Related Experiment Videos
High-level aminoglycoside resistance among enterococci: evaluation of an agar screen susceptibility test
E Nicastri1, A Tarasi, U Visco Comandini
1Patologia Medica II, Policlinico Umberto I, Università degli Studi, La Sapienza, Roma, Italy.
Abstract:
Seventy-five enterococci from infected (63 isolates) and colonized (12 isolates) patients hospitalized in various divisions of the Policlinico Umberto I, University of Rome, were in vitro studied for high-level resistance (HLR) to gentamicin (HLRG) and streptomycin (HLRS) with adoption of a standard broth dilution and an agar screen test. The employed procedures provided equal results for 100% of the 75 isolates. Of these, 21 (28%) showed HLRG and 43 (57%) HLRS. Combined HLRG and HLRS were found in 18 (24%) isolates, whereas HLRS or HLRG alone were found in 25 (33%) and 3 (4%) isolates respectively. It is concluded that HLR to aminoglycosides may represent a major problem in Italian institutions. Along with other established procedures, the agar screen test employed in the study may be used to detect this antibiotic resistance in enterococci.
Insights
High-level resistance to gentamicin and streptomycin in enterococci is a significant concern in Italian hospitals. The agar screen test effectively detects this antibiotic resistance in enterococci.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Pharmacy
Background:
- Enterococci are opportunistic pathogens frequently associated with hospital-acquired infections.
- High-level aminoglycoside resistance (HLAR) in enterococci can compromise treatment efficacy, particularly for serious infections.
- Surveillance of antibiotic resistance patterns is crucial for effective infection control in healthcare settings.
Purpose of the Study:
- To investigate the prevalence of high-level resistance (HLR) to gentamicin (HLRG) and streptomycin (HLRS) in enterococcal isolates from a university hospital.
- To evaluate the concordance between standard broth dilution and agar screen tests for detecting HLR in enterococci.
- To highlight the clinical significance of aminoglycoside resistance in enterococci within Italian healthcare institutions.
Main Methods:
- In vitro susceptibility testing of 75 enterococcal isolates from infected and colonized patients.
- Utilized standard broth dilution and agar screen tests to determine high-level resistance to gentamicin and streptomycin.
- Analyzed resistance patterns, including combined and individual high-level resistance to aminoglycosides.
Main Results:
- A significant proportion of enterococcal isolates exhibited high-level resistance: 28% to gentamicin (HLRG) and 57% to streptomycin (HLRS).
- Combined HLRG and HLRS were observed in 24% of isolates.
- Both tested methods (broth dilution and agar screen) yielded identical results for all 75 isolates, demonstrating 100% concordance.
Conclusions:
- High-level aminoglycoside resistance in enterococci poses a substantial challenge in Italian healthcare facilities.
- The agar screen test is a reliable and effective method for detecting HLR in enterococci, complementing standard antimicrobial susceptibility testing.
- Continuous monitoring and implementation of appropriate diagnostic tools are essential for managing aminoglycoside resistance in enterococci.