Why is Bacterial Resistance to Ampicillin a Concern?

Ampicillin is an antibiotic in the penicillin family that was one of the first in its class to work against a broad range of bacteria and has been in use since 1961. It works by penetrating bacteria defenses and inhibiting the production of a vital enzyme needed during the replication process. In recent years, resistance to ampicillin is developing among a variety of bacteria due to its many years of human application and extensive use in animal feed. Resistance to ampicillin is a cause for concern because it makes these bacteria more difficult and expensive to treat. In some cases, strains of bacteria can develop resistance to multiple antibiotics, making them very dangerous and almost impossible to eradicate.

Antibiotics have revolutionized the treatment of many diseases and saved countless lives. Penicillin was the first discovered antibiotic, or antimicrobial, in 1927, and it went into wide use by the 1940s. Ampicillin, introduced in 1961, belongs to the same family of drugs. It works by entering the bacteria through its outer membrane and preventing it from making a necessary enzyme for the replication process. Without this enzyme, the bacteria is unable to complete synthesis of the cell wall, which it needs to survive.

As time has gone by, many strains of bacteria have developed resistance to ampicillin, thus creating a potentially dangerous situation. There are several identified causes for this phenomenon. One is the overuse of antibiotics in general, which leads to larger numbers of bacteria that are tolerant to the presence of antimicrobial agents since they must adapt to survive. Resistance to an older antibiotic such as ampicillin can develop simply because it has been in circulation much longer, and there has been ample opportunity for bacteria to adapt.

The fact that ampicillin is used extensively in animal feed is of particular concern. This has caused several food-borne bacteria that are also capable of infecting humans and causing illness to develop resistance to ampicillin. Examples of these bacteria include strains of E.coli, and salmonella. These bacteria have developed a gene for ampicillin resistance that can be transferred from one to another through a process called horizontal transfer, thereby allowing the problem to spread. Existence in the food supply is an avenue for the rapid spread of bacteria that possess resistance to ampicillin to large numbers of the human population.

Resistance to ampicillin is a cause for concern because it makes the bacteria quite difficult to treat. Often a long and expensive course of treatment with a combination of drugs is necessary to clear infections of resistant bacteria. Another danger is that the bacteria will develop resistance to multiple antibiotics. This can be particularly dangerous because the bacteria become progressively more difficult to treat as additional antibiotic resistance develops. Some of these "super bacteria" become deadly and almost impossible to eliminate, a journey that often begins with ampicillin resistance.