Listeriosis

Introduction to Listeria Listeriosis, also translated as Listeria, is an acute infectious disease caused by Listeria monocytogenes (or Listeria monocytogenes) . Most patients have infections when the immune function is low, mainly in newborns, the elderly, pregnant women and immunodeficiency patients. Listeriosis is caused by Listeria monocytogenes, and Listeria has three strains, and only Listeria monocytogenes can cause human infection. More common in neonates and immunodeficient children. basic knowledge The proportion of illness: 0.003% Susceptible people: more common in newborns, the elderly, pregnant women and immunodeficiency patients Mode of infection: digestive tract spread Complications: sepsis osteomyelitis peritonitis cholecystitis ataxia

Cause of Listeriosis

(1) Causes of the disease

Listeria monocytogenes is Gram-positive bacillus, facultative anaerobic, no spores, 1 to 3 m long, flagellate and motility, growing in a variety of media, alkali-resistant and acid-resistant, most suitable The culture temperature is 35-37 ° C, the growth is less than 4 ° C, can ferment a variety of sugars, acid production does not produce gas, catalase-positive, methyl red and VP reaction positive, in serum-containing glucose protein water It can form a mucopolysaccharide capsule, which can produce a hemolytic ring on blood agar plates, arranged in pairs in cerebrospinal fluid specimens, shaped like cocci, which can be mistaken for pneumococcal bacteria. When Gram staining is excessively decolorized, its shape is like influenza bacillus, sometimes with Diphtheria-like bacilli are also highly confusing, and they need to be identified according to their biochemical characteristics.

(two) pathogenesis

After invading the gastrointestinal tract, the pathogen is taken up by the epithelial cells of the small intestine microvilli, infecting macrophages, and spreading to the whole body with macrophages. Listeria can produce hemolysin, which can be associated with cell membranes. Cholesterol binds and causes the death of macrophages. The pathogen is similar to M. tuberculosis and Salmonella. It is an intracellular parasite that can multiply in mononuclear-macrophages. Many factors can affect Listeria in cells. Growth and disease, such as iron compounds, catalase, superoxide dismutase, bacterial surface components and hemolysin, etc., the host's killing effect on these bacteria mainly depends on cellular immunity, experiments have shown that mice infected with Liszt After the bacteria, the mother cells of T cells are transformed and propagated in the spleen and local lymph nodes. If the cells are passively transferred to normal mice, the latter can resist the lethal infection of Listeria; while the serum cannot passively transfer disease resistance. Ability, the specific protective ability of T cells depends on macrophages. Under the action of sensitized T cells, macrophages can quickly mobilize to the site of inflammation, phagocytose pathogens, and enhance killing. Ability of pathogenic bacteria, animal experiments also demonstrated that glucocorticoid and (or) cytotoxic drugs can effectively inhibit the cell-mediated immunity, the animals are affected by small doses of Listeria infection in death.

Pregnant women are very mild after being infected, but when they are transmitted to the fetus or newborn through the placenta or birth canal, they often cause serious infections in the latter two. The pathological examination of the fetus shows that the organs of the whole body are disseminated, and the multiple needle tips are yellow and white. Small abscess, most prominent in the liver, followed by the spleen, adrenal gland, lung, gastrointestinal tract, central nervous system, etc., microscopic examination of necrotic foci and a large number of neutrophils and mononuclear cells infiltration, necrotic areas and surrounding areas can be found Lan-positive bacilli, meningitis patients with autopsy were seen as suppurative soft meningitis and ependymitis, often accompanied by spleen congestion, focal necrosis and inflammation of the liver, adrenal gland and lung.

Listeria disease prevention

Since Listeria is infected by food, it is necessary to pay attention to food hygiene. If you do not drink raw milk, do not eat raw vegetables and uncooked meat, etc., people with immune dysfunction should avoid Patients with Listeria disease should actively treat pregnant women with Listeria disease to prevent neonatal or fetal infections. When the disease is found in the neonatal room, it should be isolated to prevent transmission, and more ampicillin or penicillin treatment is used. Damycin, tetracycline, chloramphenicol, erythromycin, kanamycin, sulfadiazine, etc. are also effective.

