Community-acquired pneumonia (CAP) is an infectious inflammation of the lung parenchyma (including the alveolar wall, i.e., the interstitial lung) that occurs outside the hospital, including pneumonia that develops during the incubation period after hospital admission due to an infection by a pathogen with a defined incubation period. The composition and drug resistance characteristics of CAP vary significantly among countries and regions and have changed over time. In recent years, the diagnosis and treatment of CAP has faced many new problems due to the aging of the social population, the increase of immune-compromised hosts, the change of pathogens and the rise of antibiotic resistance. Recently, the Chinese Society of Respiratory Medicine completed two nationwide epidemiological surveys of CAP with larger samples. On this basis, and taking into account the latest research advances in the diagnosis and treatment of CAP abroad, the Guidelines for the diagnosis and treatment of community-acquired pneumonia (draft) developed in 1999 have been appropriately revised, aiming to guide the clinic in establishing a reliable diagnosis, comprehensively assessing the disease, determining management guidelines, improving prognosis, minimize inappropriate empirical treatment, reduce the pressure of antibiotic selection, delay drug resistance, and conserve medical and health resources.
I. Clinical diagnosis of CAP based on
1. Newly developed cough, coughing sputum or aggravation of existing respiratory disease symptoms with purulent sputum, with or without chest pain.
2, fever.
3.Signs of solid lung and/or smell of wet woven grass
4, Neutrophils account for about 50-70% of the total number of leukocytes, with a cell diameter of 10-12 μm and a lobulated nucleus. Generally 2~5 lobes, normal people 2~3 lobes mostly. When the body is severely infected by bacteria, a large number of new cells enter the blood from the bone marrow, and the rod-shaped nucleus with 2-lobed nuclei increases, which is called nuclear left shift; if the cells with 4- to 5-lobed nuclei increase, it is called nuclear right shift, indicating that the hematopoietic function of bone marrow is impaired. An increase in immature neutrophilic leukocytes, i.e., an increase in the proportion of neutrophils, naive type and rod nuclei neutrophils, is called nuclear left shift. The presence of a left nuclear shift in conjunction with an increase in total leukocyte count indicates enhanced hematopoiesis and an active defense phase of the body, while a left nuclear shift in conjunction with a decrease in total leukocyte count indicates a decrease in bone marrow function. In severe infections, there are often naive neutrophils in the peripheral blood (in the classification, if the number of rods and naive neutrophils exceeds 5%, it is called nuclear left shift), and toxic particles may appear in the cytoplasm. When the resistance of the body is low and the infection is severe, the number of white blood cells may not increase significantly or even decrease, and the prognosis is poor.
5. Chest X-ray shows lamellar or patchy infiltrative shadows or interstitial changes, with or without pleural effusion.
The clinical diagnosis can be established after any 1 of the above 1-4 items plus item 5, and excluding tuberculosis, lung tumor, non-infectious interstitial lung disease, pulmonary edema, pulmonary atelectasis, pulmonary embolism, pulmonary eosinophilic infiltration and pulmonary vasculitis.
Second, the pathogenic diagnosis of CAP
1, sputum bacteriological examination specimen collection, delivery and laboratory processing: sputum is the most convenient and non-invasive pathogenic diagnostic specimens, but sputum is easily contaminated by oropharyngeal bacteria. Therefore, the quality of sputum specimens, timely delivery and laboratory quality control will directly affect the rate of bacterial isolation and interpretation of results, must be standardized: (1) collection: try to collect specimens before antibiotic treatment. Patients are instructed to rinse their mouth first and are instructed or assisted to cough deeply and retain purulent sputum for examination. Patients without sputum to check Mycobacterium and Pneumocystis can be used hypertonic saline nebulized aspirate to guide sputum. Three early morning sputum specimens should be collected for fungal and mycobacterial examinations; for usual bacteria, the specimens should be screened cytologically first. For anaerobic bacteria and pneumocystis, the positive rate of examination using bronchoalveolar lavage fluid (BALF) specimens may be higher. (2) Send: Send the specimen as soon as possible, not more than 2 h. Delayed specimens or specimens to be processed should be stored at 4°C (suspected Streptococcus pneumoniae infections are not included) and preserved specimens should be processed within 24 h. (3) Laboratory processing: Pick a purulent portion of the smear for Gram staining and microscopically screen the eligible specimen (squamous epithelial cells <10/low magnification field, multinucleated leukocytes >25/low magnification field, or a ratio of <1:2.5). The competent specimens were inoculated on both blood agar plates and chocolate plates, with selective medium or other media added if necessary. The standard 4-zone delineation method was used to inoculate for semi-quantitative culture. Smear oil microscopy to see the typical form of Streptococcus pneumoniae or Haemophilus influenzae has diagnostic value.
