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Synthetic nanoparticles (NPs) have become more widely used in the disinfection and health sectors owing to their ability to effectively penetrate biological systems. Recent research has demonstrated the ability of microbial proteins and enzymes to function as reducing agents throughout the NP-production process, providing a different option to chemical and physical techniques. This method not only saves money and is effective, but also has the least possible environmental impact. This work used Lactobacillus spp., as the reducing and capping agent to create zinc oxide nanoparticles, (ZnO NPs). Numerous analytical techniques were employed to examine the generated ZnO NPs; these techniques include ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). As an opportunistic pathogenic bacterium, Enterobacter cloaca possesses several virulence characteristics that enable it to infiltrate target tissues. However, bacteria can become resistant to antibiotics, which in turn makes treating bacterial infections becomes more difficult. With the development of science at the biotechnology level, using zinc oxide ZnO NPs on isolates of Enterobacter cloacae, we conducted research in the promising field of nanotechnology. The impact of three different concentrations of ZnO NPs on the gene expression of Enterobacter cloaca lipopolysaccharide transport (Lpt) proteins in isolates obtained from some patients suffering of various infections was investigated. Bacteria with the highest multidrug resistance were selected for further analysis. Expression of LptC gene was reduced significantly at concentration of 125 mg/mL (P < 0.01) for all the isolate that treated with ZnO NPs. [ABSTRACT FROM AUTHOR]

Enterobacter cloacae produces insecticidal proteins capable of causing toxicity in pests, but the insecticidal mechanisms of these proteins for insect control remain unclear. To elucidate the mechanisms, the purified insecticidal protein from E. cloacae NK was administered to Galleria mellonella larvae either by intraperitoneal injection or by feeding. The number of hemocytes, apoptosis in immune cells, and polyphenol oxidase (PO) activity of G. mellonella larvae were detected by hemocytometer, Annexin V-FITC/PI, and UV-vis spectrophotometer, respectively. With the extension of the invasion time of NK insecticidal protein, the number of hemocytes in G. mellonella larvae decreased significantly (p < 0.05), whereas the apoptosis rate of hemocytes increased. The activity of PO showed a trend of rising-peak-sharp decline and the melanization reaction was deepened simultaneously. Moreover, the phagocytosis and coating capabilities of hemocytes decreased, and the intraperitoneal injection method was more effective than the feeding method. Taking together, the insecticidal protein of E. cloacae NK inhibits and destroys the cellular immune response of G. mellonella larvae, which suggests an important role in killing the host insect. [ABSTRACT FROM AUTHOR]

Enterobacter cloacae (EC) is a significant emerging pathogen that is occasionally associated with lung infection, surgical site infection, urinary infection, sepsis, and outbreaks in neonatal intensive care units. In light of the fact that there is currently no approved vaccine or therapeutic option for the treatment of EC, the current study was developed to concentrate on applications based on modern computational approaches to design a multi-epitope-based E. cloacae peptide vaccine (MEBEPV) expressing the antigenic determinants prioritized from the EC genome. Integrated computational analyses identified two potential protein targets (phosphoporin protein-PhoE and putative outer-membrane porin protein) for further exploration on the basis of pangenome subtractive proteomics and immunoinformatic in-depth examination of the core proteomes. Then, a multi-epitope peptide vaccine was designed, which comprised shortlisted epitopes that were capable of eliciting both innate and adaptive immunity, as well as the cholera toxin's B-subunit, which was used as an adjuvant in the vaccine formulation. To ensure maximum expression, the vaccine's 3D structure was developed and the loop was refined, improving the stability by disulfide engineering, and the physicochemical characteristics of the recombinant vaccine sequence were found to be ideal for both in vitro and in vivo experimentation. Blind docking was then used for the prediction of the MEBEPV predominant blinding mode with MHCI, MHCII, and TLR3 innate immune receptors, with lowest global energy of −18.64 kJ/mol, −48.25 kJ/mol, and −5.20 kJ/mol for MHC-I, MHC-II, and TLR-4, respectively, with docked complexes considered for simulation. In MD and MMGBSA investigations, the docked models of MEBEPV-TLR3, MEBEPV-MHCI, and MEBEPV-MHCII were found to be stable during the course of the simulation. MM-GBSA analysis calculated −122.17 total net binding free energies for the TLR3-vaccine complex, −125.4 for the MHC I-vaccine complex, and −187.94 for the MHC II-vaccine complex. Next, MM-PBSA analysis calculated −115.63 binding free energy for the TLR3-vaccine complex, −118.19 for the MHC I-vaccine complex, and −184.61 for the MHC II-vaccine complex. When the vaccine was tested in silico, researchers discovered that it was capable of inducing both types of immune responses (cell mediated and humoral) at the same time. Even though the suggested MEBEPV has the potential to be a powerful contender against E. cloacae-associated illnesses, further testing in the laboratory will be required before it can be declared safe and immunogenic. [ABSTRACT FROM AUTHOR]

