Pneumococcal pneumonia is a type of bacterial pneumonia that is caused by Streptococcus pneumoniae (pneumococcus). It is the most common bacterial pneumonia found in adults, the most common type of community-acquired pneumonia, and one of the common types of pneumococcal infection. The estimated number of Americans with pneumococcal pneumonia is 900,000 annually, with almost 400,000 cases hospitalized and fatalities accounting for 5-7% of these cases. Symptoms
The symptoms of pneumococcal pneumonia can occur suddenly, presenting as a severe chill, followed by a severe fever, cough, shortness of breath, rapid breathing, and chest pains. Other symptoms like nausea, vomiting, headache, fatigue, and muscle aches could also accompany initial symptoms. The coughing can occasionally produce rusty or blood-streaked sputum. In 25% of cases, a parapneumonic effusion may occur. Chest X-rays will typically show lobar consolidation or patchy infiltrates. Treatment
In most cases, once pneumococcal pneumonia has been identified, doctors will prescribe antibiotics. These antibiotics usually help alleviate and eliminate symptoms between 12 and 36 hours after the initial dose. Despite most antibiotics effectiveness in treating the disease, sometimes the bacteria can resist the antibiotics, causing symptoms to worsen. Age and health of the infected patient can also contribute to the effectiveness of the antibiotics. A vaccine has been developed for the prevention of pneumococcal pneumonia, recommended to children under age five as well as adults over the age of 65.
Transmission via the secretions of carriers can result from direct interpersonal contact or contact with a contaminated surface. Bacteria on contaminated surfaces can be easily cultured. In conditions with sufficient nutrients, pneumococci can survive for 24 hours and avoid desiccation for multiple days. Reduced transmission has been observed amongst children with Pneumococcal conjugate vaccine (PCV) immunization as acquisition of a new strain of S. pneumoniae is inhibited by pre-existing colonization. Immunoglobulin G (IgG) immunization with high antibody concentration can also inhibit acquisition. These antibodies require the agglutinating function of the Fc fragment. For successful acquisition in a new host, pneumococcus must successfully adhere to the mucous membrane of the new host’s nasopharynx. Pneumococcus is able to evade detection by the mucous membrane when there is a higher proportion of negatively charged capsules. This clearance is mediated by Immunoglobulin A1 (IgA1) which is abundant on the URT mucosal surfaces. Colonization
Transparent and opaque colony morphology has been observed for pneumococci. Airway colonization is observed in transparent phenotypes of serotypes, while survival in bloodstreams is observed for opaque phenotypes. Colonizable strains exhibit resistance against neutrophilic immune response. Successful colonization requires S. pnuemoniae to evade detection by the nasal mucus and attach to epithelial surface receptors. Asymptomatic colonization occurs when S. pneumoniae bind to N-acetyl-glucosamine on epithelium without inflammation. However, co-infection with a pre-existing inflammatory URT infection results in an over-expression of the epithelial receptors utilized by S. pneumoniae, thus increasing the likelihood of colonization.