Overview
Listeriosis is an acute infectious disease caused by Listeria monocytogenes [or Listeriosis monocytogenes]. It occurs in immunocompromised patients, mainly in newborns, the elderly, pregnant women and immunodeficient patients. There are three strains of Listeria monocytogenes, and only Listeria monocytogenes can cause human infection. Listeria monocytogenes can cause infection in humans. It is most common in newborns and immunodeficient children.
Etiology
Listeria monocytogenes is a gram-positive bacillus, parthenogenetic anaerobic, sporeless, 1-3 micrometers long, flagellum and power, growth in a variety of media, alkali-intolerant and not acid-resistant, the optimal incubation temperature of 35-37 ℃, less than 4 ℃ growth is poorer, able to ferment a variety of sugars, acid production does not produce gas, hydrogen peroxidase-positive, positive methyl red and V-P reaction, in the serum-containing glucose peptones In serum-containing glucose peptone water, it can form mucopolysaccharide pods, and produce hemolytic rings on blood agar plates. It is arranged in pairs in cerebrospinal fluid specimens, and is shaped like a coccobacillus.
Symptoms
The incubation period varies from a few days to a few weeks, and the most common clinical listeriosis is meningitis; followed by bacteremia without localized manifestations, with or without meningitis, substantial lesions of the central nervous system in about 10% of cases, and endocarditis in 5% of cases, with other rare cases of uveitis due to hematogenous dissemination, endophthalmitis, cervical lymphadenitis, pneumonia, pustulothorax, myocarditis, peritonitis, hepatitis, hepatic abscess, cholecystitis, osteomyelitis, and arthritis. Osteomyelitis and arthritis, etc.
1. Meningitis (meningoencephalitis)
Most common in newborns after three days of life and immunocompromised adults, diabetes mellitus, cirrhosis or glucocorticoid treatment, 30% of the patients have no obvious cause, the onset of disease is rapid, there are severe headache, vertigo, nausea, fever, cervical stiffness and other signs of meningeal irritation, some patients have convulsions, irritability and disorientation, the symptoms are similar to those of other pus-fungus-induced meningitis, the severe cases can be coma in 24-48h, and some patients are more likely to have meningitis than others. A few patients have slow onset, long and recurrent course, about 1/4 patients have focal neurological damage, such as lesions involving the brain parenchyma can have encephalitis, brainstem meningitis (rhombencephalitis) and brain abscess, there can be convulsions, mild hemiparesis, seizures and cerebral herniation, etc., some patients only have low-grade fever and personality changes, the disease is biphasic, in the first 3-10 days of the disease, there are only fever, headache, vomiting, and other prodromal symptoms, and then there are asymmetric In the first 3-10 days of the disease, there are only prodromal symptoms such as fever, headache, vomiting, and then asymmetric paralysis of the V, VI, VII, VIII, IX, and X pairs of cerebral nerves, and ataxia, paresis, and sensory retardation, etc. The CSF examination of the patients with uncomplicated meningitis is mostly normal, or there is only a mild lymphocytosis and an increase in the content of proteins, and the majority of the patients with parenchymal lesions of the CNS have positive blood cultures.
2.Septicemia
Listeriosis infection of septicemia type can be seen in adults and newborns, adults are mostly seen in immunosuppressed people, newborns are mostly seen in the first 3 days of life, and their mothers are mostly asymptomatic carriers, and most of them are infected by placenta during labor and delivery, which is known as granulomatous infantile septicemia, and it is the third most common type of neonatal infection caused by Listeria monocytogenes, after E.coli and group B streptococcus. After E. coli and group B streptococcus, this bacterium is the third most common pathogen causing neonatal septicemia and meningitis. Clinical manifestations are similar to other gram-negative septicemia, but the leukocyte classification of large monocytes can be as high as 8% or more, and if the patient does not have lymphoma, it will assist in the diagnosis, and a positive blood culture can confirm the diagnosis.
3. Neonatal septic granulomatosis
Transplacental infection, the child’s internal organs (liver, spleen, lungs, kidneys) and brain and other tissues show multiple abscesses and/or granulomas, the amniotic fluid is cloudy and stained by meconium, the patient is debilitated, often accompanied by conjunctivitis, pharyngitis, red papules on the skin, most often in the trunk and limbs, the patient may have respiratory and circulatory failure, the mortality rate is high.