Listeriosis complications Complications sepsis osteomyelitis peritonitis cholecystitis ataxia

1. If the pregnant woman is suffering from listeriosis after 5 months of pregnancy, the fetus may be seriously affected.

2. Most men with meningitis have sepsis at the same time. Some patients may only present with sepsis. The clinical manifestations are not different from those caused by other bacteria. Listeria can also cause endocarditis and arthritis. Osteomyelitis, peritonitis and cholecystitis, exposure to sick animals can also cause purulent skin infections or purulent conjunctivitis.

In addition, disseminated abscess of multiple organs into granuloma, respiratory or circulatory failure, severe sequelae, limb paralysis, ataxia, aphasia, eye movement paralysis, facial paralysis, sphincter dysfunction.

Listeria disease symptoms common symptoms ataxia nausea back pain abdominal pain diarrhea pustular orientation disorder chills empyema low fever

The incubation period ranges from a few days to several weeks. The most common clinical disease is meningitis (about 50% to 60%), followed by bacteremia with no localization (25% to 30%). The central nervous system with or without meningitis is about 10%, and endocarditis accounts for 5%. Others have rare uveitis caused by blood-borne dissemination, endophthalmitis, and cervical lymphadenitis. , pneumonia, empyema, myocarditis, peritonitis, hepatitis, liver abscess, cholecystitis, osteomyelitis and arthritis.

1. Meningitis (meningoencephalitis)

More common in neonates and immunocompromised adults after three days of birth, 30% of patients with diabetes, cirrhosis or glucocorticoid steroids have no obvious incentives, acute onset, severe headache, dizziness, nausea, fever, Cervical stimuli such as neck stiffness, some patients have convulsions, irritability and disorientation, the symptoms are similar to other meningitis caused by pyogenic bacteria, severe cases can be comatose within 24 to 48 hours, a few onset slow, long course and repeated, About one-fourth of patients have focal nerve injury. In most patients, the number of white blood cells in cerebrospinal fluid is (0.110)×109/L, of which 2/3 is polymorphic nucleus, half glucose content is <2.8mmol/L, protein content is 0.5. ~ 3.0g / L, such as lesions involving the brain parenchyma may have encephalitis, brainstem meningitis (rhombiccephalitis, rhomboncephalitis) and brain abscess, may have convulsions, hemiparesis, seizures and cerebral palsy, etc., some patients only Have low fever and personality changes, the course of the disease is biphasic, only 3 to 10 days at the beginning of the disease only fever, headache, vomiting and other prodromal symptoms, then asymmetrical V, VI, VII, VIII, IX, X on the cranial nerve Oh, in addition, its OK. Ataxia, paresis and dysesthesia such as performance, not with meningitis in patients with CSF examination were normal or only mildly increased lymphocytes and protein content increased, the majority of CNS lesions in patients with bacterial substance of blood culture positive.

2. Septicemia

Septicemia Listeria infection can be found in adults (unexplained) and newborns. Adults are more common in immunosuppressed patients. Newborns are more common in 3 days after birth. Most of the mothers are asymptomatic carriers, and more children are more likely. The placenta is infected during childbirth and is called "granulomatous infant sepsis". This is the third most common pathogen causing neonatal sepsis and meningitis after E. coli and group B streptococci. The clinical manifestations are similar to those of other Gram-negative septicemia, but the large mononuclear cells in the white blood cell classification can be as high as 8% or more. If the patient has no lymphoma, it has the significance of assisting diagnosis. The blood culture positive can be diagnosed.

3. Neonatal septic granulomatosis

Through placenta infection, multiple internal organs (liver, spleen, lung, kidney) and brain and other tissues present multiple abscesses and/or granuloma. Amniotic fluid turbidity is stained by meconium, and the patient is weak, often accompanied by conjunctivitis. Pharyngitis, red papules on the skin, often on the trunk and extremities, children may have respiratory and circulatory failure, and the mortality rate is high.

4. Pregnancy infection

Pregnant women account for 1/3 of patients with listeriosis, can occur at any time of pregnancy, but more common in the next 3 months, may have chills, fever, sore throat, myalgia, back pain, spastic abdominal pain And diarrhea, signs are not special, generally do not affect the fetus, serious infection can cause miscarriage, stillbirth, premature birth or neonatal infection.

