Penicillin is derived from a fungi named Penicillium. They are a group of Beta-lactam antibiotics, which are used in the treatment or prevention of bacterial infections originated by susceptible, particularly gram-positive, organisms. They are usually bactericidal in action when given in therapeutic doses.
Penicillins are effective in treating a variety of infections caused by susceptible bacteria like Clostridium, Neisseria, staphylococci, streptococci, and Listeria.
Therapeutic Uses
- Urinary tract infections (UTIs).
- Respiratory tract infections (RTIs).
- Syphilis and gonorrhea.
- Bacillary dysentery and typhoid.
- Meningitis.
- Infections in the bones and joints.
- Infections of the skin and soft tissues.
- Bronchitis and pneumonia.
Classification of Penicillin
Penicillins can be classified into various classes considering their origins, administration routes, antimicrobial spectrum, beta-lactamase resistance, and acid resistance.The figure below shows the therapeutic classification of penicillins with examples based on above parameters.
Figure 1. Therapeutic Classification of Penicillin | Adapted from Sahoo and Banik1
Important Classes of Penicillin
Natural Penicillins (Penicillin V, Penicillin G, Benzathine, Procaine Penicillin)
Streptococcus Pneumoniae Source: Nathan Reading, CC-BY-2.0, via Flickr |
Penicillinase-Resistant or Beta-Lactamase Resistant Penicillins (Oxacillin, Dicloxacillin, Cloxacillin, Methicillin, Nafcillin)
Staphylococcus Aureus Source: Nathan Reading, CC-BY-2.0, via Flickr |
This class of penicillins are specifically designed to combat staphylococcal species as well as gram (+) cocci strains that produce penicillinase. For this reason, these penicillins are often called as anti-staphylococcal penicillins.
Aminopenicillins (Amoxicillin, Bacampicillin, Ampicillin) – Acid Stable Penicillins
The aminopenicillins were the first class of penicillins, which were discovered as active agents against several gram (-) bacteria (e.g. H. influenzae and E. coli). This class of penicillins have acid resistant properties, and for this reason they are available in oral dosage forms.Orally administered drugs (amoxicillin, Bacampicillin and ampicillin) of this class are usually used in several mild infections, including sinusitis, tonsillitis, otitis media, bronchitis, bacterial diarrhea and UTIs. For the otitis media treatment, Amoxicillin is considered as the drug of choice.
Extended Spectrum Penicillins
Extended Spectrum Penicillins are also called as anti-pseudomonal penicillins. They include both acylaminopenicillins (mezlocillin, piperacillin, and azlocillin) and alpha-carboxypenicillins (ticarcillin and carbenicillin). The antibiotics of this class of penicillin have similar spectrum of antimicrobial activity as compared to aminopenicillins.However, these penicillins have an additional anti-bacterial activity against many organisms (gram-negative) of the Enterobacteriaceae family, including several strains of Pseudomonas aeruginosa. The antibiotics of this class may be administered alone or in combination with Aminoglycosides. In addition, like the aminopenicillins, drugs of this class are also vulnerable to inactivation by beta-lactamases.
Medical Reference
- Sahoo BM, Banik BK. Therapeutic Potentials of β‐Lactam: A Scaffold for New Drug Development. Synthetic Approaches to Nonaromatic Nitrogen Heterocycles. 2020 Oct 29:59-88.
This post first appeared on Medical-Reference - A Pioneer In Medical Blogging, please read the originial post: here