Hematological profiles of patients with tuberculosis and nontuberculous mycobacteria infections in Bamako, Mali.

Background: Pulmonary tuberculosis (TB) remains one of the main causes of morbidity and mortality in Mali. Nontuberculous mycobacteria (NTM) infections are very common but are often cofounded with TB because of the similarity of symptoms, which makes the diagnosis difficult. Hematological abnormalities associated with TB have been described, but not with NTM. Therefore, the goal of this study was to compare the hematological parameters of patients infected with TB and NTM infections. Methods: A cross-sectional study enrolling TB and NTM participants was conducted in 2018-2020. Five milliliters of venous blood and sputum samples were collected from each participant to determine the hematological parameters using the RUBY CELL-DYN Ruby Version 2.2 ML. A BACTEC MGIT 960 and multiplex reverse transcription-polymerase chain reaction were used to distinguish Mycobacterium tuberculosis from NTM, respectively. Results: Of the total 90 patients enrolled, there was a decrease in hemoglobin and hematocrit levels in both the groups (P = 0.05). In addition, we found that the percentages of basophil cells (P = 0.01) and mean values of platelets (P = 0.04) were significantly higher in TB patients than those of NTMs. Moreover, the mean of absolute values of eosinophil cells of TB patients was significantly lower than those of NTMs (P = 0.03). Conclusion: We found significant statistical differences in basophils, platelets, and eosinophils in differentiating TB and NTM in this pilot study. Future studies with patients at different clinical stages are needed to confirm the hematological profiles of TB and NTM patients.

Hepatitis B Virus in West African Children: Systematic Review and Meta-Analysis of HIV and Other Factors Associated with Hepatitis B Infection.

While Hepatitis B virus (HBV) and the human immunodeficiency virus (HIV) are endemic in West Africa, the prevalence of HBV/HIV coinfection and their associated risk factors in children remains unclear. In this review, we sought to assess HBsAg seroprevalence among 0- to 16-year-olds with and without HIV in West African countries and the risk factors associated with HBV infection in this population. Research articles between 2000 and 2021 that reported the prevalence of HBV and associated risk factors in children in West Africa were retrieved from the literature using the Africa Journals Online (AJOL), PubMed, Google Scholar, and Web of Science databases as search tools. StatsDirect, a statistical software, was used to perform a meta-analysis of the retained studies. HBV prevalence and heterogeneity were then assessed with a 95% confidence interval (CI). Publication bias was evaluated using funnel plot asymmetry and Egger's test. Twenty-seven articles conducted across seven West African countries were included in this review. HBV prevalence among persons aged 0 to 16 years was 5%, based on the random analysis, given the great heterogeneity of the studies. By country, the highest prevalence was observed in Benin (10%), followed by Nigeria (7%), and Ivory Coast (5%), with Togo (1%) having the lowest. HBV prevalence in an HIV-infected population of children was (9%). Vaccinated children had lower HBV prevalence (2%) than unvaccinated children (6%). HBV prevalence with a defined risk factor such as HIV co-infection, maternal HBsAg positivity, undergoing surgery, scarification, or being unvaccinated ranged from 3-9%. The study highlights the need to reinforce vaccination of newborns, screening for HBV, and HBV prophylaxis among pregnant women in Africa, particularly in West Africa, to achieve the WHO goal of HBV elimination, particularly in children.

Dynamics of SARS-CoV-2 variants characterized during different COVID-19 waves in Mali.

Background: The emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants may have contributed to prolonging the pandemic, and increasing morbidity and mortality related to coronavirus disease 2019 (COVID-19). This article describes the dynamics of circulating SARS-CoV-2 variants identified during the different COVID-19 waves in Mali between April and October 2021. Methods: The respiratory SARS-CoV-2 complete spike (S) gene from positive samples was sequenced. Generated sequences were aligned by Variant Reporter v3.0 using the Wuhan-1 strain as the reference. Mutations were noted using the GISAID and Nextclade platforms. Results: Of 16,797 nasopharyngeal swab samples tested, 6.0% (1008/16,797) tested positive for SARS-CoV-2 on quantitative reverse transcription polymerase chain reaction. Of these, 16.07% (162/1008) had a cycle threshold value ≤28 and were amplified and sequenced. The complete S gene sequence was recovered from 80 of 162 (49.8%) samples. Seven distinct variants were identified: Delta (62.5%), Alpha (1.2%), Beta (1.2%), Eta (30.0%), 20B (2.5%), 19B (1.2%) and 20A (1.2%). Conclusions and perspectives: Several SARS-CoV-2 variants were present during the COVID-19 waves in Mali between April and October 2021. The continued emergence of new variants highlights the need to strengthen local real-time sequencing capacity and genomic surveillance for better and coordinated national responses to SARS-CoV-2.

