Combinatorial effects of antibiotics and enzymes against dual-species Staphylococcus aureus and Pseudomonas aeruginosa biofilms in the wound-like medium

Abstract

Bacterial biofilms are one of the major issues in the treatment of chronic infections such as chronic wounds, where biofilms are typically polymicrobial. The synergy between species can occur during most polymicrobial infections, where antimicrobial resistance enhances as a result. Furthermore, self-produced extracellular polymeric substance (EPS) in biofilms results in a high tolerance to antibiotics that complicates wound healing. Since most antibiotics fail to remove biofilms in chronic infections, new therapeutic modalities may be required. Disruption of EPS is one of the effective approaches for biofilm eradication. Therefore, degradation of EPS using enzymes may result in improved chronic wounds healing. In the current study, we investigated the efficacy of trypsin, β-glucosidase, and DNase I enzymes on the degradation of dual-species biofilms of Pseudomonas aeruginosa and Staphylococcus aureus in a wound-like medium. These species are the two most common bacteria associated with biofilm formation in chronic wounds. Moreover, the reduction of minimum biofilm eradication concentration (MBEC) of meropenem and amikacin was evaluated when combined with enzymes. The minimum effective concentrations of trypsin, β-glucosidase, and DNase I enzymes to degrade biofilms were 1 μg/ml, 8 U/ml, and 150 U/ml, respectively. Combination of 0.15 μg/ml trypsin and 50 U/ml DNase I had a significant effect on S. aureus-P. aeruginosa biofilms which resulted in the dispersal and dissolution of all biofilms. In the presence of the enzymatic mixture, MBECs of antibiotics showed a significant decrease (p < 0.05), at least 2.5 fold. We found that trypsin/DNase I mixture can be used as an anti-biofilm agent against dual-species biofilms of S. aureus-P. aeruginosa.

Dissolution of Biofilm Secreted by Three Different Strains of Pseudomonas aeruginosa with Bromelain, N-Acetylcysteine, and Their Combinations

“…Bacterial colonization on surgical implants may be treated with bactericides; however, the presence of biofilms presents a barrier to the treatment, mainly because they impede drug penetration and act as reservoirs for bacterial colony formation with protection from the host's innate immune system. Hence, the removal of the biofilm alone may eradicate the bacterial colonies, since they will become more susceptible to the immune system, while subsequent treatment with bactericides may result in complete eradication [42].…”

We Are One: Multispecies Metabolism of a Biofilm Consortium and Their Treatment Strategies

“…Combination therapies, comprising of a matrix degrading agent and an antibacterial agent, have also shown efficacy in dealing with biofilm infections. An antibiotic – Dnase1 (degrades extracellular DNA) combination therapy was shown to disrupt the EPS, enhancing the antibiofilm effects of antibiotics in clearing bacterial single-species biofilms ( Fanaei Pirlar et al, 2020 ). A combination of DNase1 and plant-based essential oils also disrupted the biofilm of methicillin-resistant S. aureus ( Rubini et al, 2018 ).…”

The Two Weapons against Bacterial Biofilms: Detection and Treatment

“…For instance, combination of DNase I (that denatures the eDNA) and dispersin B was found to inhibit staphylococcal skin colonization in an in vivo model [ 156 ]. Other studies were able to demonstrate the efficacy of combining biofilm-degrading enzymes with antimicrobial agents [ 157 , 158 , 159 ]. This is the case of meropenem and amikacin antibiotics that were combined with a trypsin/DNase I mixture against S. aureus – P. aeruginosa dual strain biofilms.…”

“…This is the case of meropenem and amikacin antibiotics that were combined with a trypsin/DNase I mixture against S. aureus – P. aeruginosa dual strain biofilms. The minimal biofilm eradication concentration (MBECs) values of both antibiotics were shown to decrease significantly when combined with the enzyme mixture [ 159 ].…”

“…Although being recognized as a potential relevant treatment in the fight against biofilms, the use of enzymes that degrade biofilm matrix is still very limited due to problems such as high cost associated with their production, handling procedures, and difficult large-scale production [ 159 ].…”