Organism which has specific affinity for growing around prosthesis –
**Core Concept**
The question is testing the student's knowledge of biofilm formation and the organisms responsible for medical device-related infections. Biofilm formation is a complex process involving the attachment of microorganisms to a surface, followed by the production of a protective matrix that allows them to grow and multiply in a protected environment.
**Why the Correct Answer is Right**
The organism that has a specific affinity for growing around prostheses is Staphylococcus epidermidis. This bacterium is a common inhabitant of the human skin and is known to form biofilms on medical devices, such as prosthetic joints, catheters, and vascular grafts. The biofilm matrix produced by S. epidermidis is composed of a complex mixture of extracellular polymeric substances, including polysaccharides, proteins, and DNA, which provide protection against antibiotics and the host immune system. The ability of S. epidermidis to form biofilms is mediated by the production of adhesins, such as the MSCRAMM proteins, which allow the bacterium to attach to the surface of the prosthesis.
**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because while Staphylococcus aureus can also form biofilms, it is not as commonly associated with medical device-related infections as S. epidermidis.
**Option B:**
This option is incorrect because Escherichia coli is a gram-negative bacterium that is more commonly associated with urinary tract infections and other types of infections, rather than medical device-related infections.
**Option C:**
This option is incorrect because Pseudomonas aeruginosa is a gram-negative bacterium that can form biofilms, but it is more commonly associated with respiratory infections and other types of infections, rather than medical device-related infections.
**Clinical Pearl / High-Yield Fact**
The use of antimicrobial coatings and surface modifications can help to prevent biofilm formation on medical devices and reduce the risk of device-related infections. This is particularly important for devices that are implanted for extended periods, such as prosthetic joints and vascular grafts.
**Correct Answer: D. Staphylococcus epidermidis**