. 2022 Jun 15;10(4):e00621-22. doi: 10.1128/spectrum.00621-22

TABLE 3.

Beta-lactam combination therapies against E. faecalis: Time-kill assay change in log₁₀ CFU/mL from the initial inoculum at 24 h

	Ampicillin + ceftriaxone			Penicillin + ceftriaxone
Isolate	0.25 × MIC	0.5 × MIC	1 × MIC	0.25 × MIC	0.5 × MIC	1 × MIC
Isolates with penicillin MIC ≤ 2 mcg/mL
JH2-2	−2.04 ± 0.12^b^,^c	−4.13 ± 0.00^a^,^c	−4.13 ± 0.00^a^,^c	+1.12 ± 0.08	+0.45 ± 0.82	−3.01 ± 0.08^a
e2003	−4.05 ± 0.00^a	−4.05 ± 0.00^a	−4.05 ± 0.00^a	+1.90 ± 0.17	−3.7 ± 0.25^a^,^c	−4.05 ± 0.00^a
e2006	−4.05 ± 0.00^a	−4.05 ± 0.00^a	−4.05 ± 0.00^a	−2.96 ± 0.12^b^,^c	−4.05 ± 0.00^a^,^c	−4.05 ± 0.00^a
e2011	−3.68 ± 0.09^a^,^c	−4.14 ± 0.00^a^,^c	−4.14 ± 0.00^a	+1.60 ± 0.23	−4.11 ± 0.05^a^,^c	−3.95 ± 0.10^a^,^c
e2012	+1.20 ± 0.32	−4.01 ± 0.00^a^,^c	−4.01 ± 0.00^a^,^c	+1.02 ± 0.25	−3.94 ± 0.00^a^,^c	−3.92 ± 0.12^a
e2014	−4.05 ± 0.00^a^,^c	−4.05 ± 0.00^a^,^c	−4.05 ± 0.00^a^,^c	−0.38 ± 0.24^b^,^c	−3.98 ± 0.00^a^,^c	−4.05 ± 0.00^a^,^c
e2015	−4.12 ± 0.00^a^,^c	−4.12 ± 0.00^a^,^c	−4.12 ± 0.00^a	−1.2 ± 0.12^b^,^c	−2.2 ± 0.29^b^,^c	−4.12 ± 0.00^a
e2017	−2.31 ± 0.16^b^,^c	−3.99 ± 0.00^a^,^c	−3.99 ± 0.00^a	−2.84 ± 0.04^b^,^c	−2.61 ± 0.11^b^,^c	−3.99 ± 0.00^a
e2020	−4.09 ± 0.00^a^,^c	−4.09 ± 0.00^a^,^c	−4.09 ± 0.00^a	−0.16 ± 0.55^b	−4.06 ± 0.05^a^,^c	−4.09 ± 0.00^a
e2025	−3.89 ± 0.00^a^,^c	−4.28 ± 0.00^a^,^c	−4.28 ± 0.00^a	−2.01 ± 0.14^b^,^c	−4.06 ± 0.00^a^,^c	−4.28 ± 0.00^a^,^c
e2029	+1.73 ± 0.01	−3.75 ± 0.45^a^,^c	−3.44 ± 0.89^a^,^c	+0.97 ± 0.68	−1.57 ± 0.71^b^,^c	−4.07 ± 0.00^a
e2031	−3.16 ± 0.44^a^,^c	−4.11 ± 0.00^a	−4.11 ± 0.00^a	−4.05 ± 0.09^a^,^c	−3.76 ± 0.25^a^,^c	−4.11 ± 0.00^a
e2032	+1.63 ± 0.12	−2.49 ± 0.09^b	−4.14 ± 0.00^a	+1.82 ± 0.24	−0.05 ± 0.19^b	−4.14 ± 0.00^a^,^c
Isolates with penicillin MIC of 4 mcg/mL
e2008	−0.40 ± 0.03^b	−2.56 ± 0.12^b	−3.44 ± 0.04^a	+1.00 ± 0.07	+0.46 ± 0.10	−2.5 ± 0.04^b
e2009	−0.57 ± 0.25^b	−2.61 ± 0.07^b	−4.08 ± 0.00^a	+1.73 ± 0.09	+1.12 ± 0.19	−2.15 ± 0.20^b^,^c
e2010	+0.19 ± 0.06	−1.51 ± 0.06^b	−3.35 ± 0.10^a	+1.00 ± 0.08	+0.70 ± 0.03	−0.82 ± 0.00^b
e2018	+1.46 ± 0.00	+0.4 ± 0.02	−3.37 ± 0.07^a	+1.97 ± 0.23	+1.66 ± 0.05	−1.49 ± 0.06^b
e2024	−3.42 ± 0.71^a^,^c	−3.92 ± 0.00^a^,^c	−3.92 ± 0.00^a	−3.51 ± 0.02^a^,^c	−3.92 ± 0.00^a^,^c	−3.92 ± 0.00^a
e2027	+1.18 ± 0.19	−0.31 ± 0.13^b^,^c	−2.75 ± 0.44^b^,^c	+1.66 ± 0.02	+0.95 ± 0.24	−2.12 ± 0.11^b
e2028	+1.26 ± 0.20	−1.21 ± 0.33^b	−3.64 ± 0.18^a	+1.99 ± 0.03	+1.56 ± 0.08	−1.27 ± 0.25^b

Bactericidal activity was observed, defined as ≥3-log₁₀ decrease in CFU/mL from initial inoculum.

Bacteriostatic activity was observed, defined as <3-log₁₀ decrease in CFU/mL from initial inoculum.

Synergy was detected as indicated by gray shading, defined as ≥2-log₁₀ decrease in CFU/mL at 24 h from the most active single agent was observed.