Spectrum of bactericidal action of amylmetacresol/2,4-dichlorobenzyl alcohol lozenges against oropharyngeal organisms implicated in pharyngitis.

PURPOSE: Pharyngitis is commonly caused by a self-limiting upper respiratory tract infection (URTI) and symptoms typically include sore throat. Antibiotics are often inappropriately used for the treatment of pharyngitis, which can contribute to antimicrobial resistance, therefore non-antibiotic treatments which have broad antiseptic effects may be more appropriate. Amylmetacresol (AMC) and 2,4-dichlorobenzyl alcohol (DCBA) are present in some antiseptic lozenges and have established benefits in providing symptomatic relief and some in vitro antiviral action.

METHODS

Seven bacterial species associated with pharyngitis, namely Streptococcus pyogenes, Fusobacterium necrophorum, Streptococcus dysgalactiae subspecies equisimilis, Moraxella catarrhalis, Haemophilus influenza, Arcanobacterium haemolyticum and Staphylococcus aureus, were exposed to an AMC/DCBA lozenge dissolved in artificial saliva. In vitro bactericidal activity was measured as a log reduction in colony-forming units (CFUs).

RESULTS

Bactericidal activity was recorded against all organisms after 1 minute. Greater than 3 log10 reductions in CFUs were observed at 1 minute for S. pyogenes (log10 reduction CFU/mL ± SD, 5.7±0.1), H. influenza (6.1±0.1), A. haemolyticum (6.5±0.0) and F. necrophorum (6.5±0.0), at 5 minutes for S. dysgalactiae (6.3±0.0) and M. catarrhalis (5.0±0.9) and at 10 minutes for S. aureus (3.5±0.1).

CONCLUSION

An AMC/DCBA lozenge demonstrated a greater than 99.9% reduction in CFUs against all tested species within 10 minutes, which is consistent with the time a lozenge remains in the mouth. Patients with uncomplicated bacterial pharyngitis may benefit from the antibacterial action of antiseptic AMC/DCBA lozenges. Furthermore, AMC/DCBA lozenges may be more relevant and appropriate than antibiotics for pharyngitis associated with a self-limiting viral URTI.