High-level gentamicin-resistant Enterococcus faecium strains isolated from bone marrow transplant patients: accumulation of antibiotic resistance genes, large plasmids and clonal strain dissemination.
Twenty-six high-level gentamicin-resistant (HLGR) Enterococcus faecium strains colonising neutropenic bone marrow transplant patients were studied. Polymerase chain reaction analysis showed that high-level gentamicin resistance was mediated by the aac(6')-Ia-aph(2'')-Ie gene; the aph(2'')-Id gene responsible for gentamicin resistance was also detected in 16 strains. Multiple antibiotic resistance was related to the presence of aph(3')-IIIa, ant(6)-Ia, erm(B), erm (A) and tet(M) genes. Strains clustered into 18 groups according to their plasmid content as well as 16 pulsed-field gel electrophoresis (PFGE) patterns. Although the majority of PFGE patterns were single isolates, three microclones were identified. Hybridisation showed that in the majority of the strains the aac(6')-aph(2'') gene resided on a large plasmid of ca. 96kb detected only on PFGE gels. Based on these findings, colonisation by HLGR E. faecium strains was a result of either possibly related plasmid spread or strain dissemination.
Abbassi
Mohamed Salah
MS
Laboratory of the National Bone Marrow Transplantation Centre, Street Djebel-Lakdhar, Bab-Saadoun, 1006 Tunis, Tunisia.
Achour
Wafa
W
Hassen
Assia Ben
AB
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016026:Bone Marrow Transplantation / Q000009:adverse effects*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D016984:Enterococcus faecium / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D005839:Gentamicins / Q000494:pharmacology; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D009503:Neutropenia / Q000139:chemically induced; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012015:Reference Standards
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D005839:Gentamicins