A Comparison of Antibiotics' Resistance Patterns of E. coli and B. Subtilis in their Biofilms and Planktonic Forms.

Background: A biofilm refers to a community of microbial cells that adhere to surfaces that are surrounded by an extracellular polymeric substance. Bacteria employ various defence mechanisms, including biofilm formation, to enhance their survival and resistance against antibiotics.

Objective: The current study aims to investigate the resistance patterns of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) in both biofilms and their planktonic forms.

Methods: E. coli and B. subtilis were used to compare resistance patterns in biofilms versus planktonic forms of bacteria. An antibiotic disc diffusion test was performed to check the resistance pattern of biofilm and planktonic bacteria against different antibiotics such as penicillin G, streptomycin, and ampicillin. Biofilm formation and its validation were done by using quantitative (microtiter plate assay) and qualitative analysis (Congo red agar media).

Results: A study of surface-association curves of E. coli and B. subtilis revealed that surface adhesion in biofilms was continuously constant as compared to their planktonic forms, thereby confirming the increased survival of bacteria in biofilms. Also, biofilms have shown high resistance towards the penicillin G, ampicillin and streptomycin as compared to their planktonic form.

Conclusion: It is safely inferred that E. coli and B. subtilis, in their biofilms, become increasingly resistant to penicillin G, ampicillin and streptomycin.