Antimicrobial resistance has recently been considered an emerging catastrophe globally. The public health and environmental threats were aggravated by the injudicious use of antibiotics in animal farming, aquaculture, and croup fields, etc. Consequently, failure of antibiotic therapies is common because of the emergence of multidrug-resistant (MDR) bacteria in the environment. Thus, the reduction in antibiotic spillage in the environment could be an important step for overcoming this situation. Bear in mind, this research was focused on the green synthesis of chitosan nanoparticles (ChiNPs) using Citrus lemon (Assam lemon) extract as a cross-linker and application in controlling MDR bacteria to reduce the antibiotic spillage in that sector. For evaluating antibacterial activity, Staphylococcus aureus and Escherichia coli were isolated from environmental specimens, and their multidrug-resistant pattern were identified both phenotypically by disk diffusion and genotypically by detecting methicillin- (mecA), penicillin- (blaZ), and streptomycin (aadA1)-resistance encoding genes. The inhibitory zone’s diameter was employed as a parameter for determining the antibacterial effect against MDR bacteria revealing 30 ± 0.4 mm, 34 ± 0.2 mm, and 36 ± 0.8 mm zones of inhibition against methicillin- (mecA) and penicillin (blaZ)-resistant S. aureus, and streptomycin (aadA1)-resistant E. coli, respectively. The minimum inhibitory concentration at 0.31 mg/mL and minimum bactericidal concentration at 0.62 mg/mL of yielded ChiNPs were used as the broad-spectrum application against MDR bacteria. Finally, the biocompatibility of ChiNPs was confirmed by showing a negligible decrease in BHK-21 cell viability at doses less than 2 MIC, suggesting their potential for future application in antibiotic-free farming practices.

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 λ_max 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.

This review discusses receptor-binding domain (RBD) mutations related to the emergence of various SARS-CoV-2 variants, which have been highlighted as a major cause of repetitive clinical waves of COVID-19. Our perusal of the literature reveals that most variants were able to escape neutralizing antibodies developed after immunization or natural exposure, pointing to the need for a sustainable technological solution to overcome this crisis. This review, therefore, focuses on nanotechnology and the development of antiviral nanomaterials with physical antagonistic features of viral replication checkpoints as such a solution. Our detailed discussion of SARS-CoV-2 replication and pathogenesis highlights four distinct checkpoints, the S protein (ACE2 receptor coupling), the RBD motif (ACE2 receptor coupling), ACE2 coupling, and the S protein cleavage site, as targets for the development of nano-enabled solutions that, for example, prevent viral attachment and fusion with the host cell by either blocking viral RBD/spike proteins or cellular ACE2 receptors. As proof of this concept, we highlight applications of several nanomaterials, such as metal and metal oxide nanoparticles, carbon-based nanoparticles, carbon nanotubes, fullerene, carbon dots, quantum dots, polymeric nanoparticles, lipid-based, polymer-based, lipid–polymer hybrid-based, surface-modified nanoparticles that have already been employed to control viral infections. These nanoparticles were developed to inhibit receptor-mediated host–virus attachments and cell fusion, the uncoating of the virus, viral gene expression, protein synthesis, the assembly of progeny viral particles, and the release of the virion. Moreover, nanomaterials have been used as antiviral drug carriers and vaccines, and nano-enabled sensors have already been shown to enable fast, sensitive, and label-free real-time diagnosis of viral infections. Nano-biosensors could, therefore, also be useful in the remote testing and tracking of patients, while nanocarriers probed with target tissue could facilitate the targeted delivery of antiviral drugs to infected cells, tissues, organs, or systems while avoiding unwanted exposure of non-target tissues. Antiviral nanoparticles can also be applied to sanitizers, clothing, facemasks, and other personal protective equipment to minimize horizontal spread. We believe that the nanotechnology-enabled solutions described in this review will enable us to control repeated SAR-CoV-2 waves caused by antibody escape mutations.

