Table 5.

Time lag between use and resistance: P. aeruginosa

Antibiotic use	P. aeruginosa Total: 10 studies14–17,20,25–27,33,37
	Resistance to/resistance mechanism
	Aminoglycosides	Carbapenems	Cephalosporins 3 + 4G	Fluoroquinolones	Penicillin +  β-lactamase inhibitor	Overproduction of MexXY-OprMa	3/4-class MDRb P. aeruginosa	CRc or 3/4-class MDRb P. aeruginosa	XDRd P. aeruginosa
Aminoglycosides	1 month26					0–6 months20
Carbapenems	0 quarters37	0 months17	0–1 months25	0 quarters37	0–1 months25	0–6 months20	1 quarter37
		0–1 months14,25
		1 month27
		0–2 months33
		1–6 months16
		0–1 quarters15
		1 quarter37
Cephalosporins, 3 + 4G	0 quarters37	0–1 months25	0–1 months25	0 quarters37	0–1 months25		0–1 quarters37		0 quarters37
			2 months17
			0–2 quarters37
Cephalosporins, 2 + 3 + 4G						0–6 months20
Fluoroquinolones	1 month26 0–1 quarters37			1 month17		0–6 months20
Penicillins + β-lactamase inhibitor		0–1 months25	0–1 months25		0 months14	0–5 months20		0 quarters37
		1 month16	0 quarters37		0–1 months25			0–1 quarters15

2+3+4G, 2^nd and 3^rd and 4^th generation; CR, combined resistance; MDR, multi-drug resistant; XDR, extensively drug-resistant.

^aOverproduction of MexXY-OprM in P. aeruginosa leads to low-level resistance to aminoglycosides, fluoroquinolones and 4G cephalosporins.

^b3/4-class MDR P. aeruginosa = non-susceptible or resistant to three or four of the following agents: piperacillin/tazobactam, ceftazidime, meropenem, ciprofloxacin. Definition as stated by Willman 2013³⁷ and is not a universal definition.

^cCombined resistant P. aeruginosa = combined resistance (CR) to ≥3 of ceftazidime, antipseudomonal penicillins, fluoroquinolones, aminoglycosides.³⁷

^dXDR P. aeruginosa = XDR, i.e. resistant to at least one agent in all, or all but one or two, antimicrobial categories.