Overview of Pseudomonas aeruginosa pneumonia
Pseudomonas aeruginosa pneumonia (PAP) is a pneumonia caused by infection with Pseudomonas spp. The most common pathogen is Pseudomonas aeruginosa (commonly known as Pseudomonas aeruginosa), and it often occurs in patients who are immunocompromised or with underlying diseases such as bronchiectasis. It is a common cause of hospital-acquired infections, and can also occur in patients with community-acquired infections.
Etiology
Pseudomonas aeruginosa belongs to the genus Pseudomonas, which is widely distributed in nature and normal human skin, intestinal tract and respiratory tract, and is one of the more common conditionally pathogenic bacteria in clinical practice. Pseudomonas aeruginosa has a strong resistance to the external environment, can survive for a long time in a humid place, is not sensitive to ultraviolet light, and can only be killed by heating at 55℃ for 1 hour.
Symptoms
1. Common symptoms
Cough, cough sputum, most patients cough yellow pus sputum, a few sputum for the typical bright green pus sputum, hemoptysis is rare. There are obvious symptoms of poisoning, with sepsis-like systemic manifestations such as high fever, malaise, drowsiness and heart failure. Chest tightness, shortness of breath, progressive cyanosis, and relatively slow heart rhythm. When the disease worsens, peripheral circulatory failure may occur and enter a state of shock. Respiratory failure may occur in patients with original respiratory dysfunction.
2. Atypical symptoms
Due to the wide distribution of Pseudomonas aeruginosa, the bacteria can be isolated from normal human skin, hands, hospital mattresses, medical equipment, especially nebulizers and artificial respirators. It can be transmitted to human beings through a variety of ways, so it can cause various complications or infections outside the respiratory system. For example, sepsis, endocarditis, urinary tract infections, central nervous system infections, gastrointestinal tract infections, as well as corneal ulcers or keratitis, otitis media and mastoiditis, sinusitis, and multiple vertebral osteomyelitis.
Examination
1. Routine blood tests
The white blood cell count is often in the normal range, elevated after a few days, and naïve cells can be seen. Leukocytes>20×109/L, neutrophils are mostly increased, eosinophils can also be increased, but it is not specific for diagnosis.
2. Blood biochemical examination
Blood sedimentation increases rapidly, and hypokalemia, hyponatremia and hypochloremia may occur. Liver and kidney function may be impaired.
3. Pathogenetic examination
(1) Sputum smear: sputum smear is a simple and rapid examination method, which is bright green or yellowish green to the naked eye and has the special odor of Pseudomonas aeruginosa. The sputum smear can be stained with Gram’s stain, which can initially distinguish between Gram’s stain positive and negative bacteria, which is valuable for guiding the use of antibiotics before sputum culture examination.
(2) Sputum bacterial culture: sputum bacterial culture is the main method of diagnosing pathogens. Anti-pollution lower respiratory secretion specimens isolated Pseudomonas aeruginosa is a more reliable evidence for the diagnosis of Pseudomonas aeruginosa pneumonia.
4. X-ray examination
Typical changes are bilateral multiple scattered patchy shadows or nodular shadows, mostly within 1cm in diameter, which may involve several lobes, and the lower lobes are common. Such small nodules may rapidly fuse and expand into larger patchy blurred shadows with multiple small abscesses, and may also be accompanied by a small amount of pleural effusion.
Diagnosis
In general, Pseudomonas aeruginosa pneumonia should be considered in the following clinical situations:
1. A history of chronic lung disease with prolonged coughing and abundant sputum of yellowish-green pus or pus-blood sputum.
2. History of long-term glucocorticoid and antibiotic therapy with fever and worsening respiratory symptoms.
3. Chest X-ray suggests extensive lung lesions, diffuse nodular or reticular changes in both lungs or small abscess formation.
4. Two consecutive sputum cultures detect Pseudomonas aeruginosa. A single positive sputum culture is not enough to diagnose Pseudomonas aeruginosa pneumonia; it must be determined by the number of colonies, the results of consecutive cultures, and the clinical situation, including the pathogenic conditions of the patient, the development of the disease, and the changes in X-rays.
Treatment
Selection of sensitive and effective antibiotic drugs is the centerpiece of the treatment of this disease. Before the results of pathogen culture and drug sensitivity test are available, appropriate antibacterial drugs can be selected according to experience.
1. Drug therapy
Antibacterial drugs with strong effect on Pseudomonas aeruginosa include semi-synthetic penicillin, such as carbenicillin, alloxacillin and piperacillin, of which piperacillin is the most commonly used. Among cephalosporins, ceftazidime and cefoperazone have stronger effects. Other β-lactams such as imipenem and amitramine; aminoglycosides such as gentamicin, tobramycin, and amikacin; and fluoroquinolones such as ofloxacin, ciprofloxacin, and fleroxacin. For the elderly or patients with more serious underlying diseases or patients with certain renal impairment, the use of semi-synthetic penicillin, cephalosporin or other β-lactams can be considered first, such as allergy to the above drugs or patients who must use aminoglycosides and fluoroquinolones, the use of which should be reduced and closely observe the changes in renal function, and should be discontinued as soon as there is an aggravation of renal impairment.
2.Other
Pseudomonas aeruginosa pneumonia occurs in patients with severe underlying disease or immunocompromised, therefore, the treatment of underlying disease should be strengthened at the same time of anti-infection, local drainage and systemic supportive therapy, and the immune function should be improved. For example, attention should be paid to calorie supply and protein supplementation, diabetic patients should actively control blood glucose, and intermittent transfusion of fresh blood or leukocytes can be given to severely ill patients or those with granulocytopenia.