Satellitism is seen in cultures of?
**Satellitism in Microbiology**
**Core Concept**
Satellitism is a phenomenon observed in microbiology where the growth of certain bacteria is dependent on the presence of another bacterium, known as the "satellitic" bacterium. This occurs when the growth-promoting bacterium produces a metabolite or other substance that enhances the growth of the dependent bacterium.
**Why the Correct Answer is Right**
Satellitism is typically seen in cultures of Haemophilus influenzae, which requires the presence of factor V (NAD+) and factor X (hemin) produced by other bacteria, such as Staphylococcus aureus or Streptococcus pneumoniae, to grow. The growth of Haemophilus influenzae is inhibited in the absence of these factors, resulting in a characteristic "satellitic" growth pattern around the growth-promoting bacterium.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because satellitism is not typically associated with Escherichia coli, which is a common commensal bacterium that does not require growth factors from other bacteria.
* **Option B:** This option is incorrect because Pseudomonas aeruginosa is a highly versatile bacterium that can grow on a wide range of media and does not exhibit satellitism.
* **Option C:** This option is incorrect because Bacillus subtilis is a gram-positive bacterium that can grow on simple media and does not require the presence of other bacteria to grow.
**Clinical Pearl / High-Yield Fact**
It's essential to recognize satellitism in microbiology cultures to identify Haemophilus influenzae, which is an important pathogen in respiratory and invasive infections.
**Correct Answer:** C.