5. Focal infection

It can be caused by local contact or disseminated by blood. Infective endocarditis caused by Listeria does not occur in patients with low immune function, but is related to left heart disease. Aortic valve disease accounts for 2/3, three-pointed. Valve lesions accounted for 1/3, more men over 40 years old, patients with new or altered heart murmur, splenomegaly, liver, CNS and liver and other embolism; fever is the most common (accounting for 75%), this The disease mortality rate is high, other focal infections can be seen in skin pustules or ulcers, suppurative conjunctivitis, acute iridocyclitis, cervical lymphadenitis, arthritis, osteomyelitis, peritonitis, cholecystitis, urethritis and so on.

According to clinical characteristics, combined with epidemiological data, neonatal and pregnant women, old and frail and chronic diseases, immunosuppression, malignant tumors, organ transplantation, treatment with corticosteroids and cytotoxic drugs, etc., susceptible to this disease, patients Blood and cerebrospinal fluid, etc., can be diagnosed by cultivating pathogenic bacteria.

Examination of listeriosis

1. Blood routine The total number of white blood cells in patients is often increased. The classification of neutrophils is obvious, and mononuclear cells are not increased.

2. Cerebrospinal fluid routine Cerebrospinal fluid in most patients with meningitis looks turbid, the number of white blood cells is (100 ~ 10000) × 106 / L, of which 2 / 3 are multinucleated cells, protein content increased by 0.5 ~ 3.0g / L, and the reduction of sugar only For 40% of patients with cerebrospinal meningitis, the cerebrospinal fluid is mostly normal, or only mild protein content and lymphocytosis.

3. Bacteriological examination is the key to the diagnosis of this disease.

(1) Bacterial smear: taking smear of purulent secretion, puncture fluid, cerebrospinal fluid, living tissue cells, fetal feces, etc., and Gram staining, but it is reported that 2/3 of the patients with cerebrospinal fluid microscopy are negative, Because the form of the bacteria is often confused with Streptococcus pneumoniae, influenza bacillus, diphtheria bacilli, etc., it must be carefully identified, the immunofluorescence method is more sensitive, but the results need to be carefully judged.

(2) Bacterial culture: in the early stage of the disease, blood, cerebrospinal fluid, bone marrow, amniotic fluid, meconium, placenta, neonatal umbilical cord stump, damaged skin or mucous membrane, pregnant women vaginal discharge, etc. for bacterial culture, can be isolated from pathogenic bacteria When the specimen is sent for inspection, it is best to indicate "suspected Listeria disease" to prevent it from being mistaken for contaminated bacteria and to discard it in advance without further identification. The important point for the diagnosis of this disease is that the bacteria should be further separated from the above specimens. For biochemical and animal inoculation, it is definitely Listeria. When there are many kinds of bacteria in the specimen, it can be separated by cold enrichment. After the specimen is stained, it can be differentiated from Streptococcus by the enzyme test; The base has power and can be distinguished from the genus Corynebacterium.

4. Serological examination of the antibody is mainly due to the increase of IgM antibody, and the increase in serum antibody titer is helpful for diagnosis. However, the serum antibody test has limited diagnostic value for the disease and is only used for epidemiological studies. The reason is due to:

(1) The bacteria have common antigens with other Gram-positive bacteria such as Staphylococcus, Streptococcus, Streptococcus pneumoniae, and often cross-react and false positives.

(2) The sensitivity of serum antibody detection is poor.

(3) Specific antibodies in the serum of neonates and immunodeficiency patients are often not elevated.

5. Molecular biological detection In recent years, nucleic acid hybridization technology and PCR method have been applied for clinical diagnosis. The PCR method can detect 1×104 cfu of Listeria in 250l blood, which is sensitive.

6. routine examination to do X-ray chest X-ray, ECG, B-ultrasound and brain CT examination.

Diagnosis and identification of Listeria

Should be differentiated from influenza, miliary tuberculosis, typhoid fever, infectious mononucleosis, sepsis, meningitis and other bacterial infections, and other intrauterine infectious diseases, relying on laboratory findings to confirm the diagnosis .

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