Tobramycin

Aminoglycosides, many of which are derived directly from Streptomyces spp., are concentration-dependent bactericidal antibiotics with a broad spectrum of activity against Gram-positive and Gram-negative organisms. Inhaled tobramycin is notable for its use in treating chronic Pseudomonas aeruginosa infections in cystic fibrosis patients, as P. aeruginosa is notoriously inherently resistant to many antibiotics. However, tobramycin can also be administered intravenously and topically to treat a variety of infections caused by susceptible bacteria. Its use is limited in some cases by characteristic toxicities such as nephrotoxicity and ototoxicity, yet it remains a valuable option in the face of growing resistance to front-line antibiotics such as β-lactams and cephalosporins.

Tobramycin was approved by the FDA in 1975 and is currently available in a variety of forms for administration by inhalation, injection, and external application to the eye (ophthalmic).

Inhaled tobramycin is indicated for the management of cystic fibrosis patients with Pseudomonas aeruginosa, but is not recommended in patients under six years of age, those with forced expiratory volume in 1 second (FEV) <25 or >80% predicted, or in those with Burkholderia cepacia.

Tobramycin applied topically to the eyes is indicated for the treatment of external eye (and adjoining structure) infections by susceptible bacteria.

Tobramycin injection is indicated in adult and pediatric patients for the treatment of serious bacterial infections, including septicemia (caused by P. aeruginosa, Escherichia coli, and Klebsiella spp.), lower respiratory tract infections (caused by P. aeruginosa, Klebsiella spp., Enterobacter spp., Serratia spp., E. coli, and Staphylococcus aureus, both penicillinase and non-penicillinase-producing strains), serious central-nervous-system infections (meningitis, caused by susceptible organisms), intra-abdominal infections including peritonitis (caused by E. coli, Klebsiella spp., and Enterobacter spp.), skin, bone, and skin structure infections (caused by P. aeruginosa, Proteus spp., E. coli, Klebsiella spp., Enterobacter spp., Serratia spp. and S. aureus), and complicated and recurrent urinary tract infections (caused by P. aeruginosa, Proteus spp., E. coli, Klebsiella spp., Enterobacter spp., Serratia spp., S. aureus, Providencia spp., and Citrobacter spp.). Aminoglycosides, including tobramycin, should generally not be used in uncomplicated urinary tract infections or staphylococcal infections unless less toxic antibiotics cannot be used and the bacteria in question are known to be sensitive to aminoglycosides.

As with all antibiotics, tobramycin use should be limited to cases where bacterial infections are known or strongly suspected to be caused by sensitive organisms, and the possible emergence of resistance should be monitored closely.