Title : Novel antibiotic adjuvant exerts potent antimicrobial activity against MRSA and synergistically restores colistin activity in MDRO
Abstract:
Background: The rise in global burden of antimicrobial resistance (AMR) critically threatens human health. Multidrug resistant organisms (MDROs) are causing healthcare and community-acquired infections. In 2019, AMR of pathogens such as Escherichia coli (E .coli) and Staphylococcus aureus (S. aureus) were associated with 3.57 million deaths globally. AMR harboured by MDROs in particular affects last resort antibiotics’ activity. There is a dire need for novel antibiotic adjuvants that can restore the activity of current antibiotics in MDROs.
Aim: The aim of this study is to investigate the antimicrobial activity of the novel antibiotic adjuvant (IL) alone or in combination with existing antibiotics to restore their effect against MDRO.
Method: The bacterial strains investigated are S. aureus, methicillin resistant staphylococcus aureus (MRSA), mcr-1 encoding Colistin resistant and sensitive E. coli. Bacterial growth curves were monitored for 4 hours and overnight in presence and absence of IL with or without ceftriaxone or colistin for MRSA and E. coli respectively. Various doses of IL were initially tested to identify the minimal inhibitory concentration.
Results: The novel antibiotic adjuvant IL exerted antimicrobial activity and inhibited the growth of S. aureus and MRSA in presence or absence of Ceftriaxone (10 µg/ml). The inhibitory effect was observed during the bacterial growth curve and remained highly significant after overnight incubation. In contrast, IL adjuvant alone did not inhibit E. coli strains’ growth but exerted significant synergistic activity with colistin (10 µg/ml). The synergy of IL and Colistin inhibited E. coli strains encoding mcr-1 as well as those sensitive to Colistin. Taken together that data suggest that the novel antibiotic adjuvant IL can exert bactericidal activity and restore Colistin action against MDRO.
Conclusion: Novel antibiotic adjuvant IL alone possesses bactericidal activity against MRSA, whereas in combination with Colistin IL exerts synergistic activity against resistant E. coli strains.