Rapid Diagnosis of Drug-Resistant Tuberculosis-Opportunities and Challenges.

Global tuberculosis (TB) eradication is undermined by increasing prevalence of emerging resistance to available drugs, fuelling ongoing demand for more complex diagnostic and treatment strategies. Early detection of TB drug resistance coupled with therapeutic decision making guided by rapid characterisation of pre-treatment and treatment emergent resistance remains the most effective strategy for averting Drug-Resistant TB (DR-TB) transmission, reducing DR-TB associated mortality, and improving patient outcomes. Solid- and liquid-based mycobacterial culture methods remain the gold standard for Mycobacterium tuberculosis (MTB) detection and drug susceptibility testing (DST). Unfortunately, delays to result return, and associated technical challenges from requirements for specialised resource and capacity, have limited DST use and availability in many high TB burden resource-limited countries. There is increasing availability of a variety of rapid nucleic acid-based diagnostic assays with adequate sensitivity and specificity to detect gene mutations associated with resistance to one or more drugs. While a few of these assays produce comprehensive calls for resistance to several first- and second-line drugs, there is still no endorsed genotypic drug susceptibility test assay for bedaquiline, pretomanid, and delamanid. The global implementation of regimens comprising these novel drugs in the absence of rapid phenotypic drug resistance profiling has generated a new set of diagnostic challenges and heralded a return to culture-based phenotypic DST. In this review, we describe the available tools for rapid diagnosis of drug-resistant tuberculosis and discuss the associated opportunities and challenges.

A Public Health Insight into Salmonella in Poultry in Africa: A Review of the Past Decade: 2010-2020.

Poultry is a cheap source of animal protein and constituent of diets in Africa. Poultry can serve as a reservoir for Salmonella and cause food-borne infections in humans. This review describes Salmonella contamination of food, poultry, and the farming environment, antimicrobial resistance profiles, and serotypes of Salmonella, as well as the farming systems, antimicrobial use (AMU), hygiene, and husbandry conditions used to rear poultry in Africa. Using the PRISMA (preferred reporting items for systematic reviews and meta-analysis) guidelines, PubMed, Science Direct, and Web of Science databases were searched using a set of predefined keywords. Full-length research articles in English were examined for the period 2010-2020 and relevant information extracted for the narrative synthesis. Of the articles that met the inclusion criteria, 63.1% were conducted on farms and among households, while 36.9% were undertaken at government-controlled laboratories, which quarantine imported birds, processing plants, and retail outlets. The farming systems were intensive, semi-intensive, and extensive. AMU was described in 11.5% of the studies and varied within and across countries. Multidrug-resistant (MDR) Salmonella isolates were detected in 30 studies and the prevalence ranged from 12.1% in Zimbabwe to 100% in Egypt, Ethiopia, Nigeria, Senegal, and South Africa. A total of 226 different Salmonella serotypes were reported. Twenty-four (19.7%) of the studies reported food-borne Salmonella contamination in eggs, poultry, and poultry products at retail outlets and processing plants. The apparent extensive use of antimicrobials and circulation of MDR Salmonella isolates of various serotypes in Africa is a concern. It is important to implement stricter biosecurity measures on farms, regulate the use of antimicrobials and implement surveillance systems, in addition to food safety measures to monitor the quality of poultry and poultry products for human consumption.

Heat Shock Protein 90 (HSP90) Inhibitors as Anticancer Medicines: A Review on the Computer-Aided Drug Discovery Approaches over the Past Five Years.

