Toward a Universal Unit for Quantification of Antibiotic Resistance Genes in Environmental Samples.

Surveillance of antibiotic resistance genes (ARGs) has been increasingly conducted in environmental sectors to complement the surveys in human and animal sectors under the "One-Health" framework. However, there are substantial challenges in comparing and synthesizing the results of multiple studies that employ different test methods and approaches in bioinformatic analysis. In this article, we consider the commonly used quantification units (ARG copy per cell, ARG copy per genome, ARG density, ARG copy per 16S rRNA gene, RPKM, coverage, PPM, etc.) for profiling ARGs and suggest a universal unit (ARG copy per cell) for reporting such biological measurements of samples and improving the comparability of different surveillance efforts.

"One Health" perspective on prevalence of co-existing extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae: a comprehensive systematic review and meta-analysis.

BACKGROUND: The Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) bacterial isolates that produce extended-spectrum ß-lactamases (ESBLs) contribute to global life-threatening infections. This study conducted a systematic review and meta-analysis on the global prevalence of ESBLs in co-existing E. coli and K. pneumoniae isolated from humans, animals and the environment. METHODS: The systematic review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) [ID no: CRD42023394360]. This study was carried out following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. One hundred and twenty-six eligible studies published on co-existing antibiotic resistance in E. coli and K. pneumoniae between 1990 and 2022 were included. RESULTS: The pooled prevalence of ESBL-producing E. coli and K. pneumoniae was 33.0% and 32.7% for humans, 33.5% and 19.4% for animals, 56.9% and 24.2% for environment, 26.8% and 6.7% for animals/environment, respectively. Furthermore, the three types of resistance genes that encode ESBLs, namely blaSHVblaCTX-M,blaOXA, and blaTEM, were all detected in humans, animals and the environment. CONCLUSIONS: The concept of "One-Health" surveillance is critical to tracking the source of antimicrobial resistance and preventing its spread. The emerging state and national surveillance systems should include bacteria containing ESBLs. A well-planned, -implemented, and -researched alternative treatment for antimicrobial drug resistance needs to be formulated.

Aquatic yeasts: diversity, characteristics and potential health implications.

There has been a rising interest in the levels, diversity and potential impacts of yeasts in aquatic environments. Some of the species isolated from such niches are known pathogens or have pathogenic and antifungal resistance features. This deems it necessary to understand the characteristics and potential health implications of such environmental yeasts species. Studies on these subjects are limited. Most studies on aquatic yeasts have linked them to water pollution. However, the current gold standards to determine microbial pollution of water use bacteria as the main indicator organisms. Including yeasts in water quality standards may provide a different dimension on the quality of water when determining its fit-for-use properties. Pathogenic yeasts cause superficial infections or life-threatening infections, especially in immunocompromised people. Some of the yeast species isolated in recent studies were resistant to commonly used antifungal agents of clinical and veterinary relevance. With the high prevalence rate of HIV in sub-Saharan Africa, particularly in South Africa, antifungal resistance is a public concern as it poses serious medical and economic challenges. Most available studies are concerned with clinical environments only. There is, thus, a need to review the literature that also focuses on aquatic environments.

Ecological guild and enzyme activities of rhizosphere soil microbial communities associated with Bt-maize cultivation under field conditions in North West Province of South Africa.

Insecticidal proteins expressed by genetically modified Bt maize may alter the enzymatic and microbial communities associated with rhizosphere soil. This study investigated the structure and enzymatic activity of rhizosphere soil microbial communities associated with field grown Bt and non-Bt maize. Rhizosphere soil samples were collected from Bt and non-Bt fields under dryland and irrigated conditions. Samples were subjected to chemical tests, enzyme analyses, and next generation sequencing. Results showed that nitrate and phosphorus concentrations were significantly higher in non-Bt maize dryland soils, while organic carbon was significantly higher in non-Bt maize irrigated field soil. Acid phosphatase and ß-glucosidase activities were significantly reduced in soils under Bt maize cultivation. The species diversity differed between fields and Bt and non-Bt maize soils. Results revealed that Actinobacteria, Proteobacteria, and Acidobacteria were the dominant phyla present in these soils. Redundancy analyses indicated that some chemical properties and enzyme activities could explain differences in bacterial community structures. Variances existed in microbial community structures between Bt and non-Bt maize fields. There were also differences between the chemical and biochemical properties of rhizosphere soils under Bt and non-Bt maize cultivation. These differences could be related to agricultural practices and cultivar type.

