A synthetic peptide sensitizes multi-drug resistant Pseudomonas aeruginosa to antibiotics for more than two hours and permeabilizes its envelope for twenty hours

Table 2 Post-Antibiotic Effect (PAE) and Score of Post-Antibiotic Effect-associated Permeabilization (S-PAEP) induced by P4–9

Strain	PAE^a(h)	PAEP^b (h)	Antibiotic (MIC)^c	Final concentration in μg/mL (times x MIC)	S-PAEP^d (h)
Strain	PAE^a(h)	PAEP^b (h)	Antibiotic (MIC)^c	Final concentration in μg/mL (times x MIC)	0	1	2
Ps4	1.45 + 0.02	2–3	NOV (512)	64 (1/8)	4.8 + 0.1	2.7 + 0.05	0.45 + 0.01
		2–3	FOS (512)	64 (1/8)	2.27 + 0.05	2.12 + 0.04	1.60 + 0.03
		2–3	RIF (16)	2 (1/8)	0.6 + 0.01	0.6 + 0.01	0.25 + 0.01
		2–3	ERY (128)	16 (1/8)	1.04 + 0.02	0.82 + 0.02	0.78 + 0.02
		2–3	CAZ (64)	16 (1/4)	14.24 + 0.3	14.24 + 0.3	1.56 + 0.03
		2–3	CAZ (64)	4 (1/16)	2.0 + 0.04	1.25 + 0.03	0.1 + 0.01
		2–3	CEF (1024)	512 (1/2)	0.8 + 0.02	0.7 + 0.01	0.7 + 0.01
		n.f^e	CIP (2)	0.25 (1/8)	0.7 + 0.01	< 0.25	< 0.25
PAO1	1.9 + 0.03	2–3	NOV (1024)	64 (1/16)	7.81 + 0.16	2.58 + 0.05	0.87 + 0.02
LC1–6	0.75 + 0.04	2–3	NOV (8192)	512 (1/16)	7.62 + 0.15	4.29 + 0.1	0.87 + 0.02
PAΔADD	1.2 + 0.026	2–3	CAZ (64)	16 (1/4)	4.27 + 0.1	3.42 + 0.07	3.32 + 0.07
h2Dh3	1.2 + 0.026	2–3	CAZ (64)	16 (1/4)	4.27 + 0.1	3.42 + 0.07	3.32 + 0.07

^a Post-antibiotic effect assessed by turdidimetry (Bioscreen). PAEs y S-PAEPs values are the average of three and two independent experiments, respectively, each of them performed in triplicate. Differences were analyzed by Kruskal–Wallis test followed by Mann–Whitney’s U test
^b Duration of Post-Antibiotic Effect-associated Permeabilization
^c NOV, novobiocin; FOS, fosfomycin; RIF, rifampin; ERY, erythromycin; CAZ, ceftazidime; CEF, cephalothin; CIP, ciprofloxacin. MICs (μg/mL) are in parenthesis
^d Score of Post-Antibiotic Effect-associated Permeabilization. Delay in h caused by exposure to a sub-MIC concentration of an antibiotic added at the indicated time (0 h, 1 h, 2 h) after the beginning of growth in peptide-free medium. S-PAEP was assessed by turdidimetry (Bioscreen)
^e Determination was not feasible due to resistance to antibiotic

ISSN: 1423-0127