The most commonly cultivated species of Psidium is P. Guava fruit today is considered minor in terms of commercial world trade, but it is widely grown in the tropics, enriching the diet of hundreds of millions of people in those areas of the world. The guava leaves are 2 to 6 inches long and 1 to 2 inches wide, aromatic when crushed, and appear dull-green with stiff but coriaceous with pronounced veins .There are bioactive components in the guava leaf that can fight against pathogens, regulate blood glucose levels, and can even aid in weight loss.
The essential oil extract showed inhibitory activity against S. The researchers concluded that guava leaf extracts and essential oil are very active against S.
The mechanism by which they can inhibit the microorganisms can involve different modes of action.
It has been reported that these oils and extracts penetrate the lipid bilayer of the cell membrane, rendering it more permeable, leading to the leakage of vital cell contents [22, 23].  evaluated the antibacterial activities of guava against gram-positive and gram-negative bacteria testing ethanol and water extract of P.
guajava leaves, stem, bark and root, and aqueous extract against Staphylococcus aureus were found to be more active by using ethanol and water extract than with just aqueous extract [1, 7].  reported that the oil showed a strong resistance against Yarrowia lipolytica which is a pathogenic yeast.  have also reported the antibacterial effect of guava leaves extracts and found that they inhibited the growth of the S. Gnan and Demello  testing guava leaf extract found good antimicrobial activity against nine different strains of Staphylococcus aureus.
The antibacterial activity of guava leaf extract was tested against acne developing organisms by Qa'dan et al.