Aeromonas pneumonia
Introduction
Introduction to Aeromonas pneumonia Aeromonas currently has 10 strains, mainly A. hydrophilic, A. caviae and A. sobria. Wait. In the past, Aeromonas was considered to be a low-virulence conditional pathogen. In recent years, acute gastroenteritis, sepsis and respiratory tract, biliary and urinary tract infections caused by it have been reported. basic knowledge The proportion of illness: 0.0002% Susceptible people: no specific population Mode of infection: non-infectious Complications: sepsis
Cause
Aeromonas pneumonia
(1) Causes of the disease
Aeromonas hydrophila was isolated from a stool specimen of a colitis patient as early as 1937. This genus is a Gram-negative Brevibacterium, (1 to 4) m × (0.4 to 1) m. Arranged in single or double, blunt ends, single flagella, shuttle-like power, no spores, thin capsule, aerobic and facultative anaerobic bacteria, grayish white, smooth, moist on the blood plate , bulge, colony about 2mm in diameter, 76% strain has -type hemolytic ring, 3 to 5 days colony becomes dark green, lactose is not formed on intestinal selective medium (such as SS, EMB, MacConkey agar plate, etc.) Fermenting colonies, colonies are more turbid, milky gray and odorless, positive for oxidase test, can be distinguished from E. coli, the use of sugar by this genus is fermentative, acid production or acid production, with capital and fake The genus is distinguished.
The pathogen is cultured at 30 ° C to produce acid in glucose, mannitol, maltose and trehalose, usually accompanied by gas production. In the production of acid in sucrose, arabinose, and sorbitol, the antigenic structure of the bacterium is still unclear.
(two) pathogenesis
Pathogenic Aeromonas can produce enterotoxin, hemolysin, leukocidin, epithelial cell adhesion factor, cell pyknosis factor; and various cell enzymes, such as proteases, gelatinase, etc., enterotoxin-producing strains The surface can be covered with dense cilia under the electron microscope. The enterotoxin can make the intestinal effusion of the suckling mouse edema and translucent. It can also change the morphology of CHO cells (Chinese hamster ovary cells), from oval to fusiform, and even atrophy. Solution, hemolysin can dissolve human, rabbit, sheep red blood cells, the bacteria have strong pathogenicity to cold-blooded animals such as frogs and fish, guinea pigs, rats, hamsters and other warm-blooded animals can cause body muscles after inoculation of the bacteria Necrosis and death, when the body's systemic or local defense function is reduced, the bacteria can cause pneumonia, acute gastroenteritis, cellulitis and cholecystitis, meningitis and other diseases.
Prevention
Aeromonas pneumonia prevention
Main measures:
1 Avoid eating contaminated water and food.
2 Try not to contact patients and sick animals.
3 Active treatment of the primary disease, to prevent the occurrence of cross-infection, improve the body's resistance.
Complication
Aeromonas pneumonia complications Complications sepsis
Combined with sepsis. An acute systemic infection in which Aeromonas enters the blood circulation and grows in the blood to produce toxins. Lighter only has general symptoms of infection, and severe cases can occur with septic shock, DIC, and multiple organ failure. The performance is: first chills or chills, followed by high fever, heat type, relaxation or heat retention; weak, severe malnutrition and small babies can have no fever, and even lower body temperature. Apathetic or irritated, severe cases may appear pale or gray, unconscious. The extremities are cold, shortness of breath, rapid heart rate, and decreased blood pressure.
Symptom
Symptoms of Aeromonas pneumonia Common symptoms Abdominal pain Low heat sepsis Nausea diarrhea
Pneumonia
Often secondary to certain chronic diseases, such as blood diseases, liver cirrhosis, uremia, tumors, etc., lung damage can occur fever, cough, cough, chest pain and other symptoms, if combined with sepsis, the prognosis is more serious.
2. Acute gastroenteritis type
Mainly manifested as low fever (below 38 ° C), nausea, vomiting, abdominal pain, diarrhea, watery stool or cholera-like diarrhea, diarrhea sometimes prolonged for several weeks, generally clinical manifestations of light, no complications, the course of disease is shorter than acute bacillary dysentery.
3. Local skin infection type
The wound may be exposed to contaminated soil, local infection may occur after the water source, local ulceration, necrosis or cellulitis and skin soft tissue abscess may occur.
4. Other
Can involve other kinds of organs, such as meningitis, cholecystitis, osteomyelitis, endocarditis, supracondylar inflammation and necrotizing myositis.
Examine
Examination of Aeromonas pneumonia
1. Direct smear can generally take sputum, pus and fecal specimens, after direct smear, dry fixation with Gram stain after microscopic examination, Aeromonas is Gram-negative Brevibacterium, both ends are obtuse, no spores .
2. Bacterial culture specimens can be cryopreserved at 4 °C with phosphate buffer, transplanted into MacConkey plates every 1, 3, 7 days, directly inoculated on MacConkey plates, and then cultured at 35 ° C for 24 h. The genus is a lactose-free fermenting colony, and the colony is thicker and thicker, and the size is about 1.5 to 2 mm.
X-ray showed large lobar consolidation or diffuse patchy shadows, with a small number of bronchopneumonia or bilateral peripheral infiltration.
Diagnosis
Diagnosis and identification of Aeromonas pneumonia
Diagnosis must be combined with clinical comprehensive judgment, with reference to the history of epidemiology, if blood, sputum culture positive can be diagnosed, if pneumonia combined with gastroenteritis type, fecal culture can obtain pathogenic bacteria, which is helpful for diagnosis.
The disease must be differentiated from acute cheese pneumonia, bronchiectasis and pneumonia caused by other bacteria. Gastroenteritis type needs to be differentiated from diarrhea caused by other pathogens.
