Antimicrobial agents used in chemotherapy to treat cancer are mostly derived out of Streptomyces species. Microbial agents include some of the bacteria, yeast, fungus and other microbes, which are used in making antibiotics to fight antibacterial or antifungal infections. Some antibiotics are used in cancer as chemotherapeutic agents. These are anti tumor antibiotics. When cancer chemotherapy was newly found and nitrogen mustard was used to treat tumors, there was a theory laid down of using antibiotic therapy to treat cancers as the way it is used in tuberculosis. Antibiotic is basically a chemical substance produced by a living microorganism, that is detrimental to other microorganisms.

The anthracyclines and the related drug bleomycin are antibiotics derived from the fungus called Streptomyces verticillus. This occurs naturally in the soils in Japan. This can also be cultivated. These chemotherapy drugs form free radicals that disrupt the structure of cellular DNA. They are used in treating leukemia, lymphoma, breast cancer etc.

Bleomycin is similar to anthracyclines and is derived from the same fungus. However, it has a different chemical composition and reacts differently in the cells. It is effectively used along with other chemotherapy agents for treating lymphoma and testicular cancer. However, anthracyclines cause damage to the heart. This is one of the major side effects. Bleomycin damages the lungs due to the free radical activity. Some common antibiotic chemotherapy agents are bleomycin, dactinomycin, doxorubicin, idarubicin, mitozantrone, epirubicin, daunorubicin, etc.

Antibiotics are released naturally into the soil by bacteria and fungi. However, their importance was not known until the use of penicillin was discovered in 1941. Since then antibiotics have revolutionized the treatment of bacterial infections and fungal in humans and animals. Antibiotics used in cancer chemotherapy are called antineoplastic agents. Antineoplastic agents are divided into categories based on their action. Most drugs display their effects in a certain part of the cell cycle i.e. either the cell growth phase, cell division phase or the resting phase. Hence, most chemotherapy treatments require two or more of these agents. One drug is used to stop the growth of the cancer cells in a certain phase, whereas another agent plays a different role.

Most children who undergo chemotherapy are prescribed certain antibiotics later. Children on chemotherapy take antibiotics two to three days each week to prevent pneumocystis pneumonia (PCP). They are generally for six months after chemotherapy. However, there are certain risks involved and hence it is the doctor’s decision if these prophylactic antibiotics should be given.

Chemotherapy as a term was formed on the basis that drugs have affinities towards certain cells. These were called nature’s ”magic bullets” i.e. the antibodies that targeted the pathogens. This concept was there for about 50 years in mid twentieth century. However in the 1970s and 80s there was a lot of research on anti cancer drugs done in the USA which led to the fact that these anticancer drugs did not the kill tumor cells directly but induced them to die naturally. This process is called apoptosis or programmed cell death. This was based on nucleic acid studies of cell biology. This was a paradigm shift especially in the beginning of the twenty first century in 2001 when the first signal transduction inhibitor (STI) drug was used and many similar drugs were under development. The signal transduction inhibitors inhibit the transmission of a signal in the form of a messenger ribonucleic acid (RNA) from the chromosomal gene where peptides are assembled. Hence, they block the gene’s expression in a cancer mode. Now, about 50 anticancer drugs acting by different modes of action like antimetabolites, antibiotics, enzymes, plant alkaloids, biologics and alkylating agents in chemotherapy are developed and used in various combinations in treating localized or metastasized cancers.

Talking about antimicrobial agent and chemotherapy the use of antimicrobial agents in chemotherapy led to the development of many more advanced drugs which are used now and research is going on to develop even better drugs.