. 2023 Jan 20;5(1):dlad001. doi: 10.1093/jacamr/dlad001

Table 4.

Time lag between use and resistance: E. coli and Klebsiella spp.

Antibiotic use	E. coli Total: 5 studies^{18,26,28,33,34}				Klebsiella spp.^a Total: 4 studies^19,31,33,39
	Resistance to/resistance mechanism				Resistance to
	Cephalosporins (NS)	Cephalosporins 3 + 4G	ESBL production	Fluoroquinolones	Carbapenems	Cephalosporins (NS)	Fluoroquinolones	Polymyxins
Carbapenems					1–2 months¹⁹		2–3 months¹⁹	0 years³¹
					6 months³³
					0 years³¹
					1 year³⁹
Cephalosporins (NS)	1–12 months³³					1–6 months³³
Cephalosporins 1 + 2G					0 years³¹			0 years³¹
Cephalosporins 3 + 4G		0–3 months³⁴	1 month²⁶					0 years³¹
Cephalosporins 3 + 4G		4 months²⁶	1 month²⁶					0 years³¹
Fluoroquinolones		1–5 months³⁴	2 months²⁶	2–4 months¹⁸	1 year³¹		2–3 months¹⁹	1 year³¹
Fluoroquinolones		3 months²⁶	2 months²⁶	4–6 months²⁸	1 year³¹		2–3 months¹⁹	1 year³¹
Penicillins ± β-lactamase inhibitor		3 months³⁴						1 year³¹
Polymyxins					0–1 years³¹			0 years³¹

1+2G, 1^st and 2^nd generation; 3+4G, 3^rd and 4^th generation; E.coli, Escherichia coli; ESBL, extended-spectrum β-lactamase; NS, not specified; spp., species.

Klebsiella spp. includes K. pneumoniae (two studies^31,39), K. pneumoniae and K. oxytoca (one study³³), and Klebsiella spp. (one study¹⁹).