This project was designed to evaluate the antimicrobial efficacy of Chloroform and
ethanol extracts of Calotropis procera (C .procera) and Eucalyptus globulus (E. globulus)
against Multiple Drug Resistant (MDR) Staphylococcus aureus isolated from human origin. This
study was conducted to evaluate the antimicrobial potential of C. procera and E. globulus alone
and in combination with antibiotics to check synergism between medicinal plants and resistant
antibiotics.
S.aureus is a major pathogen which causes various infections. Infectious diseases affect
millions of people around the world and in the history these diseases are major cause of mortality
and morbidity across the globe. In past few decades rate of mortalities are continuously
increasing because of acquired resistance of S. aureus against multiple drugs, thus it is utter need
of time to discover some alternatives to antibiotics so that we can resolve this dilemma of
antibiotic resistance. Plant extracts are hope for this purpose as they have many compounds
which have potential to lower down the number of micro-organisms. Plants have benefits over
other as they are non toxic, non-reactive and have least side effects.
Total 20 samples of human origins were procured from Department of Microbiology,
UVAS Lahore and were subjected to check their antibiotic resistance profile against
Erythromycin, Amoxicillin and Ciprofloxacin by Kirby Bauer disc diffusion assay. Out of 20,
nine resistant isolates were separated. Among them three were resistant to Erythromycin, three to
Amoxicillin and three to Ciprofloxacin.
Summary
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Leaves of C. procera and E. globulus were processed in Chloroform and ethanol
Solvents. Antimicrobial activity was evaluated by agar gel well diffusion assay in which zone of
inhibitions were measured. Minimum inhibitory concentration (MIC) of plant extracts was
evaluated by micro broth dilution method. Best antimicrobial activity was observed by ethanolic
extract of E. globulus.
Then combine effect of sub-inhibitory concentrations (SICs) of plant extracts and
minimum inhibitory concentration of antibiotics were determined by Well Diffusion assay. Four
different sub inhibitory concentrations of plant extracts i.e.10μg/ml, 20μg/ml, 40μg/ml and
80μg/ml were used in combination with fixed concentration of antibiotics i.e.100μg/ml to check
combinational effect of both. At selected sub-inhibitory concentration plant extract alone did not
show any antibacterial activity. Two of the isolates had shown modulation when amoxicillin and
plant extracts combination was used against them. The isolate labeled as S.aureus 4 showed
modulation with the use of Ethanolic extract of Calotropis procera and S.aureus 5 had shown
modulation with the use of chloroform extract of Calotropis procera. For further confirmation
two more concentrations of 160μg/ml and 320μg/ml were used along with100μg/ml Amoxicillin
against same isolates S.aureus 4 and 5. Zone of inhibition was observed with increased diameter
indicating modulation of two isolates. While erythromycin and ciprofloxacin resistant isolates
didn’t show any modulation.
Data of antibiotic resistance and resistance modulation using plant extracts was analyzed
by one way analysis of variance (ANOVA) followed by Duncan’s multiple range(DMR)
posthoc test using Statistical package for social sciences (SPSS) 17.0 Statistical software at α <
0.05.