Extracts of Gomphrena celosioides Mart as potential treatment for urinary tract infections against antibiotic resistant β-lactamase producing uropathogens

Abstract

Gomphrena celosioides Mart is used traditionally for the treatment of urinary tract infections (UTIs) and related diseases in Asia and Africa. The study evaluated the antibacterial and anti-biofilm potentials of G. celosioides against β-lactamase producing Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. The leaves, twigs, flowers and a combination of all plant parts of G. celosioides were extracted with hot water and acetone. Antibacterial activity was investigated through spectrophotometric and p-iodonitrotetrazolium chloride colorimetric methods. The crystal violet staining method was employed to determine the biofilm inhibition ability of the extracts. Safety levels of the extracts was evaluated against Vero monkey kidney cells through the MTT colorimetric assay. No antibacterial activity was displayed by any of the water extracts against tested organisms. However, all acetone extracts showed good antibacterial activity with minimum inhibitory concentrations (MICs) from 0.04 to 0.31 mg/mL. This corresponded to minimum percentage bacteriostatic activity ranging from 50.5 to 90%, showing a dose dependent pattern. All extracts including the water extracts, which did not show any sign of antibacterial activity at the highest concentration tested, showed promising anti-biofilm activity above 50% against all strains at the planktonic and biofilm formation stages. However, activity exhibited by the acetone extracts against E. coli at 0 and 24 h was weak. The tested MICs of acetone extracts including ciprofloxacin in the proliferation assay were more active against the organisms at 24 h except for S. aureus where all samples were more active at 18 h. A selectivity index between 0.61 and 4.75 showed that the extracts are relatively safe. Following the promising biological activity observed in this study, future studies such as identification of active constituents, mechanisms of action and in vivo evaluations are required.