Exploring Plant-Derived Antimicrobials: Comparative Activity of Andrographis paniculata and Jatropha curcas Extracts against Resistant Klebsiella Species

Abstract

The emergence of multidrug-resistant Klebsiella pneumoniae and Klebsiella quasipneumoniae necessitates the exploration of alternative antimicrobial agents. This study evaluated the antibacterial efficacy of aqueous, hexane, and methanol leaf extracts of Andrographis paniculata and Jatropha curcas against clinical Klebsiella isolates. Disk diffusion assays revealed concentration-dependent antibacterial activity across extracts, with selective resistance observed in certain strains. The aqueous extract of A. paniculata exhibited activity against most isolates, with a maximum inhibition zone of 19.00 ± 0.25 mm, though strains 41F and 72F were resistant. The hexane extract showed broader activity, including superior efficacy compared to Ciprofloxacin against strain 41F, with a peak inhibition of 21.00 ± 0.20 mm. Methanol extract demonstrated the highest antibacterial activity overall, yielding a maximum inhibition zone of 31.00 ± 0.23 mm. Similarly, J. curcas extracts displayed notable antibacterial effects. The aqueous, hexane, and methanol extracts produced maximum inhibition zones of 22.00 ± 0.19 mm, 22.00 ± 0.30 mm, and 21.00 ± 0.15 mm, respectively, with enhanced activity against strain 41F compared to ciprofloxacin. Against K. quasipneumoniae, activity was only observed at higher concentrations (200 – 400 mg/mL), with hexane extract of A. paniculata showing the highest inhibition (17.00 ± 0.10 mm). Minimum inhibitory concentrations (MICs) ranged from 50 – 200 mg/mL and minimum bactericidal concentrations (MBCs) from 100–400 mg/mL for K. pneumoniae, while K. quasipneumoniae showed MICs of 100 – 200 mg/mL and MBCs of 200 –400 mg/mL. The findings highlight the potent antibacterial potential of A. paniculata and J. curcas, particularly methanol and hexane extracts, as promising candidates for the development of alternative therapies against resistant Klebsiella infections.