Genotypic diversity and epidemiology of high-level gentamicin resistant Enterococcus in a Chinese hospital.
OBJECTIVE
To investigate the antibiotics resistance of Enterococcus, the aminoglycoside-modifying enzymes (AME) and homology of high-level gentamicin resistant (HLGR) Enterococcus in clinical specimens for the implementation of effective infection control measures.


METHODS
The resistance of 13 antimicrobial agents was determined by Kirby-Bauer (K-B) or agar dilution method. And the HLGR and high-level streptomycin resistant (HLSR) isolates were screened by agar screen. Production of beta-lactamases was tested by the nitrocefin disc method. The aminoglycoside-modifying enzyme genes were detected by polymerase chain reaction (PCR). Pulsed-field gel electrophoresis (PFGE) was used to analyze the homology of HLGR isolates from in-patients.


RESULTS
No isolates resistant to linezolid, vancomycin and teicoplanin were found. Ampicillin-resistant isolates did not produce beta-lactamases and 68 HLGR isolates were screened at the rate of 64.2%. The positive rate of aac(6')-Ie-aph(2'')-Ia was 86.8% and 3 isolates had the new AME gene designated aph(2'')-Ie mostly similar to aph(2'')-Id. Among 51 HLGR isolates from in-patients, PFGE grouped 17 Enterococcus faecalis (E. faecalis) isolates into 4 clusters (A-D), and 33 Enterococcus faecium (E. faecium) isolates into 8 clusters (A-H), of which the A cluster is the main.


CONCLUSIONS
HLGR has become the important antibiotic resistance pathogen causing nocosomial infection. And the aac(6')-Ie-aph(2'')-Ia gene was the main aminoglycoside-modifying enzyme gene leading to HLGR.
Qu
Ting-Ting
TT
Department of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, No. 79, Qing Chun Road, Hangzhou, Zhejiang 310003, China. quxuerong@21cn.com
Chen
Ya-Gang
YG
Yu
Yun-Song
YS
Wei
Ze-Qing
ZQ
Zhou
Zhi-Hui
ZH
Li
Lan-Juan
LJ
D000123:Acetyltransferases / Q000235:genetics; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002681:China / Q000453:epidemiology; D017931:DNA Primers / Q000737:chemistry; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000235:genetics; D016984:Enterococcus faecium / Q000187:drug effects* / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics; D005838:Genotype; D005839:Gentamicins / Q000494:pharmacology*; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology* / Q000235:genetics / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D017931:DNA Primers; D005839:Gentamicins; C108453:6'-aminoglycoside acetyltransferase-2''-aminoglycoside phosphotransferase; D000123:Acetyltransferases; C425933:APH(2'')-Ic protein, Enterococcus faecalis; D017853:Phosphotransferases (Alcohol Group Acceptor); C048564:aminoglycoside 2''-phosphotransferase