungi and crops.

Additional examinations are prescribed in some circumstances. People at risk for legionella inflammation of the lung tissue (for example, patients who smoke, have chronic lung diseases, are over 40 years old, receive chemotherapy or take immunosuppressants for organ transplantation) should be urine tested for legionella antigens, which remains positive for a long time after the start. Treatment, but only reveals L pneumophila serological group 1 (70% of cases).

A fourfold increase in antibody titers to> 1: 128 (or in a single serum with a recovery> 1: 256) is also considered diagnostic. These tests are specific (95-100%), but not very sensitive (40-60%); thus, a positive test indicates an infection, but a negative test does not exclude it.

Infants and young children with a possible RSV infection should be promptly tested for antigens in nasal or pharyngeal smears. No other tests for viral pneumonia exist; viral culture and serological tests are rarely available in the clinic.

The study by PCR (for mycoplasma and chlamydia) is not yet sufficiently accessible, but it has good prospects due to its high sensitivity and specificity, as well as the speed of implementation.

The test for SARS-associated coronavirus exists, but its role in clinical practice is unknown, and its use is limited beyond the known outbreaks. In rare situations, you need to consider the possibility of anthrax.

[30], [31], [32], [33], [34], [35], [36]

Treatment of the pneumonia

To identify those patients who can safely be treated on an outpatient basis, and those requiring hospitalization due to the high risk of complications, a risk assessment is conducted. Forecasting should reinforce, rather than replace, clinical data, since the choice of the place of treatment is influenced by many invaluable factors - compliance, the ability of self-care and the desire to avoid hospitalization. Hospitalization in ICUA is required for patients who need artificial ventilation of the lungs, and patients with arterial hypotension (systolic blood pressure <90 mmHg). Other criteria for hospitalization in the ICU include the frequency of respiratory movements greater than 30 / min, PaO2 / on inhaled O2 (PO2) less than 250, multi-part inflammation of the lung tissue, diastolic blood pressure less than 60 mm Hg. Art., confusion and blood urea more than 19.6 mg / dl. Adequate treatment involves initiating antibiotic therapy as soon as possible, preferably no later than 8 hours after the onset of the disease. Supportive treatment of pneumonia includes fluids, antipyretic and analgesic drugs and O2 for patients with hypoxemia.

Since microorganisms are difficult to identify, antibiotics are selected based on the likely pathogens and the severity of the disease. The agreed recommendations are developed by many professional organizations. Recommendations should be adapted to the local characteristics of the sensitivity of pathogens, available drugs and the individual characteristics of the patient. It is important that none of the guidelines contain recommendations for the treatment of viral pneumonia.

In children with bronchiolitis caused by RSV, ribavirin and specific immunoglobulin are used in monotherapy and in combination, but the data on their effectiveness are contradictory. Ribavirin is not used in adults with RSV infection. Amantadine or rimantadine orally at a dose of 200 mg once a day, taken within 48 hours of the onset of the disease, reduce the duration and severity of symptoms in patients with suspected influenza during an epidemic, but the effectiveness in preventing unwanted outcomes of influenza pneumonia is unknown. Zanamivir (10 mg in the form of inhalation 2 times a day) and oseltamivir (orally 2 times a day, 75 mg, with an extremely severe course of 2 times 150 mg) are equally effective in reducing the duration of symptoms caused by influenza A or B, if the reception is started within 48 hours from the onset of symptoms, although zanamivir may be contraindicated in patients with bronchial asthma. Acyclovir 5-10 mg / kg intravenously every 8 hours for adults or 250-500 mg / m2 of body surface intravenously every 8 hours for children protects against lung infection caused by varicella virus. If the patient has not started treatment with antiviral drugs in the first 48 hours after the onset of the disease, they should also be used by patients with the flu 48 hours after the onset of the disease. Some patients with viral inflammation of the lung tissue, especially the flu, develop additional bacterial infections, and they need antibiotics directed against S. Pneumoniae, H. Influenzae and Staphylococcus aureus. With empirical therapy, the condition of 90% of patients with bacterial pneumonia is improved, which is manifested by a decrease in cough and shortness of breath, normalization of temperature, a decrease in chest pain and a decrease in the number of blood leukocytes. The lack of improvement should cause suspicion of an atypical microorganism, resistance to an antibiotic with an inadequate spectrum of action, co-infection or superinfection with a second pathogen, obstructive endobronchial damage, immunosuppression, distant foci of infection with re-infection (in case of pneumococcal infection) or insufficient adherence to treatment (in case of outpatients). If none of these causes is confirmed, treatment failure appears to be the result of inadequate immune defenses.

Treatment of pneumonia of viral genesis is not carried out, since most viral pneumonia is resolved without it.

Patients over 35 years old, 6 weeks after treatment, should undergo a repeat X-ray examination; the persistence of the infiltrate causes suspicion of a possible malignant endobronchial formation or of tuberculosis.

[37], [38], [39], [40], [41]

Prevention

Some forms of community-acquired pulmonary inflammation can be prevented by using a pneumococcal conjugate vaccine (for patients <2 years old), N. Influenzae B (HIB) vaccine (for patients <2 years old), and influenza vaccine (for patients> 65 years old). Pneumococcal, HIB and influenza vaccines are also recommended for high-risk patients. High-risk patients who are not vaccinated against the flu can be given amantadine, rimantadine, or oseltamivir during influenza epidemics.

[42], [43]

Forecast

The status of candidates for outpatient treatment usually improves within 24-72 hours. The condition of hospitalized patients may improve or worsen depending on the accompanying pathology. Aspiration is a major risk factor for death, as well as old age, the number and nature of concomitant pathology, and certain pathogens. Death can be caused directly by pneumonia, by progression to septic syndrome affecting other organs, or by exacerbation of major underlying diseases.

Pneumococcal infection is still the cause of approximately 66% of all fatal cases of community-acquired pneumonia with a known pathogen. Total mortality in hospitalized patients is approximately 12%. Adverse prognostic factors include age less than 1 year or over 60 years; involving more than one share; the content of leukocytes in the peripheral blood is less than 5000 / μl; concomitant pathology (heart failure, chronic alcoholism, hepatic and renal failure), immunosuppression (agammaglobulinemia, anatomical or functional asplenizm), infection with serotypes 3 and 8, and hematogenous spread with positive blood cultures or extrapulmonary complications (arthritis, meningitis or hepatitis, or meningitis or hepatitis) Infants and children are at particular risk for pneumococcal otitis media, bacteremia and meningitis.

Mortality in legionella infections is 10–20% among patients with community-acquired pneumonia and higher among immunosuppressive or hospitalized patients. Patients who respond to treatment recover very slowly, radiological changes usually persist for more than 1 month. Most patients require hospitalization, many require respiratory ventilation support, and 10–20% die, despite adequate antibiotic therapy.

Mycoplasma pneumonia has a favorable prognosis; almost all patients recover. Chlamydia pneumoniae responds more slowly to treatment than mycoplasma, and tends to recur after premature discontinuation of treatment. Young people usually recover, but mortality among the elderly reaches 5-10%.

[44], [45], [46]