Cancer is a disease caused by the uncontrolled, abnormal growth of cells in different anatomic sites. In 2018, it was predicted that the worldwide cancer burden would rise to 18.1 million new cases and 9.6 million deaths. Anticancer compounds, often known as chemotherapeutic medicines, have gained much interest in recent cancer research. These medicines work through various biological processes in targeting cells at various stages of the cell's life cycle. One of the most significant roadblocks to developing anticancer drugs is that traditional chemotherapy affects normal cells and cancer cells, resulting in substantial side effects. Recently, advancements in new drug development methodologies and the prediction of the targeted interatomic and intermolecular ligand interaction sites have been beneficial. This has prompted further research into developing and discovering novel chemical species as preferred therapeutic compounds against specific cancer types. Identifying new drug molecules with high selectivity and specificity for cancer is a prerequisite in the treatment and management of the disease. The overexpression of HSP90 occurs in patients with cancer, and the HSP90 triggers unstable harmful kinase functions, which enhance carcinogenesis. Therefore, the development of potent HSP90 inhibitors with high selectivity and specificity becomes very imperative. The activities of HSP90 as chaperones and cochaperones are complex due to the conformational dynamism, and this could be one of the reasons why no HSP90 drugs have made it beyond the clinical trials. Nevertheless, HSP90 modulations appear to be preferred due to the competitive inhibition of the targeted N-terminal adenosine triphosphate pocket. This study, therefore, presents an overview of the various computational models implored in the development of HSP90 inhibitors as anticancer medicines. We hereby suggest an extensive investigation of advanced computational modelling of the three different domains of HSP90 for potent, effective inhibitor design with minimal off-target effects.

Molecular epidemiology and genetic diversity of Mycobacterium tuberculosis complex in referral health centers of Bamako, Mali: What is new?

BACKGROUND AND AIMS: Tuberculosis (TB) remains an important global health issue worldwide. Despite this scourge threatening many human lives, especially in developing countries, thus far, no advanced molecular epidemiology study using recent and more accurate tools has been conducted in Mali. Therefore, this study aimed to use variable-number tandem repeats of mycobacterial interspersed repetitive units (MIRU-VNTR) technology coupled with the spoligotyping method to accurately determine the hot spots and establish the epidemiological transmission links of TB in Bamako, Mali. METHODS: In a cross-sectional study, 245 isolates of Mycobacterium tuberculosis complex (MTBC) were characterized using spoligotyping and MIRU-VNTR, and an epidemiological investigation was conducted. RESULTS: Of the 245 isolates, 184 (75.1%) were formally identified. The most widespread strain was the Cameroon strain (83; 45.1%). Eight major clusters were identified: Ghana (27; 14.7%), West African 2 (22; 12%), Haarlem (13; 7.1%), H37Rv (t) (8; 4.3%), Latin American Mediterranean (8; 4.3%), and Uganda I and II (6; 3.3%). Statistical analysis showed a significant difference between lineages from the respective referral health centers of Bamako, Mali (P = 0.01). CONCLUSION: This study establishes, for the first time, an accurate spatial distribution of circulating MTB strains in Bamako, Mali. The data was used to identify strains and "hot spots" causing TB infection and can also be used for more targeted public health responses, particularly for hot spots of drug-resistant strains.

Multiple expansions of globally uncommon SARS-CoV-2 lineages in Nigeria.

Disparities in SARS-CoV-2 genomic surveillance have limited our understanding of the viral population dynamics and may delay identification of globally important variants. Despite being the most populated country in Africa, Nigeria has remained critically under sampled. Here, we report sequences from 378 SARS-CoV-2 isolates collected in Oyo State, Nigeria between July 2020 and August 2021. In early 2021, most isolates belonged to the Alpha "variant of concern" (VOC) or the Eta lineage. Eta outcompeted Alpha in Nigeria and across West Africa, persisting in the region even after expansion of an otherwise rare Delta sub-lineage. Spike protein from the Eta variant conferred increased infectivity and decreased neutralization by convalescent sera in vitro. Phylodynamic reconstructions suggest that Eta originated in West Africa before spreading globally and represented a VOC in early 2021. These results demonstrate a distinct distribution of SARS-CoV-2 lineages in Nigeria, and emphasize the need for improved genomic surveillance worldwide.

High SARS-CoV-2 Seroprevalence among Healthcare Workers in Bamako, Mali.