4. Pregnancy infection
Listeriosis in pregnant women accounted for 1/3, can occur in any period of pregnancy, but the next three months is common, there can be chills, fever, sore throat, myalgia, dorsal pain, cramping abdominal pain and diarrhea, signs are not special, usually does not affect the fetus, severe infection can cause miscarriage, stillbirth, preterm delivery or neonatal infection.
5. Focal infection
It can be caused by local contact or by bloodstream dissemination. Infective endocarditis due to Listeria monocytogenes does not occur in immunocompromised individuals, but is associated with damage to the heart valves, aortic valve lesions account for 2/3 of the cases, tricuspid valve lesions account for 1/3 of the cases, and it is more common in males over 40 years of age. Patients present with a new or altered cardiac murmur, splenomegaly, hepatomegaly, and a variety of embolisms of the central nervous system (CNS) and the liver; fever Most common (75% of cases), the disease has a high mortality rate, other focal infections can be seen in skin pustules or ulcers, purulent conjunctivitis, acute iridocyclitis, cervical lymphadenitis, arthritis, osteomyelitis, peritonitis, cholecystitis, and urethritis.
Examination
1. Blood routine
The total number of leukocytes in the patient’s blood is often increased, and the increase of neutrophils is obvious in the classification, while monocytes are not increased.
2. Cerebrospinal fluid
The cerebrospinal fluid of patients with meningitis is mostly turbid in appearance, with a white blood cell count of (100~10,000)×106/L, 2/3 of which are multinucleated cells, and the protein content is increased up to 0.5~3.0g/L, while the sugar content is decreased only in 40% of the cases, while the routine of cerebrospinal fluid of patients with uncomplicated meningitis is mostly normal, or there is only a slight increase in the protein content and increase in the number of lymphocytes.
3. Bacteriologic examination
It is the key to diagnose this disease.
(1) Bacterial smear: take purulent secretion, puncture fluid, cerebrospinal fluid, biopsy cells, fetal feces and so on, and perform Gram staining, but it is reported that cerebrospinal fluid microscopic examination is negative in 2/3 of the patients.
(2) Bacterial culture In the early stage of the disease, blood, cerebrospinal fluid, bone marrow, amniotic fluid, fetal feces, placenta, umbilical cord stumps of newborns, damaged skin or mucous membranes, and vaginal excretions of pregnant women are taken for bacterial culture, which can isolate the causative organisms.
4. Serologic examination
Antibody response to the bacteria is mainly immunoglobulin M (IgM) antibody elevation, double serum antibody potency increases to help diagnosis, but the serum antibody test has limited diagnostic value of the disease, only for epidemiological studies, mainly due to: ① the bacterium and staphylococcus, streptococcus, Streptococcus pneumoniae, and other Gram-positive bacteria with common antigens, often cross-reactivity, false positives. ② Poor sensitivity of serum antibody detection. ③ The specific antibody in the serum of newborns and immunodeficiency patients is often not elevated.
5. Molecular biology test
In recent years, the application of nucleic acid molecular hybridization technology and polymerase chain reaction (PCR) method for clinical diagnosis, the application of PCR method can be measured in 250µl of blood 1 × 104cfu of Listeria monocytogenes, with high sensitivity.
6.Routine examination
X-ray chest radiograph, electrocardiogram, ultrasound and brain CT.
Diagnosis
Diagnosis is based on etiology, clinical manifestations and laboratory tests.
Treatment
Antimicrobial treatment is usually carried out.
1. Ampicillin
Ampicillin is the best drug of choice, safe for pregnant women and infants, and can reach effective concentration in the brain.
(1) Patients with meningitis Ampicillin is given intravenously for 3 to 4 weeks.
(2) Immunocompromised patients should be treated with ampicillin combined with gentamicin.
2. Penicillin
(1) Patients with infected heart valves should be treated with penicillin combined with tobramycin.
(2) For patients allergic to penicillin, methotrexate combined with sulfamethoxazole should be given intravenously.
3. Other antibiotics
Tetracycline, chloramphenicol, erythromycin, kanamycin, sulfadiazine, etc. are also effective.