Legionella General Practice

History of Legionella

In 1976, a member of the Philadelphia Veterans Association of the United States had an outbreak of acute febrile respiratory disease'''' after study '''' found a bacterium named Legionella pneumophila. Subsequently, many related bacteria were temporarily included in this genus, and retrospective studies found cases of Legionnaires' disease as early as 1943. More than 30 Legionella species have been proposed. '''' At least 19 are the causative agents of human pneumonia. The most common pathogen is Legionella pneumophila (85% ~ 90% of cases), followed by L.micdadei (5% ~ 10%), followed by L.bozemanii and L.dumoffii. Such bacteria are morphologically similar. ''' have common biochemical characteristics. ''' cause similar diseases.

The scope of the two diseases includes:(1) asymptomatic serum changes;(2) self-limited influenza-like pathological condition without pneumonia '''' sometimes called Ponteac fever (Pontiac fever);(3) Legionnaires' disease as the most serious and common type of pneumonia;(4) localized '''' rare soft tissue infection.

Legionnaires' disease accounts for 1% to 8% of community-acquired pneumonia requiring hospitalization. It accounts for about 4% of fatal hospital-acquired pneumonia. Most cases are sporadic and occur in late summer and early autumn. Human-to-human transmission has not been confirmed. Legionella pneumophila is prevalent when the water supply system is contaminated or aerosol-forming pathogens spread through the evaporative gas from the condenser of the air conditioning system or contaminated shower showerhead. Legionnaires' disease can occur at any age, but most people are middle-aged men. Identified risk factors include smoking '''' alcohol abuse and immunosuppression '''' especially immunosuppression caused by corticosteroids.

Four Legionella is a pathogenic bacteria hidden in the air conditioning and refrigeration device. It floats in the air with the cold wind. After being inhaled into the human body, symptoms of upper respiratory tract infection and fever will appear. In severe cases, it can lead to respiratory failure and renal failure. Legionella was first named after the upper respiratory tract infection caused by the confined indoor operation of the army. Legionnaires' disease is a very serious and sometimes fatal form of pneumonia. Legionnaires' disease is caused by the bacterium Legionella, which occurs in the natural environment and spreads in warm water and hot flashes. Artificial water supply systems can sometimes provide a living environment for the proliferation of Legionella. These systems include showers, mineral pools, fountains, and cooling towers for air conditioning equipment. People are usually infected with Legionnaires' disease by breathing in mist from water sources contaminated with Legionella.

It is estimated that 8000 to 18000 people are infected with Legionnaires' disease every year in the United States. Some people infected with Legionnaires' disease show mild symptoms, or even no signs of illness at all. Patients with Legionnaires' disease usually have fever, chills, and a dry cough or expectoration. Some patients also have muscle pain, headache, fatigue, loss of appetite, and occasional diarrhea. The incubation period of this disease is about. In many cases, it takes 5 to 6 days for symptoms to appear. Legionnaires' disease can be treated with antibiotics such as erythromycin, and the earlier the treatment, the better. The first known outbreak of Legionnaires' disease occurred in Philadelphia in 1976, where 221 people contracted the disease and 34 died. Because most of the dead were members of the legion, it was called Legionnaires' disease or Legionnaires' disease. The second major outbreak of the disease was at Stafford Hospital in England in 1985. This time 28 of the 101 people infected died.

[edit this paragraph] Treatment

Gangmycosis is a lung infection caused by bacteria in the Legionella family. Most of them are scattered or small epidemics, or outbreaks may occur. Infections are caused by air conditioning, water supply systems, and water sources contaminated by aerosol inhalation. The disease is characterized by pneumonia with systemic toxemia symptoms, severe cases of peripheral loop failure, respiratory failure. Chest X-ray performance in the early stage for single leaf patchy shadow, followed by lung consolidation, lesions rapidly developed to multiple lobes, there may be lung abscess formation or a small amount of pleural effusion sign. Confirmation depends on the detection of specific antibodies and the isolation of bacteria in sputum, pleural effusion, and lung biopsy specimens. Erythromycin and rifampicin are effective in the treatment of this disease.

Clinical manifestations:

1. Slow onset, repeated chills, high fever, headache, myalgia, fatigue, abdominal pain, vomiting, diarrhea and systemic failure. Most patients have cough, chest pain, a small amount of mucus sputum, and bloody sputum. Severe patients have dyspnea, cyanosis, and even respiratory failure, neuropsychiatric symptoms, delirium, disorientation and so on.

2. Acute volume, shortness of breath. There are rales and signs of realism in the lungs. About 20% have relatively slow pulse. A few patients have pleural frictions.

Diagnosis basis:

1. It can be epidemic or sporadic onset, mostly occurring in middle-aged and elderly people or patients with chronic diseases.

2. Fever, sweating, cough, cough white phlegm, with chest pain, myalgia and fatigue. Nervous, mental symptoms or nausea, vomiting, diarrhea, severe cases may appear renal failure performance.

3. Difficulty in breathing, relatively slow pulse. The lungs may have wet rales and signs of transformation or pleural friction.

4. The total number of white blood cells increased, liver function can be abnormal, blood urea nitrogen increased.

5. Chest X-ray showed a single or multi-leaf patchy shadow with rapid changes, often accompanied by abscess formation and pleural effusion.

6. Special examination: direct fluorescent antibody test positive. Lung biopsy tissue was positive for Legionella with special staining; indirect fluorescent antibody test was positive. Specific serum antibody titration> 1:256, or double serum contrast 4 times higher; Radioimmunoassay or Merion immunosorbent assay determination of soluble bacterial antigens in urine, sputum, pleural fluid and lung tissue special culture with Legionella pneumophila growth.

Principles of treatment:

1. Antimicrobial therapy.

2. symptomatic treatment.

3. Support therapy.

Principles of medication:

1. The mild cases were mainly oral erythromycin and other auxiliary drugs.

2. The heavier patients were treated with erythromycin by intravenous drip for 2-3 weeks, and other auxiliary drugs.

3 severe patients with erythromycin intravenous drip, can be combined with rifampicin, doxycycline. Support symptomatic and other comprehensive treatment. In order to avoid recurrence, the course of disease should be more than 3 weeks.

4. Aminoglycoside antibiotics, penicillin and cephalosporins are ineffective for this disease.

Auxiliary examination:

1. The examination project for patients with early Legionella pneumonia is mainly based on the examination frame limit "A;

2. When the disease needs to be differentiated from pneumonia infected by other pathogenic bacteria, the examination project may include the examination frame limit "A", "B" or "C".

Efficacy evaluation:

1. Cure: normal body temperature, symptoms and signs disappeared, X-ray showed that the lung shadow was completely absorbed; sputum or bronchial lavage fluid culture was negative.

2. improvement: normal body temperature, symptoms and signs disappeared, X-ray showed that the lung shadow was basically absorbed; sputum or bronchial lavage fluid culture was negative.

3. Unhealed: No change or deterioration of symptoms and signs after 1 month of treatment.