In Mali, a country in West Africa, cumulative confirmed COVID-19 cases and deaths among healthcare workers (HCWs) remain enigmatically low, despite a series of waves, circulation of SARS-CoV-2 variants, the country's weak healthcare system, and a general lack of adherence to public health mitigation measures. The goal of the study was to determine whether exposure is important by assessing the seroprevalence of anti-SARS-CoV-2 IgG antibodies in HCWs. The study was conducted between November 2020 and June 2021. HCWs in the major hospitals where COVID-19 cases were being cared for in the capital city, Bamako, Mali, were recruited. During the study period, vaccinations were not yet available. The ELISA of the IgG against the spike protein was optimized and quantitatively measured. A total of 240 HCWs were enrolled in the study, of which seropositivity was observed in 147 cases (61.8%). A continuous increase in the seropositivity was observed, over time, during the study period, from 50% at the beginning to 70% at the end of the study. HCWs who provided direct care to COVID-19 patients and were potentially highly exposed did not have the highest seropositivity rate. Vulnerable HCWs with comorbidities such as obesity, diabetes, and asthma had even higher seropositivity rates at 77.8%, 75.0%, and 66.7%, respectively. Overall, HCWs had high SARS-CoV-2 seroprevalence, likely reflecting a "herd" immunity level, which could be protective at some degrees. These data suggest that the low number of cases and deaths among HCWs in Mali is not due to a lack of occupational exposure to the virus but rather related to other factors that need to be investigated.

Molecular Epidemiology of Salmonella enterica in Poultry in South Africa Using the Farm-to-Fork Approach.

The presence of the zoonotic pathogen Salmonella in the food supply chain poses a serious public health threat. This study describes the prevalence, susceptibility profiles, virulence patterns, and clonality of Salmonella from a poultry flock monitored over six weeks, using the farm-to-fork approach. Salmonella was isolated using selective media and confirmed to the genus and species level by real-time polymerase chain reaction (RT-PCR) of the invA and iroB genes, respectively. Antimicrobial susceptibility profiles were determined using Vitek-2 and the Kirby-Bauer disk diffusion method against a panel of 21 antibiotics recommended by the World Health Organisation Advisory Group on Integrated Surveillance of Antimicrobial Resistance (WHO-AGISAR). Selected virulence genes were identified by conventional PCR, and clonality was determined using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). Salmonella was present in 32.1% of the samples: on the farm (30.9%), at the abattoir (0.6%), and during house decontamination (0.6%). A total of 210 isolates contained the invA and iroB genes. Litter, faeces, and carcass rinsate isolates were classified as resistant to cefuroxime (45.2%), cefoxitin (1.9%), chloramphenicol (1.9%), nitrofurantoin (0.4%), pefloxacin (11.4%), and azithromycin (11%). Multidrug resistance (MDR) was observed among 3.8% of the isolates. All wastewater and 72.4% of carcass rinsate isolates were fully susceptible. All isolates harboured the misL, orfL, pipD, stn, spiC, hilA, and sopB virulence genes, while pefA, spvA, spvB, and spvC were absent. In addition, fliC was only present among the wastewater isolates. Various ERIC-PCR patterns were observed throughout the continuum with different subtypes, indicating the unrelated spread of Salmonella. This study concluded that poultry and the poultry environment serve as reservoirs for resistant and pathogenic Salmonella. However, there was no evidence of transmission along the farm-to-fork continuum.

Antituberculosis Therapy and Gut Microbiota: Review of Potential Host Microbiota Directed-Therapies.

Tuberculosis (TB) remains a major public health concern with millions of deaths every year. The overlap with HIV infections, long treatment duration, and the emergence of drug resistance are significant obstacles to the control of the disease. Indeed, the standard first-line regimen TB treatment takes at least six months and even longer for the second-line therapy, resulting in relapses, drug resistance and re-infections. Many recent reports have also shown prolonged and significant damage of the gut microbial community (dysbiosis) from anti-TB drugs that can detrimentally persist several months after the cessation of treatment and could lead to the impairment of the immune response, and thus re-infections and drug resistance. A proposed strategy for shortening the treatment duration is thus to apply corrective measures to the dysbiosis for a faster bacterial clearance and a better treatment outcome. In this review, we will study the role of the gut microbiota in both TB infection and treatment, and its potential link with treatment duration. We will also discuss, the new concept of "Host Microbiota Directed-Therapies (HMDT)" as a potential adjunctive strategy to improve the treatment effectiveness, reduce its duration and or prevent relapses. These strategies include the use of probiotics, prebiotics, gut microbiota transfer, and other strategies. Application of this innovative solution could lead to HMDT as an adjunctive tool to shorten TB treatment, which will have enormous public health impacts for the End TB Strategy worldwide.

