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Increasing prevalence of high-level gentamicin resistance among Enterococci isolated in Greece
A Tsakris1, S Pournaras, A N Maniatis
1Department of Microbiology, Medical School, Aristotle University of Thessaloniki, GR 54 006 Thessaloniki, Greece. atsakris@med.auth.gr
Abstract:
High-level gentamicin-resistant enterococci (HLGRE) (MIC >512 microg/ml) were frequently recovered in the AHEPA University Hospital, Thessaloniki, Greece, during a 15-month period (67/158, 42.4%). PCR testing showed that high-level gentamicin resistance was attributable to the presence of the aac(6')-aph(2") gene, while the recently described genes aph (2")-Ic and aph(2")-Id were not detected. High-level gentamicin resistance could be transferred with varying frequency from 41 of 57 Enterococcus faecalis and 5 of 10 Enterococcus faecium isolates. All transconjugants acquired high-level resistance to streptomycin. HLGRE cause therapeutic problems in our region, since none of the clinically available aminoglycosides can be used in severe infections.
Insights
High-level gentamicin-resistant enterococci (HLGRE) are common, linked to a specific gene, and transferable between strains. This resistance poses significant treatment challenges, limiting aminoglycoside options for severe infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Research
Background:
- High-level gentamicin resistance (HLGRE) in enterococci presents a growing clinical challenge.
- Enterococcus faecalis and Enterococcus faecium are significant nosocomial pathogens.
- Limited therapeutic options exist for infections caused by multidrug-resistant enterococci.
Purpose of the Study:
- To investigate the prevalence and molecular basis of HLGRE in a Greek hospital.
- To determine the transferability of HLGRE among enterococcal strains.
- To assess the clinical implications of HLGRE in the study region.
Main Methods:
- Surveillance of enterococcal isolates over a 15-month period.
- Polymerase Chain Reaction (PCR) to identify resistance genes.
- Bacterial conjugation experiments to assess gene transfer.
- Minimum Inhibitory Concentration (MIC) testing for aminoglycoside resistance.
Main Results:
- HLGRE was frequently recovered (42.4%) from enterococcal isolates.
- The aac(6 egular)-aph(2") gene was identified as the cause of HLGRE; aph(2")-Ic and aph(2")-Id were absent.
- HLGRE was transferable from Enterococcus faecalis and Enterococcus faecium isolates.
- Transconjugants also acquired high-level streptomycin resistance.
- No clinically available aminoglycosides were effective against HLGRE in severe infections.
Conclusions:
- The aac(6 egular)-aph(2") gene is the primary driver of HLGRE in this Greek hospital.
- HLGRE is transferable, contributing to its spread.
- The prevalence of HLGRE significantly limits treatment options for severe enterococcal infections.