Enterobacter cloacae infection

Introduction to Enterobacter cloacae infection Enterobacter Cloacae is widely found in nature and can be detected in human and animal feces, water, soil, and plants. It is one of the normal intestinal strains, but it can be used as a conditional pathogen, along with cephalosporins. The widespread use of bacteriocin, Enterobacter cloacae has become an increasingly important pathogen of nosocomial infections, causing bacterial infections, often involving multiple organ systems, including skin and soft tissue infections, urinary tract infections, respiratory infections and sepsis. Because Enterobacter cloacae can produce extended-spectrum -lactamases (ESBLs) and AmpC enzymes, the drug resistance is serious, which brings new challenges to clinical treatment. basic knowledge The proportion of illness: 0.004% - 0.005% Susceptible people: no special people Mode of infection: respiratory transmission Complications: septic shock, diffuse intravascular coagulation, lung abscess, brain abscess

Etiology of Enterobacter cloacae infection

Pathogen infection (30%):

Enterobacter cloacae is a member of the genus Enterobacteriaceae, which is a Gram-negative bacterium, having a width of about 0.6-1.1 m, a length of about 1.2-3.0 m, and a flagella flag (6-8 flagella). Dynamic positive, no spores, no capsule, its optimal growth temperature is 30 ° C, facultative anaerobic, can grow on ordinary medium, forming large and moist mucous colonies, not hemolyzed on blood agar, in Eosin-methylene blue agar (EMB) is pink and viscous. It is pink or red on MacConkey agar and is viscous. It is white or milky white if grown on SS agar, opaque and viscous. In the fermentation of sugar: lactose, sucrose, sorbitol, raffinose, rhamnose, melibiose are positive, can not produce yellow pigment, ornithine decarboxylase test (+), arginine double hydrolase Test (+), lysine decarboxylase test (-), (-), Enterobacter cloacae has three antigenic components of O, H and K. The culture of most strains can be strongly mixed after boiling at 100 ° C for 1 h. The homologous O serum agglutinates, while the live bacteria and its agglutination are weak or non-aggregating, indicating a K antigen, The viable culture of non-aggregated in the serum of O was heated at 100 °C for 1 h, and the bacterial suspension was treated with 50% ethanol or 1 mol of hydrochloric acid. It became agglutinable at 37 ° C for 18 h, but it did not lose its O after heating at 60 ° C for 1 h. The agglutination, antiserum prepared by boiling the heated bacterial suspension does not contain K lectin, and the Enterobacter cloacae antigen table established by Sakazaki consists of 53 O antigen groups, 56 H antigens and 79 serotypes.

1O antigen: slide agglutination test is a routine method for the determination of Enterobacter cloacae, concentrated saline solution of overnight agar culture, heated at 100 ° C for 1 h, washed with centrifugation, and diluted with O serum for agglutination, although serum titer At 500-1000, but still diluted 1:10 for slide agglutination, it is better to use a higher dilution of antiserum, a strong reaction can occur in a few seconds, and cross-reaction is less, in different O antigen Delayed and unilateral reactions were observed, and although most O antigen populations can be measured with moderately diluted unabsorbed sera, it is often necessary to determine specific O antigens using the absorbed group-specific serum.

2H antigen: Determination of H antigen, the conventional method is a tube agglutination test, using a dynamic active overnight broth culture, the medium is a trypsin soy broth containing 0.2% glucose and infusion broth, cultured in broth culture An equal amount of 0.6% formalin was added, and the unabsorbed serum of the bactericidal titer of 10,000 to 20,000 was usually diluted 1:1000, 0.1 ml of H serum diluted 1:100 was placed in a small test tube, and then 1.0 ml of formaldehyde solution was added. The treated broth culture, the test tube was read in a water bath at 50 ° C for 1 ~ 2 hours, the results of the Enterobacter cloacae, the external antigen relationship: although there are multiple species in the genus Enterobacter, the Enterobacter cloacae is the only pair It carries out antigen research, so the relationship between the antigens between Enterobacter cloacae and other Enterobacter species is still unclear. It has been reported in the past that most Enterobacter cloacae can be serotyped by Klebsiella capsular capsules. Sakisaki's research proves that the mucus produced by Enterobacter cloacae is not a true capsule, and there is no obvious relationship between O antigen and K antigen between Klebsiella and Enterobacter cloacae.

Pathogenesis

As a Gram-negative bacterium, endotoxin plays a pathogenic role. In addition, the bacterium has strong resistance to disinfectants and antibiotics, which is an important factor in the increasing number of nosocomial infections. Obtaining resistance to antibiotics, especially to -lactam antibiotics, should be valued by clinicians.

