TABLE 2.

Disk susceptibility of host strain, clones, and S. marcescens parent strain^a

Antibiotic	Zone diam (mm) for:
	E. coli NM522-pTZ19	SCH909	pGM172	pST2
Neomycin	19	8	18	18
Kanamycin	24	6	10	26
Tobramycin	22	7	10	24
5′-Episisomicin	22	12	12	22
Gentamicin	25	8	12	24
Amikacin	26	22	22	26
Isepamicin	30	26	28	30
Netilmicin	26	18	14	26
2′-N-Ethylnetilmicin	30	12	12	30
Apramycin	28	28	28	30
6′-N-Ethylnetilmicin	24	26	30	28
Fortimycin A	30	6	30	30

^aDisk susceptibility data show a typical AAC(6′)-II profile for the clone of the entire fusion protein but not for that of the ant(3")-Ii moiety. The sequence of the ant(3")-Ii gene is 84% similar to those of the known ant(3")-Ia gene from Tn21 and ant(3")-Ib from pSa. aac(6′)-IId is a point mutation of aac(6′)-Ib resulting in the amino acid change L119→S, which changes the specificity from Ak^r Gm^s to Ak^s Gm^r.