OVERVIEW
Escherichia coli (also known as E. coli) pneumonia has increased significantly in recent years, and is the second most common pathogen causing community-acquired Gram-negative bacillus pneumonia after Klebsiella pneumoniae, accounting for 12% to 45% of Gram-negative bacillus pneumonias, and 2.0% to 3.3% of all pneumococcal pathogens. Elderly and frail patients, patients with various chronic underlying diseases, tracheal intubation, long-term use of corticosteroids and other immunosuppressant therapy, long-term use of antibiotics resulting in bacterial dysbiosis, and a variety of immunoglobulin defective patients, etc., for the susceptibility of this disease.
Etiology
Escherichia coli is a conditionally pathogenic bacterium. The endotoxin of E. coli can cause leukocytes to attach to the blood vessel wall, resulting in an increase in the white blood cell count. Endotoxin can also cause thrombocytopenia and disseminated intravascular coagulation, and activate the complement bypass pathway, releasing vasoactive substances and leading to toxic shock.
Symptoms
The clinical manifestations of E. coli pneumonia are similar to those of acute pneumonia in general, and may be characterized by chills, fever, cough, sputum, chest pain, cyanosis and dyspnea. Sputum is often thick or purulent, and may have a fishy odor. Some cases are accompanied by gastrointestinal symptoms such as nausea, vomiting, abdominal pain and diarrhea. Severe cases may have drowsiness and other disorders of consciousness and peripheral circulation.
Lung signs may include decreased breath sounds and wet rales in the lower lungs bilaterally, and signs of solid lesions in the lungs are rare. 40% of the patients may develop pyothorax with corresponding signs, which mostly occurs on the side with severe lesions.
Examination
1. Laboratory examination
Peripheral blood leukocytes and neutrophils are increased, and the nuclear pattern is left shifted. Escherichia coli can be isolated by culture from sputum, pleural fluid, blood and even urine. Pleural fluid examination may be plasma exudative or purulent.
2. X-ray examination
X-ray shows multilobar diffuse patchy infiltration shadow, mainly in the two lower lungs. Occasionally, there are solid signs, and medium-sized pus cavity formation and pleural effusion can often be found, and pyothorax is also common.
Diagnosis
There are many types of Gram-negative bacilli that can cause pneumonia, with similar clinical manifestations and lack of specificity in auxiliary tests, so the diagnosis of E. coli pneumonia needs to be combined with etiology. The disease should be considered when there are symptoms of pneumonia, a history of chronic disease with long-term use of antibiotics or immunosuppressants, accompanied by gastrointestinal symptoms and even mental symptoms, and rapid progression of the disease, which may be complicated by pyothorax. Sputum smear examination can distinguish whether the pathogen is gram-negative bacillus, sputum culture should be positive to exclude the contamination of oropharyngeal colonization bacteria, so first of all, qualified sputum specimens should be taken, that is, the ratio of leukocytes and epithelial cells in sputum smear is more than 2.5 for qualified sputum. The diagnosis can also be established if Escherichia coli is cultured from pleural fluid and blood specimens. DNA probes or PCR methods can be used when conditions permit. Pneumonia is also diagnostic if it is secondary to a urinary tract infection and both urine and sputum cultures are positive for E. coli.
Complications
Lung abscess, pleural effusion or pyothorax, shock, cardiopulmonary insufficiency.
Treatment
The basic principle of treatment for E. coli pneumonia is to actively deal with the underlying disease, choose appropriate antibiotics, and promptly deal with complications.
1. General treatment
Stop cough, expectorate, relieve pain, stop bleeding, and replenish fluids in appropriate amount. Maintain water, electrolyte and acid-base balance, keep warm, rest, and eat enough nutritious and easily digestible food. Oxygen therapy should be given in case of hypoxia. Actively deal with primary and underlying diseases.
2. Anti-infection treatment
(1) β-lactams Cephalosporins or broad-spectrum penicillins combined with aminoglycoside antibiotics are commonly used in the treatment of E. coli pneumonia.
(2) Aminoglycosides Gentamicin, tobramycin, amikacin and nertilmicin can be used in the treatment of E. coli pneumonia.
(3) Quinolones Ciprofloxacin, ofloxacin, levofloxacin, and sparfloxacin (sparfloxacin) are powerful antibacterials against E. coli, but the proportion of drug resistance has increased in recent years.
The dose and course of antibiotics should be increased in patients who develop lung abscess, pleural effusion or pyothorax, and those with pyothorax formation should be drained, and antibiotics should be injected intrapleurally to prevent pleural thickening and adhesions. Those with concurrent shock and cardiopulmonary insufficiency should be treated accordingly, and mechanical ventilation treatment should be given when necessary, etc., and nursing care should be strengthened, and those with conditions can be admitted to respiratory monitoring ward.
Prevention
In addition to improving the resistance of patients, in the hospital environment, patients should be properly isolated, patients’ feces should be disinfected, and the disinfection and management of toilets, taps, cups, etc. in the hospital should be strengthened. The concept of asepsis should be strictly enforced on medical and nursing staff, and the use of implantable instruments should all be subject to strict operating principles.