Antimicrobial activities of four varieties of Capsicum annuum fruits cultivated in southeast Nigeria against multidrug-resistant and susceptible organisms

Abstract

Due to increasing drug resistance in microbial pathogens and side effects of certain antimicrobial agents, there is a need to search for cheaper, effective and less toxic novel antimicrobial agents that would overcome these disadvantages. Our study evaluated the antimicrobial activities of ethanolic extracts from four different varieties of Capsicum annuum cultivated at Nsukka viz. Capsicum annuum var. shombo, Capsicum annuum var. tatashi, Capsicum annuum var. Nsukka yellow pepper and Capsicum annuum var. atarugu, against multidrug-resistant (MDR) Listeria monocytogenes and MDR Escherichia coli, Candida albicans, Cryptococcus neoformans and Aspergillus flavus. All the varieties of Capsicum annuum fruits showed variable antimicrobial activities and were bactericidal as well as fungicidal. However, they showed fungistatic activity against Aspergillus flavus. The minimum inhibitory concentration (MIC) for MDR E. coli isolates was between 9.4 - 37.5 mg/ml, while the minimum bactericidal concentration (MBC) ranged from 18 - 37.5 mg/ml. Antibiotic susceptible E. coli isolates had MIC values between 4.7 and 37 mg/ml and MBC range between 9.4 and 37 mg/ml. Similar results were obtained for C. annuum var. tatashi and C. annuum var.  shombo with MIC range of 9.4 - 37 mg/ml and MBC range of 18 - 37 mg/ml for MDR E. coli isolates while multidrug-susceptible (MDS) E. coli isolates had MIC range of 7.8 – 18 mg/ml and MBC range of 9.4 - 31 mg/ml. The range of MIC values for L. monocytogenes observed for all the four extracts was 9.4 - 37.5 mg/ml while the MBC range was between 14.1 - 37.5 mg/ml. This study shows that Capsicum annuum has both antibacterial and antifungal activities and might be a useful source of antibiotics and food preservatives.