examined. His suspicions were supported by the untimely death of a friend, a physician who contracted a fatal wound
infection after a postmortem examination of a woman who had died of a puerperal infection. The dead physician’s
wound had been caused by a scalpel used during the examination, and his subsequent illness and death closely
paralleled that of the dead patient.
Although Semmelweis did not know the true cause of puerperal fever, he proposed that physicians were somehow
transferring the causative agent to their patients. He suggested that the number of puerperal fever cases could be
reduced if physicians and medical students simply washed their hands with chlorinated lime water before and after
examining every patient. When this practice was implemented, the maternal mortality rate in mothers cared for by
physicians dropped to the same 1% mortality rate observed among mothers cared for by midwives. This demonstrated
that handwashing was a very effective method for preventing disease transmission (Figure 3.8). Despite this great
success, many discounted Semmelweis’s work at the time, and physicians were slow to adopt the simple procedure of
handwashing to prevent infections in their patients because it contradicted established norms for that time period.
Figure 3.8 Ignaz Semmelweis (1818–1865) was a proponent of the importance of handwashing to prevent transfer
of disease between patients by physicians.
Around the same time Semmelweis was promoting handwashing, in 1848, British physician John Snow conducted
studies to track the source of cholera outbreaks in London. By tracing the outbreaks to two specific water sources,
bothofwhich were contaminated bysewage, Snowultimately demonstrated that cholera bacteria were transmitted via
drinking water. Snow’s work is influential in that it represents the first known epidemiological study, and it resulted
in the first known public health response to an epidemic. The work of both Semmelweis and Snow clearly refuted
the prevailing miasma theory of the day, showing that disease is not only transmitted through the air but also through
contaminated items.
Although the work of Semmelweis and Snow successfully showed the role of sanitation in preventing infectious
disease, the cause of disease was not fully understood. The subsequent work of Louis Pasteur, Robert Koch, and
Joseph Lister would further substantiate the germ theory of disease (Figure 3.9).
While studying the causes of beer and wine spoilage in 1856, Louis Pasteur discovered properties of fermentation by
microorganisms. He had demonstrated with his swan-neck flask experiments (Figure 3.4) that airborne microbes,
not spontaneous generation, were the cause of food spoilage, and he suggested that if microbes were responsible for
food spoilage and fermentation, they could also be responsible for causing infection. This was the foundation for the
germ theory of disease.
Meanwhile, British surgeon Joseph Lister was trying to determine the causes of postsurgical infections. Many
physicians did not give credence to the idea that microbes on their hands, on their clothes, or in the air could infect
patients’ surgical wounds, despite the fact that 50% of surgical patients, on average, were dying of postsurgical
infections.[15]Lister, however, was familiar with the work of Semmelweis and Pasteur; therefore, he insisted on
- Alexander, J. Wesley. “The Contributions of Infection Control to a Century of Progress”Annals of Surgery201:423-428, 1985.
Chapter 3 | The Cell 89