Pneumococcal meningitis: symptoms, diagnosis, treatment

In addition to inflammation of the lungs and pleura, middle ear and paranasal sinuses, soft tissues and joints, pneumococcal infection can cause an inflammatory process in the meninges - pneumococcal meningitis. The ICD-10 code for this type of bacterial meningitis is G00.1. [1]

Epidemiology

Meningococcal disease is ubiquitous, but according to the World Health Organization, the highest incidence of bacterial meningitis (10 cases per 1,000 population) occurs in sub-Saharan Africa, in the so-called "meningitis belt".

At the same time, pneumococcal meningitis in children under the age of five years is estimated on a global scale at 17 cases per 100,000.

The CDC estimates that there are 150,000 hospital admissions for pneumococcal pneumonia each year in the United States. [2]

And its lethality in some regions of the world exceeds 73%. 

Pneumococcal meningitis accounts for 61% of meningitis cases in Europe and the United States. [3]

Causes of the pneumococcal meningitis

The causes of this type of meningitis are gram-positive alpha-hemolytic bacteria Streptococcus pneumoniae of several serotypes, called  pneumococci . Along with meningococci (Neisseria meningitidis), pneumococci are recognized as the most common causative agent of bacterial meningitis and the most common cause of bacterial, in particular pneumococcal, meningitis in adults. And up to a quarter of all cases of pyogenic meningitis of bacterial origin are purulent pneumococcal meningitis.

Inflammation of the membranes of the brain caused by pneumococcal infection may be a consequence of its spread from the upper respiratory tract, lungs, middle ear, paranasal sinuses by the hematogenous route (with blood flow). The presence of bacteria in the systemic circulation - pneumococcal bacteremia - leads to their entry into the cerebrospinal fluid (cerebrospinal fluid), and with it - into the soft  membranes of the brain .

In addition, damage to the meninges is possible with direct penetration of the infection into the brain - as a result of TBI with a skull fracture.

Risk factors

Widespread asymptomatic nasopharyngeal carriage of S. Pneumoniae (15% in children under 2 years of age, 49.6% in children from 2 to 5 years of age, 35.4% in children over 5 years of age) is considered a serious prerequisite for pneumococcal inflammation of the cerebral membranes in children. [4]

Also recognized risk factors for its development are:

• advanced age;
• a weakened immune system (including with HIV and in people with a removed or non-functioning spleen);
• recent pneumococcal otitis media, pneumonia, pharyngitis, tonsillitis, sinusitis (frontal, sphenoid sinus, maxillary cavity, ethmoid labyrinth);
• diabetes;
• renal and / or liver failure;
• alcohol abuse. [5], [6]

 

Pathogenesis

How is pneumococcal meningitis transmitted? Transmission of S. Pneumoniae, which colonizes the respiratory tract, occurs as a result of direct contact by airborne droplets (when coughing and sneezing). But pneumococcal meningitis itself is not considered contagious.

The pathogenesis of pneumococcal lesions is due to their toxin pneumolysin and antigens that allow the infection to protect itself from the cellular immune system of the nasopharyngeal mucosa.

The interaction of bacterial cells with human tissues (first of all, the epithelium of the mucous membranes of the respiratory tract) is provided by carbohydrate phosphate-containing heteropolymers of the bacterial cell wall in the form of teichoic acid.

Following the adhesion of the epithelium, invasion of the blood flow follows, and pro-inflammatory mediators are released into the blood - IL-1-β, TNF-α, macrophages of the MIP class, etc.

At the same time, the release of inflammatory mediators and binding to extracellular matrix glycoproteins facilitates the penetration of S. Pneumoniae through the blood-brain barrier (BBB) into the brain. In addition, the destruction of the BBB enhances the impact of pneumococci on vascular endothelial cells and an increase in the production of reactive nitrogen by their enzymes. Pneumococcal surface protein C can bind receptors for laminin, an adhesive glycoprotein in the basement membranes of endothelial cells in brain microvessels.

Further, the bacteria freely multiply and activate circulating antigen-presenting cells and neutrophilic granulocytes (microglial cells) of the brain with an increase in the intensity of the inflammatory process in the soft cerebral membranes. More about pathogenesis [7]

Symptoms of the pneumococcal meningitis

The first signs of pneumococcal meningitis are manifested by severe hyperthermia (with body temperature up to + 39 ° C) and a sharp headache.

Other symptoms quickly appear, including: nausea and vomiting, weakness, hypersensitivity to light, neck stiffness, convulsions, rapid breathing, agitation and anxiety, and impaired consciousness. Possible  liquorrhea . In infants, there is a protrusion of the fontanel zone and an unusual posture with the head and neck arched back (opisthotonus).

Read more in the publication -  Symptoms of meningeal syndrome

Complications and consequences

Pneumococcal meningitis can cause severe consequences and complications in the form of: [8]

• subdural effusion;
• accumulation of fluid inside the skull (hydrocephalus) (16.1%), which leads to increased intracranial pressure and diffuse cerebral edema (28.7%);
• convulsive syndrome; (27.6%)
• hearing loss; (19.7%)
• vision loss;
• mental retardation (indicative of changes in the hippocampus);
• behavioral and emotional problems;
• paralysis.

Inflammation affecting the cavity between the pia mater and arachnoid (subarachnoid space) often leads to the development of inflammation of the brain substance - encephalitis or inflammation of the cerebral ventricles - ventriculitis. [9], [10]

Diagnostics of the pneumococcal meningitis

In addition to examining and fixing the existing symptoms, the diagnosis of pneumococcal inflammation of the meninges requires laboratory tests.

Tests are required: PCR blood test,  [11]serological blood test - for  antibodies to pneumococcus in the blood serum , as well as a  general analysis of cerebrospinal fluid  (CSF) (leukocyte count (WBC) with differentiation, total protein), blood glucose (or cerebrospinal fluid glucose) which are used in conjunction with medical history and epidemiology to confirm possible diagnoses). [12]

Instrumental diagnostics includes computer or magnetic resonance imaging of the brain and encephalography. [13], [14]

Differential diagnosis

Differential diagnosis is carried out, first of all, with meningitis of fungal and viral etiology, reactive and parasitic meningitis, as well as cerebral tumors and neurosarcoidosis.

Treatment of the pneumococcal meningitis

Treatment of meningitis caused by pneumococcal infection involves parenteral antibiotics. [15]

An antibiotic susceptibility test shows which antibiotics will be most effective in treating a bacterial infection.[16]

Rehabilitation after pneumococcal meningitis lasts quite a long time, and patients who have undergone it are registered with a neurologist for at least 12 months. And in case of severe complications, disability is given.

Prevention

An effective measure for the prevention of bacterial meningitis of this etiology is  vaccination against pneumococcal infection with  conjugated (PCV) and polysaccharide vaccines (PPV). [17]

The CDC recommends that all children under 2 years of age and all adults 65 years of age and older be vaccinated. [18]

Forecast

It is difficult to call the prognosis of this disease favorable, because, despite advances in the field of medicine, mortality among patients with pneumococcal meningitis is higher than among patients with meningococcal meningitis (30% versus 7%). In 34% of episodes, the outcome was unfavorable. Risk factors for poor outcome were older age, presence of otitis or sinusitis, absence of rash, low Glasgow Coma Scale score at admission, and tachycardia.