Streptomycin

Streptomycin is the oldest aminoglycoside antibiotic obtained from Streptomyces griseus. Its use is now restricted to the treatment of tuberculosis. It has a narrow antimicrobial spectrum mainly covering aerobic gram-negative bacilli.

Indication.

Sensitive organisms include —

• H. ducreyi, Brucella,
• Yersinia pestis,
• Francisella tularensis
• M. tuberculosis.
• E. coli,
• H. influenzae,
• V. cholerae, Shigella and Klebsiella.
• All other organisms, including Pseudomonas, are unaffected.

Clinical uses.

• Tuberculosis.
• Subacute bacterial endocarditis (SABE): The drug is given together with penicillin/ampicillin/vancomycin for 4–6 weeks.
• Plague: It affects rapid cure (in 7–12 days)
• Tularemia: Streptomycin is the drug of choice; effects cure in 7–10 days.
• In other cases, e.g. urinary tract infection, peritonitis and septicaemias.

Resistance.

• One-step mutation.
• Acquisition of plasmid, which codes for the inactivating enzymes.
• Resistance organisms may emerge within two days of therapy in the intestinal and urinary tracts.
• Cross-resistance is only partial and mostly unidirectional. It occurs between streptomycin and other aminoglycosides.

Adverse effects

• Vestibular disturbances.
• Hypersensitivity reactions include; rashes, eosinophilia, fever and exfoliative dermatitis.

Pain at the

• injection site is common.
• Paraesthesias and scotoma may occur.

Contraindication.

• Topical use of the drug is contraindicated for fear of contact sensitization.
• Pregnancy due to risk of fetal ototoxicity.

Dosage.

• AMBISTRYN-S 0.75, 1 g dry powder per vial for injection.
• Acute infections: 1 g (0.75 g in those above 50 yr age) intramuscular. OD or BD for 7–10 days.
• Tuberculosis: 1 g or 0.75 g intra muscular. OD or thrice weekly for 30–60 days.