Facile synthesis of CuONPs using Citrus limon juice for enhancing antibacterial activity against methicillin-resistant Staphylococcus aureus, beta-lactamase and tetracycline-resistant Escherichia coli.

Antimicrobial resistance (AMR) resulting from indiscriminate use of antibiotics in various fields of agriculture such as livestock farming, aquaculture, and croup fields become an emerging catatroph for the health (human, animal) and environment. Among those, poultry farming has been considered as one of the major contributors of multidrug-resistant (MDR) bacteria. Focusing this, the present research is designed for green synthesis of copper oxide nanoparticles (CuONPs) with the aim of their application in antibiotic-free poultry farming for curving use of antibiotics in that sector. For that, antibacterial CuONPs were nanoformulated to decrease the required doses of bulk CuSO4. We used a CuSO4·5H2O solution as a Cu2+ source and Citrus limon juice as a reducing agent as well as capping agent. Particle yield was initially confirmed by the λmax specific to CuONPs (295 nm) using UV-Vis spectroscopy. The presence of the Cu-O group during particle formation and crystallinity with the purity of yielded NPs was confirmed with Fourier-transform infrared spectroscopy and X-ray diffractometry. The round to spherical CuONPs of 92-155 nm average size was confirmed with atomic force, scanning electron, and transmission electron microscopy. The concentration of yielded NPs was calculated with the dynamic light scattering. The physical characterization tools indicated a maximum CuONPs yield with a 0.001 M ion source with 15% reducing agents after 12 h reduction. Antibacterial effectivity was tested against methicillin-resistant Staphylococcus aureus and tetracycline- and beta-lactamase-resistant Escherichia coli, confirmed by PCR amplicon band at 163 bp, 643 bp, and 577 bp for the mecA, blaTEM-1 and tetA genes, respectively. An antibiogram assay of CuONPs showed a maximum zone of inhibition of 26 ± 0.5 mm for the synthesized particles. The minimum inhibitory and bactericidal concentrations were 1.6 µg ml-1 and 3.1 µg ml-1, respectively, for broad-spectrum application. Finally, the biocompatibility of CuONPs was determined by demonstrating a nonsignificant decrease of BHK-21 cell viability at <2 MIC doses for complying their future in vivo applicability.

Complete genome sequence of the multidrug-resistant clinical isolate Acinetobacter baumannii KBN10P05679: Insights into antimicrobial resistance genotype and potential virulence traits.

OBJECTIVES: Acinetobacter baumannii, a nosocomial pathogen, exhibits multidrug resistance and is a major concern worldwide. We therefore aimed to evaluate the genomic features of the clinical strain A. baumannii KBN10P05679 to elucidate its antibiotic resistance mechanisms and virulence factors. METHODS: In silico multilocus sequence typing, phylogenetic identification, genome annotation, genome analysis, antibiotic susceptibility testing, and biofilm formation assay were performed, and the expression levels of antibiotic resistance- and biofilm-related genes were investigated. RESULTS: The complete genome of KBN10P05679 comprises a circular chromosome of 3 990 428 bp and two plasmids (74 294 and 8731 bp) and was assigned to the ST451 sequence type. Clusters of Orthologous Gene annotation identified 3810 genes, including those involved in amino acid transport and metabolism, transcription, inorganic ion transport, energy production and conversion, replication, recombination and repair, and carbohydrate and protein metabolism. The antibiotic resistance genes were investigated by searching the Comprehensive Antibiotic Resistance Database, and the genome was found to harbour 30 different antibiotic resistance genes. Analysis of the Virulence Factor Database revealed 86 virulence factor genes in the KBN1005679 genome. The KBN10P05679 strain was found to have a higher capacity for biofilm formation and expressed biofilm-related genes at a higher level than the other tested strains. CONCLUSIONS: The antibiotic resistance genotype and potential virulence factor-related data obtained in this study would help direct future studies for developing the control measures for this multidrug-resistant pathogen.

Engineering of lysin by fusion of antimicrobial peptide (cecropin A) enhances its antibacterial properties against multidrug-resistant Acinetobacter baumannii.