Pathogenic features of heterotrophic plate count bacteria from drinking-water boreholes.

Evidence suggests that heterotrophic plate count (HPC) bacteria may be hazardous to humans with weakened health. We investigated the pathogenic potential of HPC bacteria from untreated borehole water, consumed by humans, for: their haemolytic properties, the production of extracellular enzymes such as DNase, proteinase, lipase, lecithinase, hyaluronidase and chondroitinase, the effect simulated gastric fluid has on their survival, as well as the bacteria's antibiotic-susceptible profile. HuTu-80 cells acted as model for the human intestine and were exposed to the HPC isolates to determine their effects on the viability of the cells. Several HPC isolates were α- or ß-haemolytic, produced two or more extracellular enzymes, survived the SGF treatment, and showed resistance against selected antibiotics. The isolates were also harmful to the human intestinal cells to varying degrees. A novel pathogen score was calculated for each isolate. Bacillus cereus had the highest pathogen index: the pathogenicity of the other bacteria declined as follows: Aeromonas taiwanensis > Aeromonas hydrophila > Bacillus thuringiensis > Alcaligenes faecalis > Pseudomonas sp. > Bacillus pumilus > Brevibacillus sp. > Bacillus subtilis > Bacillus sp. These results demonstrated that the prevailing standards for HPCs in drinking water may expose humans with compromised immune systems to undue risk.

Preliminary evidence of differences in cadmium tolerance in metal-free stocks of the standard earthworm test species Eisenia andrei (Oligochaeta).

To test whether metal-tolerant and metal-sensitive earthworm specimens could be an inherent part of metal-free earthworm populations, (i) we used DNA barcoding to identify and categorize earthworms from 8 populations of the standard test species Eisenia andrei, and (ii) the earthworms carrying three of the identified COI haplotypes (named Hap1, hap3 and Hap3) were paired up and exposed to Cd in order to assess the difference in Cd sensitivity between the breeding pairs. A total of six breeding pairs were exposed to 0, 25, 50 and 100 mg Cd/kg for 4 weeks at 20 °C. The survival of the breeding pairs, their change in biomass and cocoon production were assessed. For all of the endpoints assessed, the results indicated that couple 6 (Hap3 × Hap3) was the most sensitive breeding pair whereas couple 4 (Hap1 × Hap3) was the least sensitive one. The analysis of Cd tissue contents revealed that with increasing Cd concentration, Cp6 (Hap3 × Hap3) could accumulate significantly more Cd than any other breeding pair (p ≤ 0.01). Our findings indicate that E. andrei may harbour intrinsically Cd-tolerant and Cd-sensitive individuals and that this may be due to individual differences in Cd accumulation kinetics. In the context of ecotoxicological testing, our results underline the importance of using genetically diverse populations in laboratory testing to prevent generating flawed data from genetically homogeneous laboratory stocks. Although we do not regard the present mitochondrial haplotypes as proxy for possibly nuclear encoded traits, we discuss the necessity of a standardised earthworm barcoding protocol that could help not only to confirm the taxonomy of laboratory earthworm stocks but also to select genetically diverse stocks suitable for laboratory testing.

Analysis of physico-chemical and bacteriological quality of drinking water in Mafikeng, South Africa.

Mafikeng, the capital of the North West Province, receives water from two sources, namely the Molopo eye and the Modimola dam. Once treated, the potable water is mixed and supplied to the city via distribution systems. This study was designed to assess the quality of drinking water in Mafikeng and also to determine whether the water from the two sources has an impact on the mixed water quality. Physico-chemical parameters and bacteriological quality (faecal coliforms (FCs), total coliforms (TCs), heterotrophic bacteria and Peudomonas spp.) was monitored at three drinking water sites weekly for 4 months. The results revealed that the physico-chemical quality of the water was generally acceptable. The pH ranged from 5.7 ± 0.18 to 8.6 ± 0.14, the temperature ranged from 18.3 ± 0.69 to 25.1 ± 0.69 °C and the total dissolved solids (TDS) ranged from 159.9 ± 22.44 to 364.4 ± 12.44 mg/l. These values are within the target water quality range for drinking water as prescribed by WHO, Department of Water Affairs and SANS 241. What is of concern was the microbial quality of the water. FCs, TCs, heterotrophic bacteria and Pseudomonas spp. were present in some of the treated water samples. The most significant finding of this study is that all drinking water samples were positive for Pseudomonas spp. (>100/100 ml).

