**Core Concept**
Non-surgical infections in a surgical patient are often referred to as "iatrogenic" infections, which are complications resulting from medical treatment. These infections can arise from various sources, including the hospital environment, medical devices, and healthcare personnel.

**Why the Correct Answer is Right**
In a surgical patient, non-surgical infections can be caused by:
- **Endogenous flora**: Bacteria that are normally present on the patient's skin or mucous membranes, such as Staphylococcus aureus or Streptococcus species.
- **Exogenous flora**: Bacteria that are introduced from the hospital environment, medical devices, or healthcare personnel, such as Pseudomonas aeruginosa or Enterococcus species.
- **Contaminated medical devices**: Equipment or supplies that are not properly sterilized or disinfected, leading to the transmission of infectious agents.
- **Healthcare-associated infections**: Infections that are spread through healthcare personnel, such as Clostridioides difficile (C. diff) or norovirus.

**Why Each Wrong Option is Incorrect**
*Option A:* This option is incorrect because, although it is a type of infection, it is not a common cause of non-surgical infections in a surgical patient.
*Option B:* This option is incorrect because it is a type of infection that is typically caused by a specific pathogen, not a general cause of non-surgical infections.
*Option C:* This option is incorrect because, although it is a type of infection, it is not a common cause of non-surgical infections in a surgical patient.

**Clinical Pearl / High-Yield Fact**
To minimize the risk of non-surgical infections in a surgical patient, healthcare personnel should follow strict infection control practices, including hand hygiene, proper use of personal protective equipment (PPE), and thorough cleaning and disinfection of medical devices and equipment.

**Correct Answer:** D.