Table 1.

Minimum inhibitory concentrations of various antimicrobial agents against groups of Gram-negative bacteria including isolates with defined resistance mechanisms.

Organism (No. Tested) and Antimicrobial Agent	Concentration (mg/L)
	Mode	MIC50	MIC90	Range
Enterobacterales (n = 197)
Alafosfalin	2	2	> 8	≤0.031–>8
Di-alanyl fosfalin	> 8	8	> 8	≤ 0.031–> 8
β-Cl-Ala-β-Cl-Ala	> 8	> 8	> 8	2–> 8
Fosfomycin	4	4	> 32	0.125–> 32
E. coli (n = 53)
Alafosfalin	0.063	0.125	0.25	≤ 0.031–2
Di-alanyl fosfalin	0.25	0.5	2	≤ 0.031–> 8
β-Cl-Ala-β-Cl-Ala	8	8	> 8	2–> 8
Fosfomycin	0.5	0.5	1	0.125–8
K. pneumoniae (n = 87)
Alafosfalin	2	2	> 8	0.25–> 8
Di-alanyl fosfalin	> 8	> 8	> 8	0.5–> 8
β-Cl-Ala-β-Cl-Ala	> 8	> 8	> 8	8–> 8
Fosfomycin	4	8	> 32	2–> 32
E. cloacae (n = 27)
Alafosfalin	1	1	1	0.125–4
Di-alanyl fosfalin	4	> 8	> 8	0.25–> 8
β-Cl-Ala-β-Cl-Ala	> 8	> 8	> 8	8–> 8
Fosfomycin	16	16	32	4–> 32
CPE (n = 128)
Alafosfalin	2	1	4	≤ 0.031–> 8
Di-alanyl fosfalin	> 8	8	> 8	0.063–> 8
β-Cl-Ala-β-Cl-Ala	> 8	> 8	> 8	2–> 8
Fosfomycin	16	4	32	0.125–> 32
ESBL (n = 47)
Alafosfalin	2	2	> 8	≤ 0.031–> 8
Di-alanyl fosfalin	> 8	8	> 8	≤ 0.031–> 8
β-Cl-Ala-β-Cl-Ala	> 8	> 8	> 8	2–> 8
Fosfomycin	> 32	8	> 32	0.125–> 32
AmpC (n = 22)
Alafosfalin	> 8	4	> 8	0.063–> 8
Di-alanyl fosfalin	> 8	> 8	> 8	0.063–> 8
β-Cl-Ala-β-Cl-Ala	> 8	> 8	> 8	8–> 8
Fosfomycin	32	8	> 32	0.125–> 32

Abbreviations: MIC₅₀: concentration of antimicrobial required to inhibit 50% of isolates. MIC₉₀: concentration of antimicrobial required to inhibit 90% of isolates. CPE: carbapenemase-producing Enterobacterales; ESBL: Enterobacterales with extended spectrum β-lactamase; AmpC: Enterobacterales with acquired AmpC β-lactamase.