Pseudomonas cepacia pneumonia

Introduction to Pseudomonas cepacia pneumonia Pseudomonas cepacia pneumonia (pseudomonascepaciapneumonia) is a lung infection caused by pseudomonascepacia, mainly in patients with severely impaired immune mechanisms (such as blood diseases, malignant tumors) and cystic fibrosis patients, most of the disease Progressive aggravation, and Pseudomonas cepacia resistant to most antibiotics, the prognosis is poor. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: respiratory transmission Complications: cystic fibrosis

The cause of Pseudomonas cepacia pneumonia

(1) Causes of the disease

This strain is one of the non-fluorescent Pseudomonas species, which is widely grown in the external environment. It is first discovered as a plant pathogen that can cause onion head rot. This strain was formerly known as pseudomonas kingii, omnivorous Pseudomonas multivoranse and EO-1 population, according to nucleic acid homology, Pseudomonas cepacii and Pseudomonas mallei, pseudomonas pseudomallei and cutaneous pseudonym Pseudomonas pickettii is closely related and has a long relationship with the common Pseudomonas aeruginosa.

The bacterium is a single-ended bacterium, which is a specific aerobic, non-fermenting glucose gram-negative bacillus. The cells are long and have uneven staining granules. The Sudan black staining is dark black granules. The normal agar medium is 37 ° C. It grows well, does not grow at 5 °C, and grows at 41 °C. Most of the strains can grow on the McCain culture medium. The colonies are opaque. The bacteria can produce fluorescent pigments during the growth process, that is, purple fluorescence under ultraviolet light. The strains are grayish white, and some strains are yellow and then form a purplish red pigment, which is a phenothiazine pigment. One strain may produce one or several pigments. The strains newly isolated from clinical specimens often have no pigmentation, and for maltose, Oxidative decomposition of lactose, negative hydrolysis of arginine, no reduction of nitrate, production of lysine decarboxylase, other biological characteristics similar to Pseudomonas aeruginosa, this strain does not hydrolyze starch, which can be distinguished from Rhizopus.

The bacterium can still multiply under nutrient deficiencies, and it can grow from many substances, from simple salts such as ammonium acetate to complex organic molecules such as 2,4,5-trichlorophenoxyacetic acid (a herbicide). Even using penicillin G as a nutrient, the bacteria often contaminate tap water, nebulizers, thermometers, etc. in hospital environments.

Can survive in a variety of disinfectants, such as quaternary ammonium benzylamine (Zehmer), chlorhexidine and povidone iodine, and thus cause the prevalence of Pseudomonas cepacia hospital infection, can lead to endocarditis , sepsis, postoperative and burn wound infections, peritonitis, osteomyelitis, arthritis, meningitis, pneumonia, lung abscess, and therefore in the blood, urine, pus, pleural effusion and bronchoalveolar lavage fluid of these patients The bacteria are detected, and the bacteria have strong reproductive growth capacity and resistance to many disinfectants and preservatives used now, making it a more difficult to treat hospital infection.

Some Pseudomonas cepacii strains are more infectious and pathogenic than other strains. Individual strains are associated with most new infections, and infections in different regions are also associated with individual strains.

(two) pathogenesis

Pseudomonas cepacia is an opportunistic pathogen and has low virulence to healthy humans and animals. Animal experiments have shown that inhalation of a certain amount of Pseudomonas cepacia in rats with leukopenia can cause Pseudomonas cepacia pneumonia; Bacteria inhaled by healthy rats are immediately cleared by the mucociliary system and local bactericidal action, without causing pneumonia. In patients with severely impaired immune mechanisms and/or advanced cystic fibrosis, Pseudomonas cepacia passes contaminated atomization Inhalers, lung function meters, ventilators, etc. directly enter the respiratory tract, especially in patients with tracheal intubation or tracheotomy, bacteria bypass the mucociliary system, directly into the lower respiratory tract, causing infection, some patients may have onion sinus The bacteria grow to form aspiration pneumonia.

Most strains produce proteases (gelatinase) and lipase. Bacteria may directly destroy lung tissue by releasing toxins and enzymes, causing necrotizing or other types of pneumonia, lung abscess, etc. Some strains can synthesize phenazine pigments, which can block pigments. Lymphocyte proliferation, some patients also have immune complex formation involved in tissue destruction, such as Pseudomonas aeruginosa infection, may have synergistic effect with Pseudomonas aeruginosa.