2, the collection of serological specimens: the collection of 2 to 4 weeks between the acute phase and the recovery period of the double serum specimens, mainly for the determination of atypical pathogens or respiratory virus-specific antibody titers.
3, test results of diagnostic significance: (1) determine: ① blood or pleural fluid culture to pathogenic bacteria; ② specimens cultured by fiberoptic bronchoscopy or artificial airway suction with pathogenic bacteria concentration ≥ 105 CFU/ml (semi-quantitative culture ++), BALF specimens ≥ 104 CFU/ml (+ to ++), anti-pollution brush or anti-pollution BALF specimens ≥ 103 CFU/ml (+) ③ respiratory specimens cultured to Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila; ④ serum Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila antibody titers showed 4-fold or more changes (increase or decrease), while Mycoplasma pneumoniae antibody titers (complement binding test) ≥ 1:64, Chlamydia pneumoniae antibody titers (microimmunofluorescence test) ≥ 1:32, and Legionella pneumophila antibody titers ( indirect fluorescence antibody method) ≥ 1:128; ⑤ positive urinary antigen test (enzyme-linked immunoassay) for Legionella pneumophila type I; (6) 4-fold or more change (increase or decrease) in antibody titer for serum influenza virus, respiratory syncytial virus, etc.; (7) positive urinary antigen test (immunochromatographic method) for Streptococcus pneumoniae (except children). (2) Significant: ① moderate or above growth of dominant bacteria in culture of qualified sputum specimens (≥+++); ② small amount of bacterial growth in qualified sputum specimens, but consistent with smear microscopy results (Streptococcus pneumoniae, Haemophilus influenzae, and Catamobacter); ③ multiple cultures of the same bacteria within 3 d; ④ serum Chlamydia pneumoniae IgG antibody titer ≥1:512 or IgM antibody titer ≥1:16 (micro immunofluorescence (3) No significance: ① sputum culture with bacteria of normal flora of the upper respiratory tract (such as Streptococcus gramineus, Staphylococcus epidermidis, non-pathogenic Neisseria, diphtheria-like bacilli, etc.); ② sputum culture for a small amount (<+++) of growth of multiple pathogenic bacteria; ③ does not meet (1) ), (2) in any 1.
4, the choice of pathogenic diagnostic methods: (1) outpatient treatment of mild and moderate patients do not need to be generally pathogenic examination, only when the initial empirical treatment is ineffective. (2) Routine blood cultures and pathogenic examination of respiratory specimens should be performed simultaneously in hospitalized patients. Any combined pleural effusion and capable of puncture should undergo diagnostic thoracentesis and extract pleural fluid for routine pleural fluid, biochemical and pathogenic examination. (3) The invasive diagnostic technique is only selectively applied to patients with CAP: (1) when empirical treatment is ineffective or the disease still progresses, especially when antimicrobial drugs have been changed more than once and are still ineffective; (2) when infection by specific pathogens is suspected and the causative agent cannot be clarified with respiratory specimens obtained by conventional methods; (3) when the immunosuppressed host with CAP is ineffective with antimicrobial drugs; (4) when it needs to be distinguished from non-infectious (3) When the immunosuppressed host has CAP and antimicrobial therapy is ineffective; (4) When the differential diagnosis is needed with non-infectious pulmonary infiltrative lesions.
Criteria for admission to hospital for CAP and evaluation of the severity of the disease
Hospitalization criteria: Hospitalization is recommended when one of the following criteria is met, especially when two or more conditions coexist; (1) Age ≥ 65 years. (2) Presence of one of the following underlying diseases or associated factors: 1) chronic obstructive pulmonary disease; 2) diabetes mellitus; 3) chronic cardiac or renal insufficiency; 4) malignant solid tumor or hematologic disease; 5) acquired immunodeficiency syndrome (AIDS); 6) aspiration pneumonia or presence of factors predisposing to aspiration; 7) hospitalization for CAP within the last 1 year; 8) abnormal mental status; 9) post splenectomy (10) after organ transplantation; 11) chronic alcoholism or malnutrition; 12) long-term use of immunosuppressive drugs. (3) The presence of one of the following abnormal signs: (1) respiratory rate ≥ 30 breaths/min; (2) pulse ≥ 120 breaths/min; (3) arterial systolic blood pressure < 90 mmHg (1 mmHg = 0.133 kPa); (4) body temperature ≥ 40°C or < 35°C; (5) impaired consciousness; (6) the presence of extra-pulmonary infections such as sepsis and meningitis. (4) Presence of one of the following laboratory and imaging abnormalities: ①WBC>20×109/L or <4×109/L, or neutrophil count <1×109/L; ②Pa02<60mmHg, Pa02/Fi02<300, or PaC02>50mm Hg when breathing air; ③Blood creatinine (SCr) >106μmol/L or blood urea nitrogen ( BUN) >7.1 mmol/L; ④ hemoglobin <90 g/L or erythrocyte pressure product (HCT) <30%; ⑤ plasma albumin <25 g/L; ⑥ evidence of sepsis or diffuse intravascular coagulation (DIC), such as positive blood culture, metabolic acidosis, prolonged prothrombin time (PT) and partial thromboplastin time (APTT), and thrombocytopenia; ⑦ X-ray Chest radiograph showing lesions involving more than 1 lobe, the presence of cavities, rapid spread of lesions, or the presence of pleural effusion.
