Random amplified polymorphic DNA typing of enterococcus faecalis isolated from Lebanese individuals

In this study we assessed the utility of random amplified polymorphic DNA in the subtyping of 38 isolates of Enterococcus faecalis. Method: Twenty of 38 subtypes were recovered from urinary tract infections and 18 from rectal swabs of hospitalized patients with no enterococcal infections. All isolates were initially identified by conventional bacteriological methods and the API 20 Streptococcus system. Biotyping was done on the basis of hippurate hydrolysis (HH) test using API 20S. Susceptibility of the isolates to vancomycin, teicoplanin, ampicillin and gentamicin was performed by the disk diffusion and the agar dilution methods. Antimicrobials were selected based on treatment regimen adopted by clinicians. DNA was extracted from all isolates using the PureGene kit and Random Amplified Polymorphic DNA Typing (RAPD) was done using a 10 mer and 22 mer primers reflecting the GC content of the genome. Results: Our data have shown that 38 tested isolates were E. faecalis. Thirteen of 38 were of fecal origin and 6/38 were of urine origin. All 19 isolates were of biotype I (HH positive). The remaining 5 of fecal origin and 14 of urine origin were of biotype II (HH negative). All isolates were susceptible to vancomycin, teicoplanin and ampicillin except 3 urine and 1 fecal isolates that showed resistance to ampicillin. All urine isolates were resistant to gentamicin while 3 of 18 fecal isolates were susceptible to this antimicrobial agent. RAPD data have shown that 2/19 biotype I isolates, showed one RAPD pattern and were susceptible to teichoplanin and vancomycin; and 2/19 showed a different pattern and were susceptible to all tested antimicrobials except gentamicin. All 4 isolates were of urine origin. The remaining 15 biotype I isolates had different patterns. In addition, of 19 biotype II isolates, 2 showed one pattern and the remaining 17 different patterns. Two isolates were of urine origin and resistant to gentamicin. The RAPD patterns were reproducible. Conclusion: These observations suggest that RAPD is efficient for subtyping E. faecalis and may be useful as a tool in epidemiologic investigations.