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Antibiotics are medications used to fight bacterial infections; they will not harm viruses, fungal infections or parasites. Antibiotics are usually taken orally in pill form, but can be administered through intravenous injection (into a vein), intramuscular injection (into a muscle, to treat skin infections) or as a skin ointment. There are many types of antibiotics and some have proven to be more effective than others at treating specific types of infection. "Broad spectrum" antibiotics are medications that harm or kill a wide variety of infectious bacterial agents.
About 90 percent of the antibiotics used today are created by chemically isolating them from bacteria, although a few are completely manufactured. Antibiotics are used both to treat bacterial infection of the heart, and in limited cases, to prevent bacterial infection. Some of the antibiotics that may be used for these purposes include:
| Generic Name |
Brand Name(s) |
| amoxicillin |
Amoxil, Larotid |
| Penicillin v, g |
Pen-Vee-K, Pen G |
| ampicillin |
Marcillin, Principen |
| cephalexin |
Keflex, Biocef |
| gentamicin |
Cidomycin, Garamycin |
| cefazolin |
Ancef |
| erythromycin |
E-mycin |
| tetracycline |
Robitet, Panmycin |
| clarithromycin |
Biaxin |
| azithromycin |
Zithromax |
| vancomycin |
Vancocin |
Antibiotics harm microorganisms in a variety of ways. Most antibiotics fall into one of the following categories:
- Cell wall synthesis inhibitors. These antibiotics will not harm existing bacteria cells, but they prevent new cells from forming. Infections grow and spread because the bacteria cells multiply, doubling once every 20 minutes. When bacteria split, they create a wall or container for the new cell. Some antibiotics prevent the bacteria from forming this cell wall, thus preventing them from multiplying.
- Cell membrane inhibitors. These antibiotics directly kill bacteria cells by causing the outer membrane of the cell to break down. Most medications of this kind, however, are not effective when given systemically (to the entire body through the bloodstream) and are currently only used as topical antibiotics, such as skin ointments or creams.
- Protein synthesis inhibitors. These antibiotics prevent the bacteria from converting proteins to energy, effectively starving the bacteria to death.
- Nucleic acid synthesis inhibitors. These antibiotics keep bacteria cells from growing by interrupting communications between the bacteria and its DNA, the blueprint or "brain" of the bacteria, that tells it how to make proteins in order to survive and reproduce.
- Competitive inhibitors. These antibiotics are mostly synthetic (manufactured). They are similar to the material in bacteria that regulate their growth. Once inside the bacteria, the antibiotics replace the bacteria's own growth factors, thus preventing the infection from spreading.
A number of researchers have studied possible links between bacteria and heart disease. For example, one theory speculates that low-level infection of the coronary arteries with chlamydia pneumoniae (a type of pneumonia) may accelerate atherosclerosis and increase risk for heart attack. Other researchers have looked at the role of periodontal bacteria, which can enter the bloodstream through tiny cuts in the gums and travel through the body. These periodontal bacteria have been discovered in the heart, although the newest studies show that the risk of contracting an acute infection from these bacteria is very low. Rather, some researchers believe that their chronic presence in the heart may hasten the development of atherosclerotic heart disease.
The underlying factor that might explain why bacterial infection raises the risk of atherosclerosis or hastens its development is inflammation. In response to the bacterial infection, the body mounts an immune system response that is characterized by the release of inflammatory chemicals. These chemicals are the same ones that cause inflammation of the artery wall in atherosclerosis. By increasing the inflammatory load throughout the body, it is possible that bacterial infection may directly contribute to atherosclerosis. While this is a tantalizing possibility, however, studies have not shown that therapy with antibiotics can reduce the risk of heart attack.
In fact, even the widespread use of preventive antibiotics in oral surgery and dental procedures has not been conclusively proven in a well-designed, double-blinded study to reduce the risk of endocarditis. As a result, the American Heart Association in 2007 revised its guidelines for the use of antibiotics before common dental procedures. Today, only patients at high risk of bad outcomes from infective endocarditis, an infection of the endocardium, are advised to take antibiotics.
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