Diagnostic criteria for severe pneumonia: The presence of 1 or more of the following signs can be diagnosed as severe pneumonia, which requires close observation, active treatment and, when available, ICU admission is recommended for treatment: (1) impaired consciousness. (2) Respiratory rate ≥ 30 breaths/min. (3) Pa02 < 60 mmHg, Pa02/Fi02 < 300, requiring mechanical ventilation therapy. (4) Arterial systolic pressure <90 mmHg, (5) Complicated septic shock. (6) X-ray chest film showing bilateral or multi-lobe lung involvement, or lesion enlargement ≥50% within 48h of admission. (7) Oliguria: urine output <20ml/h, or <80ml/4h, or concomitant acute renal failure requiring dialysis treatment.
IV. Risk factors for CAP infection with specific pathogens and recommendations for initial empirical anti-infective therapy
Risk factors for susceptibility to certain specific pathogens: If a patient has a combination of certain risk factors (Table 2) or the presence of certain comorbidities (Table 3), he or she will be at risk for infection with a specific pathogen and should be considered for treatment.
Recommendations for initial empirical anti-infective therapy: China is a vast country with great differences in natural environment and socioeconomic development, and the epidemiological distribution of CAP pathogens and antibiotic resistance rates are not uniform, and further research and accumulation of information are needed. The treatment recommendations in Table 4 are only principle-based and must be selected in the context of specific situations.
A few notes and cautions: (1) Treatment with oral anti-infective drugs with good bioavailability should be recommended as much as possible for previously healthy patients with mild disease and normal gastrointestinal function. (2) The rate of insensitivity (including intermediary and resistance) of CAP pathogenic Streptococcus pneumoniae to penicillin in adults in China is around 20%, and penicillin intermediary level (MIC 0.1-1.0 mg/L) resistant Streptococcus pneumoniae pneumonia can still be selected, but the dose needs to be increased, such as penicillin G 2.4 million U intravenous drip, 1 time/4-6 h. When high level resistance or high risk factors of resistance exist should be Choose ceftriaxone, cefotaxime, ertapenem, respiratory quinolones or vancomycin. (3) Streptococcus pneumoniae is generally more than 60% resistant to macrolides in China, and most of them are highly resistant. Therefore, macrolides alone should not be applied when CAP is suspected to be caused by Streptococcus pneumoniae, but macrolides still have good efficacy against atypical pathogens. (4) Bronchiectasis complicated by pneumonia, Pseudomonas aeruginosa is a common pathogen, and the choice of drugs for empirical treatment should take this into account. In addition to the above recommended drugs, some advocate the combination of quinolones or macrolides, which are believed to easily penetrate or destroy the bacterial biofilm. (5) In case of suspected inhalation factors, drugs with anti-anaerobic effects such as ampicillin/sulbactam sodium, amoxicillin/clavulanic acid, etc. should be preferred, or combined with metronidazole, clindamycin, etc. Moxifloxacin and other respiratory quinolones effective against anaerobic bacteria can also be used. (6) Combined application of empirical antiviral therapy is generally not recommended for patients suspected of influenza virus infection. Combined application of antiviral therapy should be considered only for high-risk patients with typical influenza symptoms (fever, myalgia, general malaise and respiratory symptoms), onset of illness <2 d, and during the influenza epidemic. (7) For life-threatening severe pneumonia, early treatment with broad-spectrum, potent antibacterial drugs is recommended, and after stabilization, targeted therapy according to pathogenesis or step-down therapy can be administered. Antibiotic therapy should be started as early as possible, and the first dose of antibiotic therapy should be sought within 4h after the diagnosis of CAP to improve efficacy, reduce morbidity and mortality, and shorten hospital stay. (8) Anti-infective treatment can generally be discontinued 3-5 d after the fever subsides and the main respiratory symptoms improve significantly, but the course of treatment varies depending on the different pathogens and severity of the disease. For common bacterial infections, such as Streptococcus pneumoniae, medication can be administered until 72h after the patient's fever has subsided; for infections caused by pathogenic bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella spp. or anaerobic bacteria that can easily lead to lung tissue necrosis, a course of antimicrobial drugs ≥ 2 weeks is recommended. For atypical pathogens, the course of treatment should be slightly longer, such as 10-14 d for Mycoplasma pneumoniae and Chlamydia pneumoniae infections and 10-21 d for Legionella spp. infections.(9) In addition to effective anti-infective therapy for severe pneumonia, nutritional support therapy and drainage of respiratory secretions are also very important.
