Over the counter (OTC) throat lozenges could be contributing to antimicrobial resistance (AMR) according to research presented at this year's European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) hosted in Amsterdam.
The inappropriate use of these antibiotic-containing medications could be hindering the WHO’s plans to tackle AMR. Many of these products are available in various European countries including the UK. The problem is that the concentrations of these topical antibiotics were not high enough to kill some bacteria, which could contribute to AMR.
The researchers exposed three different types of bacteria: Staphylococcus aureus, Acinetobacter baumannii, Streptococcus pyogenes and Haemophilus influenza to decreasing concentrations of the antibiotics neomycin, bacitracin and tyrothricin, at 37 °C, the normal body temperature.
Although some of the antibiotics worked against some of the bacteria at the concentrations used in cough sweets, S. pyogenes showed growth in very week concentrations of neomycin while S. aureus showed growth in higher concentrations after 144 hours. The S. aureus bacteria were found to have developed cross resistance to gentamicin, fusidic acid, and ciprofloxacin.
“We were concerned to find that some of the OTC antibiotics used in sore throat preparations were not sufficiently concentrated to prevent growth of common human pathogens and are enabling these pathogens to develop resistance,” said Adrian Shephard of Reckitt Benckiser Healthcare. “Our work raises doubt about the continued OTC availability of these antibiotics for the treatment of sore throats, especially considering the primarily viral nature of the condition.”
These findings emphasise the need for more careful and potentially controlled use of OTC medications to prevent further worsening of AMR.