Question 1: All of the following organisms are involved in post-splenectomy sepsis except
- A. Staphylococcus aureus (Correct Answer)
- B. Neisseria meningitidis
- C. Haemophilus influenzae
- D. Streptococcus pneumoniae
Explanation: ***Staphylococcus aureus***
- While *Staphylococcus aureus* can cause various infections, it is **not typically considered a primary encapsulated organism** for which the spleen's filtering function is critical, and therefore, it is **less commonly implicated in overwhelming post-splenectomy infection (OPSI)** compared to encapsulated bacteria.
- The risk of OPSI is significantly higher with **encapsulated bacteria** due to the spleen's role in clearing these pathogens.
*Neisseria meningitidis*
- *Neisseria meningitidis* is an **encapsulated bacterium** and a well-known cause of **meningitis and sepsis**, particularly in individuals with **asplenia**.
- The **spleen plays a crucial role in filtering encapsulated organisms** from the bloodstream, making asplenic individuals highly susceptible.
*Haemophilus influenzae*
- **Encapsulated strains** of *Haemophilus influenzae* (especially type b) are a significant cause of invasive infections in asplenic patients, including **meningitis and epiglottitis**.
- The **lack of splenic immune function** impairs the body's ability to clear these bacteria.
*Streptococcus pneumoniae*
- *Streptococcus pneumoniae* is the **most common cause of OPSI** (overwhelming post-splenectomy infection) due to its **polysaccharide capsule**.
- The spleen is essential for **opsonization and phagocytosis** of encapsulated bacteria, a function lost post-splenectomy.
Question 2: The pathogenic organism responsible for the causation of Donovaniasis is
- A. Herpes simplex virus
- B. Klebsiella granulomatis (Correct Answer)
- C. Haemophilus ducreyi
- D. Chlamydia trachomatis
Explanation: ***Klebsiella granulomatis***
- This bacterium is the causative agent of **granuloma inguinale**, also known as **donovaniasis**.
- It infects macrophages and causes chronic, progressive **genital ulcers** with a characteristic beefy-red appearance.
*Herpes simplex virus*
- This virus causes **genital herpes**, characterized by painful **vesicular or ulcerative lesions** that tend to recur.
*Haemophilus ducreyi*
- This bacterium causes **chancroid**, characterized by painful, soft chancres with **ragged, undermined borders**.
*Chlamydia trachomatis*
- This bacterium is responsible for several sexually transmitted infections, including **lymphogranuloma venereum (LGV)**, which presents with transient genital lesions followed by painful, suppurative lymphadenopathy, and **genital chlamydial infections** which often cause urethritis or cervicitis.