Enterobacter pneumonia
Introduction
Introduction to Enterobacter pneumonia Enterobacter pneumonia (enterobacterpneumonia) has been extremely rare in the past, in recent decades. With the increase in the application of broad-spectrum antibiotics and respiratory medical devices, Enterobacter pneumonia has accounted for 9.4% of hospital-acquired pneumonia, including those caused by Enterobacter cloacae and Enterobacter aerogenes. Clinically, Enterobacter pneumonia often occurs in debilitated or immunosuppressed patients, and is easily caused by contaminated medical devices, often accompanied by bacteremia and poor response to various antibiotic treatments. basic knowledge The proportion of illness: the incidence rate is 0.05% Susceptible people: no specific people Mode of infection: non-infectious Complications: bacteremia, Enterobacter pneumonia
Cause
Enterobacter pneumonia
(1) Causes of the disease
Enterobacter Escherichia coli (E. cloacae), Enterobacter aerogenes (E. aerogenes), E. agglomerans, E. gergoviae, Enterobacter sakazakii (E) .sakazakii) and E. taylorae, in which Enterobacter cloacae and Enterobacter aerogenes are clinically important conditions causing pneumonia, sepsis, urinary tract infections and meningitis; Bacillus is an important nosocomial infection pathogen that can contaminate infusions and cause sepsis and other infections.
Enterobacter bacteria are widely distributed in the natural environment, soil, sewage, rotten vegetables and dairy products can be found, Enterobacter cloacae and Enterobacter aerogenes can be colonized in the gastrointestinal tract and respiratory tract, is part of the normal flora.
The biological characteristics of Enterobacter bacteria are similar. The representative bacteria are Enterobacter cloacae. The bacteria are 1.2-3.2 m long and 0.6-1.0 m wide. They are motivated and have flagella around them. Most of the fermentation mannitol, sorbitol, lactose, and sucrose. , arabinose and rhamnose, do not produce hydrogen sulfide and strontium, VP reaction is positive, MR reaction is negative, gluconate is positive, ornithine decarboxylase is produced, all bacteria grow well on common medium, each strain The colonies are not characteristic and require a series of biochemical reactions to be identified.
Enterobacter bacteria can be classified by serum, bacteriocin, biochemical tests, phage, etc., and the methods can be used for mutual verification and compensation. In the US Central Public Health Laboratory, the most reliable serological method is used. As a primary method for identifying strains, further serotypes are further typed with phage, and it has been demonstrated that these typing methods are effective in most cases, but in some cases, biotyping is useful. The method of confirming the effect is that the Enterobacter cloacae is currently divided into 53 O antigens, 57 H antigens, and 79 serotypes are separated from 170 strains.
(two) pathogenesis
In addition to blood line spreaders, it is generally believed that Enterobacteriaceae bacteria, including Enterobacter bacteria, are different from non-Enterobacteriaceae bacteria such as Pseudomonas aeruginosa. They often reside in the oropharynx before entering the lower respiratory tract. Reach to the lower respiratory tract by inhalation or direct dissemination.
The ability of bacteria to enter the lower respiratory tract depends on the number and duration of bacteria adhering to the mucosa. The more bacteria that adhere, the longer the duration, the greater the likelihood of infection. According to the study, except for the patient's whole body and lower respiratory tract. In addition to the immune function, the structure of the airway epithelium, the surface structure of the Enterobacter bacteria and the local microenvironment are important factors influencing adhesion.
In the airway epithelium, many critical diseases lead to an increase in bacterial receptors on epithelial cells, thereby increasing bacterial adhesion; airway epithelial cell cilia dysfunction, reducing the elimination of invading bacteria; mucosal epithelial cell surface fiber binding protein concentration decreased The reduction of the blocking of bacterial binding sites can increase the colonization of bacteria in the lower respiratory tract. The airway mucosa is damaged by intubation or sucking, the basement membrane is exposed, and the bacteria may adhere to the connective tissue under the mucosa.
In terms of bacteria, the amount of bacterial pili, the ability to stimulate mucus secretion, the decomposing activity of fibronectin and its substances such as cilia stabilizing substances, proteases and mucin degradation products can affect the colonization of the lower respiratory tract, Enterobacter Most strains have type I pili, and a few can also produce type III pili and/or MR adsorbin, which has strong adhesion. In addition, some bacteria can produce substances that affect ciliary function and reduce bacterial clearance. Enterobacteria may also break down fiber-binding proteins to expose bacterial binding sites on the surface of mucosal epithelial cells.
In the airway mucosal microenvironment, the chemical composition and characteristics of the airway secretions are changed to affect the colonization of bacteria. First, some primary diseases increase the pH of the airway secretions, increase the adhesion of bacteria, and secondly When inflammation occurs in the tract, neutral elastase breaks down IgA and fibronectin, increasing bacterial adhesion.
Pathological changes: Enterobacter pneumonia, the vast majority of bronchial pneumonia, often involving multiple sites, more than half of the two sides, leafy consolidation is less common, inhaled infection, the following lungs are more common, inflammation begins from the bronchi, through small The bronchial wall causes suppurative inflammation, consolidation and necrosis of surrounding tissues, and multiple microabscesses are formed. The bloodstream dissemination is caused by perivascular infiltration and small infarcts of nodular lung tissue, followed by massive neutrophil infiltration and multiple occurrences. Sexual abscess.
