Внебольничная пневмония: причины, диагностика и лечение.

Community acquired pneumonia (CAP) refers to pneumonia (any of several lung diseases) contracted by a person outside of the healthcare system. In contrast, hospital acquired pneumonia (HAP) is seen in patients who have recently visited a hospital or who live in long term care facilities. CAP is common, affecting people of all ages, and its symptoms occur as a result of oxygen absorbing areas of the lung (alveoli) filling with fluid. This inhibits lung function, causing dyspnea, fever, chest pains and cough. CAP, the most common type of pneumonia, is a leading cause of illness and death worldwide. Its causes include bacteria, viruses, fungi and parasites. CAP is diagnosed by assessing symptoms, performing a physical examination, by x ray or by sputum examination. Patients with CAP sometimes require hospitalization, and it is treated primarily with antibiotics, antipyretics and cough medicine. Some forms of CAP can be prevented by vaccination and by abstaining from tobacco products.

It is possible for a fetus to develop a lung infection before birth by aspirating infected amniotic fluid or through a blood borne infection which crossed the placenta. Infants can also inhale contaminated fluid from the vagina at birth. The most prevalent pathogen causing CAP in newborns is Streptococcus agalactiae, also known as group B streptococcus (GBS). GBS causes more than half of CAP in the first week after birth. The most common viral causes are influenza, parainfluenza, human respiratory syncytial virus, human metapneumovirus and adenovirus. Less common viruses which may cause serious illness include chickenpox, SARS, avian flu and hantavirus. Evaluation begins with a physical examination by a health provider, which may reveal fever, an increased respiratory rate (tachypnea), low blood pressure (hypotension), a fast heart rate (tachycardia) and changes in the amount of oxygen in the blood. Palpating the chest as it expands and tapping the chest wall to identify dull, non resonant areas can identify stiffness and fluid, signs of CAP. Listening to the lungs with a stethoscope (auscultation) can also reveal signs associated with CAP. A lack of normal breath sounds or the presence of crackles can indicate fluid consolidation. Increased vibration of the chest when speaking, known as tactile fremitus, and increased volume of whispered speech during auscultation can also indicate the presence of fluid.

Most newborn infants with CAP are hospitalized, receiving IV ampicillin and gentamicin for at least ten days to treat the common causative agents streptococcus agalactiae, listeria monocytogenes and escherichia coli. To treat the herpes simplex virus, IV acyclovir is administered for 21 days.

Treatment of CAP in children depends on the child's age and the severity of illness. Children under five are not usually treated for atypical bacteria. If hospitalization is not required, a seven day course of amoxicillin is often prescribed, with co trimaxazole as an alternative when there is allergy to penicillins. Further studies are needed to confirm the efficacy of newer antibiotics.

In 2001 the American Thoracic Society, drawing on the work of the British and Canadian Thoracic Societies, established guidelines for the management of adult CAP by dividing patients into four categories based on common organisms: to ten days. A shorter course of these antibiotics has been investigated, however, there is not sufficient evidence to make recommendations. Outpatients with underlying illness or risk factors: Although this group does not require hospitalization, they have underlying health problems such as emphysema or heart failure or are at risk for DRSP or enteric gram negative bacteria. They may be treated with a quinolone active against streptococcus pneumoniae (such as levofloxacin) or a β lactam antibiotic (such as cefpodoxime, cefuroxime, amoxicillin or amoxicillin/clavulanic acid) and a macrolide antibiotic, such as azithromycin or clarithromycin, for seven to ten days. Hospitalized patients without risk for pseudomonas: This group requires intravenous antibiotics, with a quinolone active against streptococcus pneumoniae (such as levofloxacin), a β lactam antibiotic (such as cefotaxime, ceftriaxone, ampicillin/sulbactam or high dose ampicillin plus a macrolide antibiotic (such as azithromycin or clarithromycin) for seven to ten days. Intensive care patients at risk for pseudomonas aeruginosa: These patients require antibiotics targeting this difficult to eradicate bacterium. One regimen is an intravenous antipseudomonal beta lactam such as cefepime, imipenem, meropenem or piperacillin/tazobactam, plus an IV antipseudomonal fluoroquinolone such as levofloxacin. Another is an IV antipseudomonal beta lactam such as cefepime, imipenem, meropenem or piperacillin/tazobactam, plus an aminoglycoside such as gentamicin or tobramycin, plus a macrolide (such as azithromycin) or a nonpseudomonal fluoroquinolone such as ciprofloxacin. For mild to moderate CAP, shorter courses of antibiotics (3–7 days) seem to be sufficient.

Some CAP patients require intensive care, with clinical prediction rules such as the pneumonia severity index and CURB 65 guiding the decision whether or not to hospitalize. Patients with underlying illnesses (such as Alzheimer's disease, cystic fibrosis, COPD, tobacco smoking, alcoholism or immune system problems) have an increased risk of developing pneumonia.