Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis

ABSTRACT Enterococcus faecalis infective endocarditis treatment with ampicillin plus ceftriaxone has not changed the mortality rates by over 30%. We identified borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF; penicillin MIC 4–8 µg/mL, breakpoint ≤8 µg/mL) isola...

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Main Authors: Olivia Gladys Funk, Ruhma Khan, Zeel Shah, Jaclyn A. Cusumano
Format: Article
Language:English
Published: American Society for Microbiology 2025-06-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.02718-24
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author Olivia Gladys Funk
Ruhma Khan
Zeel Shah
Jaclyn A. Cusumano
author_facet Olivia Gladys Funk
Ruhma Khan
Zeel Shah
Jaclyn A. Cusumano
author_sort Olivia Gladys Funk
collection DOAJ
description ABSTRACT Enterococcus faecalis infective endocarditis treatment with ampicillin plus ceftriaxone has not changed the mortality rates by over 30%. We identified borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF; penicillin MIC 4–8 µg/mL, breakpoint ≤8 µg/mL) isolates that have decreased ampicillin-ceftriaxone activity, which is present in 25% of isolates in New York City. Alternatively, ceftaroline is more active against E. faecalis than ceftriaxone. We compared the activity of ampicillin or penicillin plus ceftriaxone or ceftaroline against nine borderline-PRASEF and seven penicillin-susceptible (penicillin MIC ≤2 µg/mL) E. faecalis isolates via 24 h time-kill assays. MICs were obtained via broth microdilution per CLSI. Ampicillin, penicillin, and ceftaroline were tested at subinhibitory concentrations (0.25 × MIC and 0.5 × MIC) and ceftriaxone at the free plasma steady-state concentration (17.2 µg/mL). All experiments were completed in duplicate with a starting inoculum of 106 CFU/mL. After 24 h, antimicrobial activity was measured as ≥2-log10 CFU/mL decrease from the initial inoculum. Combinations were assessed for synergy (≥2-log10 CFU/mL decrease from the most active single agent). Ceftriaxone and ceftaroline MICs were more likely to be higher in borderline-PRASEF isolates compared to penicillin-susceptible isolates. Ceftaroline-based combinations more often demonstrated synergy and activity than ceftriaxone combinations. When assessed by penicillin MIC, ceftriaxone-based combinations less frequently demonstrated synergy and activity against borderline-PRASEF isolates compared to ceftaroline-based combinations. Ceftaroline-based combinations may be an effective alternative targeting E. faecalis, including borderline-PRASEF.IMPORTANCEThe preferred therapy for treatment of Enterococcus faecalis infective endocarditis is ampicillin plus ceftriaxone; however, there is a need for alternative treatments given the unchanged mortality rates exceeding 30%. Recent data show decreased ampicillin-ceftriaxone activity against borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF), which is present in 25% of isolates. Ceftaroline is an alternative cephalosporin that has been explored as it does not carry the risks ceftriaxone has to increase vancomycin resistance and Clostridoides difficile infection. Ceftaroline also provides saturation of both essential penicillin-binding protein (PBP) 4 and non-essential PBP2/3, whereas ceftriaxone only binds to PBP2/3. The activity of ceftaroline-based combinations against borderline-PRASEF is unknown. This study demonstrates the ability of ampicillin or penicillin plus ceftaroline to maintain activity against borderline-PRASEF where ampicillin or penicillin plus ceftriaxone combination activity is limited.
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spelling doaj-art-26909ccb4cdc44c3b83dcdea410a2e212025-08-20T02:24:26ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-06-0113610.1128/spectrum.02718-24Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalisOlivia Gladys Funk0Ruhma Khan1Zeel Shah2Jaclyn A. Cusumano3Long Island University, Brooklyn, New York, USALong Island University, Brooklyn, New York, USALong Island University, Brooklyn, New York, USALong Island University, Brooklyn, New York, USAABSTRACT Enterococcus faecalis infective endocarditis treatment with ampicillin plus ceftriaxone has not changed the mortality rates by over 30%. We identified borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF; penicillin MIC 4–8 µg/mL, breakpoint ≤8 µg/mL) isolates that have decreased ampicillin-ceftriaxone activity, which is present in 25% of isolates in New York City. Alternatively, ceftaroline is more active against E. faecalis than ceftriaxone. We compared the activity of ampicillin or penicillin plus ceftriaxone or ceftaroline against nine borderline-PRASEF and seven penicillin-susceptible (penicillin MIC ≤2 µg/mL) E. faecalis isolates via 24 h time-kill assays. MICs were obtained via broth microdilution per CLSI. Ampicillin, penicillin, and ceftaroline were tested at subinhibitory concentrations (0.25 × MIC and 0.5 × MIC) and ceftriaxone at the free plasma steady-state concentration (17.2 µg/mL). All experiments were completed in duplicate with a starting inoculum of 106 CFU/mL. After 24 h, antimicrobial activity was measured as ≥2-log10 CFU/mL decrease from the initial inoculum. Combinations were assessed for synergy (≥2-log10 CFU/mL decrease from the most active single agent). Ceftriaxone and ceftaroline MICs were more likely to be higher in borderline-PRASEF isolates compared to penicillin-susceptible isolates. Ceftaroline-based combinations more often demonstrated synergy and activity than ceftriaxone combinations. When assessed by penicillin MIC, ceftriaxone-based combinations less frequently demonstrated synergy and activity against borderline-PRASEF isolates compared to ceftaroline-based combinations. Ceftaroline-based combinations may be an effective alternative targeting E. faecalis, including borderline-PRASEF.IMPORTANCEThe preferred therapy for treatment of Enterococcus faecalis infective endocarditis is ampicillin plus ceftriaxone; however, there is a need for alternative treatments given the unchanged mortality rates exceeding 30%. Recent data show decreased ampicillin-ceftriaxone activity against borderline-penicillin-resistant, ampicillin-susceptible E. faecalis (borderline-PRASEF), which is present in 25% of isolates. Ceftaroline is an alternative cephalosporin that has been explored as it does not carry the risks ceftriaxone has to increase vancomycin resistance and Clostridoides difficile infection. Ceftaroline also provides saturation of both essential penicillin-binding protein (PBP) 4 and non-essential PBP2/3, whereas ceftriaxone only binds to PBP2/3. The activity of ceftaroline-based combinations against borderline-PRASEF is unknown. This study demonstrates the ability of ampicillin or penicillin plus ceftaroline to maintain activity against borderline-PRASEF where ampicillin or penicillin plus ceftriaxone combination activity is limited.https://journals.asm.org/doi/10.1128/spectrum.02718-24Enterococcus faecalisceftarolinepenicillinceftriaxoneampicillin
spellingShingle Olivia Gladys Funk
Ruhma Khan
Zeel Shah
Jaclyn A. Cusumano
Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis
Microbiology Spectrum
Enterococcus faecalis
ceftaroline
penicillin
ceftriaxone
ampicillin
title Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis
title_full Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis
title_fullStr Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis
title_full_unstemmed Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis
title_short Comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against Enterococcus faecalis
title_sort comparison of ceftriaxone versus ceftaroline in combination with ampicillin or penicillin against enterococcus faecalis
topic Enterococcus faecalis
ceftaroline
penicillin
ceftriaxone
ampicillin
url https://journals.asm.org/doi/10.1128/spectrum.02718-24
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