Antibiotic-resistant heterotrophic plate count bacteria and amoeba-resistant bacteria in aquifers of the Mooi River, North West province, South Africa.

Groundwater in the Mooi River catchment is prone to mining, agricultural, municipal and septic tank pollution. In this study physico-chemical and microbiological parameters were determined using appropriate methods. Bacterial isolates were identified by 16S rRNA sequencing (heterotrophic plate count (HPC) bacteria and amoeba-resistant bacteria (ARB)) and multiplex polymerase chain reaction (Escherichia coli). Antibiotic resistance tests were also performed. Physico-chemical parameters were generally within target water quality ranges for drinking water. HPC bacteria ranged between 10(5) and 10(7) colony-forming units (cfu)/ml. E. coli were enumerated from Trimpark, School and Cemetery. The Blaauwbank borehole was negative for faecal streptococci. Pseudomonas spp. were most abundant in the bulk water. Opportunistic pathogens isolated included Pseudomonas aeruginosa, Acinetobacter, Aeromonas, Alcaligenes, Flavobacterium, Bacillus cereus and Mycobacterium spp. Varying patterns of antibiotic resistance were observed. Most HPC bacterial isolates were resistant to cephalothin and/or amoxicillin and a few were resistant to erythromycin and streptomycin. Pseudomonas spp. was also the most abundant ARB. Other ARBs included Alcaligenes faecalis, Ochrobactrum sp. and Achromobacter sp. ARBs were resistant to streptomycin, chloramphenicol, cephalothin, and/or amoxicillin compared to HPCs. The presence of E. coli and ARB in these groundwater sources indicates potential human health risks. These risks should be further investigated and quantified, and groundwater should be treated before use.

Metal- and antibiotic-resistant heterotrophic plate count bacteria from a gold mine impacted river: the Mooi River system, South Africa.

The Wonderfonteinspruit, South Africa, is highly impacted by a century of gold mining activities. The aim of this study was to investigate the physico-chemical properties of the Wonderfonteinspruit and the receiving Mooi River system, the levels of antimicrobial (metals and antibiotics) resistance characteristics and heterotrophic bacteria levels in these water systems. Various physico-chemical parameters were determined. R2A agar and R2A agar supplemented with antimicrobials were used to enumerate heterotrophic bacteria. Morphologically distinct antimicrobial-resistant isolates were purified and screened for antibiotic susceptibility by a disc diffusion method. Selected isolates were identified, and minimum inhibitory concentration ranges determined. Among the antimicrobial resistant isolates, 87% were resistant to at least one antibiotic. Of these, almost 50% were resistant to more than 3 antibiotic classes. A large proportion was resistant to all 7 antibiotics tested. Phyla detected were Proteobacteria, Firmicutes and Bacteriodetes. High MIC levels for metals and antibiotics were detected among all the genera. Results demonstrate potential impacts of physico-chemical properties on levels of antimicrobial-resistant bacteria. Metal-resistant bacteria were also resistant to multiple antibiotics, suggesting that metal pollution from mining may be responsible for co-selection and maintenance of antibiotic-resistant bacteria in this aquatic system.

Detection of mecA positive staphylococcal species in a wastewater treatment plant in South Africa.

We investigated the prevalence of antibiotic resistant staphylococci and detection of resistant, virulence, and Spa genes in a South African wastewater treatment plant. Species identified were Staphylococcus aureus, S. lentus, S. arlettae, S. cohnii, S. haemolyticus, S. nepalensis, S. sciuri (now Mammaliicoccus sciuri), and S. xylosus. Isolates showed high resistance to methicillin (91%), ampicillin (89%), ciprofloxacin (86%), amoxycillin (80%), ceftazidime (74%), and cloxacillin (71%). Multiple antibiotic resistance (MAR) index for the isolates exceeded 0.2 (0.50-0.70). Among the isolates, 77% were mecA-positive. All S. aureus strains were positive for nuc and 7 Spa gene types. The present study highlights possibility of treated wastewaters being potential reservoir for antibiotic-resistant staphylococci. This is a cause for concern as wastewater effluents are decanted into environmental waters and these are, in many cases, used for various purposes including recreation (full contact), religious (full body submersion), and drinking water for some rural communities and water for livestock.

