Table 1.

Bacterial isolates and specific resistance mechanisms used in the evaluation of the RAST method

Species (number of isolates) and antimicrobial agents tested (BMD as referencea)	Number of R isolates	Resistance mechanism identifiedb
E. coli (n = 60)
piperacillin/tazobactam	14	SHV-12 CTX-M VIM-1 OXA-1 OXA-48 NDM-1
cefotaxime	25
ceftazidime	20
meropenem	3
ciprofloxacin	21
amikacin	1
gentamicin	17
tobramycin	20
K. pneumoniae (n = 52)
piperacillin/tazobactam	18	SHV-5 CTX-M KPC OXA-48
cefotaxime	20
ceftazidime	16
meropenem	6
ciprofloxacin	21
amikacin	3
gentamicin	16
tobramycin	17
P. aeruginosa (n = 53)
piperacillin/tazobactam	17	multiple and mixed resistance mechanisms
ceftazidime	15
imipenem	15
meropenem	11
ciprofloxacin	24
gentamicin	14
tobramycin	11
S. aureus (n = 54)
cefoxitin (screen)	21	MRSA
norfloxacin (screen)	17
gentamicin	8
erythromycin	17
clindamycin	7
E. faecalis (n = 23)
ampicillin	0	VRE (vanA, vanB) HLAR
imipenem	0
gentamicin (screen)	17
linezolid	2
vancomycin	9
E. faecium (n = 34)
ampicillin	31	VRE (vanA, vanB) HLAR
imipenem	33
gentamicin (screen)	19
linezolid	6
vancomycin	22
S. pneumoniae (n = 56)
oxacillin (screen)	24	benzylpenicillin non-WT (screen positive with oxacillin 1 μg disc and with benzylpenicillin MICs of 0.125–4 mg/L)
norfloxacin (screen)	8
erythromycin	26
clindamycin	10
trimethoprim/ sulfamethoxazole	11
Control strains (n = 5)
E. coli ATCC 25922 P. aeruginosa ATCC 27853 S. aureus ATCC 29213 E. faecalis ATCC 29212 S. pneumoniae ATCC 49619		–

For more information on isolates and MIC distributions, see Tables S1 to S7.

^aBMD was used as reference, with the exceptions listed as ‘screen’, where EUCAST standard disc diffusion screen tests were used. For S. aureus, PCR was used as reference for methicillin resistance.

^bIn some cases, resistance genes/mechanisms were identified through WGS.