TABLE 2.

Prevalence of β-lactamase types detected among 6,421 isolates from 63 study sites

Isolates that express β-lactamases	No. of sites with isolates/total no. of sites (%)	No. of positive isolates/total no. of isolates (%)	% of isolates in:
			ICUs	Non-ICUs
ESBL-producing isolates	40/63 (63)	200/6,421 (3.1)	3.4	2.6
All Enterobacteriaceae	40/63 (63)	200/4,106 (4.9)	5.6	3.6
K. pneumoniae	25/63 (40)	96/853 (11.3)	13.7	4.7
E. coli	25/63 (40)	42/1616 (2.6)	3.6	1.6
E. cloacae	19/63 (19)	25/453 (5.5)	4.3	14.3
K. oxytoca	19/63 (19)	18/137 (13.1)	9.2	23
S. marcescens	3/63 (4.8)	5/306 (1.6)	0.4	8.9
P. mirabilis	3/63 (4.8)	5/359 (1.4)	3.1	0
C. amalonaticusc	2/63 (3.2)	2/15 (3.3)	18.2	NDa
C. koseri	2/63 (3.2)	2/57 (3.5)	5.3	0
E. aerogenes	2/63 (3.2)	2/189 (1.1)	0.6	3.3
Klebsiella sp.	1/63 (1.6)	1/8 (ND)	ND (1/3)	ND (0/5)
Citrobacter sp.	1/63 (1.6)	1/1 (ND)	ND (1/1)	ND
C. freundii	1/63 (1.6)	1/112 (0.9)	0	2.6
Transferable AmpC	16/63 (25)b
AmpC-producing K. pneumoniae	12/63 (19)	28/853 (3.3)	3.5	2.6
K. pneumoniae isolates coproducing ESBLs and imported AmpCs	7/63 (11)	17/853 (2.0)	2.6	0.4
Class A carbapenemase-producing isolates	3/63 (4.8)	3/6,421 (0.05)	7.1	0
K. pneumoniae	1/63 (1.6)	1/853 (0.1)	0.16	0
E. cloacae	2/63 (3.2)	2/453 (0.4)	0.5	0
Class B or D carbapenemase-producing isolates	0/63 (0)	0/6,421 (0)	0	0

^aND, percentage not determined if less than 10 isolates in denominator.

^bAlthough the prevalence was only determined for AmpC-producing K. pneumoniae isolates, additional transferable AmpC β-lactamases were also detected in some ICU isolates of K. oxytoca (n = 5), P. mirabilis (n = 5), and Salmonella (n = 2), but prevalence data could not be determined because not all isolates of these organisms were investigated for AmpC production.

^cCitrobacter amalonaticus.