Streptococcus pneumoniae, also known as pneumococcus, is a non-spore forming, a gram-positive bacterium, and a significant human pathogenic bacterium. Pneumococcus is usually found in various parts of the world and is commonly hosted in the human body specifically in the upper respiratory tract (Ballough, n.d.). Many people including adults and children carry the bacteria in their nasopharynx (nasal passages). The bacteria can be spread from one person to another through respiratory droplets that occur when a carrier of the same sneezes or coughs. An image of the bacteria is shown below.
Virulence factors refer to molecules often produced by viruses, bacteria, protozoa, and fungi adding to their effectiveness and allowing them to colonize a host’s niche and enter or exit a host’s cells. One virulence factor of Streptococcus pneumoniae is a polysaccharide capsule responsible for the release of pneumococci from the host by preventing phagocytosis (Paterson, Blue, & Mitchell, 2006). Pneumolysin is another virulence factor that inhibits lymphocyte proliferation and antibody synthesis (Paterson, Blue, & Mitchell, 2006). Cell wall products are released by another virulence factor known as the autolysin.
The signs and symptoms of Streptococcus pneumoniae are often dependent on the affected body parts. However, signs and symptoms of invasive infection may include chills, fever, and irritability (Ballough, n.d.). Also, the incubation period varies since the signs and symptoms can show within one to three days after exposure or long after exposure.
Streptococcus pneumoniae infects the lungs in stages. The first stage involves the stimulation of a serous fluid by the cell of the bacterium, and the fluid fills up the lung alveoli mediating the spread of bacteria throughout the lungs. In the second stage, the Streptococcus pneumoniae attracts neutrophils that also invade the alveoli with the recruitment of red blood cells also occurring at this stage. Essentially, the inflammatory response of the host causes the buildup of fluids in the lungs causing the damage. Immune response against the bacteria is supported by complement activities such as the activation of inflammatory responses and opsonization (Ballough, n.d.). However, the bacteria develop several virulence factors that impair complement activity helping in the evasion from the immune system.
There are different treatment plans for Streptococcus pneumoniae infections. In the case of severe infections, the preferred and most used medication is penicillin G whereas penicillin V is used for mild pneumococcal infections. However, the treatment success rate is going down because of the growing cases of penicillin-resistant S. pneumoniae. The bacteria have natural transformation systems that cause the exchange of genetic material between two organisms leading to the development of antibiotic resistance.
For the diagnosis of S. pneumoniae, a gram stain is often performed on the infected patient’s sputum. A person can be diagnosed with S. pneumoniae infection if neutrophils and greater than ten-gram positive diplococci are found in the sputum. Focus can also be on blood agar because when on blood agar, it is expected that S. pneumoniae will exhibit alpha-hemolysis characterized as a zone of green coloring surrounding the bacteria’s colonies on the agar (Ballough, n.d.).
The populations that are highly at risk for infection are children, the elderly, as well as individuals with weakened immune systems. Research shows that by 2000, S. pneumoniae infections resulted in between 100,000 and 135,000 hospitalizations for pneumonia in the U.S. alone. Studies further argue that Alaska’s native adults are highly at risk of S. pneumoniae infections since they often have to remain indoors and live in crowded conditions paving the way for the fast spread of the bacteria.
Crowded environments are often associated with S. pneumoniae. The bacteria are also common during winter and early spring seasons although areas around the tropics witness an all-year round occurrence. Other situations or environments associated with S. pneumoniae are nursing homes and childcare centers. The fact that S. pneumoniae rely primarily on carbohydrates as a carb source means that foods with high carbohydrate content may be associated with the bacteria (Buckwalter& King, 2012).
S. pneumonia infections are deadly because the bacteria secrete a toxin that can lead to severe bleeding in the lungs in some patients causing death within days.
Some of the precautions that can be taken to prevent S. pneumoniae infections include getting pneumococcal vaccines and practicing hygiene and cleanliness through washing hands often, cleaning hands with hand sanitizer if soap and water are not available, covering mouth and nose with a tissue or sleeve when sneezing or coughing, as well as avoiding close contact with people infected with S. pneumoniae.
Ballough, R. (n.d.). Streptococcus pneumoniae. Retrieved from http://web.uconn.edu/mcbstaff/graf/Student%20presentations/Streptococcuspneu/Spneumoniae.html
Buckwalter, C. M., & King, S. J. (2012). Pneumococcal carbohydrate transport: Food for thought. Trends in Microbiology, 20(11), 517-522. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4630977/
Paterson, G. K., Blue, C. E., & Mitchell, T. J. (2006). Role of two-component systems in the virulence of Streptococcus pneumoniae. Journal of Medical Microbiology, 55(4), 355-363. Retrieved from http://jmm.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.46423-0