Enterobacter cloacae (EC) is a significant emerging pathogen that is occasionally associated with lung infection, surgical site infection, urinary infection, sepsis, and outbreaks in neonatal intensive care units. In light of the fact that there is currently no approved vaccine or therapeutic option for the treatment of EC, the current study was developed to concentrate on applications based on modern computational approaches to design a multi-epitope-based E. cloacae peptide vaccine (MEBEPV) expressing the antigenic determinants prioritized from the EC genome. Integrated computational analyses identified two potential protein targets (phosphoporin protein-PhoE and putative outer-membrane porin protein) for further exploration on the basis of pangenome subtractive proteomics and immunoinformatic in-depth examination of the core proteomes. Then, a multi-epitope peptide vaccine was designed, which comprised shortlisted epitopes that were capable of eliciting both innate and adaptive immunity, as well as the cholera toxin’s B-subunit, which was used as an adjuvant in the vaccine formulation. To ensure maximum expression, the vaccine’s 3D structure was developed and the loop was refined, improving the stability by disulfide engineering, and the physicochemical characteristics of the recombinant vaccine sequence were found to be ideal for both in vitro and in vivo experimentation. Blind docking was then used for the prediction of the MEBEPV predominant blinding mode with MHCI, MHCII, and TLR3 innate immune receptors, with lowest global energy of −18.64 kJ/mol, −48.25 kJ/mol, and −5.20 kJ/mol for MHC-I, MHC-II, and TLR-4, respectively, with docked complexes considered for simulation. In MD and MMGBSA investigations, the docked models of MEBEPV-TLR3, MEBEPV-MHCI, and MEBEPV-MHCII were found to be stable during the course of the simulation. MM-GBSA analysis calculated −122.17 total net binding free energies for the TLR3-vaccine complex, −125.4 for the MHC I-vaccine complex, and −187.94 for the MHC II-vaccine complex. Next, MM-PBSA analysis calculated −115.63 binding free energy for the TLR3-vaccine complex, −118.19 for the MHC I-vaccine complex, and −184.61 for the MHC II-vaccine complex. When the vaccine was tested in silico, researchers discovered that it was capable of inducing both types of immune responses (cell mediated and humoral) at the same time. Even though the suggested MEBEPV has the potential to be a powerful contender against E. cloacae-associated illnesses, further testing in the laboratory will be required before it can be declared safe and immunogenic.

Pathogenic bacterial strains that cause serious infections particularly among individuals with immune-deficiency can exhibit antibiotic-resistance against the available therapeutic options thereby constituting a public health concern. In this study, we evaluated the occurrence of carbapenem-resistant Enterobacter species isolated from different environmental samples collected from selected study areas in the Eastern Cape Province, South Africa. Our study further aimed to evaluate the antimicrobial-resistant (AMR) profiles of the confirmed isolates recovered from hospital wastewater effluents, wastewater treatment plants and other environmental sources including river water and farm samples. Results revealed out of 142 PCR-confirmed Enterobacter spp., 115 isolates (81%) were classified as Enterobacter cloacae. The confirmed species exhibited phenotypic resistance in decreasing order for doripenem (80%), meropenem (75%), imipenem (72%) and ertapenem (66%) and carbapenem-resistance genes (CRGs) were detected in 29% of Enterobacter spp. isolates. Our findings confirm the presence of CRGs among bacterial isolates populating environmental niches. [ABSTRACT FROM AUTHOR]

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (TOFMS) is now widely used to detect pathogens in clinical settings in Japan. Here, we report the ability of TOF-MS to detect bacteria from blood culture (BC) broths, and compare the efficacy of TOF-MS to that of conventional culture methods. Bacteria were correctly detected from 63 monomicrobial samples within 80 minutes; results matched those obtained by conventional BC methods, although the conventional methods took 2-3 days. In addition to the 63 monomicrobial samples, another three polymicrobial samples were tested; notably, the infecting bacteria were not correctly identified in two of these three samples. To better assess the TOF-MS detection of polymicrobial samples, we tested various ratios of mixed broth samples, including combinations of the bacteria that we were unable to detect in clinical samples. Combinations of Enterobacter cloacae and Pseudomonas aeruginosa were correctly detected at a culture ratio of 2:1, but not in the 3:1 mixture. These results suggested that TOF-MS is a strong tool for the rapid and correct detection of pathogens from monomicrobial BC samples, though results need to be carefully checked when handling known or suspected polymicrobial samples. [ABSTRACT FROM AUTHOR]

Toxic goby fish ( Yongeichthys criniger ) containing tetrodotoxin (TTX), from Zhanjiang, Guangdong province, China, were screened for TTX-producing bacteria. Two toxic bacterial strains were isolated from the liver of Y. criniger and respectively denoted XC3-3 and XL-1. TTX production by the strains was confirmed by mouse bioassay, enzyme-linked immunosorbent assay and high performance liquid chromatography coupled with mass spectrometry. Based on morphological, physiological and biochemical characteristics and 16S rDNA phylogenetic analysis, strain XC3-3 was identified as Enterobacter cloaca and XL-1 was closely related to Rahnella aquatilis . These findings show for the first time that TTX-producing bacteria are symbiotic bacteria in goby and suggest that bacterial strains are at least partially responsible for TTX accumulation in Y. criniger . [ABSTRACT FROM AUTHOR]