In 1847, what observation did a scientist make regarding handwashing by physicians?

The observation made in 1847 regarding handwashing by physicians is significant because it was one of the earliest understandings of the importance of hygiene in medical practice. The scientist, Ignaz Semmelweis, conducted studies and noticed that women giving birth in hospitals were experiencing higher rates of infection and mortality due to puerperal fever compared to those assisted by midwives in less sanitary conditions. He hypothesized that the doctors were transferring infectious material from cadavers to patients through their hands.

By implementing a strict handwashing regime using a chlorinated lime solution, Semmelweis observed a dramatic decline in infections among patients. This groundbreaking revelation underscored how handwashing could serve as a critical intervention in reducing the spread of pathogens in medical settings. Therefore, the reduction of infections is the correct answer as it highlights the foundational understanding of germ theory and infection control that evolved from Semmelweis's work. This principle remains a cornerstone of medical practice today, emphasizing the essential role of cleanliness in patient care.