<p>Oxytetracycline inhibits cell growth by inhibiting translation. It binds to the 30S ribosomal subunit and prevents the amino-acyl tRNA from binding to the A site of the ribosome. The binding is reversible in nature. Oxytetracycline is lipophilic and can easily pass through the cell membrane or passively diffuses through porin channels in the bacterial membrane.<br />
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The broad-spectrum effectiveness of this ointment against both gram-positive and gram-negative organisms is enhanced by the particular effectiveness of polymyxin B against infections associated with gram-negative organisms, especially those due to Pseudomonas aeruginosa, where polymyxin B is the antibiotic of choice. In addition, there is evidence to indicate that polymyxin B sulfate possesses some antifungal activity.</p>