The effect of propolis on bacteria causing upper tract respiratory infection in Benin University in 2010. In the study, a total of 250 throat swabs were obtained from patients (age between 15 - 30 years) who were diagnosed with upper respiratory tract infection. Propolis infused discs were applied to the surface of inoculated plates to assure complete contact of disc with agar. Following incubation period, the number of bacteria colonies was reduced. The researchers concluded that propolis showed antimicrobial activity against H. influenzae, K. pneumoniae, S. pneumoniae, M. catarrhalis, and S. pyogenes.

Reference: Ophori, E.A., and Wemabu, E.C., 2010. Antimicrobial activity of propolis extract on bacteria isolated from the nasopharynx of patients with upper respiratory tract infection admitted to Central Hospital, Benin City, Nigeria. African Journal of Microbiology Research, 4(16), pp.1719-1723.