Journal of
Microbiology and Antimicrobials

  • Abbreviation: J. Microbiol. Antimicrob.
  • Language: English
  • ISSN: 2141-2308
  • DOI: 10.5897/JMA
  • Start Year: 2009
  • Published Articles: 166

Full Length Research Paper

Occurrence and implications of resistance to antibiotics and organic acids in Enterococcus faecalis isolated from fruit juices marketed in Ado-Ekiti

David O. M.*, Falegan C. R. and Fagbohun E. D.
Department of Microbiology, University of Ado-Ekiti, P. M. B. 5363, Ado-Ekiti, Ekiti State, Nigeria
Email: [email protected]

  •  Accepted: 09 April 2012
  •  Published: 30 April 2012



The study investigated the growth of Enterococcus faecalis in various fruit juice products, their resistance to antibiotics and their ability to be grown in the presence of most organic acids commonly employed as preservatives. E. faecalis strains were isolated from seven out of nine fruit juices using serial dilution and pour plate method. The total bacterial counts observed in the juice samples ranged between 20 to 460 colony forming unit per 100 ml (CFU/100 ml) with the highest and least values detected in fruit juice brands EXT and MNN respectively. The total coliform count in brand EXT exceeded those in all the other samples (275 CFU/100 ml) but enterococcal load in the fruit juices was within the range of 10 CFU/100 ml to 65 CFU/100 ml in MNN and LCS brands respectively. The isolates were all susceptible to vancomycin while resistance was observed to other antibiotics evaluated. Resistance was highest for erythromycin (93%); while penicillin and tetracycline exhibited less resistance (90%).  E. faecalis strains isolated from brand TTT (EFTT) FAL (EFFA) and BST (EFBT) were all inhibited at higher concentrations of acetic acid (1.25 and 5.0% w/v) while lower concentrations (0.31% and below) could not effectively inhibit the growth of the isolates. The inhibitory effect of citric acid was pronounced in EFFA. At 0.31% w/v all the isolates were inhibited except EFFA. Benzoic acid had inhibitory effect on just two of the five strains, while formic acid showed no inhibition to all the isolates. EFFA and EFXT were also resistant to ethanoic acid at the different concentrations. Excellent manufacturing practices must be adopted during the production of commercial juice, as appropriate precautions will prevent contamination. Since most organic acids used for the preservation of most juice allow the survival of E. faecalis, there is a need to provide rational basis for designing interventions that are needed to assure the microbiological safety of final products.


Key words: Antimicrobial resistance, Enterococcus faecalis, fruit juice, bacterial count, organic acids