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Antimicrobial Resistant Organism

Definition and history of antimicrobials

What are the antimicrobials?

Antibiotics are substances produced by microorganisms that prevent the growth of other microorganisms. The term “antibiotics” was first described by S.A. Waksman in 1942. In general, antibiotics are used in combination with antibacterial agents and antimicrobial agents; however, these two words have a meaning different to that of the term antimicrobials. Antibacterial agents refer to artificially synthesized or semi-synthetic drugs and do not include antifungal, antiviral, and antiprotozoal agents; therefore, the term “antimicrobial agents” is recommended to imply this characteristics.

History of antimicrobials

Ⅰ. Era of natural substances

Antimicrobials have long been used by human. The antimicrobials obtained from nature and their use has been reported since ancient times, and it is recorded that infectious diseases were treated with the bark of trees, roots of the ipecacuanha, and extracts obtained from fungi. These "natural antimicrobials" have long been used as folk remedies.

Ⅱ. Era of synthetic chemical substances

Around 1910, P. Ehrlich developed Salvarsan by using synthetic organic chemistry. Salvarsan was used to treat syphilis, which is recorded as the first example of healing a disease with chemotherapy. In 1932, Prontosil of the azo family was synthesized by J. Klarer and F. Mietzsch, and in 1934, it was proved to be effective in the treatment of streptococcal infections, by the German pharmacologist G. Domagk. In addition, the use of Prontosil in the treatment of puerperal fever in the UK has dramatically reduced the mortality rate. This can be considered the true beginning of the era of antimicrobial chemotherapy, because various sulfonamide compounds have been developed as antimicrobials since the success of Prontosil.

Ⅲ. Era of antimicrobials produced by microorganisms

n 1928, A. Fleming discovered accidently that the growth of staphylococci was poor in molded agars. This substance was successfully concentrated and named “penicillin.” Fifteen years later, in 1943, penicillin was used to treat humans with infectious diseases. At the time of its first usages, penicillins saved lives of countless patients who were infected by staphylococci during World War II. However, owing to the indiscriminate use of penicillin, penicillin-resistant strains began to appear, and around 1960s, the resistance rate reached 80%; therefore, the second-generation penicillins, methicillin was developed, but methicillin-resistant strains were soon identified.

Following the beta-lactam antimicrobials, aminoglycosides including streptomycin and kanamycin, have been developed. These antimicrobials had broad-spectrum including tuberculosis, however, clinical strains exhibiting resistance to these antimicrobials were soon discovered.

Subsequently, many other antimicrobials have been developed. Until the 1980s, new antimicrobials were developed mainly by isolating antimicrobial substances from microorganisms obtained from various habitats in nature. Subsequently, new drugs have been developed to improve pharmacological effects or to reduce side effects by chemical modifications of known drugs. The chronology of the major antimicrobials is as follows.

Ⅳ. Recent trends in antimicrobial development

Although there is an urgent need of new antimicrobials with the emergence of multidrug-resistant bacteria, not much benefit is realized owing to their short-term use in a small number of patients compared to the effort devoted to fastidious clinical trials and strict regulations; thus, studies to develop antimicrobials are insufficient. Considering the insufficient development of new antimicrobials, the importance of proper usage of antimicrobials through the antimicrobials stewardship calls more attention.