Evaluating Vancomycin Susceptibility Trends against Clinical Enterococcus Faecalis Isolates and its Association with Daptomycin and Linezolid Susceptibility
Faculty Mentor
Olivia Gladys Funk
Major/Area of Research
Infectious Diseases, Antimicrobial Resistance, Antibiotics, Pharmacy (PharmD)
Description
INTRODUCTION: Vancomycin-resistant enterococci (VRE) are a major cause of hospital-acquired infections, with mortality rates up to 21%. Enterococcus faecium more commonly are VRE compared to Enterococcus faecalis. (82.2% vs. 9.8%). Limited treatment options are available and emerging antibiotic resistance, such as borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF) add to the challenges. Remaining available therapies include daptomycin and linezolid. This study aimed to characterize E. faecalis vancomycin, daptomycin and linezolid susceptibility patterns.
METHOD: A total of 270 E. faecalis isolates from a New York City health system underwent vancomycin susceptibility testing via manual broth microdilution. Categorization followed Clinical and Laboratory Standards Institute breakpoints: susceptible (≤4 μg/mL), intermediate (8-16 μg/mL), and resistant (≥32 μg/mL). A subset of 222 isolates underwent daptomycin and linezolid susceptibility testing via E-test in the clinical microbiology lab. Both daptomycin and linezolid susceptibility breakpoints were as susceptible (≤2 μg/mL), intermediate (4 μg/mL), and resistant (≥8 μg/mL). Penicillin susceptibility was previously assessed, with borderline resistance defined as an MIC of 4-8 μg/mL and susceptibility defined as an MIC of 1-2 μg/mL. Vancomycin MICs were correlated to daptomycin and linezolid susceptibility patterns.
CONCLUSION: Among 270 E. faecalis isolates, 11.48% were VRE, and 27.04% were borderline-PRASEF. VRE was more frequently observed among isolates with borderline penicillin MICs (39.73%) compared to those with penicillin MICs < 4 μg/mL (1.01%). Daptomycin susceptibility was more common in VRE (83.87%) than in VSE (70.14%), and a similar trend was observed with linezolid, with susceptibility rates of 90.32% in VRE and 73.95% in VSE. These findings highlight the need for continued surveillance of daptomycin resistance, while linezolid remains a reliable treatment option.
Evaluating Vancomycin Susceptibility Trends against Clinical Enterococcus Faecalis Isolates and its Association with Daptomycin and Linezolid Susceptibility
INTRODUCTION: Vancomycin-resistant enterococci (VRE) are a major cause of hospital-acquired infections, with mortality rates up to 21%. Enterococcus faecium more commonly are VRE compared to Enterococcus faecalis. (82.2% vs. 9.8%). Limited treatment options are available and emerging antibiotic resistance, such as borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF) add to the challenges. Remaining available therapies include daptomycin and linezolid. This study aimed to characterize E. faecalis vancomycin, daptomycin and linezolid susceptibility patterns.
METHOD: A total of 270 E. faecalis isolates from a New York City health system underwent vancomycin susceptibility testing via manual broth microdilution. Categorization followed Clinical and Laboratory Standards Institute breakpoints: susceptible (≤4 μg/mL), intermediate (8-16 μg/mL), and resistant (≥32 μg/mL). A subset of 222 isolates underwent daptomycin and linezolid susceptibility testing via E-test in the clinical microbiology lab. Both daptomycin and linezolid susceptibility breakpoints were as susceptible (≤2 μg/mL), intermediate (4 μg/mL), and resistant (≥8 μg/mL). Penicillin susceptibility was previously assessed, with borderline resistance defined as an MIC of 4-8 μg/mL and susceptibility defined as an MIC of 1-2 μg/mL. Vancomycin MICs were correlated to daptomycin and linezolid susceptibility patterns.
CONCLUSION: Among 270 E. faecalis isolates, 11.48% were VRE, and 27.04% were borderline-PRASEF. VRE was more frequently observed among isolates with borderline penicillin MICs (39.73%) compared to those with penicillin MICs < 4 μg/mL (1.01%). Daptomycin susceptibility was more common in VRE (83.87%) than in VSE (70.14%), and a similar trend was observed with linezolid, with susceptibility rates of 90.32% in VRE and 73.95% in VSE. These findings highlight the need for continued surveillance of daptomycin resistance, while linezolid remains a reliable treatment option.