TABLE 3.

Downregulation of antibiotic targets in biofilms treated with peptide 1018^a

Gene	Mean ± SD fold change	Function	Biological role
gyrA	−4.74 ± 2.2	DNA gyrase subunit A	DNA replication
gyrB	−5.00 ± 0.45	DNA gyrase subunit B	DNA replication
pbpG	−4.53 ± 2	d-Alanyl-d-alanine endopeptidase	Cell wall
ftsI	−2.63 ± 1.0	Penicillin-binding protein 3	Cell wall
pelB	−4.83 ± 0.43	Biofilm matrix protein	Exopolysaccharide synthesis
nirS	−4.5 ± 2	Nitrite reductase precursor	Denitrification

^aResults of qRT-PCR performed on RNA extracted from flow cell biofilms. We evaluated the dysregulation of genes involved in antibiotic resistance: gyrA and gyrB are known targets of ciprofloxacin, pbpG and ftsI are involved in ceftazidime and imipenem resistance, and pelB is involved in tobramycin resistance. The gene nirS is involved in biofilm formation. We determined the fold decrease in gene expression by mature biofilms treated with 0.8 μg/ml of peptide 1018 for 24 h compared to the level of expression by untreated mature biofilms.