Development of a clinically feasible translational medical approaches in the treatment of Pseudomonas aeruginosa and Acinetobacter baumannii persistent biofilm infections.
Authors:   , Wannigama Dhammika 
Published: September 2023

Despite strengthened antimicrobial therapy, biofilm infections of Pseudomonas aeruginosa and Acinetobacter baumannii are associated with poor prognosis and limited therapeutic options. Assessing antibiotics on planktonic bacteria can result in failure against biofilm infections. Currently, antibiotics to treat biofilm infections are administered empirically, usually without considering the susceptibility of the biofilm objectively before beginning treatment. For effective therapy to resolve biofilm infections it is essential to assess the efficacy of commonly used antibiotics against biofilms. Here, we offer a robust and simple assay to assess the efficacy of antibiotics against biofilms. In the present work, we carefully optimized the incubation time, detection range, and fluorescence reading mode for resazurin-based viability staining of biofilms in 96-well-plates and determined minimal biofilm eradication concentrations (MBECs) for P. aeruginosa and A. baumannii isolates from patients with chronic infection. By applying this assay, we demonstrated that antibiotic response patterns varied uniquely within the biofilm formation of various clinical samples. MBEC-50 and 75 have significant discriminatory power over minimal inhibitory concentrations for planktonic suspensions to differentiate the overall efficiency of an antibiotic to eradicate a biofilm. The present assay is an ideal platform on which to assess the efficacy of antibiotics against biofilms in vitro to pave the way for more effective therapy.
In-vitro characterization and evaluation of novel peptide mediated therapeutic approach in the treatment of biofilm infections by Pseudomonas aeruginosa, Haemophilus influenzae and Acinetobacter baumannii
The community behavior of bacterial biofilm infections may contribute towards enhanced disease pathogenesis. The consequently high mortality/morbidity rates associated to community and hospital-acquired pneumonia, ventilator-associated pneumonia, chronic obstructive pulmonary disease, cystic fibrosis, asthma, and bronchitis in conjunction with the global crisis of antibiotic resistance has promoted the search for novel therapeutic strategies to fight biofilm infections in the lung. The action of 17 novel anti-biofilm peptide candidates were firstly evaluated against clinical isolates of P. aeruginosa, A. baumannii and nontypeable H. influenzae via a high-throughput plate-based assay, coupled with confocal microscopy using live/dead bacteria staining. The ability of candidate peptides to eliminate biofilm on human primary airway epithelial cell cultures derived from children with CF were assessed using an air-liquid interface (ALI) cell culture biofilm model together with GFP tag bacteria.  Six candidate peptides (HDP- 25, 26, 43, 101, 102, and 103) were active at eradicating P. aeruginosa, A. baumannii and nontypeable H. influenzae biofilms at relatively low concentrations (16-128μg/ml). High doses of current conventional antibiotics (512-1024μg/ml) were unable to eradicate these biofilms. HDP 102 was the most potent peptide, driving >90% bio-volume reduction in airway epithelial cells and a 74% reduction of bacterial attachment to these cells. These findings highlight the potential of host defence peptides as a novel option to treat chronic bacterial biofilm infections in lung. Insights gained through this work may offer solutions for targeted approaches to treat bacterial biofilms and improve the outcome of patients with chronic lung infections.