Antibiotic Susceptibility Testing, Plasmid Detection and Curing of Clinically Isolated Enterococcus Species

Vancomycin resistant enterococci (VRE) are a major medical concern globally. Their significantly greater prevalence and the ability to transfer resistance to vancomycin from other bacteria made them an object of interest and intense research. The isolates of Enterococcus sp. were subjected to antibiotic susceptibility testing before curing. The three Enterococcus species exhibited different antibiotic resistance profile. Pre-curing antibiotic resistance of nosocomial isolates compared with community acquired isolates revealed that high percentage of the nosocomial isolates were resistant to antibiotics compared to community isolate. Post-curing antibiograms of the isolates showed different resistant and susceptibility pattern. Also, DNA plasmid pre-curing and post curing analysis of the isolates showed different resistance pattern. Six of the 15 representative isolates selected on the basis of their high pre-curing antibiotic resistance for plasmid analysis with 0.8% agarose electrophoresis were positive for plasmid DNA. Four (4) of the positive isolates (E. faecium, E. faecium, E. faecalis, and E. avium) had plasmid fragment of greater than 1000 bp while two (2) of them (E. faecalis and E. faecalis) had fragments of between 100 and 500 bp. The remaining nine (9) had no plasmid DNA. The study revealed the pathogenicity factors demonstrated with the enterococcal isolates.