Small abscesses caused by any route, if the treatment is delayed, small abscesses may fuse to form a large abscess, such as involving the subpleural, and may also have suppurative pleurisy.
Prevention
Enterobacter pneumonia prevention
1. Reducing prophylactic antibiotics According to research, antibiotics, especially cephalosporin antibiotics, can increase the carrying rate of Enterobacter in hospitalized patients. Therefore, reducing antibiotic prophylaxis can prevent the occurrence of Enterobacter pneumonia.
2. Topical application of non-absorbed oral antibiotics reduces the colonization of oropharyngeal and enterobacteria of the gastrointestinal tract, which can reduce the incidence of Enterobacter infection in patients in the ICU.
3. Preventing the development of E. coli colonization into infections Studies have shown that the use of active or passive immunopharmaceuticals can prevent the colonization of Enterobacteriaceae into infection, but most of them are currently in the experimental stage.
4. Suspect and outbreak infections are immediately classified to determine the appropriate control measures.
Complication
Enterobacter pneumonia complications Complications bacteremia enterobacter pneumonia
One of the common complications of Enterobacter pneumonia is bacteremia. It is reported in the literature that among various causes of Enterobacter bacteremia, respiratory infections first occur, and then develop into bacteremia accounted for 11%, second only to abdominal organs. And those with urinary tract infections, so if you suspect that the lung infection is caused by blood source dissemination or accompanied by bacteremia, blood culture should be carried out, such as Enterobacteriaceae, you can confirm the diagnosis.
Symptom
Enterobacter pneumonia symptoms common symptoms sputum sputum leukocytosis dyspnea hemoptysis
Enterobacter pneumonia is similar to other Gram-negative bacilli pneumonia. It has a rapid onset, chills and fever, body temperature often between 37.7 and 38.8 °C, cough is obvious, cough is more, it is mucopurulent, but with Craybai Bacillus pneumonia is different, hemoptysis and blood stasis are rare, such as extensive lesions, may have difficulty breathing.
Physical examination can be anxious, cyanosis, often in both lungs and wet voices, lungs are rare signs of physical changes, such as blood-borne infections, lung signs are sometimes absent, but often found in the urinary tract and digestive tract and other lungs The performance of external infections.
Examine
Examination of Enterobacter pneumonia
1. The total number of white blood cells can be increased or normal, but neutrophils are often increased, and anemia is more common.
2. Urine routine, renal function and liver function Enterobacter septicemia with pneumonia, urine routine, renal function and liver function may be abnormal.
3. Sputum bacterial culture is the only means to diagnose Enterobacter pneumonia. Clinically coughed sputum is contaminated by other bacteria in the oropharynx. It can be obtained by percutaneous puncture, percutaneous lung puncture and fiberoptic bronchoscopy. Cough culture is used, and the specimens need to be pre-cultured and applied with appropriate selection medium to improve the reliability of the results.
(1) Treatment of cough: The coughed sputum is washed with physiological saline for 5 to 9 times (the average reduction of contaminated bacteria is 100 times), and the smear is directly examined. If the fluoroscopy is under low magnification, the white blood cells are >25, scale. Epithelial cells <10, and then sputum plus 1% to 2% protease or acetylcysteine incubated at 37 ° C, when the bacterial concentration > 106 / ml, it is considered that the culture has diagnostic significance, further a series of Biochemical reactions and typing to determine the species, strain and type.
(2) Selection medium: Because of the low concentration of Enterobacter in the sputum specimens, the selection medium should be used to increase the positive rate of culture. The composition of the medium is selected: 2% cellobiose, 0.1% yeast extract, 0.03% Sodium deoxycholate, 10g/ml cephalosporin, 1% agar and Andrades indicator, most of the Enterobacter cloacae cultured at 37 ° C for 24h, due to pH changes, pigmentation, most fecal coliforms grow slowly or not at all , Enterobacter aerogenes can also grow on this medium.
4. X-ray examination of chest X-ray often shows double lower lung bronchial pneumonia, but a few only see increased lung texture without significant pulmonary parenchymal infiltration, a small number of patients with inhaled infection, the right upper lobe and the lower back of the lower lobe can be seen in a wider range Real shadows, visible voids, but far less common than Klebsiella pneumoniae, blood-borne infection cases, chest radiographs seen irregular irregular nodular density, diameter 4 ~ 10mm, throughout the lungs, such as disease development, Then the nodules increase the fusion.
Diagnosis
Diagnosis and identification of Enterobacter pneumonia
The clinical manifestations of Enterobacter pneumonia are not characteristic. Similar to other Gram-negative bacilli pneumonia, it is difficult to diagnose only by clinical manifestations. High-risk groups have fever during hospitalization, increased bronchial purulent secretion, leukocytosis, lesions in the lungs or in the original New infiltration on the basis of lung lesions is the basis for diagnosis. Diagnosis and differential diagnosis depend on bacteriological examination.
It should be differentiated from Gram-negative bacilli pneumonia such as Pseudomonas aeruginosa pneumonia, Klebsiella pneumoniae, Haemophilus influenzae pneumonia, and Proteus pneumoniae.