A systematic review and meta-analysis on prevalence and antimicrobial resistance profile of Escherichia coli isolated from water in africa (2000-2021).

Water is essential for the survival of humans, animals and plants. Numerous research has been conducted on the prevalence and antibiotic resistance of Escherichia coli (E. coli) in water from various African countries, however, there is lack of comprehensive analysis of published literature. We conducted a systematic review and meta-analysis following the PRISMA guidelines where articles published in English language between January 2000 and March 2022 were searched from ScienceDirect, PubMed, Google Scholar, Scopus, African Journal Online (AJO), and Africa Index Medicus (AIM). Comprehensive Meta-Analysis (CMA) Ver 3.0 software was used to analyze the data. The pooled prevalence estimate (PPE) with 95% confidence interval was calculated using the random-effects model (CI). The overall PPE and antimicrobial resistance trends of E. coli isolated from water was screened from 4009 isolates which were isolated from 2586 samples. We extracted data from 17 studies including drinking water (n = 6), rivers (n = 5), wastewaters (n = 4) and wastewater/river (n = 1) which are all covering 27 countries in Africa with 3438 isolates. The PPE of E. coli in water was 71.7% (0.717; 95% CI: 0.562-0.833). The highest PPE antibiotic resistance was against penicillin followed by erythromycin, and ampicilin with resistance rates of 93.4%, 92.3%, and 69.4%, respectively. This systematic review provides critical evidence of E. coli consolidated prevalence and antibiotic resistance profiles, as well as regions where future studies and enhanced reporting could be beneficial in the African continent.

Effects of Cry1Ab transgenic maize on lifecycle and biomarker responses of the earthworm, Eisenia andrei.

A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this study several endpoints were compared which included biomass changes, cocoon production, hatching success, a cellular metal-stress biomarker (Neutral Red Retention Time; NRRT) and potential genotoxic effects in terms of Randomly Amplified Polymorphic DNA sequences (RAPDs). NRRT results indicated no differences between treatments (p > 0.36), and NRRT remained the same for both treatments at different times during the experiment (p = 0.18). Likewise, no significant differences were found for cocoon production (p = 0.32) or hatching success (p = 0.29). Conversely, biomass data indicated a significant difference between the control treatment and the Bt treatment from the second week onwards (p < 0.001), with the Bt treatment losing significantly more weight than the isoline treatment. Possible confounding factors were identified that might have affected the differences in weight loss between groups. From the RAPD profiles no conclusive data were obtained that could link observed genetic variation to exposure of E. andrei to Cry1Ab proteins produced by Bt maize.

Draft Genome Sequences of Multidrug-Resistant Shiga Toxin-Producing Escherichia coli O116:H25 Strains from Ready-to-Eat Foods Sold in Lagos, Nigeria.

Draft genomes of multidrug-resistant Shiga toxin-producing Escherichia coli (STEC) strains IPK9(1) and IKS1(2), which were isolated from ready-to-eat foods (kokoro and shawarma) sold in Lagos, Nigeria, are reported. The genomes possessed genetic determinants for virulence and the antibiotic resistance gene for macrolide-associated resistance mdf(A). Ready-to-eat foods increase public health threats in Nigeria.

Prevalence and antimicrobial resistance profiles of Campylobacter species in South Africa: a "One Health" approach using systematic review and meta-analysis.

