Abstract

Otu, Joseph Ubi*, Thomas, Paul Sunday, Ugor, Sunday Offering, Nyambi, Sunday Edim

ABSTRACT

  The increasing number of multidrug-resistant bacterial pathogens causing diverse infections is a major public health concern worldwide, particularly in hospitals and other health care settings. So, the search for new alternative products to solve this problem is the question of the age. Plants are recognized in the pharmaceutical industry due to their broad spectrum of structural diversity and their wide range of pharmacological activities. This study is designed to assess the bioactive components, antibacterial and antibiofilm activity of the fractions of Ageratum conyzoides (Goat weed) leaf against multidrug-resistant (MDR) Streptococcus pneumoniae isolated from a hospital in Southern Nigeria. The test organism was collected from Microbiology Laboratory, University of Calabar Teaching Hospital (UCTH), Calabar, Nigeria. The isolate was authenticated by standard bacteriological methods. The test organism was subjected to antimicrobial susceptibility profiling using disc diffusion technique to determine multidrug resistance status. Based on previous preliminary in vitro screening, A. conyzoides leaf fractions were subjected to GC-MS analysis to identify and quantify various phytoconstituents. Antibacterial activity of the leaf fractions was determined by agar well diffusion method. MICs and MBCs were evaluated using microdilution assay. A modified crystal violet assay was used to determine antibiofilm activity of the fractions and Optical Densities (ODs) were recorded. Results showed that the isolate was multidrug-resistant with percentage resistance of 46.66%. Phytochemical screening revealed the presence of saponins, tannins, flavonoids alkaloids, triterpenes/steroids, cardiac glycosides and free anthraquinone in the plant. GC-MS analyses of fractions revealed various phytochemicals and their concentrations in percentage, which include phytol, benzenedicarboxylic acid, phenols, flavones, etc. Fractions from A. conyzoides (especially n-hexane and ethyl acetate fractions) demonstrated strong antibacterial activity with zones of inhibition ranging from 9mm to 23mm. MICs and MBCs of the various fractions varied, with the lowest MIC (6.25mg/mL) from n-hexane fraction. ODs indicated that the fractions had remarkable capacity to reduce biofilm formation. This study has demonstrated that the fractions of A. conyzoides leaf had varying degrees of antibacterial activity against bacterial planktonic and biofilm forms. Therefore, this evidence suggests that this plant can be used as alternative treatment measures to conventional antibiotics if properly harnessed.