Dihydrostreptomycin sulfate NEW

Dihydrostreptomycin sulfate is a semi-synthetic antibiotic derived from streptomycin, which is produced by the bacterium Streptomyces griseus. It is a member of the aminoglycoside class of antibiotics. Its primary use is in veterinary medicine; its use in humans has been largely discontinued due to significant toxicity concerns, particularly irreversible ototoxicity (damage to the inner ear).

Key Characteristics

• Chemical Class: Aminoglycoside antibiotic

  Source: Semi-synthetic derivative of streptomycin.

  Difference from Streptomycin: Dihydrostreptomycin is created by chemically reducing the aldehyde group (-CHO) in streptomycin to a hydroxylmethyl group (-CH₂OH). This small change was initially thought to improve stability but did not reduce its severe toxicity.

  Form: Typically available as a white or off-white crystalline powder that is soluble in water.

Mechanism of Action

Like all aminoglycosides, dihydrostreptomycin is bactericidal (it kills bacteria). Its mechanism involves:

1. Binding to the 30S Subunit: It binds irreversibly to the 30S ribosomal subunit inside bacterial cells.

2. Disrupting Protein Synthesis: This binding misreads the genetic code (mRNA), leading to the production of faulty, non-functional proteins.

3. Causing Cell Death: The accumulation of these defective proteins ultimately leads to the death of the bacterial cell.

It is particularly effective against aerobic Gram-negative bacteria and some Gram-positive bacteria.

Primary Applications and Uses

1. Veterinary Medicine:

• This is its main and almost exclusive modern application. It is used to treat bacterial infections in livestock (e.g., cattle, pigs) and sometimes pets.

  It is often formulated in combination with other antibiotics (e.g., penicillin) for a broader spectrum of action.

  Used to treat infections like Gram-negative sepsis, respiratory infections, and enteritis.

2. Historical Human Use:

• It was briefly used in humans in the mid-20th century to treat diseases like tuberculosis, plague, and other serious infections.

  This use was abandoned when it was discovered that dihydrostreptomycin caused an unacceptably high incidence of permanent and profound hearing loss (ototoxicity) and kidney damage (nephrotoxicity) at a rate higher than streptomycin.

Safety and Toxicity

The key reason for its restricted use is its severe adverse effects:

• Ototoxicity: The most significant risk is irreversible damage to the cochlea (the auditory part of the inner ear), leading to permanent sensorineural hearing loss and sometimes vestibular dysfunction (loss of balance).

  Nephrotoxicity: It can cause acute kidney injury and damage to the renal tubules.

  Residues: In veterinary use, there are strict withdrawal periods mandated before treated animals can be used for food (milk, meat) to prevent antibiotic residues from entering the human food supply.

Summary

In essence, Dihydrostreptomycin sulfate is a potent aminoglycoside antibiotic whose use is now confined almost entirely to veterinary medicine. While effective, its application is carefully controlled due to its potent and irreversible toxic side effects, which led to its discontinuation in human therapeutics. It serves as an important tool for treating serious bacterial infections in animals under professional veterinary guidance.