Antibiotics




Antibiotics

█ BRIAN HOYLE

The security and stability of a country depends in part on the health of its citizens. One of the factors that influence the health of people is infectious disease (a disease that can be spread from person to person or from another living being to a human). A variety of infectious diseases are caused by bacteria.

Some bacterial infections can be treated using compounds that are collectively known as antibiotics. Antibiotics can be naturally produced. For example, the first antibiotic discovered (penicillin; discovered in 1928 by Sir Alexander Fleming) is produced by a species of a mold microorganism. There are a variety of different naturally produced antibiotics, while many other antibiotics have been chemically produced. Finally, antibiotics act only on bacteria and are not effective against viruses.

Prior to the discovery of penicillin there were few effective treatments to battle or prevent bacterial infections. Pneumonia, tuberculosis, and typhoid fever were virtually untreatable. And, in those persons whose immune system was not functioning properly, even normally minor bacterial infections could prove to be be life-threatening.

In nature, antibiotics help protect a bacteria or eukaryotic cell (i.e., plant cell) from invading bacteria. In the laboratory, this is evident as the inhibition of growth of bacteria in the presence of the antibiotic-producing species. This screening can be automated so that thousands of samples can be processed each day.

The chemical synthesis of antibiotics is now very sophisticated. The antibiotic can be tailored to affect a specific target on the bacterial cell. Three-dimensional modeling of the bacterial surface and protein molecules is an important aid to antibiotic design.

Penicillin is in a class of antibiotics called beta-lactam antibiotics. The name refers to the chemical ring that is part of the molecule. Other classes of antibiotics include the tetracyclines, aminoglycosides, rifamycins, quinolones, and sulphonamides. The action of these antibiotics is varied. The targets of the antibiotics are different. Some antibiotics disrupt and weaken the cell wall of bacteria (i.e., beta-lactam antibiotics), which causes the bacteria to rupture and die. Other antibiotics disrupt enzymes that are vital for bacterial survival (aminoglycoside antibiotics). Still other antibiotics target genetic material and stop the replication of deoxyribonucleic acid (DNA) (i.e., quinolone antibiotics).

Antibiotics can also vary in the bacteria they affect. Some antibiotics kill only a few related types of bacteria and are referred to as narrow-spectrum antibiotics. Other antibiotics such as penicillin kill a variety of different bacteria. These are the broad-spectrum antibiotics.

Following the discovery of penicillin, many different naturally occurring antibiotics were discovered and still many others were synthesized. They were extremely successful in reducing many infectious diseases. Indeed, in the 1970s the prevailing view was that infectious diseases were a thing of the past. However, beginning in the 1970s and continuing to the present day, resistance to antibiotics is developing.

As of 2002, the problem of antibiotic resistance is so severe that many physicians and security analysts think that the twenty-first century will initiate the "post antibiotic era." In other words, the use of antibiotics to control infectious bacterial disease will no longer be an effective strategy.

Resistance to a specific antibiotic or a class of antibiotics can develop when an antibiotic is overused or misused. If an antibiotic is used properly to treat an infection, then all the infectious bacteria should be killed directly, or weakened such that the host's immune response will kill them. However, if the antibiotic concentration is too low, the bacteria may be weakened but not killed. The same thing can happen if antibiotic therapy is stopped too soon. The surviving bacteria may have acquired resistance, which can be genetically transferred to subsequent generations of bacteria. For example, many strains of Mycobacterium tuberculosis , the bacterium that causes tuberculosis, are resistant to one or more of the antibiotics used to treat the lung infection. Some strains of Staphylococcus aureus that can cause boils, pneumonia, or bloodstream infections, are resistant to most (and with one strain, all) antibiotics.

The increasing antibiotic resistance of bacteria, and the resulting increase in infectious diseases, is a security risk. Disease can decimate the population. The misery and economic hardship that results can cause political instability. In underdeveloped countries, this instability can lead to anger directed at developed countries such as the United States. Even in developed countries, the increasing numbers of people needing hospitalization and medical care can strain the health care system.

The availability of antibiotics to combat bacterial epidemics has always been challenging. The appearance and rapid increase in an infection can tax the ability of a healthcare system to respond with medicines including the appropriate antibiotics.

The threat of biological warfare, such as the aerial distribution of Bacillus anthracis , the agent of anthrax, has made the provision of large quantities of antibiotics a priority for the United States and other nations. Plants that manufacture antibiotics are designed with sterility of manufacture in mind, not security. Disabling an antibiotic manufacturing facility would be a crippling blow to any potential biowarfare response.

Even if a large supply of a particular antibiotic were available, the emergency response would be challenging, as the antibiotic would need to be distributed to many people (i.e., millions in the event of an aerial release of the anthrax bacterium) within hours.

█ FURTHER READING:

PERIODICALS:

Inglesby, Thomas V. "Bioterrorist Threats: What the Infectious Disease Community Should Know about Anthrax and Plague." Emerging Infections 5. Washington, DC: American Society for Microbiology Press, 2001.

ELECTRONIC:

Central Intelligence Agency. "The Global Infectious Disease Threat and Its Implications for the United States." January 2000.< http://www.cia.gov/cia/publications/nie/report/nie99–17d.html > (22 November 2002).

World Health Organization. "Strengthening Global Preparedness for Defense against Infectious Disease Threats." Statement to the United States Senate Committee on Foreign Relations Hearing on The Threat of Bioterrorism and the Spread of Infectious Diseases. 5 September 2001. < http://www.who.int/emc/pdfs/Senate_hearing.pdf >(24 November 2002).

SEE ALSO

Biocontainment Laboratories
Biological Warfare
CDC (United States Centers for Disease Control and Prevention)
L-Gel Decontamination Reagent
Pathogens
Public Health Service (PHS), United States




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