TABLE 1.

Species and resistance mechanism distribution of the 200 challenge strains tested on the two chromogenic media

Group and resistance mechanism	Species	No. of isolates growing on:		No. of isolates tested
		BM	OX
Enterobacteria
ESBL	E. coli	45	45	45
	K. pneumoniae	22	22	22
	E. aerogenes	20	20	20
	E. cloacae	5	5	5
	C. freundii	3	3	3
	K. oxytoca	3	3	3
Carbapenemase	K. pneumoniae	2	2	2
AmpC cephalosporinase	E. coli	9	9	12
	E. aerogenes	11	11	11
	C. freundii	6	5	6
	M. morganii	2	3	3
	K. pneumoniae	2	2	2
K1-OXY penicillinase	K. oxytoca	8	8	8
OXA-30 penicillinase	E. coli	3	3	6
Susceptible (wild type)	E. coli	0	0	4
	K. pneumoniae	0	0	2
	E. aerogenes	0	0	1
	K. oxytoca	0	0	1
Nonfermenters	P. aeruginosa	21	20	21
	S. maltophilia	13	2	15
	A. baumannii	8	7	8