V. Evaluation, treatment and timing of inpatient discharge after initial treatment of CAP
1, 48-72h after the initial treatment should be evaluated for the condition and diagnosis. Effective treatment response is first manifested by a decrease in body temperature, respiratory symptoms can also be improved, leukocyte recovery and X-ray chest lesion absorption generally appear later. Where there is significant improvement in symptoms, the original treatment can be maintained without necessarily considering the results of sputum pathogenesis. After significant improvement of symptoms, the parenteral administration can be changed to oral administration of similar or similar antibacterial spectrum, or agents sensitive to the causative agent, and sequential treatment can be used.
2. If the symptoms do not improve after 72h of initial treatment or once improve and then worsen, the treatment is considered ineffective, and the common reasons and treatment are as follows: (1) Drugs fail to cover the causative organism or bacterial resistance, combine with laboratory sputum culture results and evaluate their significance, adjust anti-infective drugs prudently, and repeat pathogenic examination. (2) Special pathogenic infections, such as mycobacteria, fungi, lung-hugging bacteria, viruses including SARS and human avian influenza, or endemic infectious diseases. The relevant information should be reanalyzed and examined accordingly, including further testing for the usual bacteria and, if necessary, invasive examination techniques to clarify the pathogenic diagnosis and adjust the treatment plan. (3) In case of complications (septic chest, migratory lesions, etc.) or the presence of host factors affecting the efficacy (e.g. immune damage), further examination and confirmation should be performed and the treatment should be handled accordingly. (4) If the diagnosis of CAP is wrong, the diagnosis of CAP should be re-verified to clarify whether it is a non-infectious disease.
3.Discharge criteria: After effective treatment, patients can be discharged when their condition improves significantly and the following six criteria are met (except for those whose original underlying diseases can affect the judgment of the following criteria): (1) normal body temperature for more than 24 h. (2) heart rate ≤ 100 times/min at calm, (3) respiration ≤ 24 times/min at calm, (4) systolic blood pressure ≥ 90 mmHg, (5) no oxygenation The arterial oxygen saturation is normal under the circumstances. (6) can receive oral medication, no mental disorders and other conditions.
VI. Prevention
Smoking cessation and avoidance of alcohol abuse can help prevent the occurrence of pneumonia. Preventive vaccination with Streptococcus pneumoniae vaccine and/or influenza vaccine can reduce the chance of pneumonia in some specific groups. The currently used polyvalent Streptococcus pneumoniae vaccine is a polysaccharide podocyte antigen derived from multiple serotypes and is effective in preventing 85% to 90% of invasive Streptococcus pneumoniae infections. Persons recommended for Streptococcus pneumoniae vaccination: frail children and adults; elderly people over 60 years of age; children and adults with recurrent upper respiratory tract infections (including sinusitis and otitis media); persons with chronic underlying disease of the lungs, heart, liver or kidneys; patients with diabetes; patients with cancer; patients with sickle cell anemia; patients with Hodgkin’s disease; persons with immune system dysfunction; persons with splenectomy; persons requiring Immunosuppressive therapy; long-term residents of nursing homes or other care facilities. The scope of inactivated influenza vaccination is somewhat broader than that of pneumococcal vaccine, and the recommended vaccine recipients include: elderly people over 60 years of age; patients with chronic diseases and frail people; staff of medical and health institutions, especially front-line clinical staff; elementary school students and kindergarten children; staff of nursing homes, elderly care centers, and childcare institutions; service industry workers, especially taxi drivers. Civil aviation, railroad and highway transportation staff, commercial and tourism service workers, etc.; people who travel frequently or travel to home and abroad.