Antibacterial and Antibiofilm Activities of Nonpolar Extracts of Allium stipitatum Regel. against Multidrug Resistant Bacteria

Abstract

The present study assessed the in vitro antibacterial and antibiofilm potential of hexane (ASHE) and dichloromethane (ASDE) extracts of Allium stipitatum (Persian shallot) against planktonic cells and biofilm structures of clinically significant antibiotic resistant pathogens, with a special emphasis on methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and emerging pathogens, Acinetobacter baumannii and Stenotrophomonas maltophilia. Antibacterial activities were determined through disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill kinetics, and electron microscopy. Antibiofilm activity was assessed by XTT [2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide] reduction assay and by confocal laser scanning microscopy (CLSM). The zone of inhibition ranged from 13 to 33 mm, while the MICs and MBCs ranged from 16 to 1024 μg mL−1. Both ASHE and ASDE completely eradicated overnight cultures of the test microorganisms, including antibiotic resistant strains. Time-kill studies showed that the extracts were strongly bactericidal against planktonic cultures of S. aureus, MRSA, Acinetobacter baumannii, and S. maltophilia as early as 4 hours postinoculation (hpi). ASHE and ASDE were shown to inhibit preformed biofilms of the four biofilm phenotypes tested. Our results demonstrate the potential therapeutic application of ASHE and ASDE to inhibit the growth of gram-positive and gram-negative biofilms of clinical significance and warrant further investigation of the potential of A. stipitatum bulbs against biofilm-related drug resistance.

Antibacterial and Antivirulence Activity of Glucocorticoid PYED-1 against Stenotrophomonas maltophilia

“…At the concentrations tested in biofilm assay, PYED-1 did not affect planktonic growth (data not shown). Several studies demonstrated that novel classes of antimicrobial compounds inhibit S. maltophilia biofilm formation [28][29][30][31][32][33]. In further support of this, our results showed that PYED-1 at 64 µg/mL significantly inhibited S. maltophilia biofilm formation on a polystyrene abiotic surface.…”

Investigating Ghanaian Allium Species for Anti-Infective and Resistance-Reversal Natural Product Leads to Mitigate Multidrug-Resistance in Tuberculosis

“…For example, the biofilm inhibition properties of A. sativum, A. stipitatum , A . orientale and A. porrum have been documented [ 19 , 20 , 21 , 22 ]. The inhibition of bacterial efflux pumps has also been suggested as a strategy to inhibit biofilm formation [ 23 ].…”

Bioactive 2-(Methyldithio)Pyridine-3-Carbonitrile from Persian Shallot (Allium stipitatum Regel.) Exerts Broad-Spectrum Antimicrobial Activity

“…In our earlier study, we identified dichloromethane extract of Allium stipitatum or Persian shallot, popularly known as “Mooseer”, a wild edible plant mostly found in the cold mountains of central, south, and western Iran, some provinces of Turkey, and central Asia, to exhibit strong antimicrobial and wound-healing activity [20,21,22,23,24]. Pyridine- N -oxide alkaloids and analogs of disulfides from A. stipitatum were reported to possess moderate to strong antibacterial activity against MDR S. aureus , Mycobacterium tuberculosis , Escherichia coli , and Klebsiella and Proteus species [25,26].…”