Toxicogenicity and mechanistic pathways of aflatoxin B1 induced renal injury.

The study investigated the toxicogenic effects, molecular mechanisms and proteomic assessment of aflatoxin B1 (AFB1 ) on human renal cells. Hek293 cells were exposed to AFB1 (0-100 µM) for 24 h. The effect on cell viability was assessed using the methylthiazol tetrazolium (MTT) assay, which also produced the half maximal inhibitory concentration (IC50 ) used in subsequent assays. Free radical production was evaluated by quantifying malondialdehyde (MDA) and nitrate concentration, while DNA fragmentation was determined using the single cell gel electrophoresis (SCGE) assay and DNA gel electrophoresis. Damage to cell membranes was ascertained using the lactate dehydrogenase (LDH) assay. The concentration of ATP, reduced glutathione (GSH), necrosis, annexin V and caspase activity was measured by luminometry. Western blotting and quantitative PCR was used to assess the expression of proteins and genes associated with apoptosis and oxidative stress. The MTT assay revealed a reduction in cell viability of Hek293 cells as the AFB1 concentration was increased, with a half maximum inhibitory concentration (IC50 ) of 32.60 µM. The decreased viability corresponded to decreased ATP concentration. The upregulation of Hsp70 indicated that oxidative stress was induced in the AFB1 -treated cells. While this implies an increased production of free radicals, the accompanying upregulation of the antioxidant system indicates the activation of defense mechanisms to prevent cellular damage. Thus, membrane damage associated with increased radical formation was prevented as indicated by the reduced LDH release and necrosis. In addition, cytotoxic effects were evident as AFB1 activated the intrinsic pathway of apoptosis with corresponding increased DNA fragmentation, p53 and Bax upregulation and increased caspase activity, but externalization of phosphatidylserine (PS), a major hallmark of apoptosis, did not occur in AFB1 treated renal cells. The results suggest that AFB1 induced oxidative stress leading to cell death by the intrinsic pathway of apoptosis in renal cells.

Influenza Viruses: Harnessing the Crucial Role of the M2 Ion-Channel and Neuraminidase toward Inhibitor Design.

As a member of the Orthomyxoviridae family of viruses, influenza viruses (IVs) are known causative agents of respiratory infection in vertebrates. They remain a major global threat responsible for the most virulent diseases and global pandemics in humans. The virulence of IVs and the consequential high morbidity and mortality of IV infections are primarily attributed to the high mutation rates in the IVs' genome coupled with the numerous genomic segments, which give rise to antiviral resistant and vaccine evading strains. Current therapeutic options include vaccines and small molecule inhibitors, which therapeutically target various catalytic processes in IVs. However, the periodic emergence of new IV strains necessitates the continuous development of novel anti-influenza therapeutic options. The crux of this review highlights the recent studies on the biology of influenza viruses, focusing on the structure, function, and mechanism of action of the M2 channel and neuraminidase as therapeutic targets. We further provide an update on the development of new M2 channel and neuraminidase inhibitors as an alternative to existing anti-influenza therapy. We conclude by highlighting therapeutic strategies that could be explored further towards the design of novel anti-influenza inhibitors with the ability to inhibit resistant strains.

Di-2-picolylamine triggers caspase-independent apoptosis by inducing oxidative stress in human liver hepatocellular carcinoma cells.

Di-2-picolylamine (DPA) is an organic compound that has been shown to possess antioxidant properties when conjugated to form a metal complex. The basis of this study was to determine the effects of DPA on the proliferation and apoptosis of human hepatocellular carcinoma cells and elucidate the possible mechanisms. The methylthiazol tetrazolium assay served to measure cell viability and generated an IC50 of 1591 µM. Luminometry was used to investigate caspase activity and ATP concentration. It was observed that the decreased cell viability was associated with reduced ATP levels. Despite increased Bax and caspase 9 activity, cell death was caspase independent as indicated by the reduction in caspase 3/7 activity. This was associated with the downregulation poly(ADP-ribose) polymerase cleavage (Western blotting). However, the Hoescht assay depicted nuclear condensation and apoptotic body formation with elevated DPA levels suggesting DNA damage in HepG2 cells. DNA damage assessed by the comet assay confirmed an increased comet tail formation. The presence of oxidative stress was investigated by quantifying reactive species (malondialdehyde and nitrates concentration) and Western blotting to confirm the expression of antioxidant proteins. The DPA increased lipid peroxidation (RNS), a marker of oxidative stress, consequently causing cell death. The accompanying upregulation of stress-associated proteins superoxide dismutase (SOD2), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and Hsp70 verifies oxidative stress.

