Pediatric Listeriosis

Introduction to pediatric listeriosis 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. basic knowledge The proportion of illness: 0.005% Susceptible people: children Mode of transmission: mother-to-child transmission, contact transmission. Complications: meningitis abortion premature labor ataxia

Causes of pediatric 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.

Pediatric disease prevention

People with immune dysfunction should avoid contact with patients with Listeria disease. Active treatment of pregnant women with listeriosis can prevent neonatal or fetal infections. When the disease is found in the neonatal room, it should be isolated to prevent transmission.

Newborn mothers who have previously had a Listeria infection should be cultured in the third phase of pregnancy for cervical secretions and stool culture to determine if they are carriers of Listeria monocytogenes. Prophylactic treatment can then be performed during prenatal and delivery to prevent vertical infection of the newborn. But the value of this method has not been proven.

In addition, because Listeria is infected by food, it is necessary to pay attention to food hygiene, such as not drinking raw milk, not eating raw vegetables and uncooked meat. Food should be protected from contamination with Listeria monocytogenes (eg unsterilised milk, vegetables contaminated with cattle and sheep) as they can cause infections in the mother and fetus.

1. Meat, poultry, fish and other foods must be cooked before they can be eaten. Most meats reach a temperature of 71 ° C to be fully cooked. The meat in the leg of the poultry must reach 82 °C to be cooked. If you can't measure the actual temperature of the meat, wait until the meat is not bloodshot. If the middle part of the fish is no longer transparent, eat it again! For safety reasons, it is best to boil completely. Be careful not to taste the food until it is cooked.

2, do not eat cooked food, smoked meat, fish, pickled fish, meat. Before you eat, be sure to heat up to the heat. Some foods are pre-heated, such as hot dogs, but it is best to reheat them to the heat. Canned foods or shelf-stable foods that do not require refrigeration can be consumed directly.

3, leftovers should be fully heated before eating.

4. Do not eat milk or dairy products that have not been sterilized unless they are marked on the label by high temperature sterilized milk.

5, fruits and vegetables should be thoroughly cleaned or peeled before eating.

6, raw and cooked separately. Separate and store raw meat and vegetables and cooked food separately.

7. Those perishable foods and cooked foods should be eaten as soon as possible after opening the package, even if the shelf life has not expired, because the shelf date on the package is usually for unopened food.

8. Finally, in order to ensure that the food is not contaminated by various pathogenic bacteria, it is preferable to set the temperature of the refrigerator compartment to 2 to 4 ° C, and the temperature of the freezer compartment to be set to 18 ° C or below. You can use a thermometer to monitor the temperature inside the refrigerator at any time.

It should be noted that Listeria is a very stubborn pathogen, and they can survive and reproduce even at low temperatures. Therefore, leftovers and cooked foods should be heated as much as possible.

Complications of pediatric listeriosis Complications meningitis abortion premature labor ataxia

Early onset can be complicated by meningitis, miscarriage, stillbirth, premature delivery, myocarditis, disseminated abscess of multiple organs into granuloma, respiratory or circulatory failure, severe sequelae, limb paralysis, ataxia, aphasia, eye movement paralysis, Facial muscle paralysis, sphincter dysfunction and so on.

Pediatric Listeria Symptoms Common Symptoms Pain Growth Slow Diarrhea Moxibustion Meningitis Drowsiness Meningeal Stimulation Septicemia Back Pain

More common in neonates and immunodeficiency sick children, neonatal cases can be divided into early and late hair, early onset within a few days after birth can also see sepsis and pneumonia, occasionally meningitis, the mother of the patient often in childbirth In the past few weeks, I have a flu-like illness. My mother can have fever during childbirth. Amniotic fluid can be stained green or brown. Newborns are often born prematurely. Herpes are common in the skin. At the same time, fever, lethargy, diarrhea, difficulty breathing, and occasional myocarditis can occur. Late-onset hair is more common in full-term children. It occurs 1 to 6 weeks after birth. The symptoms are mild. Several key symptoms are listed below:

1. Meningitis is mainly seen in infants and newborns, but in recent years there has been an increase in adult patients.

The clinical manifestations are similar to those of other bacterial meningitis. Generally, the onset is acute, and the fever is more than 39 °C. The meningeal irritation sign is obvious, often accompanied by disturbances of consciousness, such as stupor, sputum, coma, etc., convulsions, nerve and facial nerve paralysis can also occur. It is not uncommon to even involve many pairs of cranial nerves, as well as limb paralysis and cerebellar dysfunction, and may be accompanied by sepsis.

The total number of white blood cells and neutrophils in the blood around the patient, hundreds of thousands of white blood cells in the cerebrospinal fluid, mainly multinucleated cells, even mononuclear cells, protein increased sugar, cerebrospinal fluid smear visible small gram Positive bacilli, as mentioned above, this bacterium is easily misdiagnosed from the morphological form. The diagnosis is mainly based on bacterial culture, blood and cerebrospinal fluid can be isolated to the bacteria, but it should be noted that the bacteria grow slowly (2 to 12 days), and should pay attention to Identification with E. erythropolis.

The disease is more serious, with systemic convulsions and coma with high mortality, sequelae may have limb paralysis, ataxia, aphasia, eye movement paralysis, facial muscle paralysis, sphincter dysfunction.

2. Pregnancy infection can occur at any time of pregnancy, more often in the last 3 months, the symptoms are often mild, there is chills, fever, back pain, often suspected of urinary tract infection, often self-healing, does not affect the fetus, In severe cases, it can cause miscarriage, stillbirth, premature birth or neonatal infection. The diagnosis depends mainly on blood culture.

3. Neonatal septic granulomatous disease through placenta infection, children often have multiple organ disseminated abscess into granuloma, including liver, spleen, lung, kidney, brain, etc., often accompanied by conjunctivitis, pharyngitis, Red skin pimples (mostly located in the trunk and extremities), respiratory or circulatory failure, high mortality, mother's infection is helpful for diagnosis, diagnosis depends on bacterial culture positive, early application of the above antibacterial drugs can improve survival rate .

4. Septicemia, especially in immunodeficiency and neonates, can be diagnosed. The clinical manifestations are similar to those of Gram-negative septicemia. The diagnosis depends mainly on blood culture.

5. Local infections such as endocarditis, arthritis, myelitis, osteomyelitis, cholecystitis, brain abscess, laboratory personnel can also directly contact the infection and local (neck, etc.) lymphadenitis.

Examination of pediatric listeriosis

1. The total number of white blood cells in blood routine patients is often increased, the number of neutrophils increased significantly in the classification, and mononuclear cells did not increase.

2. Cerebrospinal fluid conventional meningitis patients with cerebrospinal fluid mostly opaque appearance, white blood cell count (100 ~ 10000) × 106 / L, of which 2 / 3 are multinucleated cells, protein content increased by 0.5 ~ 3.0g / L, and sugar reduction 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 used for clinical diagnosis. PCR method can detect 1×104 cfu of Listeria in 250l blood, which is sensitive.

Regular X-ray, ECG, B-ultrasound and brain CT examinations.

Diagnosis and diagnosis of pediatric listeriosis

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.

Meningitis is distinguished from other bacterial infections and is differentiated from other intrauterine infectious diseases and relies on laboratory findings to confirm the diagnosis.

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