From the Guidelines
Neomycin is a broad-spectrum aminoglycoside antibiotic that is primarily effective against gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, Proteus species, and Enterobacter species, as well as some gram-positive organisms like Staphylococcus aureus, but with minimal activity against anaerobic bacteria, fungi, and viruses 1.
Antimicrobial Spectrum
The antimicrobial spectrum of neomycin includes:
- Gram-negative bacteria: Escherichia coli, Klebsiella pneumoniae, Proteus species, and Enterobacter species
- Gram-positive bacteria: Staphylococcus aureus (but less effective against Streptococcus species)
- Minimal activity against:
- Anaerobic bacteria
- Fungi
- Viruses
Mechanism of Action
Neomycin works by binding to the 30S ribosomal subunit of bacteria, inhibiting protein synthesis and ultimately causing bacterial cell death 1.
Clinical Use
Due to its toxicity when administered systemically (potential for nephrotoxicity and ototoxicity), neomycin is primarily used:
- Topically for skin infections
- Orally for gut decontamination, where it is poorly absorbed When used topically, it is often combined with other antibiotics like polymyxin B and bacitracin in triple antibiotic ointments to provide broader coverage against potential pathogens 1.
From the FDA Drug Label
To reduce the development of drug-resistant bacteria and maintain the effectiveness of neomycin sulfate tablets, USP and other antibacterial drugs, neomycin sulfate tablets, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria The antimicrobial spectrum of neomycin includes susceptible bacteria, but the specific types of bacteria are not directly stated in the label.
- The label does mention that neomycin is effective in reducing ammonia-forming bacteria in the intestinal tract, which is beneficial in the treatment of hepatic coma. The FDA label does not provide a comprehensive list of the antimicrobial spectrum of neomycin 2.
From the Research
Antimicrobial Spectrum of Neomycin
The antimicrobial spectrum of neomycin includes a range of bacterial species. Some key points about its spectrum are:
- Neomycin is effective against certain Gram-negative bacteria, including Escherichia coli and Pseudomonas aeruginosa 3
- It is also effective against some Gram-positive bacteria, including Staphylococcus aureus and coagulase-negative staphylococci (CoNS) 3
- Neomycin has been shown to be synergistic with other antibiotics, such as bacitracin, polymyxin B, and gramicidin, against certain bacterial strains 4
- The combination of neomycin with other antibiotics, such as ampicillin and procaine penicillin, has been found to have additive effects against some bacterial strains, but no synergy was observed 4
Specific Bacterial Species
Some specific bacterial species that are susceptible to neomycin include:
- Salmonella Enteritidis, which has been shown to be inhibited by the combination of neomycin and bacitracin 4
- Staphylococcus aureus, including methicillin-resistant strains, which are susceptible to neomycin and other components of triple antibiotic ointment (TAO) 3
- Escherichia coli, Klebsiella pneumoniae, and Enterobacter species, which are susceptible to neomycin and other antibiotics, but may develop resistance due to efflux pump genes 5