Genomic Investigation into the Virulome, Pathogenicity, Stress Response Factors, Clonal Lineages, and Phylogenetic Relationship of Escherichia coli Strains Isolated from Meat Sources in Ghana.

Escherichia coli are among the most common foodborne pathogens associated with infections reported from meat sources. This study investigated the virulome, pathogenicity, stress response factors, clonal lineages, and the phylogenomic relationship of E. coli isolated from different meat sources in Ghana using whole-genome sequencing. Isolates were screened from five meat sources (beef, chevon, guinea fowl, local chicken, and mutton) and five areas (Aboabo, Central market, Nyorni, Victory cinema, and Tishegu) based in the Tamale Metropolis, Ghana. Following microbial identification, the E. coli strains were subjected to whole-genome sequencing. Comparative visualisation analyses showed different DNA synteny of the strains. The isolates consisted of diverse sequence types (STs) with the most common being ST155 (n = 3/14). Based Upon Related Sequence Types (eBURST) analyses of the study sequence types identified four similar clones, five single-locus variants, and two satellite clones (more distantly) with global curated E. coli STs. All the isolates possessed at least one restriction-modification (R-M) and CRISPR defence system. Further analysis revealed conserved stress response mechanisms (detoxification, osmotic, oxidative, and periplasmic stress) in the strains. Estimation of pathogenicity predicted a higher average probability score (Pscore ≈ 0.937), supporting their pathogenic potential to humans. Diverse virulence genes that were clonal-specific were identified. Phylogenomic tree analyses coupled with metadata insights depicted the high genetic diversity of the E. coli isolates with no correlation with their meat sources and areas. The findings of this bioinformatic analyses further our understanding of E. coli in meat sources and are broadly relevant to the design of contamination control strategies in meat retail settings in Ghana.

Prevalence and Antimicrobial Resistance of Escherichia coli Isolated from Various Meat Types in the Tamale Metropolis of Ghana.

Meats are important potential sources of foodborne pathogens including Escherichia coli. This study was conducted to determine the prevalence and antimicrobial resistance of Escherichia coli isolated from meats in the Tamale metropolis of Ghana. Isolation of Escherichia coli was done using the procedure according to the USA-FDA Bacteriological Analytical Manual. Antibiotic resistance patterns in the Escherichia coli isolates were determined by the Kirby-Bauer disk diffusion method against 8 antibiotics. The overall prevalence of Escherichia coli in the meat samples was 84.00% (189/225). Mutton (88.89%), guinea fowl (88.89%), beef (86.67%), local chicken (80.00%), and chevon (75.56%) were contaminated by Escherichia coli. The average coliform count was 4.22 cfu/cm2 and was highest in guinea fowl (4.94 log cfu/cm2) and lowest in local chicken (3.23 log cfu/cm2). The Escherichia coli isolates were highly resistant to erythromycin (85.00%), tetracycline (73.33%), and ampicillin (71.67%). The multiple antibiotic resistance (MAR) index ranged from 0.13 to 1. The Escherichia coli isolates exhibited 23 antimicrobial resistance patterns with resistant pattern TeAmpE (tetracycline-ampicillin-erythromycin) being the most common. Multidrug resistance was 68.33% (41/60) among the Escherichia coli isolates. The results showed that Escherichia coli was commonly present in the various meat types and exhibited multidrug resistances, necessitating efficient antibiotic stewardship guidelines to streamline their use in the production industry.

Fluorinated Quaternary Chitosan Derivatives: Synthesis, Characterization, Antibacterial Activity, and Killing Kinetics.

