Antibacterial activity of herbal preparation to treat sore throats

Acute sore throats are one of the most common seen conditions in general practice. The disease encompasses any upper respiratory tract infection most often caused by viruses or bacteria.

In the process to find the optimal combination for a herbal sore throat spray we carried out series of experiments with bacteria which are relevant in infections of the throat.

• Three gram positive strains of bacteria (S. aureus, K. pneumoniae, S.pyogenes) and three gram negative strains (M. catarrhali, S.pneumonia, H. influenzae) were tested.

• Test preparations were an ethanolic Echinacea purpurea (95% herba/5% radix) concentrate, a sage tincture, peppermint oil and the combination of all three preparations.

• Microdilution method was used to determine the minimal inhibitory concentration (MIC) as well as the minimal bactericidal concentration (MBC).

All pathogens with the exception of K. pneumoniae were especially sensitive on the combination whereas the single components Salvia tincture, peppermint oil and Echinacea concentrate only showed antibacterial activity against S. pneumoniae and H. influenzae. The gram-positive bacteria appeared to be more sensitive against the preformulation than the gram-negative pathogens. MIC of S. pneumoniae and H. influenzae of the preformulation were higher by a factor 10 only than of the synthetical control chlorhexidine confirming the good antibacterial activity of the combination against those two pathogens. Kill kinetics of the combination resulted in reduction of pathogens by 3 log levels in S. pneumoniae and H. influenzae.

These results show that the chosen combination has an antibacterial potency which is an important asset for a preparation used to treat sore throats.