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.
Keywords: pharyngitis, bacterial infections, antibacterial agents, Streptococcus, sore throat