Fluoroquinolone resistance (FQR) has paralleled the abuse of this class of antibiotics in Nigeria
ever since the patent rights expired in 2003. However, nature has a potent way of uncoupling
unfavourable synergies targeted against the serenity of the biosphere. In this preliminary study,
we examined the antibacterial activity of E558, a medicinal plant product against multidrugresistant
gram-negative isolates from immunocompromised patients with acute respiratory
infections. The agar-well diffusion method was employed to screen for antibacterial activity
against strains of Klebsiella pneuminiae, Escherichia coli and Pseudomonas aeruginosa. The
organisms were initially subcultured on McConkey agar followed by streaking standard
innoculum of the bacterial strains on Mueller-Hinton agar plates. A known concentration of
crude extract was loaded into the well bored on the plates and then incubated at 37 °C for 24
hours. Antibiotic susceptibility testing (AST) was carried out to monitor resistance of isolates.
Protein profiling with sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE)
as well as restriction endonuclease mapping with agarose gel electrophoresis was employed to
study alterations in the genomic DNA of selected organisms. A reverse mutation was observed in
the morphology of organisms exposed to E558 compared to the organism without exposure. AST
result further revealed that strains in the reverted zone, which were originally resistant to
fluoroquinolones and other antibiotics had become susceptible with very wide zone of inhibition
(≥ 40 mm; CLSI-sensitive). Restriction mapping and SDS-PAGE respectively revealed there are
major differences in the genomic composition and protein profile of the reverted strains when
compared to the original organisms. It can therefore be deduced that E558 possibly contains
bioactive compound(s) with potent antitumour and anti-fluoroquinolone resistance activity
