Streptomycin was first isolated by Albert Schatz. The molecular formula is C21H39N7O12. It consists of three fragments—an N-methyl-L-Glucosamine ring, an L-streptose and a streptidine ring—which are linked together by two glycosidic bonds. It also contains an elaborate network of hydrogen bonds linking selenite and streptomycin oxime ions and water molecules (refer Figure 13.2). Figure 13.2 Structure of…

Streptomycin is the first antibiotic used in the treatment of tuberculosis. It belongs to aminoglycosides compound. It is a bactericidal antibiotic. Streptomycin cannot be given orally but should be administered by regular intramuscular injections.

Penicillins are found to have low toxicity in comparison to other sulpha drugs. However, in some cases diarrhoea and allergic reactions may occur. Penicillin is hence injected after a test prick is given.

Bacteria constantly reconstruct their peptidoglycan cell walls and break down portions of the cell walls as they grow and divide. Penicillin inhibits the formation of peptidoglycan cross-links in the bacterial cell wall. This is achieved by the binding of the Lactam ring of penicillin to the enzyme transpeptidase. Hence, peptidase cannot catalyse the formation of the…

Penicillin is white or slightly yellowish white crystalline powder. All the natural penicillin is dextrorotatory. Penicillin is only sparingly soluble in water. Penicillin is hydrolysed by alkaline medium to yield penicilloic acid, which loses carbon dioxide to form penicilloic acid. If the hydrolysis of penicillin is carried out in acidic medium, the amide side chain…

Penicillin is the name given to the mixture of neutral compounds which have the molecular formula C9H11N2O48R and diff er only in R. The general structure of penicillin is given below in Figure 13.1: Figure 13.1 Structure of Penicillin R may vary and according to the nature of the functional group, penicillin may be classified as shown…

This classification of antibiotics is based on their chemical structure. Penicillin – derived from amino acids. Example: Penicillin Aminoglycosides – contain a sugar molecule linked to amino compound. Example: Streptomycin. Chloramphenicol – synthetic analogue Tetracycline – have four six-membered fused ring. Example: Tetracycline and terramycin.

Another classification of antibiotics is available, which depends upon the type of bacteria (Gram positive or Gram negative) the antibiotic can destroy. This classification was originally worked out by Christian Gram and is called Gram staining method (Table 13.1). Table 13.1 Classification of bacteria based on Gram staining method Gram positive bacteria Gram negative bacteria Diphtheria…

These include those antibiotics that are highly specific in their action. Example: Bacitracin, nystatin, and so on.

These include those antibiotics which may be used as curative agents against several ailments. Example: Penicillin, chloramphenicol, tetracycline, and so on.