Intensive Care Medicine (ICM) Practice Exam

The most threatening nosocomial infection is caused by which organism?

1. Staphylococcus

2. Salmonella

3. Klebsiella

4. Enterococcus

The correct answer is: Staphylococcus

Staphylococcus species, particularly Staphylococcus aureus, are among the most significant and threatening organisms responsible for nosocomial infections. These infections are acquired in healthcare settings and can range in severity from skin infections to more serious conditions such as pneumonia, bloodstream infections (bacteremia), and endocarditis. Methicillin-resistant Staphylococcus aureus (MRSA) is particularly concerning due to its resistance to commonly used antibiotics, which complicates treatment options and can lead to higher morbidity and mortality rates in affected patients. Staphylococcus aureus' ability to form biofilms, especially on medical devices and implants, further increases the challenge in controlling infections. Additionally, it can release toxins leading to severe tissue damage and systemic inflammatory responses. The prevalence and severity of infections caused by Staphylococcus species in intensive care settings highlight its status as a major threat in nosocomial infections. Other organisms like Salmonella, Klebsiella, and Enterococcus can also cause nosocomial infections, but they do not carry the same level of threat as Staphylococcus in terms of both prevalence and the severity of infections caused. For instance, while Klebsiella is known for causing urinary tract infections and pneumonia, it has not reached the same level of