1. Host defense function is reduced

(1) Local defense barrier damage: burns, trauma, surgery, certain interventional operations cause skin and mucous membrane damage, making Enterobacter cloacae easy to invade through the human barrier.

(2) Deficiency of the immune system: developmental disorders of the innate immune system, or acquired damage (physical, chemical, biological factors), such as radiation therapy, cytotoxic drugs, immunosuppressants, viral infections that damage the immune system, etc. Can cause opportunistic infections.

2. Provides opportunities for pathogen invasion. Various operations, indwelling catheters, venous catheters, endoscopy, mechanical ventilation, etc., make Enterobacter cloacae have access to the body, which may lead to infection.

3. Enterobacter cloacae producing -lactamase Enterobacter cloacae can produce both ESBIs and Amp C enzymes, which leads to high resistance to various antibiotics, which brings difficulties to clinical treatment. 144 strains of Enterobacter cloacae in Zhejiang Province The drug sensitivity test showed sensitivity to amoxicillin-clavulanic acid, cefuroxime, aztreonam, cefotaxime, ciprofloxacin, piperacillin-tazobactam and amikacin at 55 Below %, the sensitivity rate to cefoperazone-sulbactam and cefepime is only about 60%, and the sensitivity rate to imipenem alone is as high as 98.61%, among which high-yield Amp C enzyme strains account for 24.31%, and ESBLs-producing strains account for 36.81%.

4. Wide application of antibiotics

(1) Broad-spectrum antibacterial drugs can inhibit the normal flora of various parts of the human body, causing dysbacteriosis.

(2) The strains sensitive to antibiotics are inhibited, and the resistant strains are multiplied, which is easy to cause the spread of nosocomial infection bacteria and cause the disease in patients. In recent years, due to the widespread use of the third generation cephalosporins, it is easy to screen for high-yield Amp C enzymes. Enterobacter cloacae, leading to the prevalence of resistant bacteria.

Enterobacter cloacae infection prevention

1. Strengthen labor protection, avoid trauma and wound infection, and protect the integrity and cleanness of skin and mucous membranes.

2. Do a good job in disinfection, isolation and protection of hospital wards, wash hands frequently, prevent cross-infection of pathogenic bacteria and conditional pathogens in hospitals, and medical staff with chronic bacteria should be temporarily removed from the ward and treated.

3. Rational use of antibacterial drugs and adrenocortical hormones, pay attention to prevent dysbacteriosis, when there is infection of fungi and other resistant strains, the treatment should be adjusted in time.

4. When performing various operations, instrument examination, venipuncture, indwelling catheter and other technical operations, it should be strictly disinfected, pay attention to aseptic operation.

5. Active control, treatment of leukemia, diabetes, chronic liver disease and other chronic diseases that are easy to cause infection.

Enterobacter cloacae infection complications Complications , septic shock, diffuse intravascular coagulation, lung abscess, brain abscess

Complications are common septic shock or DIC, in addition to lung abscess, brain abscess and so on.

Symptoms of Enterobacter cloacae infection Common symptoms Relaxation of heat and shortness of breath Ascites meningitis sepsis

The clinical manifestations are diverse and generally similar to other facultative Gram-negative bacilli, which can manifest as infections of the skin, soft tissues, respiratory tract, urinary tract, central nervous system, gastrointestinal tract and other organs.

1. Septicemia: It occurs mostly in the elderly or newborns, sometimes accompanied by mixed infections of other bacteria. It is often accompanied by fever in adults and children, and there are many chills. The patients have different types of heat, which can be used for heat retention, intermittent heat, and relaxation. Heat, etc., may be associated with hypotension or shock, patients with multiple leukocytosis, and a small number of patients with leukopenia, occasionally reported thrombocytopenia, hemorrhage, jaundice, diffuse intravascular coagulation, mostly with skin symptoms, Such as purpura, hemorrhagic blisters, impetigo and so on.

2. Lower respiratory tract infections: Patients generally have severe underlying diseases, especially chronic obstructive pulmonary disease and bronchial lung cancer. Infected people often use antibiotics, and often have various immune factors such as immunosuppressive agents. , hormone application, chemotherapy radiotherapy, etc., predisposing factors: to place the most ventilator, other tracheotomy, tracheal intubation, thoracic puncture, arteriovenous catheterization, catheterization, general anesthesia, etc., may have fever or even high fever, many Cough, sputum can be white, purulent or bloodshot, but in the elderly, the symptoms are less or even asymptomatic, there may be shortness of breath, tachycardia, infection can be manifested as bronchitis, pneumonia, lung abscess, pleural cavity Fluid, shock and metastatic lesions are rare, X-ray findings are different, can be leaf, bronchitis, void or mixed, can be single-leaf disease, multi-lobular lesions or diffuse bilateral lesions.

