Proteomics Analysis Reveals a Potential Antibiotic Cocktail Therapy Strategy for Aeromonas hydrophila Infection in Biofilm

Antibiotic fitness and acquired resistance
are the two critical
factors when bacteria respond to antibiotics, and the correlations
and mechanisms between these two factors remain largely unknown. In
this study, a TMT-labeling-based quantitative proteomics method was
used to compare the differential expression of proteins between the
fitness and acquired resistance to chlortetracycline in Aeromonas hydrophila biofilm. Bioinformatics analysis
showed that translation-related ribosomal proteins, such as 30s ribosome
subunits, increased in both factors; fatty acid biosynthesis related
proteins, such as FabB, FabD, FabG, AccA, and AccD, increased in biofilm
fitness, and some pathways (including propanoate-metabolism-related
protein, such as PrpB, AtoB, PflB, AcsA, PrpD, and GabT) displayed
decreased abundance in acquired resistance biofilm. The varieties
of selected proteins involved in fatty acid biosynthesis and propanoate
metabolism were further validated by q-PCR assay or Western blotting.
Furthermore, the antibiotic-resistance-function assays showed that
fatty-acid biosynthesis should be a protective antibiotics-resistance
mechanism and a cocktail of chlortetracycline and triclosan, a fatty-acid-biosynthesis
inhibitor, exhibited more efficient antimicrobial capability than
did each antibiotic individually on biofilm, specifically on chlortetracycline-sensitive
biofilm. We therefore demonstrate that the up-regulation of fatty acid
biosynthesis may play an important role in antibiotic resistance and
suggest that a cocktail of chlortetracycline and triclosan may be
a potential cocktail therapy for pathogenic infections in biofilm.