Among several Aeromonas spp., causing diseases in fishes, Aeromonas hydrophila is the most predominant and pathogenic one. This study represents the first molecular detection, virulence profiling, and antibiogram analysis of Aeromonas hydrophila isolated from stinging catfishes (shing; Heteropneustes fossilis) and shark catfishes (pangasius; Pangasianodon hypophthalmus) in Bangladesh. Whole fish samples (n = 140) were collected from fish farming areas of Trishal upazila (stinging catfish 50; shark catfish 20) and Muktagachha upazila (stinging catfish 50; shark catfish 20), under Mymensingh district. Isolation and identification were accomplished through cultural, morphological, biochemical and finally, polymerase chain reaction (PCR) using genus- and species-specific primers, targeting 16S rDNA gene. Out of 140 samples, 38 (27.14%) isolates were found positive for A. hydrophila via conventional and PCR. The PCR-based virulence profiling showed that aerA (44.73%), hlyA (39.74%), asa1 (39.47%), ahyB (60.52%), act (21.5%), ast (28.94), alt (47.36%), ser (44.73%), lip (50%), gcat (23.68%), and ascV (21.05%) genes were detected, however, no aexT was detected. Antibiotic susceptibility test (using disc diffusion method) revealed that highest resistance (other than Penicillin Group) against Aztreonam and Cefuroxime (73.68%), and lowest against Gentamicin and Azithromycin (5.26%). MDR was detected in 71.05% isolates, and 92.11% isolates had MAR index ≥ 0.2. Statistically significant associations were observed between phenotypic resistance and specific virulence genes p ≤ 0.05. It could be concluded that MDR and virulent potential A. hydrophila are prevalent in stinging and shark catfishes of Mymensingh region, which might be a serious threat to sustainable aquaculture, food safety and public health.

Edwardsiellosis, caused by Edwardsiella tarda , is a highly pathogenic disease affecting both freshwater and marine fish, leading to mass mortality. This study encompassed the molecular detection, virulence and antibiogram profiling of E. tarda from Heteropneustes fossilis (stinging catfish). A total of 40 fish samples were collected from different fish farms in the Mymensingh district. Isolation of E. tarda was performed using selective media, followed by identification through morphological, cultural, and biochemical testing, and confirmed through polymerase chain reaction (PCR). Antibiogram was performed following the disc diffusion method, and virulence and antibiotic resistance genes were detected through PCR. 19 out of 40 fishes were positive for Edwardsiella infection and 32 E. tarda were isolated. PCR assays consistently amplified gro EL (623 bp), gyr B (415 bp), etf A (415 bp), and etf D (445 bp) genes, respectively. The prevalence of virulence genes was: gad B (17%), muk F (35%), fim A (10%), and cit C (12.5%). The antibiogram revealed that the highest resistance (90.63%) was found against cotrimoxazole and amoxicillin, whereas sensitive (100%) to gentamicin and meropenem. Among 32 isolates, 90.75% were found to be multi-drug resistant (MDR). Again, multiple antibiotic resistance (MAR) index analysis revealed the highest value of 0.61, and 93.75% of isolates have an MAR index above 0.2. Resistance gene distribution was observed as the highest (62.5%) isolates harbored the tet A gene and the lowest (21.88%) isolates harbored qnr B. It could be concluded that MDR and pathogenic potential E. tarda was present in stinging catfish, posing a potential threat to animals, humans, and the environment.

Extended-spectrum beta-lactamase (ESBL) and Carbapenemase-producing Gram-negative bacteria, particularly Klebsiella pneumoniae (ESBL-KP and CP-KP), in the food supply chain, poses a significant public health threat. Ready to eat (RTE) street foods, especially fuchka, a highly popular snack in Bangladesh, India and Southeast Asia, represents a critical breach in food safety. This study investigated the multidrug resistance (MDR) patterns of K. pneumoniae isolated from fuchka with an emphasis on phenotypic and genotypic detection of ESBL-KP and CP-KP. A total of 60 samples were collected from 15 fuchka selling points. K. pneumoniae was isolated and identified via staining, cultural methods, PCR and MALDI-ToF-MS biotyper. Antibiotic susceptibility test (AST) was accomplished using disk diffusion method, phenotypic ESBL producers was detected by combined disk test (CDT) and PCR was used to detect resistance determinant. Thirty K. pneumoniae isolates were confirmed by PCR and MALDI-ToF-MS. All showed resistance to amoxicillin and cefuroxime (100%), while most were sensitive to cefepime (96.7%), norfloxacin (96.7%), imipenem (93.3%) and meropenem (83.3%). All the isolates were MDR, with multiple-antibiotic resistance (MAR) index values ranged from 0.28 to 0.64. CDT confirmed 28 ESBL producers. Among ESBL-producing genes bla _TEM, was most prevalent (64%), followed by bla _SHV, bla _OXA-1, bla _CTX-M1, bla _CTX-M3. Among carbapenem-resistant genes, bla _BIC was most common (46%), while bla _VIM was absent. Moreover, other resistance determinants ( aad A1, aac 3IV was most prevalent (40%) but aad A1, qnr A were not detected. The presence of multidrug-resistant, ESBL- and carbapenemase-producing K. pneumoniae in fuchka represents a critical threat to public health.