Pneumococcal infection

Pneumococcal infection is an anthropozoonotic infectious disease with airborne transmission of the pathogen, characterized by the most frequent damage to the ENT organs, lungs and central nervous system.

Streptococcus pneumoniae (pneumococcus) is a gram-positive, aerobic, encapsulated diplococcus. Pneumococcal infection causes 7 million cases of otitis media, 500,000 cases of pneumonia, 50,000 cases of sepsis, 3,000 cases of meningitis, and 40,000 deaths annually in the United States. Diagnosis of pneumococcal infection is based on Gram staining. Treatment of pneumococcal infection depends on the resistance profile and includes beta-lactams, macrolides, and fluoroquinolones.

ICD-10 code

A40.3. Septicemia due to Streptococcus pneumoniae.

What causes pneumococcal infection?

Pneumococcal disease is caused by the pneumococcus bacteria, which have a pneumococcal capsule. This consists of a complex of polysaccharides that determine the serotype and contribute to virulence and pathogenicity. There are more than 91 serotypes, but the most serious diseases are caused by types 4, 6, 9, 14, 18, 19, and 23. These serotypes account for 90% of invasive infections in children and 60% of these infections in adults. However, the percentages are slowly changing, which can be partly explained by the widespread use of polyvalent vaccines.

Pneumococci usually colonize the respiratory tract, especially in winter and early spring. Spread occurs through aerosols produced by sneezing. True epidemics of pneumococcal infection are rare.

Those most susceptible to serious and invasive pneumococcal infections are those with chronic diseases (chronic cardiorespiratory diseases, diabetes mellitus, liver diseases, alcoholism), those with immunosuppression, functional or anatomical asplenia or sickle cell anemia, chronically bedridden patients, smokers, Alaska Natives and certain American Indian populations. In the elderly, even without concomitant pathology, the prognosis is usually unfavorable. Respiratory epithelium damaged by chronic bronchitis or common respiratory viruses can be a favorable background for the development of pneumococcal invasion.

What are the symptoms of pneumococcal infection?

The primary focus of infection is most often in the respiratory tract. Pneumococci can also cause otitis media, rhinosinusitis, meningitis, endocarditis, infectious arthritis, and, less commonly, peritonitis. Pneumococcal bacteremia can be the primary manifestation of the infectious process in susceptible patients, and can also accompany the acute phase of localized pneumococcal infection. Despite the treatment of pneumococcal infection, mortality rates are 15-20% in children and adults and 30-40% in elderly patients.

Pneumococcal pneumonia is the most common serious infection caused by pneumococcus. It may be lobar or (less commonly) focal (bronchopneumonia). Pleural effusion is found in 10% of cases. It may resolve spontaneously during treatment. In less than 3% of cases, encapsulated pleurisy and fibrinous-purulent effusion may occur, which will form pleural empyema. Pulmonary abscesses are rare.

Pneumococcal infection has many clinical variants.

Acute otitis media of pneumococcal etiology in infants (after the neonatal period) and children occurs with a frequency of 30-40%. More than a third of children in most populations suffer from pneumococcal otitis media in the 2nd year of life. Recurrent pneumococcal otitis is common. Mastoiditis and lateral sinus thrombosis (the most common complications of otitis media in the pre-antibiotic era) are rare today.

Rhinosinusitis can also be caused by pneumococci. It can become chronic or polymicrobial. The maxillary and ethmoid sinuses are most commonly affected. Infection in the frontal and sphenoid sinuses can spread to the meninges, leading to bacterial meningitis.

Acute purulent meningitis is often caused by pneumococcus, and can also be secondary, due to bacteremia from other foci of infection (particularly with pneumonia), as well as with direct spread of the infectious process from the ear, mastoid process or paranasal sinuses, or with a fracture of the base of the skull, in which one of these areas or the cribriform plate is damaged.

Rarely, bacteremia can result in endocarditis, even in individuals without valvular disease. Pneumococcal endocarditis causes corrosive damage to the valve cusps, leading to rapid rupture or fenestration, which in turn leads to acute heart failure.

