**Core Concept**
Proper hand hygiene is a critical component of infection control, particularly in healthcare settings. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) emphasize the importance of handwashing with soap and water or using an alcohol-based hand rub (ABHR) to prevent the transmission of healthcare-associated infections (HAIs).

**Why the Correct Answer is Right**
Cleaning hands with spirit (alcohol-based hand rub) before and after examination of each patient is a recommended practice to prevent the spread of pathogens. This is because alcohol-based hand rubs are effective against a broad spectrum of microorganisms, including bacteria, viruses, and fungi. The key mechanism of action is the denaturation of proteins and disruption of cell membranes, ultimately leading to cell death. This practice is especially crucial in high-risk settings such as operating rooms and intensive care units. The CDC and WHO guidelines recommend using ABHR when hands are not visibly soiled, as soap and water may not be readily available.

**Why Each Wrong Option is Incorrect**
* **Option B:** Visible blood stain on hand is washed with soap and water - While soap and water are effective for removing visible blood and other bodily fluids, an alcohol-based hand rub is still recommended for use after exposure to potentially infectious materials.
* **Option C:** Use of soap and Dettol only for hand washing before surgery - While soap and water are effective for handwashing, the use of Dettol alone is not sufficient for hand hygiene before surgery. An alcohol-based hand rub is preferred for its broad-spectrum antimicrobial activity.
* **Option D:** Hand rub cannot be used in place of hand washing - This statement is incorrect as hand rubs are recommended for use when hands are not visibly soiled, and handwashing with soap and water is recommended when hands are visibly dirty or contaminated with bodily fluids.

**Clinical Pearl / High-Yield Fact**
In healthcare settings, hand hygiene is considered the most effective measure to prevent the spread of healthcare-associated infections. The CDC and WHO recommend using an alcohol-based hand rub when hands are not visibly soiled, and handwashing with soap and water when hands are visibly dirty or contaminated with bodily fluids.

✓ Correct Answer: A. Cleaning hands with spirit before and after examination of each patient