Evaluation of Antibacterial Properties of Stem Extract of Andrographis paniculata- Nees on Some Antibiotic Resistant Bacterial Isolates

The aim of this research is to investigate the antibacterial and phytochemical properties of stem extract of Andrographis paniculata (Nees). The phytochemical and antibacterial activities of the stem of Andrographis paniculata were determined using standard methods. The phytochemical analysis revealed the presence of saponin, tannin, terpenoid, phlobotannin and flavonoid in methanol, n- hexane, and aqueous extracts, but there was absence of tannin in the aqueous extract. Saponin was the most abundant in the methanol extract with the value of 20.22 mg/ml, followed by the n-hexane extract (19.56 mg/ml) while the least was recorded against the aqueous extract (15.34 mg/ml). Flavonoid and terpenoid were present in appreciable amount in all the extracts. Resistant pattern against the antibiotics considered are as follows: Gentamycin (56%), Cefuroxime (100%), Ceftazidime (100%), Augmentin (100%), Ofloxacin (33%), Ampicillin (100%), Nitrofurantoin (67%), Ciprofloxacin (50%), Ceftriaxione (100%), Erythromycin (33%) and Cloxacin (100%). S. typhi, P. aeruginosa, S. dysentriae, and P. mirabilis showed complete resistance to all the antibiotics used while on the gram positive bacterial isolates, B. cereus was resistant to all the antibiotics used. All the bacterial isolates were susceptible to n- hexane and methanol extracts with the zone of inhibition ranging from 10-17 mm and 11-28 mm respectively. The aqueous extract did not exert much antibacterial activity on the tested isolates. Pseudomonas aeruginosa isolated from wound was the most susceptible to the methanol extract with the value of 28 mm. All the gram positive isolates used were more susceptible to the n- hexane extract such as S. aureus, E. faecalis and B. cereus with the zone of inhibition of 17 mm, 19 mm and 16 mm respectively. The Minimum Inhibitory Concentrations ranged between 3.125 mg/ml and 50 mg/ml. Findings from this study suggest that the stem extract of A. paniculata especially methanolic extract possess broad spectrum activities against the antibiotic resistant isolates tested, hence could be used for the treatment of infections implicated by the bacterial used in this study.