A multicopy suppressor screening approach as a means to identify antibiotic resistance determinant candidates in Yersinia pestis

Table 1 Effect of robA_Yp overexpression on antibiotic susceptibility

	IC₅₀ (μg/ml)^a			FC^c	MIC₉₉ (μg/ml)^b			FC
Y. pestis	no plasmid	pGEM-4Z	pGEM-Rob_Yp		no plasmid	pGEM-4Z	pGEM-Rob_Yp
Ofloxacin	0.01	0.01	0.05	5	0.03	0.03	0.7	23
Ciprofloxacin	0.009	0.009	0.04	4	0.02	0.02	0.09	5
Levofloxacin	0.01	0.01	0.04	4	0.02	0.02	0.09	5
Nalidixic Acid	0.5	0.8	2	3	2	2	6	3
Chloramphenicol	0.3	0.4	0.9	2	1	1	3	3
Tetracycline	0.7	1	6	6	1	3	10	3
Doxycycline	0.4	0.5	1	2	0.6	1	3	3
Kanamycin	1	0.9	0.4	0.4	2	2	2	1
Apramycin	2	3	1	0.3	6	6	4	0.7
Streptomycin	1	2	0.8	0.4	3	3	3	1
Gentamicin	0.4	0.4	0.2	0.5	1	0.4	0.4	1
E. coli	no plasmid	pGEM-4Z	pGEM-Rob_Yp		no plasmid	pGEM-4Z	pGEM-Rob_Yp
Ofloxacin	0.03	0.04	0.09	2	0.08	0.2	0.4	2
Ciprofloxacin	0.01	0.009	0.04	4	0.05	0.08	0.2	3
Levofloxacin	0.04	0.04	0.1	3	0.2	0.2	0.4	2
Nalidixic Acid	27	26	28	1	83	100	100	1
Chloramphenicol	0.3	0.3	0.8	3	2	2	13	7
Tetracycline	0.8	0.6	2	3	3	3	10	3
Doxycycline	0.3	0.2	0.6	3	1	0.6	3	5
Kanamycin	2	1	2	2	10	6	6	1
Apramycin	3	3	4	1	21	17	21	1
Streptomycin	3	2	3	2	17	13	13	1
Gentamicin	0.9	0.6	2	3	6	5	8	2

^a IC₅₀ values were calculated from sigmoidal curves fitted to triplicate sets of dose-response data. ^b MIC₉₉ values are means of triplicates. ^c Fold change (FC) values were calculated as the ratio of the IC₅₀ or MIC₉₉ of the pGEM-Rob_Yp transformants to the IC₅₀ or MIC₉₉ of the pGEM-4Z transformants. IC₅₀, MIC₉₉, and FC values <1 and values >1 were rounded to one significant digit and to the nearest non-fractional number, respectively.

ISSN: 1471-2180