Septic arthritis often results from pneumococcal bacteremia from another site of infection. It is generally similar to septic arthritis caused by other gram-positive organisms.

Spontaneous pneumococcal peritonitis most commonly occurs in patients with cirrhosis and ascites.

How is pneumococcal infection diagnosed?

Pneumococcal disease is diagnosed by identifying pneumococci early in the disease process by their typical encapsulated appearance on Gram stain. The characteristic capsule is also visualized on methylene blue staining. Culture and serotyping (when indicated) confirm identification. Serotyping of isolates may be useful for epidemiologic reasons. It allows correlations in the distribution of specific MO clones and detection of antimicrobial resistance patterns. Antimicrobial susceptibility testing should be performed on isolated strains. Pneumococci in joints may be identified by direct smears or by culture of aspirates of purulent synovial fluid.

How is pneumococcal infection treated?

When the disease is suspected, initial treatment of pneumococcal infection, pending susceptibility testing, depends on local patterns of resistance to specific groups of antimicrobials. Although beta-lactams and macrolides are the preferred treatments for pneumococcal infections, migration of resistant strains can complicate treatment. Strains highly resistant to penicillin, ampicillin, and other beta-lactams are widespread worldwide. The most common predisposing factor for resistance is the use of beta-lactam drugs within the last few months. If intermediate-resistant strains are detected, treatment with standard- or high-dose penicillin G or other beta-lactams can be considered.

Severely ill patients with nonmeningeal infection caused by highly penicillin-resistant MRSA can often be treated with ceftriaxone or cefotaxime for pneumococcal infection. If the minimum inhibitory concentration of the isolate is not too high, high doses of parenteral penicillin G (20-40 million units daily for adults) can also be used for treatment. All penicillin-resistant isolates are susceptible to vancomycin, but parenteral vancomycin does not always achieve adequate cerebrospinal fluid concentrations for the treatment of meningitis (especially when corticosteroids are used concomitantly with antibiotics). Therefore, ceftriaxone or cefotaxime and/or rifampin are often used concomitantly with vancomycin in patients with meningitis. Latest-generation fluoroquinolones, such as gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin, are effective for the treatment of respiratory infections in adults caused by highly penicillin-resistant pneumococci.

How is pneumococcal infection prevented?

A previous pneumococcal infection produces type-specific immunity that does not extend to other serotypes of the pathogen. There are currently two pneumococcal vaccines: a polyvalent polysaccharide vaccine that is directed against 23 serotypes that cause more than 80% of serious pneumococcal infections, and a conjugate vaccine that is directed against 7 serotypes of the pathogen.

The pneumococcal conjugate vaccine is recommended for all children aged 6 weeks to 5 years. The vaccination schedule depends on the child’s age and health.
If vaccination is started before 6 months, children should receive 3 vaccinations at approximately 2-month intervals, followed by a 4th vaccination at 12-15 months. The first vaccination is given at 2 months. If vaccination is started at 7-11 months, two vaccinations are given, followed by a booster dose. At 12-23 months, 2 vaccinations are given without a booster dose. From 24 months to 9 years, children receive one dose.

The polysaccharide vaccine is ineffective in children under 2 years of age, but reduces pneumococcal bacteremia in adults by 50%. There are no documented cases of pneumonia reduction. Protection from the use of this vaccine usually lasts for many years, but in highly susceptible individuals, revaccination after 5 years is desirable. The polysaccharide vaccine is indicated for people aged 65 years, as well as for individuals aged 2-65 years with increased susceptibility and before splenectomy. It is not recommended for children under 2 years of age or individuals hypersensitive to vaccine components.

For children with functional or anatomical asplenia younger than 5 years, penicillin V 125 mg orally is recommended. The duration of chemoprophylaxis is determined empirically, but some experts continue chemoprophylaxis throughout childhood and into adulthood because of the high risk of pneumococcal disease in patients with asplenia. Pneumococcal disease in children and adolescents is treated with penicillin (250 mg orally) for at least 1 year after splenectomy.