Pathogenesis (development of disease)
Bacterial meningitis is usually transmitted by droplet infection. Approximately 2.5 cases of the disease occur per 100,000 population annually. Most are infections caused by the bacteria Streptococcus pneumoniae (so-called pneumococci), Neisseria meningitidis (so-called meningococci; a good two-thirds of all cases by serogroup B, about a quarter of all cases by serogroup C), and Listeria monocytogenes, with pneumococci mostly responsible for meningitis in adults and meningococci for infection in children and adolescents.
Meningococci occur in a total of twelve serogroups, of which A, B, C, W135, and Y are responsible for the majority of illnesses worldwide. Listeria is primarily the cause of meningitis in immunocompromised individuals. For this pathogen, the source of infection can also be found in raw meat or contaminated dairy products. Especially in immunocompromised individuals, other bacteria such as E.coli can also cause severe meningitis. In acute bacterial meningitis, the bacteria usually come from the nasopharyngeal area (nasopharynx) through the bloodstream into the choroid plexus (connective tissue structure that produces cerebrospinal fluid) and thus into the cerebrospinal fluid. The inflammation spreads to the meninges (brain membranes), resulting in meningitis. In acute viral meningitis, enteroviruses, which include coxsackie and echoviruses, are found to be the primary cause. In addition, mumps, measles or varicella viruses are also frequently found. The disease is usually more harmless than bacterial meningitis, especially in adults. For further details on “viral meningitis“, see the title of the same name below.
The possible pathogen depends on the environment and age:
- Ambulatory acquired
- Infants <1 month of age: E. coli, group B streptococci, Listeria.
- Infants: Haemophilus influenzae (in the absence of vaccine protection), meningococci (> 50), pneumococci (Streptococcus pneumoniae) and others.
- Adults: pneumococci (about 50%), meningococci (Neisseria meningitidis) (about 30%), Listeria (especially in the elderly, immunodeficiency (defense weakness)), Mycobacterium tuberculosis (in HIV patients) u. a. hospital-acquired (nosocomial).
- hospital-acquired (nosocomial).
- Enterobacteriaceae, Pseudomonas aeruginosa, Staphylococci.
- Patients with immunosuppression (immunodeficiency).
- In addition: Listeria monocytogenes, Cryptococcus neoformans and others, M. tuberculosis (tuberculous meningitis, TBM) and others.
Etiology (causes)
Biographical causes
- Age
- Infants and young children
- Up to 80% of cases persons < 20 years of age
Behavioral causes
- Listeria meningitis – consumption of contaminated food such as milk or raw meat.
Disease-related causes
- Weakness of the immune system (eg due toHIV).
- Alcoholism
- Chronic urinary tract infections
- Diabetes mellitus
- Hypogammaglobulinemia – too few immunoglobulins (antibodies) in the blood.
- Head injuries with cerebrospinal fluid (CSF) – leakage of nervous fluid.
- Liver cirrhosis – connective tissue remodeling of liver tissue with functional limitations.
- Otitis media (inflammation of the middle ear)
Medication
- Cytostatics (substances that inhibit cell growth or cell division).
Operations
- After neurosurgical operations
- After splenectomy (removal of the spleen)
