Effects of a previously selected antibiotic resistance on mutations acquired during development of a second resistance in Escherichia coli

Table 5 Mutations associated with resistance to tetracycline in strains with a previously acquired resistance to amoxicillin, enrofloxacin, or kanamycin

Gene product	Gene	Mutation	Pop. frequency	Strains
Multidrug efflux pump membrane fusion lipoprotein/multidrug efflux pump RND permease	acrA/acrB*	5′ UTR (Del 485,695–711)	0.77	A_1/4
Multidrug efflux pump RND permease	*acrB*	V139F	1	A_1/4, E_4/4
Multidrug efflux pump RND permease	*acrB*	S665A	1	A_1/4
Transcriptional regulator	*acrR*	I45L	0.97	K_1/1
		P85Q	1	A_3/4, K_1/4
		E130K	1	K_1/1
		R442Q	1	K_1/1
Crotonobetainyl-CoA reductase	caiA	C154A, F155P, I156T, T157P, S158R, S159 T, A160S, Y161W, Del T162-R380	1	E_1/4
Endochitinase	chiA	W702R	1	K_1/1
Membrane associated sensor kinase	envZ	P247S	0.24–0.95	A_1/4, K_1/1
3-ketoacyl-CoA thiolase	fadI	L246 L	1	E_2/4
Peptidoglycan DD-transpeptidase	ftsI	A513S	1	K_1/1
DNA-binding transcriptional repressor	marR	Ins C after A1619472 (FS118)	1	A_1/4
ABC transporter family protein	mdlB	A16A	1	A_2/4
ABC transporter family protein	mlaA	Del F42-N43	0.93	K_1/1
Murein tripeptide ABC transporter periplasmic binding protein	mppA	F244F	1	K_1/1
Mismatch repair protein	mutL	W390 L	0.1	E_1/4
Outer membrane porin F	*ompF*	Ins 7 nt after G986771 (FS71)	0.04	E_1/4
Truncated RNase PH	rph	Del R676	1	E_1/4
RNA polymerase subunit β’	*rpoC*	Del T208-K213	1	E_1/4
DNA-binding transcriptional dual regulator	soxR	T145S, G146 T, A147L, R148A, L149G, L150R, Del E151-N155	1	E_1/4
DNA-binding transcriptional dual regulator	soxS	S2F	0.98–1	E_3/4
Bifunctional (p) ppGpp synthase/hydrolase	spoT	Ins C after T3815879 (FS223)	1	E_1/4
DNA-binding transcriptional activator	ybaO	T33P	1	E_1/4

Numbers shown indicate frequency of mutation in population. Del = deletion, Ins = insertion, underlined letters and numbers indicate nucleotides and their genomic position. Population frequency indicates the mutational frequency in the sequenced population. Strains indicates the prevalence of a mutation within different replicates. A: population with previously acquired resistance to amoxicillin, E: population with previously acquired resistance to enrofloxacin, K: population with previously acquired resistance to kanamycin. X/Y: X indicates number of replicates with particular mutation, Y indicates total number of replicates that were sequenced. Mutations associated with resistance in a wild-type background are shown in bold. Mutations associated with the previous resistance have been omitted from the table

ISSN: 1471-2164