Pneumococcal infection
The World Health Organization estimates that in 2005, pneumococcal infections were responsible for the death of 1.6 million children worldwide.
[2] It can be found in higher amounts in certain environments, especially those where people are spending a great deal of time in close proximity to each other (day-care centers, military barracks).
Pneumonia occurs if the organisms are inhaled into the lungs and not cleared (again, viral infection, or smoking-induced ciliary paralysis might be contributing factors).
The organism's polysaccharide capsule makes it resistant to phagocytosis and if there is no pre-existing anticapsular antibody alveolar macrophages cannot adequately kill the pneumococci.
[citation needed] S. pneumoniae has several virulence factors, including the polysaccharide capsule mentioned earlier, that help it evade a host's immune system.
It has pneumococcal surface proteins that inhibit complement-mediated opsonization, and it secretes IgA1 protease that will destroy secretory IgA produced by the body and mediates its attachment to respiratory mucosa.
[citation needed] People with a compromised immune system, such as those living with HIV, are also at higher risk of pneumococcal disease.
[5] In HIV patients with access to treatment, the risk of invasive pneumoccal disease is 0.2–1% per year and has a fatality rate of 8%.
[citation needed] Due to the importance of disease caused by S. pneumoniae, several vaccines have been developed to protect against invasive infection.
Notably, macrolide-resistant S. pneumoniae has been declared a medium-priority pathogen by the WHO due to its growing clinical and public health significance.
In adults recently developed fluoroquinolones such as levofloxacin and moxifloxacin are often used to provide empiric coverage for patients with pneumonia, but in parts of the world where these medications are used to treat tuberculosis, resistance has been described.
[21] Susceptibility testing should be routine with empiric antibiotic treatment guided by resistance patterns in the community in which the organism was acquired.
[citation needed] It was discovered that the pneumococcus's capsule made it resistant to phagocytosis, and in the 1920s it was shown that an antibody specific for capsular polysaccharide aided the killing of S. pneumoniae.
