Antibiotics may sometimes be called Antibacterial are chemotherapeutic agents that are naturally (Antibiotics) and synthetically (Antibacterial) produced and have lethal effect on microorganisms. In other words, Antibiotics are a type of Antimicrobial agent or drugs used in the treatment and prevention of microorganism infections. Antibiotics have the ability of either killing or inhibiting the growth of microorganism and very useful In Microbiology especially at the level of susceptibility testing and aid physicians in choosing the drugs of choice for treatment.

It should be noted that

 When bacteria are involved, the chemotherapeutic agents used are Antibiotics while when Protozoan’s or Helminthes are involved, an Anti-Helminthic drugs are used like prazinquantel, Metizan, Mebendazole.

As far as Viruses and Fungi are concerned, we use Antiviral and Anti-fungal respectively

Principles of Chemotherapeutic agents

The fundamental principle of chemotherapeutic agents is base on Selective Toxicity that is; these agents are harmful to the microorganism without injuring the host.

Spectrum of action of Antibiotics in Susceptibility testing


In Microbiology susceptibility testing, Antibiotics are selected base on their range of action on microorganism against which they are most active. This range is term Spectrum and there exist two types of Antibiotic spectrum, which are the Narrow and Broad Spectrum

Narrow Spectrum: These are chemotherapeutic agents active against few microorganisms like Penicillin while Broad Spectrum are those whose action are against a wide range of microorganism like Ciprofloxacin and Chloramphenicole.


Bacteriostatic and Bactericidal Antibiotics

Bacteriostatic antibiotic are chemical agents whose action stop or inhibit the growth of microorganism without necessarily killing them. They interfere with bacterial protein production, attack of bacterial cellular metabolism and DNA replication.


Examples of Bacteriostatic antibiotics are Chloramphenicol, clindamycin, macrolides, novobiocin, tetracyclines, trimethroprim, sulfonamides, oxazolidinone, tigecycline and many others.

Bactericidal Antibiotics are those chemotherapeutic agents whose action is to kill microorganism. They inhibits cell wall synthesis and totally destroy bacteria.a good example of these types of antibiotics are Fluoroquinolones, Metronidazoles, vancomycin, penicillins, Aminoglycosidic antibiotics, Co-trimoxazoles etc

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About the Author: Arthur Westmann

DEFFE ARTHUR (AMOEBAMANN) is the founder and author of MLTGEEKS and MLTEXPO.He’s from Cameroon and is currently a Final year State Medical Laboratory Technician (MLT MA). Beyond lab works, he’s a passionate internet user with a keen interest in web design and blogging. Furthermore He likes traveling, hanging around with friends and social networking to do in his spare time.

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