Dual Effect Against Foodborne Salmonella Isolates: Antibacterial and Antibiofilm Efficacy of Different Concentrations of Extracts from Cocos nucifera (L.) and Elettaria cardamomum (L.) Maton

This study investigates the antibacterial and antibiofilm effect of ethyl acetate and methanolic extracts of Coconut kernel/testa and Cardamom seed pods against both typical Salmonella isolates that do not ferment lactose (Lac-) and the atypical group that can ferment lactose (Lac+). Both plant extracts, including ethyl acetate and methanolic fractions, demonstrated good antibacterial activity against typical and atypical resistant Salmonella isolates, with ethyl acetate fractions of both plants exhibiting the most effective results against planktonic cells, in which ethyl acetate fraction of Cardamom seed pods showed a minimum inhibitory concentration (MIC) of 5 mg/ml against potential Extended-spectrum β-lactamase (ESBL                         (CTX-M))-producing Lac+ isolate. While the ethyl acetate fraction of Coconut kernel/testa scored an MIC of 15 mg/ml against the multidrug-resistant (MDR), potential ESBL (CTX-M)-producing Lac- isolate.

The highest bactericidal activity was observed with the Cardamom methanolic fraction against the Lac- Salmonella sample with a minimum bactericidal concentration (MBC) of 25 mg/ml. Biofilm formation ability by the Lac+ isolate was significantly diminished by the methanolic fraction of Coconut kernel/testa at a sub-minimum inhibitory concentration (SMIC) of 25 mg/ml. Likewise the methanolic fraction of Cardamom also exhibited a noteworthy reduction in biofilm formation, with a significant impact observed at 5 mg/ml of  SMIC.