TABLE 3.

Topoisomerase mutations and OST in selected clinical isolates of K. pneumoniae

Isolatea	Ciprofloxacin MIC (μg/ml)	Amino acid at DNA gyrase A position:		Amino acid at topoisomerase IV position 80	OSTb
		83	87
S8	0.5	Ser→Tyr	—c	—	−
S38	2	Ser→Tyr	—	—	−
S28	4	Ser→Tyr	—	—	C, P
S29	4	Ser→Leu	Asp→Asn	—	C, P
S30	8	Ser→Tyr	—	—	C
S37	8	Ser→Tyr	—	—	C
S7	16	Ser→Tyr	—	Ser→Ile	C, P
S9	16	Ser→Tyr	Asp→Asn	Ser→Trp	−
S12	16	Ser→Ile	Asp→Asn	Ser→Ile	−
S10	32	Ser→Tyr	Asp→Asn	Ser→Arg	C
S27	32	Ser→Tyr	Asp→Asn	Ser→Ile	−
S33	32	Ser→Tyr	Asp→Asn	Ser→Ile	−
S34	32	Ser→Ile	—	Ser→Ile	−
S5	64	Ser→Tyr	Asp→Asn	Ser→Ile	C
S13	64	Ser→Tyr	Asp→Asn	Ser→Trp	C
S31	64	Ser→Tyr	Asp→Asn	Ser→Trp	−
S42	64	Ser→Tyr	—	—	−
S6	128	Ser→Tyr	Asp→Asn	Ser→Arg	C
S32	128	Ser→Tyr	—	Ser→Trp	−
S36	128	Ser→Tyr	Asp→Asn	Ser→Trp	C

^aIsolates are listed by increasing ciprofloxacin MIC.

^bC, resistant to cyclohexane; P, resistant to pentane; −, no growth in the presence of cyclohexane or pentane.

^c—, no change at specified amino acid.