Drug Synergistic Effects of Coriandrum Sativum, Piperacillin, and Tazobactam Against Biofilms of Thioredoxin-a Protein Mutant Strains of Acinetobacter baumannii
Acinetobacter baumannii (AB) is responsible for most of nosocomial infections reported by CDC. AB contaminates hospital materials and causes infections of soft tissues. AB infections are treated with antibiotics. Unfortunately, AB's isolates are multidrug resistance (MDR) against antimicrobials; in part due to biofilm formation facilitated by the Thioredoxin (Trx) system. As such, biofilms of two wildtype (WT) and their Thioredoxin-A (ΔTrx-A) AB strains were quantified experimentally and predicted theoretically in the presence of three antibiotics; Coriandrum sativum (CS), piperacillin (PIP), and tazobactam (TAZ). Contact angles and electrophoretic mobilities were used to quantify bacterial surface tensions and surface potentials, respectively. Prior to any treatment, all strains were hydrophilic. Upon treatment with TAZ at minimum inhibitory concentration (MIC), cells became hydrophobic. When the total energies acting between AB strains and polyvinyl chloride (PVC), polystyrene latex (PSL), and polydimethylsiloxane (PDMS) were predicted, no energy barriers to interactions with PSL or PVC in the presence or absence of antibiotics were evident for all strains. In comparison, interactions were only favorable to PDMS in the absence of antibiotics. These findings clarify why AB can easily contaminate hospital materials. Experimentally, our results indicated that TAZ and TAZ-CS were largely effective against growth of AB through modulations to hydrophobicities, while treatment with PIP was ineffective. These findings suggest that TAZ should be explored as an antibiotic to be used individually against AB infections. Finally, the four investigated AB strains varied in all their properties and interactions, suggesting that antibiotic treatments should be optimized per strain.