Aims To determine the sensitivity of five strains of Staphylococcus aureus to five essential oils (EOs) and to investigate the anti-biofilm activity of lemongrass and grapefruit EOs. Methods and Results Antimicrobial susceptibility screening was carried out using the disk diffusion method. All of the strains tested were susceptible to lemongrass, grapefruit, bergamot and lime EOs with zones of inhibition varying from 2·85 to 8·60 cm although they were resistant to lemon EO. Lemongrass EO inhibited biofilm formation at 0·125% (v/v) as measured by colorimetric assay and at 0·25% (v/v) no metabolic activity was observed as determined by 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction. Grapefruit EO did not show any anti-biofilm activity. Following exposure to lemongrass EO extensive disruption to Staph. aureus biofilms was shown under scanning electron microscopy. Conclusions In comparison to the other EOs tested, lemongrass exhibited the most effective antimicrobial and anti-biofilm activity. Significance and Impact of the Study The effect of lemongrass EO highlights its potential against antibiotic resistant Staph. aureus in the healthcare environment.

The aim of this study was to determine the antimicrobial effects of lemongrass essential oil (C. flexuosus) and to determine cytotoxic effects of both test compounds on human dermal fibroblasts. Antimicrobial susceptibility screening was carried out using the disk diffusion method. Antimicrobial resistance was observed in four of five Acinetobacter baumannii strains with two strains confirmed as multi-drug-resistant (MDR). All the strains tested were susceptible to both lemongrass and citral with zones of inhibition varying between 17 to 80 mm. The mean minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of citral (mic—0.14 % and mbc—0.3 % v/v) was lower than that of Lemongrass (mic—0.65 % and mbc—1.1 % v/v) determined using the microtitre plate method. Cell viability using human dermal fibroblasts (HDF; 106-05a) was determined following exposure to both compounds and a control (Grapeseed oil) using the XTT assay and the IC₅₀ determined at 0.095 % (v/v) for citral and 0.126 % (v/v) for lemongrass. Grapeseed oil had no effect on cell viability. Live cell imaging was performed using the LumaScope 500 imaging equipment and changes in HDF cell morphology such as necrotic features and shrinkage were observed. The ability of lemongrass essential oil (EO) and citral to inhibit and kill MDR A. baumannii highlights its potential for use in the management of drug-resistant infections; however, in vitro cytotoxicity does suggest further tests are needed before in vivo or ex vivo human exposure.

Candida infections are a significant source of patient morbidity and mortality. Candida albicans is the most common pathogen causing Candida infections. Candida auris is a newly described pathogen that is associated with multi-drug-resistant candidiasis and candidaemia in humans. The antifungal effects of various essential oils and plant compounds have been demonstrated against human pathogenic fungi. In this study, the effect of cinnamon leaf and bark essential oils (CEOs) was determined against both C. albicans and C. auris. The disc diffusion (direct and vapour) and broth microdilution method was used to determine antifungal activity of the EOs against selected strains (C. albicans ATCC 10231, C. albicans ATCC 2091 and C. auris NCPF 8971) whilst the mode of action and haemolysin activity of the CEOs were determined using electron microscopy and light microscopy. Direct and vapour diffusion assays showed greater inhibitory activity of bark CEO in comparison with leaf CEO. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of bark CEO for all tested strains was below 0.03% (v/v), which was lower than the MICs of the leaf CEO (0.06–0.13%, v/v) dependent on the strain and the MFCs at 0.25% (v/v). In the morphological interference assays, damage to the cell membrane was observed and both CEOs inhibited hyphae formation. The haemolysin production assay showed that CEOs can reduce the haemolytic activity in the tested C. albicans and C. auris strains. At low concentrations, CEOs have potent antifungal and antihaemolytic activities in vitro against C. albicans and C. auris.Key points• Essential oils from Cinnamomum zeylanicum Blume bark and leaf (CBEO and CLEO) demonstrated fungicidal properties at very low concentrations.• The antifungal activity of CBEO was greater than that of CLEO consistent with other recent published literature.• The mode of action of CBEO and CLEO was damage to the membrane of C. albicans and C. auris.• Both CBEO and CLEO inhibited the formation of hyphae and reduced haemolysin production in C. albicans and C. auris.

Aims: Surveillance is a useful tool for tracking antimicrobial resistance (AMR) trends, patterns, therapeutic and policy interventions. Proper correlation of surveillance data gives meaningful insight into the underlying epidemiology and facilitates development of rational interventions. This comprehensive review aims to identify, classify and assess gaps in Global Antimicrobial Resistance and Use Surveillance System (GLASS) reporting and national action plan (NAP) implementation in Africa. Methods: Articles published in English were searched across five electronic databases (PubMed, Scopus, Embase, AJOL and Cochrane) and grey literature. Articles were screened against inclusion/exclusion criteria and data from eligible studies were retrieved and analysed. This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) on 31 July 2020 under protocol CRD42020192165. Results: Of the 4304 records found, only 32 met the initial inclusion criteria (4 peer reviews and 28 were grey literature). From these records, 41 surveillance systems were identified (30 national and 11 transnational). After final review of reported outcomes, only 23 national surveillance systems met the inclusion criteria. Indicators recorded from these systems shows lack of external quality assessment (EQA) in some systems and limited reporting of parameters such as infection origin, patient population and pathogen types. Conclusions: The outcome of the review shows that although AMR surveillance has been implemented in 23 out of the 47 countries in the region, a number of limitations exist in the surveillance methods and reporting protocols that can impair the usefulness, validity and trustworthiness of data generated from these surveillance systems.

Aspergillus species are known to cause damage to food crops and are associated with opportunistic infections in humans. In the United States, significant losses have been reported in peanut production due to contamination caused by the Aspergillus species. This study evaluated the antifungal effect and anti-aflatoxin activity of selected plant-based essential oils (EOs) against Aspergillus flavus in contaminated peanuts, Tifguard, runner type variety. All fifteen essential oils, tested by the poisoned food technique, inhibited the growth of A. flavus at concentrations ranging between 125 and 4000 ppm. The most effective oils with total clearance of the A. flavus on agar were clove (500 ppm), thyme (1000 ppm), lemongrass, and cinnamon (2000 ppm) EOs. The gas chromatography-mass spectrometry (GC-MS) analysis of clove EO revealed eugenol (83.25%) as a major bioactive constituent. An electron microscopy study revealed that clove EO at 500 ppm caused noticeable morphological and ultrastructural alterations of the somatic and reproductive structures. Using both the ammonia vapor (AV) and coconut milk agar (CMA) methods, we not only detected the presence of an aflatoxigenic form of A. flavus in our contaminated peanuts, but we also observed that aflatoxin production was inhibited by clove EO at concentrations between 500 and 2000 ppm. In addition, we established a correlation between the concentration of clove EO and AFB1 production by reverse-phase high-performance liquid chromatography (HPLC). We demonstrate in our study that clove oil could be a promising natural fungicide for an effective bio-control, non-toxic bio-preservative, and an eco-friendly alternative to synthetic additives against A. flavus in Georgia peanuts.