Most clinical isolates of Acinetobacter baumannii, a nosocomial pathogen, are multidrug-resistant (MDR), fueling the search for alternative therapies. Bacteriophage-derived endolysins have potent antibacterial activities and are considered as alternatives to antibiotics against A. baumannii infection. Gram-negative bacteria possess outer lipid membrane that prevents direct contact between the endolysins and the cell wall. We hypothesized that the fusion of antimicrobial peptide (AMP) with endolysin could help to reduce bacterial endolysin resistance and increase antimicrobial activity by membrane permeability action. Accordingly, we fused cecropin A, a commonly used AMP, with the N-terminus of AbEndolysin, which enhances the bactericidal activity of the chimeric endolysin. The bactericidal activity of cecropin A-fused AbEndolysin increased by at least 2-8 fold for various MDR A. baumannii clinical isolates. The in vitro bactericidal activity results also showed higher bacterial lysis by the chimeric endolysin than that by the parental lysin. The engineered AbEndolysin (eAbEndolysin) showed synergistic effects with the beta-lactam antibiotics cefotaxime, ceftazidime, and aztreonam, and an additive effect with meropenem and imipenem. eAbEndolysin had no cytotoxic effect on A549 cell line and rescued mice (40% survival rate) from systemic A. baumannii infection. Together, these findings suggest the potential of lysin therapy and may prompt its use as an alternative to antibiotics.

Characterization of groundwater hydrogeochemistry, quality, and associated health hazards to the residents of southwestern Bangladesh.

In this research, we intended to appraise the hydrogeochemistry and human health risks of groundwater (GW) in southwestern Bangladesh, applying hydrogeochemical techniques, GW quality index (GWQI), several pollution indices, and mathematical health risk models. The trace elements (TEs) and ionic composition of GW samples were analyzed by atomic absorption spectroscopy and ion chromatography (AAS-IC) technique. The evaporate dissolution, silicate weathering, and ionic exchange processes control the hydrogeochemistry in GW. The GWQI revealed that 34% of samples were poor to very poor quality for drinking purposes, whereas irrigation water quality indices suggested moderate suitability of GW. The mean hazard quotient (HQ) and hazard index (HI) exceeded the tolerable level for adults and children, making substantial chronic health impacts on humans. The estimated carcinogenic risk of As and Pb surpassed the upper level of 1 × 10-4 for both aged populations. Overall, the results indicate that the local inhabitants have detrimental health risks; hence, effective regulation and proper measures should be concentrated for continuous monitoring, assessment, and remediation of As, Mn, Pb, and Hg in the study area.

Salinity-induced fluorescent dissolved organic matter influence co-contamination, quality and risk to human health of tube well water, southeast coastal Bangladesh.

Salinity in the drinking water of coastal Bangladesh results from a severe socio-economic, environmental and human health safety crisis. In this paper, we analyzed 120 tube well water samples from southeast coastal Bangladesh for eight trace metals (TMs). Contamination, quality and risk of TMs to human health of tube well water influenced by salinity-induced fluorescent dissolved organic matter (FDOM) were assessed using multiple pollution indices, GW quality index (GWQI), traditional health risk, and PARAFAC models. The mean values of EC, Fe, Cd, Cr, and As surpassed the limit set by local and international standards with significant spatial variations. The results of the GWQI showed that 52.5% of the samples were within the moderate-poor quality range in the study region. PARAFAC modeling identified three groundwater FDOM constituents with a coupling of humic acid (HA), fulvic acid (FA), and degraded fulvic acid (DFA)-like substances. Moreover, the positive correlations among EC, TMs, HA, FA, and DFA proved that salinity-induced FDOM had significant contributions to the dissolution potential of contaminants in the aquifer, hence increased the mobilization of TMs. Health risk models suggested that children are more susceptible to the non-carcinogenic and carcinogenic risks than adults at the community level. The carcinogenic risks of Cd, As, Pb, and Cr via oral exposure pathway indicated the highest carcinogenic risks for both adults and children. The findings also indicated that the salinity-derived FDOM-TMs complex is the key driver to groundwater co-contaminations and elevated health impacts. Besides, high concentrations of Fe and As are the key causal issues for sustainable water safety. Thus, strict water management and monitoring plans require preventing these contaminants for sustainable community well-being in the coastal region.