Pseudomonas cepacia pneumonia prevention

In response to the direct contact and social contact transmission of the bacteria, patients infected with Pseudomonas cepacia should be isolated from uninfected patients and limit their social activities, but the latter are often objected to by patients and controversial; medical personnel contact Wash hands after the patient to reduce the chance of cross-infection; eliminate the use of nebulizer inhaler to avoid cross-infection, and disintegrate the nebulizer into the sodium hypochlorite solution every day, autoclave once a week, for sinusitis Patients should undergo sinus puncture to reduce the source of infection.

Onion Pseudomonas pneumonia complications Complications cystic fibrosis

Often combined with other serious diseases (such as malignant tumors, cystic fibrosis).

Pseudomonas cepacia pneumonia symptoms common symptoms bacterial infection repeated hyperthermia

There are three clinical manifestations of Pseudomonas cepacia pneumonia:

1 long-term asymptomatic carrier;

2 years of progressive deterioration, repeated high fever, weight reduction, repeated hospitalization;

3 The sharp and fatal condition worsens and the patient died in a short period of time. The clinical symptoms of female patients are often worse than males and the prognosis is worse. The typical clinical process is severe bacterial infection, which is characterized by repeated or persistent high fever, progressive wasting, and lung function drops sharply. Often combined with other serious diseases (such as malignant tumors, cystic fibrosis), a small number of patients may have bacteremia, pulmonary function decline in patients with Pseudomonas aeruginosa pneumonia is more serious than Pseudomonas aeruginosa pneumonia.

Examination of Pseudomonas cepacia pneumonia

1. Bacteriology test:

Different strains or ribotyping have different pathogenicity, and ribotyping is useful for assessing the relative risk of infection in patients with cystic fibrosis before lung transplantation.

According to the needs of the disease, sputum, bronchoalveolar lavage fluid, chest pus, blood, ascites, urine and other specimens can be taken. Blood specimens must be isolated and cultured after enrichment and culture. Other specimens can be directly lined with blood agar and wheat. Kangkai agar plates were identified according to their colony characteristics, morphology, staining and further biochemical reaction tests on blood agar or MacConkey agar plates. On conventional sputum medium, Pseudomonas cepacia grew slowly and colony morphology was high. Variety, Pseudomonas aeruginosa and Pseudomonas cepacia symbiosis, the former growth rate is significantly higher than the latter, so easy to be confused with Pseudomonas aeruginosa, Staphylococcus aureus, the culture of this strain can also be selectively cultured Base, such as polymyxin-carboxythiophene penicillin PC medium.

The germline-specific polymerase chain reaction (PCR) and DNA hybridization techniques have been successfully used to distinguish between Pseudomonas cepacia and Pseudomonas aeruginosa. The preparation of , PCR, DNA hybridization can be completed in one day, the next day. The autoradiography results can be seen.

Pseudomonas cepacii typing methods include: plasmid analysis, comparison of DNA fingerprinting type ribose typing, bacteriocin typing, serotyping, biochemical tests, and phenotypic analysis by pulverization field gel electrophoresis (PFGE). Fingerprint, mitochondrial DNA restriction fragment type analysis, extracellular product type analysis, etc., studies have found that the phenotype of Pseudomonas cepacii isolates is variable, and the appearance of bacterial colonies isolated from a patient within a certain period of time, Antibiotic sensitivity, pigment products are different, ribose typing can distinguish all isolates derived from a colony, phenotypic diversity may be the result of different gene expression.

2. Peripheral blood:

Increased white blood cells, accelerated erythrocyte sedimentation rate, and increased C-reactive protein.

3. X-ray performance :

Lung parenchymal infiltration is often lobular, occasionally extensive changes, may have cavity formation, pulmonary function FEV1, FEV1/FVC progressive decline.

Diagnosis and identification of Pseudomonas cepacia pneumonia

In patients with severe impaired immune function and/or cystic fibrosis, repeated or persistent high fever, progressive weight loss, sharp decline in lung function, chest X-ray showed pulmonary parenchymal infiltration, and sputum culture was positive for more than 2 consecutive times (medium) Only Pseudomonas cepacia can be diagnosed as Pseudomonas cepacia, and positive bronchoalveolar lavage fluid culture is also helpful for diagnosis.

The disease is mainly identified with Pseudomonas aeruginosa pneumonia, mainly relying on sputum culture results, sometimes combined infection of two bacteria, Pseudomonas aeruginosa pneumonia combined with bacteremia is rare.

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