OVERVIEW
Listeria meningitis is a meningitis caused by Listeria monocytogenes, which is most common in infants, young children, the elderly, and immunocompromised adult patients. In addition to meningitis, the organism can cause pregnancy infections, neonatal septic granulomas, sepsis, and focal infections such as skin abscesses, suppurative conjunctivitis, lymphadenitis, endocarditis (with more left heart damage), and osteomyelitis.
According to the different antigens of the organism and flagellum, it is divided into four serotypes, and types 1, 3, and 4 are divided into several subtypes, with antigenic structure independent of virulence. type 1 mainly infects rodents, and type 4 mainly infects ruminants. All types are pathogenic to humans, but 1a and 1b are the most common. Can grow in the ordinary refrigerator freezer, is a typical cold-resistant bacteria, but also salt tolerance, heat tolerance is strong, 50 ℃ by 40 minutes can not kill, 63 ℃ heating 15 ~ 20 minutes death, acidic, alkaline conditions are adapted. Listeria monocytogenes can produce hemolytic exotoxin, invade the host, and be phagocytosed by the host cells can reproduce in the cells, spread to the whole body with the blood flow, and small purulent foci occur in the internal organs. The bacterium can cause purulent meningitis or meningoencephalitis in infants and newborns, with a case fatality rate of up to 70%. In adults, the disease is most common in the elderly or those with chronic underlying diseases, but can also occur in previously healthy young people.
Etiology
Listeriosis monocytogenes is a gram-positive bacillus, parthenogenetic, anaerobic, non-budding, flagellated and powered. It grows in a variety of media and is resistant to alkali and not acid. The most suitable culture temperature is 30-37 ℃, below 4 ℃ growth is poor. Can ferment a variety of sugars, acid production without gas production, catalase positive, methyl red and V-P reaction positive. Can form mucopolysaccharide pods in glucose peptone water containing serum. Produces hemolytic rings on blood agar plates. Arranged in pairs in cerebrospinal fluid specimens, shaped like cocci, can be mistaken for pneumococci. When the Gram stain is overly decolorized and its shape is like influenza bacillus, sometimes it is very easy to be confused with diphtheria-like bacillus, which needs to be identified according to its biochemical characteristics.
Symptoms
Similar to other bacterial meningitis, the onset of the disease is usually rapid, and the first symptom in 90% of cases is fever, mostly above 39℃. There is severe headache, vertigo, nausea and vomiting. Signs of meningeal irritation are obvious, and often accompanied by impaired consciousness, such as rigidity, delirium, etc. Convulsions may also occur. Severe cases can be comatose within 24-48 hours. In a few cases, the onset of the disease is slow, and the course of the disease is long and recurrent. If the lesion involves the brain parenchyma, there may be encephalitis and brain abscess. Individuals with brainstem inflammation may have diplopia, dysphonia and dysphagia, facial nerve paralysis and hemiparesis.
Examination
1. Laboratory tests
The total number of leukocytes and neutrophils in the peripheral blood is increased, but monocytes are not increased. In cerebrospinal fluid (CSF), there is an increase in leukocyte count, predominantly multinucleated cells, with a few mononucleated cells, an increase in protein, and a decrease in sugar. Cerebrospinal fluid smears may reveal small gram-positive bacilli. Blood and cerebrospinal fluid culture is positive.
2. Other auxiliary examinations
In patients with concurrent brain abscess, abnormalities can be seen on EEG.
Diagnosis
The total number of leukocytes and neutrophils are increased in the patient’s peripheral blood. Monocytes are not increased. Cerebrospinal fluid routine leukocyte count is increased, mainly multinucleated cells, with a few monocytes increased; protein is increased and sugar is decreased. Cerebrospinal fluid smears may reveal small gram-positive bacilli. Positive blood and cerebrospinal fluid cultures confirm the diagnosis. Serologic examination, double serum antibody potency is increasing can assist in diagnosis, but the antigen of this bacterium and staphylococcus, streptococcus, pneumococcus have common antigen, can occur cross-reaction, so its diagnostic value is limited.PCR detection of this bacterium in cerebrospinal fluid can help to assist in the diagnosis.
Differential diagnosis
The disease should be differentiated from other purulent meningitis. If the cerebrospinal fluid cell classification is dominated by multinucleated, attention should be paid to differentiating from tuberculous meningitis or fungal meningitis. If the disease is mild and the cerebrospinal fluid cell count is not too high, it should be differentiated from viral meningitis.
Complications
Complications include brain abscess, endocarditis and abortion.
Treatment
Listeria monocytogenes is sensitive to penicillin ampicillin, gentamicin, streptomycin, chloramphenicol, quinolones, rifampicin, sulfamethoxazole, and methotrexate (compound sulfamethoxazole). Penicillin or ampicillin for its therapeutic drugs, but in vitro are not bactericidal, such as the condition is more serious, commonly used two antibiotics combined treatment, ampicillin or penicillin and aminoglycoside antibiotics have synergistic effect of joint application. Ampicillin, divided intravenous or intramuscular injection course of 4 to 6 weeks. Tobramycin and gentamicin do not easily cross the blood-brain barrier, so it is not easy to use alone. Rifampicin is easy to cross the blood-brain barrier and has a strong effect on the bacteria. Compound sulfamethazine has in vitro bactericidal effect on Listeria monocytogenes, and it can be used by those who are allergic to penicillin. Cephalosporin is not effective against Listeria meningitis. Criteria for the cure of Listeria monocytogenes meningitis: no recurrence of clinical symptoms after discontinuing antimicrobial drugs for 1 month, normal cytology of cerebrospinal fluid, and negative cerebrospinal fluid bacterial culture.
Prognosis
Those with underlying disease or generalized convulsions and coma have a high case fatality rate. Sequelae include limb paralysis, ataxia, aphasia, oculomotor paralysis, facial muscle paralysis and sphincter dysfunction.