Which of the following bacteria might be responsible for the formation of petechiae in a host?
a. Neisseria meningitidis
b. Escherichia coli O157:H7
c. Klebsiella
d. Proteus mirabilis

Verified step by step guidance

1. Understand the term 'petechiae': Petechiae are small red or purple spots on the body, caused by a minor bleed from broken capillary blood vessels.
2. Identify the bacteria associated with petechiae: Neisseria meningitidis is known to cause meningococcal infections, which can lead to petechiae due to its ability to cause disseminated intravascular coagulation (DIC).
3. Consider the pathogenic mechanisms: Neisseria meningitidis can invade the bloodstream and cause sepsis, leading to the formation of petechiae.
4. Review the other options: Escherichia coli O157:H7 is primarily associated with gastrointestinal symptoms and hemolytic uremic syndrome, not petechiae. Klebsiella and Proteus mirabilis are not typically associated with petechiae formation.
5. Conclude which bacteria is most likely responsible: Based on the information, Neisseria meningitidis is the most likely candidate for causing petechiae.

Key Concepts

Petechiae Formation

Petechiae are small, pinpoint-sized red or purple spots on the skin caused by bleeding under the skin. They can indicate various medical conditions, including infections. Understanding the mechanisms behind petechiae formation is crucial, as it often relates to vascular damage or thrombocytopenia, which can be caused by certain bacterial infections.

Neisseria meningitidis

Neisseria meningitidis, also known as meningococcus, is a bacterium that can cause severe infections, including meningitis and septicemia. It is known for its ability to invade the bloodstream, leading to disseminated intravascular coagulation (DIC) and the formation of petechiae. Recognizing its role in these conditions is essential for understanding the potential causes of petechiae.

Bacterial Pathogenicity

Bacterial pathogenicity refers to the ability of bacteria to cause disease in a host. Different bacteria have various mechanisms of virulence, such as toxin production, evasion of the immune response, and direct tissue damage. Understanding these mechanisms helps in identifying which bacteria might lead to symptoms like petechiae, as some are more likely to cause systemic infections than others.