OBJECTIVES: This study investigated the prevalence and antibiotic resistance (AR) profiles of Campylobacter spp. isolated from animals, humans, and the environment in South Africa based on available published data. METHODS: Original articles published from January 1, 1990 to January 1, 2021 were searched from PubMed, ScienceDirect, Google Scholar, Africa Index Medicus, Scopus, and African Journal Online databases. Data were analyzed with Comprehensive Meta-Analysis (version 3.0). RESULTS: After screening, articles on animals (n = 25), humans (n = 7), environment (n = 3), animals/environment (n = 2), and a (n = 1) study on animals, humans, and the environment were included in this review. The pooled prevalence estimates (PPEs) were 28.8%, 16.4%, and 28.4% in animals, humans, and the environment, respectively. The Campylobacter jejuni and Campylobacter coli species were commonly isolated from humans, animals, and the environment in South Africa. The AR profiles were screened from 2032 Campylobacter spp., with the highest PPE of AR observed against clindamycin (76.9%) and clarithromycin (76.5%). Campylobacter isolates tested with the disk diffusion assay and minimum inhibitory concentration methods recorded an overall AR prevalence of 35.3% and 37.1%, respectively, whereas multidrug resistance PPE was 35.3%. CONCLUSION: Regular surveillance of Campylobacter spp. prevalence and its antimicrobial resistance strains is recommended, as well as the formulation of a "One Health" approach for better management and control of Campylobacter spp. infection in South Africa.

A review of some characteristics, socio-economic aspects and utilization of Zulu sheep: implications for conservation.

Zulu sheep are Nguni sheep of Zululand and are adapted to the harsh conditions of KwaZulu-Natal. They are used by rural farmers for economic purposes. Their numbers are declining, indicating a potential extinction threat. Knowledge of their phenotypic and genotypic characteristics is essential for conservation planning. In this review, there is a focus on the utilization, socio-economic aspects, phenotypic and genotypic characteristics as well as a proposed breeding programme. A survey has shown that rural farmers in the areas of northern KwaZulu-Natal prefer to keep this breed for its adaptability, resistance to diseases and meat quality. Zulu sheep are small-framed multi-coloured animals. Mature males weigh up to 38 kg and females up to 32 kg. Based on four morphological traits and live weight, phenotypic diversity between three populations was estimated at 48%. A genetic diversity between these three populations was estimated at 22%. Live weight of Zulu sheep can be estimated using the heart girth and wither height measurements. Scrotum circumference of young rams (up to 22 months old) is reliable for estimating the live weight. Animals that were characterized in the studies were grazed extensively and no supplements were provided. There is therefore a potential of weight increase if these animals are reared in a semi-extensive environment. An open nucleus breeding scheme is thus recommended for a sustainable use and conservation of this breed. For more conclusive results, larger numbers of phenotypic and genetic characteristics, in larger numbers of Zulu sheep populations, should be investigated.

Wastewater treatment works change the intestinal microbiomes of insectivorous bats.

Mammals, born with a near-sterile intestinal tract, are inoculated with their mothers' microbiome during birth. Thereafter, extrinsic and intrinsic factors shape their intestinal microbe assemblage. Wastewater treatment works (WWTW), sites synonymous with pollutants and pathogens, receive influent from domestic, agricultural and industrial sources. The high nutrient content of wastewater supports abundant populations of chironomid midges (Diptera), which transfer these toxicants and potential pathogens to their predators, such as the banana bat Neoromicia nana (Vespertilionidae), thereby influencing their intestinal microbial assemblages. We used next generation sequencing and 16S rRNA gene profiling to identify and compare intestinal bacteria of N. nana at two reference sites and two WWTW sites. We describe the shared intestinal microbiome of the insectivorous bat, N. nana, consisting of seven phyla and eleven classes. Further, multivariate analyses revealed that location was the most significant driver (sex, body size and condition were not significant) of intestinal microbiome diversity. Bats at WWTW sites exhibited greater intestinal microbiota diversity than those at reference sites, likely due to wastewater exposure, stress and/or altered diet. Changes in their intestinal microbiota assemblages may allow these bats to cope with concomitant stressors.

Whole-genome sequence of multi-drug resistant Pseudomonas aeruginosa strains UY1PSABAL and UY1PSABAL2 isolated from human broncho-alveolar lavage, Yaoundé, Cameroon.

