A type of drug which is supposed to kill bacteria or other microorganisms. However, they do not kill viruses, so they don't help with colds and other diseases caused by viruses.

Every once in a while I come across an article discussing another microorganism that managed to become resistant to an antibiotic, and had had an "interesting experience" with it myself: in 1996 I managed to get myself infected with the Shigella flexneri bacterium (causing dysenteria...) and the medical lab provided me with a list of antibiotics the S. flexneri was resistant to; thus useless to take those type of medicines. That was then and in Peru. In the meantime, the MRSA can only be treated with vancomycin, and the Pneumococcus causing pneumonia is even found to be resistant to that. Imagine, since the invention to use penicillin as a medicine to combat infections, those bacteria "learned" to defend themselves against the whole list of antibiotics below: their adaptability is faster that our increasing knowledge about antibiotics. Makes you wonder who is smarter.

To kill the bacteria, yeast and fungi, there are several methods depending on the structure and physiology of the organism. I grouped them in accordance with the target site, from basic inhibition of their reproduction to interference with its physiology further down the line.

Prevention of DNA synthesis
Mitomycin C

Inhibition of RNA synthesis
Actinomycin D
Rifamycin B (and derivative Rifampicin)

Inhibition of protein synthesis
Streptomycin A

Interference with cell wall synthesis
Ampicillin (and Amoxicillin)
Cephalosporin C

Membrane transport disruption
Gramicidin A

Polypeptide antibiotics, detergents
polymyxin (derivative polysporin)

I know there are more antibiotics than the ones I mentioned (about 100 in total), but they have more or less the same biochemical fuction as one or more mentioned above, but I'd like to have a complete list, so please /msg me if you know any others and I'll add them.

The most useful sources were my Biochemistry bible from Stryer, General Microbiology written by Schlegel and my own memory.
Over time, bacteria became resistant to antibiotics. Most people think that this is because the bacteria evolve new ways of dealing with them, but this is not usually true. Most antibiotics are derived from natural sources, such as other bacteria. Penicillin is produced by a mould. This mould has existed for approximately 200 million years. Bacteria live in the soil around this mould. Bacteria have therefore had 200 million years to develop resistance.

Obviously, this is limited to the bacteria that actually live near the mould. But bacteria are capable of transferring DNA between each other, allowing resistance genes to be transferred from bacteria that have to put up with the mould to other bacteria that haven't. Bacteria that produce antibiotics as a weapon will also have resistance genes, and are also able to transfer these to others. The net result is that a single resistance gene in the population can be transferred to the rest of bacteria on the planet in very little time.

Most resistance is due to this sort of thing. A resistance gene already exists and is inserted into other bacteria. This is much, much, much faster than evolution of an entirely new mechanism, and is the reason for bacteria now being immune to most antibiotics. Research is now being done into methods of interfering with the resistance mechanisms, on the grounds that there are unlikely to be genes that protect the resistance mechanisms.

Still, even if antibiotics do end up being completely useless it won't be the end of civilization. We survived for centuries without them, after all.

Antibiotics are medications used to treat infections by living organisms. As such, they work marvelously against bacterial, rickettsial and spirochetal infections as well as amoebal and some parasitic ones. However, unfortunately, viruses are not 'alive' in the way we define life - they're more like little protein machines. Antibiotics have no effect on viruses.

Antibiotics were first introduced in the 1930s, with sulfanilamide. Penicillin was discovered by Alexander Fleming after the accidental contamination of a bacterial culture with mold in 1929. Initially, penicillin was very difficult to produce, so the urine of patients receiving penicillin was collected in order to retrieve what penicillin could be retrieved for reuse.

In recent years, antibiotics of different types have multiplied. There is hardly anyone in the US who has not had at least one course of antibiotics in their life. However, due to misuse (not taking the full course) and overuse (using antibiotics in situations where they are not indicated), antibiotic-resistant strains of bacteria are becoming more and more common, and medical workers have nightmares about bacteria that cannot be killed by anythign in our medical arsenal.


Brand/Generic Drug Names

azithromycin, clarithromycin, gentamycin, cefaclor, cefazolin, cefotaxime, cephalexin, ciprofloxacin, levofloxacin, meropenem, amoxicillin, ampicillin, cloxacillin, penicillin, sulfasalazine,doxycycline, tetracycline
Common uses
susceptible bacterial, rickettsial and spirochete infections
inhibit growth and replication of susceptible bacterial organisms
Class contraindications
allergy, cross-sensitivity
Class precautions
renal and liver disease
varies by drug
Adverse Reactions
nausea, vomiting, diarrhea, bone marrow depression, anaphylaxis
Additional Information
Assess blood and renal studies
Assess bowel pattern, urine output qd
Assess for anaphylaxis, bleeding, overgrowth of infection
Ensure culture and sensitivity is taken before beginning therapy
Administer for 10-14 days to ensure death of organism
Evaluate therapeutic response: absence of fever, malaise, fatigue, draining wounds
Date of most recent Update
August 07, 2002
Further information is available in the writeup for the specific name(s) of this medication class

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