Over-the-counter antibiotics compromising aminoglycoside activity

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Antimicrobial resistance (AMR) is a critical global health challenge.
• Over-the-counter (OTC) antibiotics, particularly in sore throat remedies, may contribute to AMR.
• Concerns exist that OTC antibiotics could induce cross-resistance to clinically important antibiotics.

Purpose of the Study:

• To investigate the in vitro impact of three antibiotics found in OTC sore throat medications on emerging AMR.
• To determine if OTC antibiotics affect the efficacy of commonly used clinical antibiotics.

Main Methods:

• Bacterial pathogens were subjected to time-kill assays with aminoglycoside antibiotics, alone and with OTC antibiotics (bacitracin, gramicidin, tyrothricin).
• Membrane damage was assessed by measuring potassium leakage and membrane potential alterations after OTC antibiotic exposure.

Main Results:

• Gramicidin significantly reduced the bactericidal activity of amikacin, tobramycin, and gentamicin against Acinetobacter baumannii.
• Gramicidin and tyrothricin diminished aminoglycoside efficacy in other key pathogens like Enterobacter cloacae, Escherichia coli, and Klebsiella pneumoniae.
• Gramicidin exposure led to significant bacterial membrane potential decrease and potassium leakage.

Conclusions:

• Gramicidin and tyrothricin interfere with aminoglycoside efficacy by disrupting bacterial membrane potential, crucial for drug uptake.
• These findings highlight a potential mechanism by which OTC antibiotics can lead to treatment failure and contribute to AMR development.
• While concurrent use may be uncommon, this study underscores a possible pathway for OTC antibiotic contribution to resistance and treatment efficacy issues.