Pseudomonas aeruginosa has been implicated in a wide range of post-operation wound and lung infections. A wide range of acquired resistance and virulence markers indicate surviving strategy of P. aeruginosa. Complete-genome analysis has been identified as efficient approach towards understanding the pathogenicity of this organism. This study was designed to sequence the entire genome of P. aeruginosa UY1PSABAL and UY1PSABAL2; determine drug-resistance profiles and virulence factors of the isolates; assess factors that contribute toward stability of the genomes; and thereafter determine evolutionary relationships between the strains and other isolates from similar sources. The genomes of the MDR P. aeruginosa UY1PSABAL and UY1PSABAL2 were sequenced on the Illumina Miseq platform. The raw sequenced reads were assessed for quality using FastQC v.0.11.5 and filtered for low quality reads and adapter regions using Trimmomatic v.0.36. The de novo genome assembly was made with SPAdes v.3.13 and annotated using Prokka v.2.1.1 annotation pipeline; Rapid Annotation using Subsytems Technology (RAST) server v.2.0; and PATRIC annotation tool v.3.6.2. Antimicrobial resistance genes and virulence determinants were searched through the functional annotation data generated from Prokka, RAST and PATRIC annotation pipelines; In addition to ResFinder and Comprehensive Antibiotic Resistance Database (CARD) which were employed to determine resistance genes. The PHAge Search Tool Enhanced Release (PHASTER) web server was used for the rapid identification and annotation of prophage sequences within bacterial genome. Predictive secondary metabolites were identified with AntiSMASH v.5.0. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and cas genes regions were also investigated with the CRISPRone and CRISPRFinder server. The genome sizes of 7.0 and 6.4 Mb were determined for UY1PSABAL and UY1PSABAL2 strains with G+C contents of 66.1% and 66.48% respectively. ß-lactamines resistance genes blaPAO, aminoglycoside phosphorylating enzymes genes aph(3')-IIb, fosfomycine resistance gene fosA, vancomycin vanW and tetracycline tetA were among identified resistance genes harboured in both isolates. UY1PSABAL bore additional aph(6)-Id, aph(3'')-Ib, ciprofloxacin-modifying enzyme crpP and ribosomal methylation enzyme rmtB. Both isolates were found harbouring virulence markers such as flagella and type IV pili; and also present various type III secretion systems such as exoA, exoS, exoU, exoT. Secondary metabolites such as pyochelin and pyoverdine with iron uptake activity were found within the genomes as well as quorum-sensing systems, and various fragments for prophages and insertion sequences. Only the UY1PSABAL2 contains CRISPR-Cas system. The phylogeny revealed a very close evolutionary relationship between UY1PSABAL and the similar strain isolated from Malaysia; the same trend was observed between UY1PSABAL2 and the strain from Chinese origin. Complete analyses of the entire genomes provide a wide range of information towards understanding pathogenicity of the pathogens in question.

Draft Genome Assemblages of 10 Xanthomonas vasicola pv. zeae Strains, Pathogens Causing Leaf Streak Disease of Maize in South Africa.

Maize bacterial leaf streak disease has spread across maize crops in South Africa and therefore potentially poses a threat to maize production and food security. Until recently, this pathogen was identified as a Xanthomonas campestris pathovar, whereas our South African genomes seem to be more divergent and create their own subclade.

Interactions of the antimicrobial peptide nisin Z with conventional antibiotics and the use of nanostructured lipid carriers to enhance antimicrobial activity.

Antimicrobial resistance is an imminent threat to the effective prevention and treatment of bacterial infections and alternative antimicrobial strategies are desperately needed. Antimicrobial peptides (AMPs) may be promising alternatives to current antibiotics or act as adjuvants to enhance antibiotic potency. Additionally, the use of biodegradable lipid nanoparticles can enhance the antibacterial activity of antibiotics and antimicrobial peptides. In this study, the interaction of the AMPs, nisin Z and melittin, with conventional antibiotics was investigated on Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli. The effectiveness of nanostructured lipid carriers (NLCs) for the entrapment of nisin Z was also evaluated. Findings revealed that nisin Z exhibited additive interactions with numerous conventional antibiotics. Notable synergism was observed for novobiocin-nisin Z combinations. The addition of the non-antibiotic adjuvant EDTA significantly improved the antimicrobial activity of free nisin Z towards E.coli. NLCs containing nisin Z were effective against Gram-positive species at physiological pH, with an increase in effectiveness in the presence of EDTA. Results indicate that nisin Z may be advantageous as an adjuvant in antimicrobial chemotherapy, while contributing in the battle against antibiotic resistance. NLCs have the potential to enhance the antibacterial activity of nisin Z towards Gram-positive bacterial species associated with skin infections.