There is an invisible war being fought at the microscopic level between bacteria and fungi. We should be glad of this because these microorganisms produce chemicals that inhibit each other, and we can use these chemicals to produce antimicrobials. Bacteria will produce antifungal and antibacterial chemicals, with the fungi doing the same. They do this to compete for the nutrients in nature. What scientists try to determine are the specific antimicrobial compounds, what kind of microorganisms they inhibit, are they safe for humans, and can they be produced in large enough quantities to be cost effective.
In the Philippines in 1949, scientist Abelardo B. Aquilar who was employed by Eli Lilly, collected soil into jars and labeled each with the date, location, and his initials. He then carefully packed them for shipment to the U.S., specifically, Indianapolis, Indiana, home of Eli Lilly Pharmaceutical Co. When the jars arrived at the company, each one’s contents were put into separate containers holding a broth designed to grow microorganisms. After a few days of incubating in the large containers the samples of the liquid contents were put on petri dishes (dishes used to grow microorganisms in laboratories) in which a variety of bacteria were introduced. One of the petri dishes showed streaks of no bacteria growth where the liquid from the large containers was applied. This is the first indication that a substance to inhibit bacteria may be in the soil samples. The organism that produced the antibacterial compound was a bacterium called Streptomyces erythreus later called Saccharopolyspora erythraea. The antibacterial compound was named erythromycin after the organism from which it was extracted.
Erythromycin was discovered at a convenient time. Penicillin had been used for a few years by 1949 and there were beginning signs of allergic reactions and resistance showing up in people who had previously received penicillin. Erythromycin worked against many of the same bacteria that penicillin was effective against and therefore could be used as an alternative.
There are a variety of dosage forms for erythromycin: oral, topical ointments, ophthalmic products, and intravenous solutions. Though it can be given orally, it is not very stable in the acidic stomach and can produce hypermotility of the gastrointestinal tract. This bothersome side effect can be taken advantage of by giving this drug to people who have a condition called gastroparesis, a slowing down of the gastrointestinal tract. Erythromycin given at low doses can cause the gastrointestinal tract to move again giving relief to this condition, however, this use is discouraged because bacterial drug resistance is a possible consequence.
Because of the instability of erythromycin in stomach acid another similar antibiotic drug was developed by Taisho Pharmaceutical Co. of Tokyo, Japan in the 1970’s and marketed in the 1980’s. This drug is clarithromycin (Biaxin) which has the same antibacterial spectrum as
erythromycin but is more stable in stomach acid. In addition, it stays in the body longer and can be given fewer times a day.
In the 1980’s a pharmaceutical company in Zagreb, Croatia, the Pliva Co., a subsidiary of Teva Pharmaceutical Co of Israel, discovered azithromycin. It was brought to the U. S. market by the Pfizer Co. as Zithromax. Azithromycin is another antibiotic and is given once a day because it stays in the body an extra-long time. Azithromycin is the drug in the famous “Z-Pack”. The Z-Pack is a dosing regimen of azithromycin in which a person takes two 250mg tablets on day one, then one 250mg tablet daily for 4 more days. This regimen has been highly effective in treating respiratory infections.
The development of antibiotics involves the invisible war amongst microorganisms and is a true international story with research conducted by people all over the world.
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