Chitosan has become an established platform biopolymer with applications in biomedical engineering, nanomedicine, and the development of new materials with improved solubility, antimicrobial activity, and low toxicity. In this study, a series of chitosan derivatives were synthesized by conjugating various perfluorocarbon chains to chitosan via Schiff base formation or nucleophilic substitution, followed by quaternization with glycidyl trimethylammonium chloride to confer non-pH-dependent permanent positive charges. Synthesized fluorinated N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride polymers were characterized and investigated for their antibacterial efficacies against multidrug-resistant bacteria including clinical isolates. The polymers showed activity against both Gram-positive and Gram-negative bacteria (MIC = 64-512 µg/mL) but with greater potency against the former. They displayed rapid bactericidal properties, based on the MBC/MIC ratio, which were further confirmed by the time-kill kinetic assays. Given the properties presented here, fluorinated quaternary chitosan derivatives can serve as great candidates to be investigated as environmentally more benign, nontherapeutic antimicrobial agents that could serve as alternatives to the heavy reliance on antibiotics, which are currently in a very precarious state due to increasing occurrence of drug resistance.

The molecular effect of 1,4,7-triazacyclononane on oxidative stress parameters in human hepatocellular carcinoma (HepG2) cells.

Antibiotic resistance poses a great threat to human, animal and environmental health. ß-Lactam antibiotics have been successful in combating bacterial infections. However, the overuse, inappropriate prescribing, unavailability of new antibiotics and regulation barriers have exacerbated bacterial resistance to these antibiotics. 1,4,7-Triazacyclononane (TACN) is a cyclic organic tridentate inhibitor with strong metal-chelating abilities that has been shown to inhibit ß-lactamase enzymes and may represent an important breakthrough in the treatment of drug-resistant bacterial strains. However, its cytotoxicity in the liver is unknown. This study aimed to determine the effect of TACN on oxidative stress in HepG2 cells. The HepG2 cells were treated with 0 to 500 µM TACN for 24 hours to obtain an IC50 for use in subsequent assays. Free radicals were measured using the thiobarbituric acid reactive substance and nitric oxide synthase assays, respectively, while antioxidant levels were assessed using luminometry (glutathione [GSH] and adenosine triphosphate [ATP]) and Western blot analysis (SOD, catalase, GPx-1, HSP70 and Nrf2). Percentage survival fluctuated as TACN concentration increased with a calculated IC50 of 545 µM. A slight increase in HSP70 and Nrf2 expression indicated the presence of stress and a response against it, respectively. However, free radical production was not increased as indicated by decreased malondialdehyde levels and reactive nitrogen species. Glutathione levels increased slightly, while ATP levels were marginally altered. The results suggest that TACN does not induce oxidative stress in HepG2 cells and can be exploited as a potential inhibitor.

Molecular mechanisms underlying the renoprotective effects of 1,4,7-triazacyclononane: a ßeta-lactamase inhibitor.

Broad-spectrum ß-lactam antibiotics such as penicillin are routinely used against both Gram-negative and Gram-positive bacteria. However, bacteria that produce ß-lactamase have developed resistance against these antibiotics by cleaving the ß-lactam ring and rendering the antibiotic inactive. To combat this effect, 1,4,7- Triazacyclononane (TACN), a cyclic organic compound derived from cyclononanes has been shown to preserve the activity of ß-lactam antibiotics by inhibiting ß-lactamase. However, its cytotoxic effects require elucidation. Given that the cytotoxic target for many therapeutics is the kidney, this study investigated the effects of TACN on human embryonic kidney cells (Hek293) cells. Hek293 cells were treated with TACN (0-500 µM) for 24 h and the cytotoxicity was assessed (MTT and LDH assay). Apoptosis was luminometrically detected by measuring phosphatidylserine externalisation and caspase activity and fluorescently detecting necrosis. DNA fragmentation was visualised using fluorescent microscopy. Expression of the apoptosis-related protein were determined by western blot. The results generated indicate that TACN does not initiate necrosis as LDH was decreased. Likewise, decreased apoptosis was supported by the decreased phosphatidylserine, caspases, Bax, cleaved PARP, IAP and NF-kB. However, increased DNA fragmentation was associated with increased p53. Therefore, effects of TACN at the nucleus, produced a p53 response to initiate DNA repair and did not culminate in cell death. The findings show that TACN is not cytotoxic to Hek293 cells via the apoptotic route. Since TACN did not induce cell death, its potential as a metallo-ß-lactamase inhibitor (MBLI) may be exploited to counteract the effect of MBL-producing bacteria. Restoring ß-lactam activity will curb the global menace of antibiotic resistance.