Legionella pneumonia
Introduction
Introduction to Legionella pneumonia Legionella pneumonia (legionellapneumonia) is a systemic disease caused by pneumonia caused by Legionella. There are 40 species of Legionella. Most of the clinical isolates are Legionellapneumophila, followed by Mick Day. Lmicdadei, other rare. Gram-negative bacilli, but lightly colored, strict aerobic bacteria, special nutritional requirements for isolation and culture in the first generation, need to use antibiotics and cysteine, iron selective special medium such as activated carbon yeast agar medium (CYE) And BCYE- medium. Adjusting the exact pH of the medium and a certain concentration of CO2 environment (2.5% to 5%) and the incubation time (at least 5 days) are the key to ensure the success of bacterial culture and isolation. The detection rate of the bacteria in clinical laboratories is very low. Most of them are based on serum antibody assays to diagnose the disease. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: myocarditis endocarditis pericarditis acute renal failure shock
Cause
Legionella pneumonia
Cause (20%):
Legionella pneumonia is a pneumonia caused by Gram-negative Legionella pneumophila. The onset is slow, and the incubation period is 2 to 10 days. In the early stage of the disease, the patient has general malaise, myalgia, chest pain, dry cough, mucus with bloodshot, high fever, difficulty in breathing, and some are insane.
Pathogenesis (10%):
Legionella is a special type of gram-negative aerobic bacterium that does not grow on normal medium and can be used in FG agar medium containing iron phosphate and L-cysteine, or buffered activated carbon yeast extract (BCYE). On agar medium, it grows slowly in the air with 2.5% CO2 at pH 6.0-6.9 and 35 °C. The colonies are fine and have brown pigmentation. Legionella contains a variety of exotoxin and endotoxin, and several toxins work together. It causes disease, mainly through the aerosol of contaminated water, and the possibility of direct inhalation of bacteria is relatively high. The mechanism of lung lesions is related to the following factors:
1 Legionella produces virulence factors that cause changes in lung parenchyma and leukocytes.
2 Legionella release chemokines, which have peptide properties and have chemotactic effects on leukocytes, which can release lysosomes and cause persistent damage to the lungs.
3 Legionella can release protein lyase, a neutral protease that cleaves the inflammatory response caused by C3 or C5 produced by chemotactic fragments.
After the bacteria invade the lung tissue, the lesion is mainly located in the alveoli, which may be retrograde from the alveoli to the respiratory bronchioles, to the larger bronchioles, to a small amount to the interstitial, or to the pleura, lymphatic vessels, thoracic ducts and blood circulation.
Prevention
Legionella pneumonia prevention
1. Close monitoring of clinical suspected Legionella patients and suspicious Legionella outbreaks.
2. Early diagnosis, reasonable treatment can greatly reduce the mortality rate of Legionnaires' disease.
3. Disinfect the environment and water sources.
Complication
Legionella pneumonia complications Complications Myocarditis Endocarditis Pericarditis Acute Renal Failure Shock
Myocarditis, endocarditis, pericarditis, heart failure, acute renal failure, shock, DIC, bronchiolitis obliterans (BO) or obliterative bronchiolitis with organizing pneumonia (BOOP).
Symptom
Legionella pneumonia symptoms common symptoms high fever abdominal pain dyspnea shortness of breath dry cough bronchial purulent secretion increased chest pain wheezing directional force disorder myalgia
The disease is generally epidemic, but it can also be sporadic, slow onset, and the incubation period is 2 to 10 days. The patient has general malaise, myalgia, chest pain, dry cough, mucus with bloodshot, high fever, difficulty breathing, and some insanity. , disorientation, coma, gastrointestinal symptoms are abdominal pain, vomiting and watery diarrhea or mucus, no pus and blood.
Signs: The patient has an acute face, shortness of breath, cyanosis, a voice and wheezing in the lungs, a relatively slow heart rate, and a fluid sign when there is fluid accumulation.
Examine
Legionella pneumonia check
White blood cell count up to (10 ~ 20) × 10 9 / L, erythrocyte sedimentation rate, may have microscopic examination of hematuria, abnormal liver function, increased blood urea nitrogen, hyponatremia and hypophosphatemia, serum creatine phosphokinase (CPK) Increased, sputum, blood and pleural effusion routine culture were negative.
X-ray manifestations were mostly unilateral diffuse flaky infiltration in the early stage, and later developed into dense large leaf consolidation, which may also involve multiple leaves. In severe cases, there may be changes in cavities and lung abscesses, and 30% of patients have a small amount of pleural effusion.
Diagnosis
Diagnosis and identification of Legionella pneumonia
Due to the intricate clinical manifestations, diagnosis must rely on special laboratory tests, including:
1, bronchial lavage or direct fluorescein-labeled antibody staining of lung tissue.
2 The antigen was tested by an enzyme-linked immunosorbent assay.
3 culturing pathogenic bacteria from lung tissue pleural effusion and intratracheal or tracheal aspirate.
Pneumonia caused by other causes, such as mycoplasmal pneumonia, parrot fever, Q fever, and viral pneumonia should be excluded.
