Therapeutic Prospects of Psidium guajava Leaves: An Antibacterial Assessment Against Clinically Important Pathogens

The rising incidence of multidrug resistance and drug toxicity has prompted the search for complementary and alternative treatments for bacterial infections.

This study aimed to screen for the phytochemical present in Psidium guajava leaves, to determine the antibacterial potential of P. guajava leaves, and to compare the effectiveness of the P. guajava leaves against current antibiotics.

Dried pulverised P. guajava leaves were macerated using different solvents and then concentrated using a rotary evaporator. The extracts were screened for phytochemicals, namely, saponins, alkaloids, tannins, flavonoids, phenols, steroids and terpenoids, according to standard testing procedures. Antibacterial discs were prepared by soaking 6-mm sterile filter paper discs in different concentrations of the various extracts. Antibacterial susceptibility testing was done using the Kirby-Bauer disc diffusion method.

Phytochemical screening confirmed the presence of all tested phytochemicals in Psidium guajava leaf extracts. The ethyl acetate extract (EAE) demonstrated significant antimicrobial activity at 100 mg/mL, showing large zones of inhibition (ZOIs) against Staphylococcus aureus (22.0 ± 6.1 mm), Escherichia coli (16.3 ± 0.9 mm) and Pseudomonas aeruginosa (15.0 ± 0.0 mm). The ethanolic extract (EE) also showed strong activity, with significant ZOI against Klebsiella pneumoniae (22.0 ± 4.3 mm) and P. aeruginosa (14.0 ± 1.0 mm). ZOI for the 100 mg/mL extracts against S. aureus were significantly larger than those for ceftazidime (19 mm), while those against P. aeruginosa exceeded tetracycline (9 mm) (p = 0.001). The MIC results confirmed the strength of the EE, with the lowest values: 3.1 mg/mL against K. pneumoniae ATCC and 6.3 mg/mL against S. aureus, E. coli and P. aeruginosa, possibly due to the presence of saponins.

P. guajava leaves contain many phytochemicals which in turn possess great antibacterial activity and therefore have great potential as a novel complementary and alternative treatment to antibiotics.