Biofilm formation occurs in suboptimal and hostile environmental conditions, where microorganisms secrete a sticky extracellular substance as a protective mechanism. Antibiotic therapy is a primary means of biofilm suppression and eradication. However, antibiotics have a difficult time penetrating biofilm and reaching the bacteria in the center of biofilm structures. Little is known about which antibiotics are truly effective at penetrating biofilm structures and eradicating. In this research, multiple antibiotics such as ampicillin, amikacin, and tetracycline are tested against a Bacillus subtilis -based biofilm. This study relates antibiotic concentration to its effectiveness against different stages of biofilm development by measuring the minimum inhibitory concentration (MIC). As expected, the MIC varied with the antibiotic used, with each requiring distinct concentrations to suppress and eradicate biofilms. Importantly, we found that larger biofilm clusters, formed after 7–9 h of growth, exhibited significantly higher resistance compared to early-stage biofilms. These findings advance our understanding of antibiotic efficacy against biofilms of varying size and maturity and carry implications for both medical treatment strategies and bioengineering applications.
Stanley et al. (Sun,) studied this question.