3. Wound infection: It is common in burn wounds, infections in surgical incisions. With the development of various operations, the bacteria can be infected almost everywhere, especially in the sternal mediastinum and the back of the spine.

4. Soft tissue infections: Common forms of infection in the community, such as hematoma under the nails, soft tissue infection after a fall.

5. Endocarditis: The most dangerous is intravenous drug addicts, prosthetic valve surgery, heart surgery.

6. Abdominal infection: Due to the migration of the bacteria or the perforation of the intestine to the peritoneum or other organs, the bacteria are gradually gaining attention in gastrointestinal-derived infections, especially in liver-related infections. Other gas gangrene such as liver, acute emphysema cholecystitis and retrograde cholangiopancreatitis, acute suppurative cholangitis caused by cholelithiasis intermittent, without ascites or perforation secondary to small bowel obstruction Peritonitis and the like.

7. Urinary tract infections: From asymptomatic bacterial urine to pyelonephritis have been reported.

8. Central nervous system infection: Enterobacter cloacae can cause meningitis, ventriculitis, brain abscess and so on.

9. Eye infections: Eye surgery is a common cause, and cataract surgery is often performed in the elderly, and thus is a common cause of such infections.

Examination of Enterobacter cloacae infection

The white blood cell count is mostly increased, and it can also be reduced. Most of the neutrophils are increased. The blood culture samples can be taken from blood, cerebrospinal fluid, urine, etc. The significance of sputum culture is still controversial. The value of drug susceptibility test should be emphasized. In terms of molecular epidemiology Methods such as PFGE, RAPD, and 16S rRNA gene sequencing have their own advantages and disadvantages.

1. Blood routine: The number of white blood cells and neutrophils are significantly increased, and there may be a left shift of the nucleus, but the lower body reaction such as low immunity or white blood cells such as the elderly and children may not be high.

2. Urine routine: Urine turbidity during urinary tract infection, white blood cells >5/HP, may be associated with red blood cells, urine protein and cast.

3. Pathogen examination

(1) Bacterial culture: blood culture and positive bone marrow culture are the main basis for diagnosis. The latter has a higher positive rate. In order to obtain a higher positive rate, specimens should be collected as much as possible before antibiotic use and during chills and high fever. For the second time, 5 to 10 ml of blood is collected every time. For patients who have been treated with antibiotics, the time of blood collection should avoid the antibiotic peak time in the blood, or add appropriate antibiotic-preventing drugs such as penicillinase, magnesium sulfate, etc. to the medium. Blood clot culture to increase the positive rate of blood culture. After sputum collection, it must be inoculated and cultured within 10 minutes. The same bacteria can be cultured several times, or the quantitative diagnosis of sputum can be more clinically meaningful. First check the white blood cell count and the number of squamous epithelial cells in the specimen to determine whether the sputum specimen is qualified. In order to avoid the contamination of the oral bacteria, you can suck from the trachea or use the fiberoptic bronchoscope to suck from the lower respiratory tract to prevent pollution. The brush is sampled for bacterial culture, and other body fluid cultures include urine of patients with urinary tract infection, cerebrospinal fluid of meningitis patients, or secretions from other infected sites. When the culture is positive, the relevant antibiotic susceptibility test should be carried out for the treatment of appropriate antibacterial drugs.

(2) bacterial smear: pus, cerebrospinal fluid, pleural effusion, ascites, sputum and other direct smear examination, can also detect pathogens, have a certain reference value for rapid diagnosis.

4. Other tests: The Limulus lysate test (LLT) is a method for determining the endotoxin in each body fluid by using a clotting protein in a lytic cell lysate to form a gel in the presence of endotoxin. Positive for the diagnosis of Gram-negative bacilli sepsis, chest X-ray examination of patients with pulmonary infection can see flaky or patchy shadows, with the clinical application of molecular biology, genetic diagnosis technology will greatly enhance the specimen Positive rate and can determine whether there is a drug resistance gene.

Chest X-rays of patients with pulmonary infection can be seen with flaky or patchy shadows.

Diagnosis and identification of Enterobacter cloacae infection

According to the clinical manifestations of each system, laboratory tests can determine the location of infection, bacterial culture to Enterobacter cloacae as the basis for diagnosis, it should be noted that the clinical manifestations of infection in patients with low immunity may be atypical, Enterobacter cloacae infection should pay attention to other Identification of Gram-negative bacilli infection, confirmed diagnosis or smear detection of Enterobacter cloacae.

Enterobacter cloacae sepsis needs to be differentiated from typhoid fever or paratyphoid fever.

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