Antibiofilm Potential of Coelomic Fluid and Paste of Earthworm Pheretima posthuma (Clitellata, Megascolecidae) against Pathogenic Bacteria

Antibiotic drug resistance is a global public health issue that demands new and novel therapeutic molecules. To develop new agents, animal secretions or products are used as an alternative agent to overcome this problem. In this study, earthworm (Pheretima posthuma) coelomic fluid (PCF), and body paste (PBP) were used to analyze their effects as antibiofilm agents against four bacterial isolates MH1 (Pseudomonas aeruginosa MT448672), MH2 (Escherichia coli MT448673), MH3 (Staphylococcus aureus MT448675), and MH4 (Klebsiella pneumoniae MT448676). Coelomic fluid extraction and body paste formation were followed by minimum inhibitory concentrations (MICs), biofilm formation time kinetics, and an antibiofilm assay, using heat and cold shock, sunlight exposure auto-digestion, and test tube methods. The results showed that the MIC values of PCF and PBP against S. aureus, P. aeruginosa, K. pneumoniae, and E. coli bacterial isolates ranged from 50 to 100 μg/mL, while, the results related to biofilm formation for P. aeruginosa, S. aureus, and K. pneumoniae strains were observed to be highly significantly increased (p < 0.005) after 72 h. E. coli produced a significant (p < 0.004) amount of biofilm after 48 h. Following time kinetics, the antibiofilm activity of PCF and PBP was tested at different concentrations (i.e., 25–200 μg/mL) against the aforementioned four strains (MH1–MH4). The findings of this study revealed that both PBP (5.61 ± 1.0%) and PCF (5.23 ± 1.5%) at the lowest concentration (25 μg/mL) showed non-significant (p > 0.05) antibiofilm activity against all the selected strains (MH1-MH4). At 50 μg/mL concentration, both PCF and PBP showed significant (p < 0.05) biofilm inhibition (<40%) for all isolates. Further, the biofilm inhibitory potential was also found to be more significant (p < 0.01) at 100 μg/mL of PCF and PBP, while it showed highly significant (p < 0.001) biofilm inhibition at 150 and 200 μg/mL concentrations. Moreover, more than 90% biofilm inhibition was observed at 200 μg/mL of PCF, while in the case of the PBP, <96% biofilm reduction (i.e., 100%) was also observed by all selected strains at 200 μg/mL. In conclusion, earthworm body fluid and paste have biologically active components that inhibit biofilm formation by various pathogenic bacterial strains. For future investigations, there is a need for further study to explore the potential bioactive components and investigate in depth their molecular mechanisms from a pharmaceutical perspective for effective clinical utilization.