Neisseria meningitidis pneumonia

　　1. Etiology

　　Neisseria meningitidis, also known as diplococcus intracellularis, is an aerobic Gram-negative cocci, usually kidney-shaped or bean-shaped, often arranged in pairs. It does not grow on ordinary culture media and is usually cultured on blood agar or chocolate agar. Bacteria grow well in an environment with 5% to 10% CO2, a temperature of 35 to 37 degrees Celsius, and a humidity of 50%. Selective culture media are beneficial for the isolation and identification of Neisseria meningitidis in sputum specimens. For example, improved Tayer-Martin (MTM) agar contains various antibiotics that can inhibit the growth of other microorganisms growing faster, thereby promoting the growth of Neisseria meningitidis. This bacterium is extremely sensitive to cold, dryness, and disinfectants, and is easily lysed in vitro, so the specimen must be sent for testing immediately after collection.

　　The identification of Neisseria meningitidis mainly relies on morphological manifestations, Gram staining, oxidation and utilization of glucose and maltose, and immune response (serological tests, such as detection of specific capsule polysaccharides). Neisseria meningitidis is a typical Gram-negative cocci, and its outer membrane layer contains lipopolysaccharide endotoxin. According to the polysaccharide of the bacterial capsule, it can currently be divided into at least 13 serotypes, among which A, B, C, X, Y, Z, and W-135 types are increasingly important in clinical practice.

　　2. Pathogenesis

　　The immune response of Neisseria meningitidis is complex. The bactericidal antibodies in neonates disappear after 6 months of birth; children and adolescents, whether suffering from severe Neisseria meningitidis infection, subclinical infection, or symbiotic Neisseria meningitidis in the upper respiratory tract that is not pathogenic, can stimulate the body to produce bactericidal antibodies. Under the promotion of complement C, bactericidal antibodies can immune lyse pathogenic bacteria. Individuals lacking bactericidal or capsule antibodies against a specific serotype are prone to colonization and infection by that serotype of bacteria. After obtaining protective antibodies with age, the possibility of illness can be greatly reduced.

　　After Neisseria meningitidis invades the human body, if the human immune system is strong, it can quickly kill the pathogen or become a carrier state; if there is a lack of immunity to this serotype in the body or the pathogen has strong virulence, the pathogen will settle in the posterior nasopharynx and invade adjacent tissues through the upper respiratory tract to cause infection. The lower respiratory tract is invaded by inhaling the pathogen-containing droplet particles, and it often occurs on the basis of excessive respiratory tract secretion caused by viral infection, mucosal injury, and reduced microbial clearance. Pathological changes such as bronchopneumonia, lobar infiltration, and even necrosis of lung tissue and abscess formation can be seen. Due to the lack of an animal model for Neisseria meningitidis pneumonia, detailed modern pathological and histological data are currently lacking.

　　Complications such as meningococcal sepsis. Refers to the invasion of Neisseria meningitidis into the blood circulation, growth and reproduction in the blood, and the production of toxins, resulting in acute systemic infection. The mild form may only have general infection symptoms, while the severe form can lead to infectious shock, DIC, multiple organ failure, and other complications. The manifestations include: initial chills or shivering, followed by high fever, which may be irregular, remittent fever, or persistent fever; weak, severely malnourished, and small infants may not have fever, or even have body temperature below normal. Lethargy or restlessness, severe cases may appear pale or blue, and consciousness may be unclear. The extremities are cold, breathing is rapid, heart rate increases, blood pressure decreases, and jaundice may occur in infants and young children.

　　The clinical course of this disease is not specific, so it is easy to be missed in clinical practice, presenting with symptoms such as cough, expectoration of purulent or frothy sputum, chest pain, chills, high fever, and accompanying changes such as pulmonary changes, moist rales, and so on. If many cases of bacterial pneumonia occur simultaneously in crowded places such as military camps, schools, nurseries, or hospitals, one should be vigilant about the possibility of this disease. If Gram-negative diplococci are found in the neutrophils on sputum smears, one should highly suspect this disease. Diagnosis depends on further bacteriological examination. Cultures of sputum or nasopharyngeal, oropharyngeal swabs are sometimes difficult to obtain positive results, and often require tracheal aspiration of specimens to possibly obtain positive results.

　　1. Eliminate the source of infection:Neisseria meningitidis is mainly transmitted through droplets, so it is very necessary to isolate and treat patients on-site to eliminate the source of infection, usually at least the first 24 hours of treatment should isolate suspected patients.

　　2. Drug and vaccine prevention:Vaccination and drug prevention are safe and effective in reducing the incidence of epidemic meningitis and controlling the spread of epidemic meningitis, playing a very important role. For carriers or susceptible populations, drug prevention can be carried out with penicillin, rifampicin, and minocycline, or immunoprophylaxis can be applied with a quadrivalent vaccine containing A, C, Y, and W-135 serotypes. However, whether drug and vaccine prevention can protect susceptible individuals from primary respiratory tract infections is currently lacking in this regard, and further observation and research are needed.

　　1. Sputum bacterial smear examination: If Gram-negative renal-shaped cocci are found in the neutrophils on the sputum smear, this disease should be highly suspected, and diagnosis depends on further bacteriological examination.

　　2. Sputum bacterial culture: It is sometimes difficult to obtain positive results from routine sputum culture or nasal pharynx, throat swab culture, and often requires sputum aspiration to obtain positive results.

　　3. X-ray manifestations are non-specific, including patchy shadow bronchopneumonia and lobar infiltration, commonly seen in the lower lobe or right middle lobe, about 20% of cases are accompanied by pleural effusion.

　　1. Two pear, 4g of Fritillaria thunbergii, 30g of rock sugar, 10g of wet bean powder. Wash the pear clean, peel, remove the core, and cut into 12 pieces. Wash Fritillaria thunbergii clean, and put the pear pieces into a steaming bowl. Add Fritillaria thunbergii and rock sugar, add 50ml of boiling water, seal the bowl mouth with wet cotton paper, and steam for 2 hours. Take out the pear pieces and arrange them in a plate. Pour the original juice into a pot, add clear...

　　2. Chicken bitter bile and sugar water. Method: Take fresh chicken bitter bile, extract the bile, and drink it in one go. Then, let them drink sugar water to remove the bitterness. Once a day, for 5 consecutive days.

　　I. Treatment

　　1. Antimicrobial drug therapy:Currently, penicillin is effective for most cases even when used in small doses. Patients with complications such as empyema or other complications can still choose penicillin, but the dose should be increased to more than 6 million U per day. For those allergic to penicillin, chloramphenicol can be used at a dose of 2-3g per day, administered in 4-6 divided doses. Third-generation cephalosporins, sulfadiazine, rifampin, and other drugs also have good efficacy for this disease.

　　2. Symptomatic supportive treatment: Include oxygen therapy, keeping warm, maintaining the humidity and patency of the respiratory tract, and at the same time, protecting the heart, brain, and kidney functions to prevent multiple organ failure.

　　II. Prognosis

　　Early diagnosis and treatment generally have a good prognosis.