TABLE 3.

Distribution of aacA4 and 16S rRNA methylase genes among the 218 amikacin-resistant isolates of Enterobacteriaceae collected from a university hospital in South Korea between 1995 and 2006

Species	No. of strains carrying the following amikacin resistance gene(s):						Total no. of strains
	aacA4 alone	armA alone	armA and aacA4	rmtB alone	rmtB and aacA4	Nonea
E. coli	5	14	14	17	1	1	52
K. pneumoniae	3	65	23	27	5		123
Klebsiella spp.		1	1				2
E. cloacae	4	17	2				23
Enterobacter spp.	1	5	1				7
S. marcescens			6				6
C. freundii			3	1			4
M. morganii		1					1
Total no. of strains	13	103	50b	45	6c	1	218

^aNo gene was detected.

^bThirteen of 50 strains transferred the armA gene alone to the recipient E. coli strain, as determined by the conjugation assay.

^cAll six strains transferred the rmtB gene alone to the recipient E. coli strain, as determined by the conjugation assay.