Genetic diversity and antibiotic resistance determinants of Enterococcus faecalis isolates causing pediatric infections in Cuba.

Genetic relationships and the antibiotic resistance determinants were studied for a total of 55 Enterococcus faecalis isolates recovered from children in a pediatric hospital in Cuba between January 2001 and December 2004. These isolates were analyzed by pulsed-field gel electrophoresis, and presence of some resistance genes to aminoglycosides, macrolides and tetracycline were examined by polymerase chain reaction. A total of 17 pulsed-field gel electrophoresis patterns were identified among 54 different patterns of pulsed-field gel electrophoresis. Particular multi-resistant E. faecalis clones were detected in different wards from the pediatric hospital. The aac(6’)-aph(2”) and aph(3’) genes was detected in all the isolates with high-level resistance to gentamicin and amikacin, respectively, whereas the ant(6) gene was detected in the 75% of isolates showing high-level resistance to streptomycin. The erm(B) gene was found in 72% of the erythromycin-resistant strains, and tet(M) was detected in all tetracycline resistant strains. The circulation of particular clones exhibiting antibiotic resistance in the pediatric hospital and the dissemination of drug-resistance genes among these strains indicated the need for the monitoring of antibiotic susceptibility to prevent the selection or dispersion of resistant strains in this hospital.