1. Penicillin G:

• Penicillin G is the drug of choice in infection caused by Pneumococci, Streptococci, Meningococci, Gonococci and Staphylococci (Non β-lactamase producing Staphylococci).
• They are effective against Spirochaetes, Bacillus anthracis and other gram positive rods, Clostridium spp and other anaerobes but inactive against Bacteroides fragillis (gram –ve rod).
• They are also active against Listeria spp and Actinomycetes.

2. Penicillin V:

• Penicillin V is used for the treatment of mild respiratory tract infection such as Pharyngitis, otitis media, sinusitis etc.
• It is oral drug.

3. Benzathine Penicillin G:

• Benzathine penicillin G is the insoluble salt of penicillin G and it is used for intramuscular injection. This is slow acting drug for prolong use.
• A single dose of 1.2 million units of benzathine penicillin G is suitable for treatment of β-hemolytic Streptococcal pharyngitis.
• 4 million units of benzathine penicillin G injected once in 1-3 weeks in an appropriate proportion measure for primary and latent Syphilis.

4. Ampicillin, Amoxycillin, Carbenicillin, Ticarcillin, azolocillin, Mezlocillin and Piperacillin:

• Ampicillin is active against coli, Salmonella, Shigella and Haemophilus influenzae but not active against indole +ve Proteus (P.vulgaris), Pseudomonas, Klebsiella and Enterobacter.
• Amphicillin and Amoxycillin are commonly used for treatment of common UTI caused by coliforms bacteria and for the treatment of mixed secondary bacterial infection of respiratory tract.
• Ampicillin was a drug of choice in meningitis caused by influenzae but now a days Ceftriazone is used because of emergence of β-lactamase producing strain of H. influenzae.
• Ampicillin and Amoxyccillin are alternative drug in typhoid fever but should not be used in non-invasive Salmonella gastroenteritis.
• Carbenicillin is active against Pseudomonas and Proteus but not against Klebsiella.
• Ticarcillin also active against Pseudomonas and proteus in lower dose than Carbenicillin.
• Azolocillin, Mezlocillin and Piperacillin have greater activities against Pseudomonas than Carbenicillin.

5. Β-lactamase resistant penicillin: Methicillin, Nafcillin, Oxacillin, Cloxacillin, Dicloxacillin

• These penicillins are used to prevent infection caused by β-lactamase producing streptococci.
• These drugs are highly protein bound therefore they consumed 1 hour before and after meals.
• Except Methicillin all β-lactamase resistant penicillin are suitable for oral administration. However methicillin is nephrotoxic and is not suitable for theurapeutic use.

6. Combination of Penicillin with β-lactamase inhibitors:

• β-lactamase inhibitors are also β-lactam group of antibiotics but with very little antimicrobial activity.
• β-lactamase inhibitors are usually used in combination with β-lactam antibiotics (penicillin) to treat infection caused by β-lactamase producing strain of bacteria.
• Commonly used β-lactamase inhibitors are; sulbactum, tazobactum and clavulanic acid.

Combination drugs commonly used are:

• Zosyn: piperacillin + tazobactum
• Unasyn: amphicillin + sulbactum
• Angmentin: amoxicillin + clavulanic acid

Clinical use of penicillin antibiotics

The post Clinical use of penicillin antibiotics appeared first on Online Biology Notes.

• β-lactam antibiotics have common b-lactam ring in their structure. Different b lactam antibiotics differ in their side chain.

There are several types of B-lactam antibiotics which are potentially important.

Some of them are:

1. Penicillin- penicillin G, methicillin, amphicillin, amoxicillin, carbenicillin, piperacillin, penicillin V
2. Cephalosporin
3. Monobactam
4. Carbapenems
5. Clavamas-clavulanic acid

1. Penicillin

2. Cephalosporin

3. Monobactams:

• The most common example of monobactam is Aztreonam. Monobactam are active against β-lactamase producing Gram –ve Enteric bacteria, Pseudomonas and Serratia. They have extended gram –ve coverage than penicillin. However they are inactive gram +ve bacteria and anaerobes.
• Individuals who are allergic to penicillin are usually not allergic to monobactams
• Monobactams binds to Penicillin binding protein (PBP) and inhibits transpeptidase activity causing filamentation of bacteria which dies later.

list of monobactam antibiotics

• Azteronam
• Tigemonam
• carumonam
• Nocardicin A

4. Carbapenems:

• Carbapenems are broad spectrum drug, virtually active against every bacteria. They are active against Gram +ve and Gram –ve bacteria including Pseudomonas, Serratia, indole positive Proteus and Bacteroid fragellis. Carbapenems are resistant to hydrolysis by β-lactamases.

Example ofcarbapenems:

• Thienamycin
• Imipenem
• Mezopenem
• Ertapenem
• Imipenem can be hydrolysed by dihydropeptidase found in renal tubules in Human, so imipenem should be administered along with dihydropeptidase inhibitors (Cilastatin).
• Meropenem and ertapenem are resiatant to hydrolyse by dihydroxypeptidase.
• Individuals allergic to penicillin should not be recommended Carbapenem drugs.
• Bacteria producing metallo-β-lactamase such as Stenotrophomonas metophila and Bacteroids fragillis are resistant to carbapenems.

5. Clavulanic acid:

• Clavulanic acid is a β-lactamase inhibitors. The resistant strain of bacteria producing βlactamase enzyme hydrolyse β-lactam antibiotics and become resistant.
• β-lactamase inhibitors have special property of inhibiting activity of β-lactamase. They are also β-lactam group of antibiotics with very litte antimicrobial activity.
• The β-lactamase inhibitors are used in combination with β-lactam antibiotics.

Beta-lactam antibiotics: Penicillin, Cephalosporin, Monobactam, Carbapenems and Clavulanic acid

The post Beta-lactam antibiotics: Penicillin, Cephalosporin, Monobactam, Carbapenems and Clavulanic acid appeared first on Online Biology Notes.