Antibiotics are specialized drugs designed to combat bacterial infections by either inhibiting bacterial growth or outright killing them. Forming a subset of the broader category of antimicrobials, antibiotics are part of a group that also encompasses anti-viral, anti-fungal, and anti-parasitic medications.
History and Definition
The term "antibiotic" was coined by Selman Waksman and was initially reserved for compounds derived from living organisms. This distinguished them from "chemotherapeutic agents", which were exclusively synthetic in origin. Over time, this distinction has blurred, with the label "antibiotic" extending to include synthetic antimicrobials, like the sulfa drugs. Historically, antibiotics such as those from the penicillin class were derived from mould.
Antibiotics are generally characterized as small molecules having a molecular weight less than 2000. Contrary to some beliefs, they are not enzymes. They are designed to be relatively harmless to the host, making them ideal for treating infections.
Efficacy and Target Specificity
Antibiotics, although revolutionary in the field of medicine, aren't a panacea for all infections. They are primarily ineffective against viral, fungal, and certain nonbacterial infections. Their efficacy varies, depending on the type of bacteria and the antibiotic used. Broadly, antibiotics can be divided into:
- Narrow-spectrum antibiotics: These target specific types of bacteria, for example, either Gram-negative or Gram-positive bacteria.
- Wide-spectrum antibiotics: These have a broader range and can affect a diverse array of bacteria.
The success of an antibiotic treatment depends on several factors:
- The location of the infection
- The antibiotic's ability to reach the infection site
- The potential of the bacteria to resist or neutralize the antibiotic
In terms of their action, some antibiotics are bactericidal, meaning they kill bacteria, while others are bacteriostatic, inhibiting bacterial growth and allowing the host's immune system to finish the job.
Administration and Usage
Antibiotics can be administered in a variety of ways:
- Oral – This is the most common method for less severe infections.
- Intravenous – Used for more acute infections.
- Topical – Such as ointments or eyedrops for localized infections.
The choice of antibiotic and its mode of administration usually hinge on the nature of the infection and the bacteria responsible. It's determined by the bacteria's sensitivity to the drug and the concentration achievable at the infection site.
Classes of Antibiotics
Antibiotics play a pivotal role in the field of modern medicine, offering an effective defense against bacterial infections. Broadly, antibiotics can be divided into two primary categories based on their operational behavior: bactericidal and bacteriostatic. The former destroys bacteria directly, while the latter inhibits their ability to reproduce. Nevertheless, it's essential to understand that these categories primarily reflect their behavior under laboratory conditions. In practical applications, both these types effectively curtail bacterial infections.
Below is a comprehensive list of different classes of antibiotics, with examples of common drugs, brand names, their primary uses, and associated side effects:
|Amikacin||Infections caused by Gram-negative bacteria, such as Escherichia coli and Klebsiella||Hearing loss, Vertigo, Kidney damage|
|Cephalosporins (First generation)|
|Cefadroxil||Gastrointestinal upset and diarrhea, Nausea (if alcohol taken concurrently), Allergic reactions|
|Cephalosporins (Second generation)|
|Cefaclor||Gastrointestinal upset and diarrhea, Nausea (if alcohol taken concurrently), Allergic reactions|
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- The Merck Manual of Medical Information - Home Edition, Robert Berkow (Ed.), Pocket (September, 1999), ISBN 0-671-02727-1.