Farha Barami, Aysha Najla Backer and. Kunhi A.A.M. (2017). Antimicrobial activity of Stachytarpheta jamaicensis and synergy with chloramphenicol. In P.J. Jisha and K. Mashhoor (Eds.) ‘Advances in Microbiology’ LAP LAMBERT Academic Publishing, Saarbrucken, Germany, pp. 110-132 (ISBN: 978-3-330-07223-7).

Abstract

Antibiotics have been effective in treating infectious diseases, but resistance to these drugs has led to the emergence of new and the re-emergence of infectious diseases. To overcome these resistance mechanisms combination therapy has been adopted. In the present study the inhibitory effect of extracts of Stachytarpheta jamaicensis and their synergy with chloramphenicol against multi drug resistant (MDR) bacteria was tested. Among the leaf and flower extracts made in different solvents acetone and methanol leaf extracts showed maximum activity against Escherichia coli and Staphylococcus aureus and minimal activity was seen in Pseudomonas aeruginosa and Candida albicans. Further studies were carried out on E. coli due to its high sensitivity. The MIC obtained for acetone, methanol, chloroform and petroleum ether flower extracts against E. coli was 256 µg/ml whereas 128 µg/ml was the MIC for leaf extracts of methanol and petroleum ether. The Checkerboard assay was performed to determine the synergistic activity and the FIC was calculated. Among the plant extracts and drug combination for the test organism E. coli MTCC443, both flower extract in methanol and leaf extract in petroleum ether showed FIC value of 0.375 whereas the FIC value for leaf extract in methanol was 0.5. The study indicated the bactericidal potentials of the secondary metabolites of S. jamaicensis with chloramphenicol through synergy against MDR strains. Further studies should focus on identifying the active component(s) and the mechanism of the synergistic action.