Anti-bacterial mechanism of baicalin-tobramycin combination on carbapenem-resistant Pseudomonas aeruginosa

Table 1 Polymerase chain reaction primers used

Gene	Sequence	Tm (℃)
VIM-1	RTF:GTTTG GTCGC ATATC GCAAC	60
VIM-2	RTR:AATGC GCAGC ACCAG GATAG	60
IMP-1	RTF:GAAGG YGTTT ATGTT CATAC	60
IMP-2	RTR:GTAMG TTTCA AGAGT GATGCC	60
OprD-1	RTF:ATGAA AGTGA TGAAG TGGAG CG	60
OprD-2	RTR:TTACA GGATC GACAG CGGAT AG	60
algD-1	RTF:CGAGAAGTCCGAACGCCACAC	60
algD-2	RTR:ATCGGCGGGAAGTCGTA	60
pslA-1	RTF:GGCCTGTTTCCCTACCT	60
pslA-2	RTR:GCGGATGTCGTGGTTG	60
lasR-1	RTF:GAAGATGGCGAGCGACCTTGGATTC	60
lasR-2	RTR:CTCGTGCTGCTTTCGCGTCTGGTAG	60
16sRNA	RTF:ACTCCTACGGGAGGCAGCAG	60
16sRNA	RTR:ATTACCGCGGCTGCTGG	60

Table 2 Differences in relative expression levels between related genes

Index	Group	Assay name	∆Ct	∆∆CT	Fold change	Up/down
1	Baicalin	VIM	15.94	2.63	0.16	Down
	Tobramycin	VIM	16.81	3.50	0.09	Down
	Baicalin + tobramycin	VIM	18.09	4.78	0.04	Down
	Control	VIM	13.31		1.00
2	Baicalin	IMP	13.73	2.58	0.17	Down
	Tobramycin	IMP	13.49	2.34	0.20	Down
	baicalin+ tobramycin	IMP	13.56	2.41	0.19	Down
	Control	IMP	11.15		1.00
3	Baicalin	OprD2	10.13	-0.11	1.08	Up
	Tobramycin	OprD2	11.40	1.16	0.45	Down
	Baicalin + tobramycin	OprD2	9.64	-0.60	1.52	Up
	Control	OprD2	10.24		1.00
4	Baicalin	algD	1.88	0.37	0.77	Down
	Tobramycin	algD	2.23	0.72	0.61	Down
	Baicalin + tobramycin	algD	3.44	1.93	0.26	Down
	Control	algD	1.51		1.00
5	Baicalin	pslA	3.29	0.63	0.65	Down
	Tobramycin	pslA	3.11	0.45	0.73	Down
	Baicalin + tobramycin	pslA	3.17	0.51	0.70	Down
	Control	pslA	2.66		1.00
6	Baicalin	lasR	1.18	-0.09	1.06	Up
	Tobramycin	lasR	1.43	0.16	0.90	Down
	Baicalin + tobramycin	lasR	1.66	0.39	0.76	Down
	Control	lasR	1.27

Table 3 Pearson correlation between the amount of biofilm formation and the expression of related genes

	RB	VIM	IMP	OprD2	algD	pslA	lasR
RB	1	0.862	0.373	-0.3548	0.178	0.223	-0.001
VIM		1	0.761	0.287	0.319	0.1321	0.007
IMP			1	-0.811		0.0505	0.471
OprD2				1	0.3155	0.683	0.214
algD					1	0.4772	0.691
pslA						1	0.935
lasR							1

Significant correlations were found between biofilm volume and VIM (P < 0.01), IMP and VIM (P < 0.05), OprD2 and IMP (P < 0.05), pslA and OprD2 (P < 0.01) and lasR and pslA (P < 0.01).

Table 4 Baseline characteristics of patients with carbapenem-resistant Pseudomonas aeruginosa bloodstream infection

Clinical variables	Patients (n = 57)
Age (yr)	58 ± 23
Length of hospital stay before infection (d)	24 ± 5
Combeites
Blood system disease	12
Solid tumor	11
Admission to intensive care unit	36
APACHE II	19 ± 7
TTP	18 ± 6
Albumin < 30 g/L	23
Underwent surgery	18
Invasive mechanical ventilation	12
Antibiotic application ≥ 7 d	37
Outcome
Sepsis and shock	22
Death	17

Table 5 Multivariate logistic regression analysis of death group and survival group in Pseudomonas aeruginosa bloodstream infection

Clinical variables	Odds ratio	95%CI	P value
APACHE II	1.27	1.02-1.58	0.033
Albumin < 30 g/L	6.72	1.18-32.57	0.035
Underwent surgery	3.56	1.03-6.22	0.048
The baicalin in combination with tobramycin	0.56	0.42-0.73	0.027