Assessment Description:
Describe a bacterial pathogen that possesses one of the following: a) Gram-positive cell wall, b) Gram-negative cell wall, c) can produce an endospore, or d) possesses a capsule. Where does the pathogen that you picked grow in the human body when it causes disease? Include relevant references.
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SOLUTION to Bio-205L Microbiology Lab - Topic 2 DQ 1.
SAMPLE 1
Hello class,
During my degree program, I have come across various concepts relating to different bacterial pathogens. This provides me with a great opportunity to explore a number of pathogens considering the characteristics given in the question. However, I will focus on Streptococcus pneumoniae, which is a Gram-positive, encapsulated bacterium that can lead to invasive bacterial disease in children and the elderly (Feldman & Anderson, 2020). These diseases include otitis media, community-acquired pneumonia, sepsis, and meningitis (Li et al., 2023). Additionally, it is important to note that bacterium's capsule, formed of polysaccharides is an important virulence factor that enables the bacterium to avoid the host's immune system. This capsule assists the bacterium in avoiding engulfment by phagocytic cells within the host, thus contributing significantly to its pathogenicity.
The Streptococcus pneumoniae also known as S. pneumoniae primarily grows and infects the respiratory tract, particularly the lungs. However, Loughran et al. (2019) underscore that it can also spread to other parts of the body causing serious clinical manifestations such as pneumonia where the bacteria multiply in the alveoli of the lungs leading to inflammation and fluid accumulation. In its most severe form, S. pneumoniae invades the bloodstream and leads to bacteremia, or cross the blood-brain barrier causing meningitis (Yang et al., 2023).
Nonetheless, S. pneumoniae can also be found as a normal flora in the human nasopharynx without causing any untoward effects in a person. However, the bacteria may switch from residing as commensal organisms to causing disease, if the host’s immunity is weakened or if the bacteria invade areas in the body that are not exposed to other microorganisms (Loughran et al., 2019). To counter it, two vaccines are registered for use, they include PPV23 and PCV13. Nevertheless, Feldman and Anderson (2020) state that despite the vaccines, there is still considerable debate about the best way to protect adults against pneumococcal infection.
References
Feldman, C., & Anderson, R. (2020). Recent advances in the epidemiology and prevention of Streptococcus pneumoniae infections. F1000Research, 9. https://doi.org/10.12688/f1000research.22341.1
Li, L., Ma, J., Yu, Z., Li, M., Zhang, W., & Sun, H. (2023). Epidemiological characteristics and antibiotic resistance mechanisms of Streptococcus pneumoniae: An updated review. Microbiological Research, 266, 127221. https://doi.org/10.1016/j.micres.2022.127221
Loughran, A. J., Orihuela, C. J., & Tuomanen, E. I. (2019). Streptococcus pneumoniae: invasion and inflammation. Microbiology Spectrum, 7(2), 10-1128. https://doi.org/10.1128/microbiolspec.gpp3-0004-2018
Yang, R., Wang, J., Wang, F., Zhang, H., Tan, C., Chen, H., & Wang, X. (2023). Blood-brain barrier integrity damage in bacterial meningitis: the underlying link, mechanisms, and therapeutic targets. International Journal of Molecular Sciences, 24(3), 2852. https://doi.org/10.3390/ijms24032852