Antimicrobial resistance requires urgent efforts towards the discovery of active antimicrobials, and the development of strategies to sustainably produce them. Defensin and defensin-like antimicrobial peptides (AMPs) are increasingly gaining pharmacological interest because of their potency against pathogens. In this study, we expressed two AMPs: defensin-d2 derived from spinach, and defensin-like actifensin from Actinomyces ruminicola. Recombinant pTXB1 plasmids carrying the target genes encoding defensin-d2 and actifensin were generated by the MEGAWHOP cloning strategy. Each AMP was first expressed as a fusion protein in Escherichia coli, purified by affinity chromatography, and was thereafter assayed for antimicrobial activity against multidrug-resistant (MDR) pathogens. Approximately 985 µg/mL and 2895 µg/mL of recombinant defensin-d2 and actifensin, respectively, were recovered with high purity. An analysis by MALDI-TOF MS showed distinct peaks corresponding to molecular weights of approximately 4.1 kDa for actifensin and 5.8 kDa for defensin-d2. An in vitro antimicrobial assay showed that MDR Pseudomonas aeruginosa and Candida albicans were inhibited at minimum concentrations of 7.5 µg/mL and 23 µg/mL for recombinant defensin-d2 and actifensin, respectively. The inhibitory kinetics of the peptides revealed cidal activity within 4 h of the contact time. Furthermore, both peptides exhibited an antagonistic interaction, which could be attributed to their affinities for similar ligands, as deduced by peptide–ligand profiling. Moreover, both peptides inhibited biofilm formation, and they exhibited no resistance potential and low hemolytic activity. The peptides also possess the ability to permeate and disrupt the cell membranes of MDR P. aeruginosa and C. albicans. Therefore, recombinant actifensin and defensin-d2 exhibit broad-spectrum antimicrobial activity and have the potential to be used as therapy against MDR pathogens.

The root of Terminalia glaucescens, stem-bark of Mangifera indica and leaves of Mitracarpus villosus were screened for antibacterial activities against 23 carbapenem-resistant Enterobacteriaceae (CRE) isolates. The phyto-constituents of the plants were extracted by cold maceration. Disc-diffusion and broth microdilution methods were used to determine the antibacterial activity and the minimum inhibitory concentration, respectively. The sensitivity of the isolates to the methanol extracts of the plant parts was between four to eight isolates (10 -26.5 mm) including Enterobacter aerogenes, Proteus mirabilis and Escherichia coli, with the highest activity shown by Mitracarpus villosus. An overall higher activity was however observed with the ethanol extracts of the plant parts with potency on twelve to fifteen isolates (9 -18.5 mm) including Enterobacter aerogenes, Proteus mirabilis, Escherichia coli and Klebsiella pneumoniae. Generally for all methanol extracts, a constant MIC value 100 mg/ml was observed for the susceptible isolates except two Enterobacter aerogenes isolates with MIC of 1 mg/ml while the MIC value of the ethanol extracts ranged from ≤ 0.1 -100 mg/ml.

The study assessed the incidence and risk factor associated with the occurrence of carbapenem-resistant Enterobacteriaceae (CRE) among hospitalized patients at three tertiary hospitals in Southwest, Nigeria. A cross-sectional study was performed over a six-month surveillance period in the locations with a total of 300 blood and urine samples. A structured close-ended questionnaire was also administered to all subjects for review of demographics and potential risk factors. Fifty-nine isolates belonging to genera Escherichia (52.5%), Enterobacter (23.8%), Klebsiella (10.2%) and Proteus (13.6%) were isolated. All the isolates were multi-drug resistant with a notable resistance (100%) to cephalosporins and significant sensitivity to nitrofurantoin. A total of 23 isolates including Escherichia coli (n = 8), Enterobacter aerogenes (n = 9), Klebsiella pneumoniae (n = 1) and Proteus mirabilis (n = 5) exhibited resistance to one or both of imipenem and meropenem. The overall incidence of CRE in the three locations at the time of study was 7.7%. Age (p = 0.01) and exposure to invasive devices were significant risk factors for CRE colonization. Although at low incidence, the occurrence of CRE among this group calls for active monitoring because of its implication fatality of infections as well as the propensity to spread.

The present study evaluated the antibacterial effects of the methanolic, ethanolic and aqueous extracts of Senna alata leaves. The extracts were tested using agar well diffusion method against selected clinical isolates: Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae. Antibiogram profile of the isolates deduced by disc diffusion method confirmed that the methanolic extract inhibited the growth of all tested organisms except for Klebsiella pneumoniae, which also showed no sensitivity to the ethanolic extract. There was no inhibition observed for the aqueous extract against all the tested organisms, indicating that the methanolic extract of the plant was more potent than the aqueous extract. Inhibitory activities were observed for gentamicin, ofloxacin and erythromycin against Staphylococcus aureus and Escherichia coli. No inhibitory activity was observed in all the antibiotics against Pseudomonas aeruginosa. In Klebsiella pneumoniae, inhibition was only observed in ofloxacin. The activity of both the methanolic and ethanolic extract of Senna alata was optimal under different concentrations, but gradually diminished as the concentration was adjusted. The activity of the plant extracts against the selected bacteria is an indication of the presence of broad spectrum bioactive compounds which could be explored in the therapy of bacterial infections.

This study revealed the reason behind the antibiotics resistance of isolated food-borne pathogens through their susceptibility testing to various antibiotics of choice. The results of the study revealed that resistance of the bacteria isolates which are Streptococcus sp., Staphylococcus aureus, Proteus vulgaris, Shigella sp., Escherichia coli, Pseudomonas aeruginosa, Bacillus sp. to different antibiotics varies and differs considerably. For instance, Pseudomonas aeruginosa showed resistance to Amoxicillin, Augmentin, Gentamicin and Tetracycline. Staphylococcus sp. isolated showed multiple resistances to Cloxacillin, Erythromycin, Amoxicillin, Augmentin and Gentamicin. Proteus vulgaris showed multiple resistances to five antibiotics in-vitro which are Augmentin, Nitrofurantoin, Amoxicillin, Cotrimoxazole and Nalidixic. The seven isolates were then assayed for plasmid profiling by agarose gel electrophoresis. All the isolates has plasmid with varying sizes of between 9–21kb. Further conjugative study will reveal more reason behind the resistance.