Effects of repeated culture in sub-inhibitory concentrations of ciprofloxacin on resistance and genetic characteristics of an ocular Pseudomonas aeruginosa isolate

Akter, Tanzina; Khan, Mahjabeen; Stapleton, Fiona; Willcox, Mark

doi:10.1007/s11274-026-05105-7

Table 1 Mutations associated with ciprofloxacin resistance acquired by PA123 during passages with and without exposure of ciprofloxacin

From: Effects of repeated culture in sub-inhibitory concentrations of ciprofloxacin on resistance and genetic characteristics of an ocular Pseudomonas aeruginosa isolate

Passage	MIC	Sub-MIC	Effect	Gene	Product	Mutation status
Growth in sub-MIC ciprofloxacin
P1	1	0.5	Leu240fs	mexS	Oxidoreductase MexS	✦ Appeared at P1; maintained through P31
P4	2	0.5	Val29Gly	GNQ09_02850	Sigma-70 family RNA polymerase sigma factor	✧ Appeared at P4; not maintained (absent from P7 onwards)
P4	2	0.5	Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P7	4	1	Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P9	8	2	Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Appeared at P9; maintained through P31
			Thr83Ile	gyrA	DNA gyrase subunit A	✧ Appeared at P9; not maintained (absent from P10 onwards)
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P10	16	4	Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Maintained
			Ala51Val	gyrA	DNA gyrase subunit A	✧ Appeared at P10; not maintained (absent from P12 onwards)
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P12	32	8	Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Maintained
			Asp87Tyr	gyrA	DNA gyrase subunit A	✦ Appeared at P12; maintained through P31
			Ala570dup	gyrA	DNA gyrase subunit A	✦ Appeared at P12; maintained through P31
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P15	64	16	His137fs	GNQ09_05810	Hypothetical protein	✦ Appeared at P15; maintained through P31
			Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Maintained
			Asp87Tyr	gyrA	DNA gyrase subunit A	✦ Maintained
			Ala570dup	gyrA	DNA gyrase subunit A	✦ Maintained
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P18	64	32	His137fs	GNQ09_05810	Hypothetical protein	✦ Maintained
			Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Maintained
			Asp87Tyr	gyrA	DNA gyrase subunit A	✦ Maintained
			Ala570dup	gyrA	DNA gyrase subunit A	✦ Maintained
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
Growth in absence of any ciprofloxacin
P19	64	0	His137fs	GNQ09_05810	Hypothetical protein	✦ Maintained
			Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Maintained
			Asp87Tyr	gyrA	DNA gyrase subunit A	✦ Maintained
			Ala570dup	gyrA	DNA gyrase subunit A	✦ Maintained
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P26	64		His137fs	GNQ09_05810	Hypothetical protein	✦ Maintained
			Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Maintained
			Asp87Tyr	gyrA	DNA gyrase subunit A	✦ Maintained
			Ala570dup	gyrA	DNA gyrase subunit A	✦ Maintained
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
P31	64		His137fs	GNQ09_05810	Hypothetical protein	✦ Maintained
			Arg342His	GNQ09_09635	EAL domain-containing protein	✦ Maintained
			Asp87Tyr	gyrA	DNA gyrase subunit A	✦ Maintained
			Ala570dup	gyrA	DNA gyrase subunit A	✦ Maintained
			Leu240fs	mexS	Oxidoreductase MexS	✦ Maintained
Changes to PA123 during growth without ciprofloxacin (control)
P18C	1	0	Pro270Gln	tagH	Type VI secretion system-associated FHA domain protein TagH	Background mutation; not resistance-related
P31C			Pro270Gln	tagH	Type VI secretion system-associated FHA domain protein TagH	Background mutation; not resistance-related
P31C			Arg48Pro	GNQ09_25310	DUF692 family protein	Background mutation; not resistance-related

fs frameshift mutation, dup duplication, ✦ mutation appeared and was maintained in all subsequent passages;✧ mutation appeared transiently and was not maintained in subsequent passages; P ciprofloxacin-exposed passage, C antibiotic-free control passage

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