The extracts and the essential oil were evaluated by the disc diffusion method with the three extracts being tested at four concentrations.They found that the methanol extract showed greatest bacterial inhibition.
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.
The guava leaves were extracted using a Soxhlet extractor and solvents in order of polarity and then concentrated in a rotary evaporator.
The essential oil was obtained from fresh leaves of guava using a Clevenger type doser and the extraction methodology of Gottlieb and Magalhães .
The leaves of guava contain an essential oil rich in cineol, tannins, triterpenes, flavonoids, resin, eugenol, malic acid, fat, cellulose, chlorophyll, mineral salts, and a number of other fixed substances [13–15].
The general techniques of medicinal plant extraction include maceration, infusion, percolation, digestion, decoction, Soxhlet extraction, aqueous-alcoholic extraction by fermentation, counter-current extraction, microwave-assisted extraction, ultrasound extraction, supercritical fluid extraction, and phytonic extraction.
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.
aureus, thus making up important potential sources of new antimicrobial compounds.
Antibacterial screening has been done selectively by many researchers in guava essential oil and solvent extract [1, 4, 20, 21].