Silver as an Antibacterial/Antimicrobial Agent
Early History – Silver has been used by many cultures as a medicine and preservative throughout history. The Greeks, Romans, and Egyptians used silver vessels for water and other liquids to keep them fresh. Hippocrates, the “Father of Medicine,” taught that silver healed wounds and controlled disease.
Around 400 B.C. he listed the singular treatment for ulcers as “the flowers of silver alone, in the finest powder.” In 69 B.C., silver nitrate was described in the contemporary pharmacopoeia. In the Middle Ages, silver house ware protected the wealthy from the plague. It also contributed a bluish-hue to their skin, resulting in the term “blue-bloods.” The Chinese emperors and their courts ate with silver chopsticks. Silver was also used in small amounts as a tonic in Ayurvedic medicine, which originated in India over a thousand years ago. Pioneers in the United States placed silver and copper coins in their water casks to retard the growth of bacteria and algae. Silver dollars were also put into their milk to keep it fresh. The Imperial Russian army lined their water casks with silver in World War I and this practice was continued by some units in the Soviet Army during World War II.
In the United States, silver first gained regulatory approval for use as an antimicrobial agent in the early 20th century. Antimicrobial properties inhibit the growth of all microbes, which includes bacteria, mold, and fungi. Antibacterial properties destroy only bacteria. By 1940, there were approximately four dozen different silver compounds on the market being used to treat infectious disease. However, synthetically manufactured antibiotics began to make their appearance. Penicillin was the first antibiotic used successfully in treating bacterial infections. By the 1950s, large numbers of antibiotics were being discovered and manufactured for the treatment of diseases caused by bacteria. Profits and ease of manufacturing antibiotics significantly reduced the use of silver.
Renewed Interest in Silver – The return of silver to conventional medicine began in the 1970s when Dr. Carl Moyer, chairman of Washington University’s Department of Surgery, received a grant to develop better methods of treatment for burn victims. Silver sulphadiazine (Silvadene, Marion Laboratories) is now used in 70 percent of burn centers in the United States. It has been discovered only recently how silver’s antibacterial and antimicrobial abilities work. Silver disables certain enzymes needed by anaerobic bacteria, viruses, yeasts, and fungus to survive. In addition, these bacteria cannot develop a resistance to silver, as they do with antibiotics, because silver attacks their food source rather than the bacteria directly. Research at Washington University School of Medicine in St. Louis has shown that silver is a bactericidal to some 650 strains of disease-causing organisms and that resistant strains cannot develop with silver the way they will with antibiotics.
Use of Silver Today – Because silver can be used in sprays, gels and coatings, its use as an antimicrobial agent continues to grow not only in hospitals and treatment centers, but also in public areas such as restaurants, airports and institutional buildings. It is used as a coating for wall coverings, sinks, flooring, climate control ducts and on bed rails. It is also used on stethoscopes, pens, clipboards, catheters, endotracheal tubes and on other portable items. Silver in endotracheal tubes is especially important in the medical field as it helps to protect patients requiring ventilator-assisted breathing from developing ventilator-associated pneumonia. Another important use for silver is in the treatment of stored municipal water supplies. This is a safer alternative to chlorine, which can lead to the formation of many hazardous compounds. Silver has been used to sterilize recycled water aboard the MIR space station and on the NASA space shuttles. Recently the IV-7 Water Purifier, an advanced broad-spectrum disinfectant using patented silver dihydrogen citrate, was donated through Project Hope to Haiti. It will be used to purify 40 million gallons of water.
Many companies are now producing silver-based antimicrobial clothing and fabric products including shoes, socks, sportswear, dish cloths, facial towels, sleeping bags and more. These items are marketed for their antibacterial and antifungal properties, plus the elimination of offensive smells. Silver is even being used as a deterrent to microbial growth in food packaging. Veterinarians also find it useful against canine parvovirus, infections of the skin, cuts or rashes, kennel cough and other diseases. More uses will continue to develop with today’s technology.