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<p>Multidrug resistance (MDR) is the ability of microorganisms, including bacteria, viruses, or parasites, to withstand the effects of multiple antimicrobial drugs that are commonly used to treat the infections they cause. As a result, these drugs become less effective or even ineffective against the pathogens. Overuse and misuse of antimicrobial agents are major contributors to MDR, leading to the frequent emergence of antibiotic-resistant strains. Therefore, there is an urgent need for innovative strategies in drug discovery and development to combat antimicrobial resistance (AMR). Quorum sensing (QS) is a sophisticated bacterial communication system that regulates gene expression in response to population density. When signalling molecules bind to specific receptors, bacteria express genes involved in virulence factors such as biofilm formation, motility, and sporulation. This study aimed to identify bacterial isolates capable of inhibiting the QS system of <i>Chromobacterium violaceum</i> and clinically relevant pathogens. A total of 66 bacterial isolates were obtained from coastal soil and water samples collected from the Gujarat coastline (Surat, Dhuvaran, Diu and Bhavnagar). Qualitative and quantitative screening identified three isolates, SB1, SB6, and SD2, with anti-QS activity against <i>C. violaceum</i> MTCC 2656. Among them, <i>Bacillus safensis</i> subsp. <i>osmophilus</i> SD2 showed the strongest activity, inhibiting violacein pigment production by 60.85 ± 5.64%. The antibiofilm activity of SD2 was further evaluated against ESKAPE pathogens. The highest inhibition was observed against <i>Pseudomonas aeruginosa</i> (40.74 ± 0.03%), followed by <i>Klebsiella pneumoniae</i> (25.09 ± 0.23%), <i>Staphylococcus aureus</i> (18.55 ± 0.22%), and <i>Escherichia coli</i> (<i>Enterobacteriaceae</i>) (17.16 ± 0.06%). The extract was less effective against <i>Enterococcus</i> spp. and <i>Acinetobacter baumannii</i> biofilms. Statistical analyses, including ANOVA, Tukey’s Honestly Significant Difference (Tukey-HSD), and the Q test, revealed significant differences in biofilm inhibition between cinnamaldehyde (the standard compound) and the SD2 extract, indicating both statistically and biologically meaningful variation in antibiofilm efficacy between the two treatments.</p>

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Anti-biofilm activity of Bacillus safensis subsp. osmophilus SD2 against multidrug resistant hospital isolates of ESKAPE group

  • 期刊论文

  • 发表日期：

    2026年1月7日

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  • Saklain Mustak Saiyad,
  • Bhakti Bajpai,
  • Chirag Patel,
  • Siddhi D. Shah,
  • Nisha Daxini

摘要

Multidrug resistance (MDR) is the ability of microorganisms, including bacteria, viruses, or parasites, to withstand the effects of multiple antimicrobial drugs that are commonly used to treat the infections they cause. As a result, these drugs become less effective or even ineffective against the pathogens. Overuse and misuse of antimicrobial agents are major contributors to MDR, leading to the frequent emergence of antibiotic-resistant strains. Therefore, there is an urgent need for innovative strategies in drug discovery and development to combat antimicrobial resistance (AMR). Quorum sensing (QS) is a sophisticated bacterial communication system that regulates gene expression in response to population density. When signalling molecules bind to specific receptors, bacteria express genes involved in virulence factors such as biofilm formation, motility, and sporulation. This study aimed to identify bacterial isolates capable of inhibiting the QS system of Chromobacterium violaceum and clinically relevant pathogens. A total of 66 bacterial isolates were obtained from coastal soil and water samples collected from the Gujarat coastline (Surat, Dhuvaran, Diu and Bhavnagar). Qualitative and quantitative screening identified three isolates, SB1, SB6, and SD2, with anti-QS activity against C. violaceum MTCC 2656. Among them, Bacillus safensis subsp. osmophilus SD2 showed the strongest activity, inhibiting violacein pigment production by 60.85 ± 5.64%. The antibiofilm activity of SD2 was further evaluated against ESKAPE pathogens. The highest inhibition was observed against Pseudomonas aeruginosa (40.74 ± 0.03%), followed by Klebsiella pneumoniae (25.09 ± 0.23%), Staphylococcus aureus (18.55 ± 0.22%), and Escherichia coli (Enterobacteriaceae) (17.16 ± 0.06%). The extract was less effective against Enterococcus spp. and Acinetobacter baumannii biofilms. Statistical analyses, including ANOVA, Tukey’s Honestly Significant Difference (Tukey-HSD), and the Q test, revealed significant differences in biofilm inhibition between cinnamaldehyde (the standard compound) and the SD2 extract, indicating both statistically and biologically meaningful variation in antibiofilm efficacy between the two treatments.