Table 1.

Activities of the selected aminoglycosides against the clinical isolates of the five bacterial species.

Isolate	Gentamicin			Gentamicin C1a			Apramycin			Paromomycin			Neomycin
	MIC		Range	MIC		Range	MIC		Range	MIC		Range	MIC		Range
	50	90		50	90		50	90		50	90		50	90
Eco	2	>64	≤0.5–>64	1	>64	1–>64	8	16	4–32	4	>64	≤0.5–>64	1	>64	≤0.5–>64
Kpn	16	>64	≤0.5–>64	>64	>64	1–>64	4	>64	2–>64	2	>64	≤0.5–>64	1	>64	≤0.5–>64
Pae	8	>64	1–>64	1	>64	≤0.5–>64	8	>64	4–>64	>64	>64	4–>64	16	>64	≤0.5–>64
Ab	>64	>64	≤0.5–>64	16	>64	2–>64	16	64	2–>64	32	>64	1–>64	8	>64	1–>64
Sau	>64	>64	≤0.5–>64	1	32	2–>64	16	16	4–16	>64	>64	≤0.5–>64	>64	>64	≤0.5–>64

MIC₅₀ and MIC₉₀ values of both GM and the GM C1a congener were similar, with only a 2-fold increase in the MIC₅₀ of GM C1a over that of GM. Importantly, this was not due to these compounds having the same or similar MIC values against exactly the same test organisms (shown in Supplementary Table S2). Good in-vitro activity of apramycin was recorded against MDR organisms, including carbapenem-resistant enterobacteria, and within a narrower range than GM or GM C1a. Eco, Escherichia coli; Kpn, K. pneumoniae; Pae, P. aeruginosa; Ab, A. baumannii; Sau, S. aureus.