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The regulatory role of zinc in bone formation extends to the activation of proteins associated with bone homeostasis. Furthermore, copper is well known for its antibacterial properties. This dual function underscores the significance of zinc and copper in maintaining a balance of bone structure and function. In light of the aforementioned, zinc sulphide/copper oxide nanocomposites were created in this instance using a straightforward coprecipitation technique. Copper oxide was used as a nanocomposite to improve the structural, morphological, and biological performance of zinc sulphide nanoparticles. The X-ray diffraction pattern confirmed a transformation in the crystal structure from cubic to rhombohedral, along with increase in intensity. Fourier transforms infrared analysis indicated the presence of functional groups. Scanning electron microscopy images demonstrated a morphological shift from non-uniform to distinct spherical nanoparticles, impacting the enhancement of material properties. The pathogenic activity of the zinc sulphide/copper oxide nanocomposites was tested against nine bacterial strains. In antimicrobial testing, zinc sulphide/copper oxide nanocomposites showed promising results, particularly against Klebsiella pneumoniae (zone of inhibition: 14 mm at 100 µg/mL compared to 7 mm by standard) and Escherichia coli (zone of inhibition: 11 mm at 100 µg/mL compared to 10 mm by standard) after 24 h with zone of inhibition matching or exceeding that of the standard (chloramphenicol). Zinc sulphide nanoparticles and zinc sulphide/copper oxide nanocomposites were evaluated for their antifungal activity against fungal stains from Trichophyton rubrum, Aspergillus niger, and Aspergillus flavus. After a 24-h period, it was discovered that zinc sulphide/copper oxide nanocomposites were effective against Aspergillus flavus (zone of inhibition: 19.4 mm at 100 µg/mL compared to 6.3 mm by standard) at all concentrations (25–100 mg/mL), with zones of inhibition identical to or greater than those of the standard (fluconazole). Certainly, based on these results, zinc sulphide/copper oxide nanocomposites could be promising materials for drug delivery. Clinical trial registration: Not applicable. [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticles (ZnONPs) are enormously popular semi-conductor metal oxides with diverse applications in every field of science. Many physical and chemical methods applied for the synthesis of ZnONPs are being rejected due to their environmental hazards. Therefore, ZnONPs synthesized from plant extracts are steered as eco-friendly showing more biocompatibility and biodegradability. Additionally, various synthesis conditions such as the type of precursor salt also play a role in influencing the physicochemical and biological properties of ZnONPs. In this study, green synthesis of ZnONPs from Acacia nilotica was carried out using zinc acetate (ZA-AN-ZNPs), zinc nitrate (ZN-AN-ZNPs), and zinc sulfate (ZS-AN-ZNPs) precursor salts. Surprisingly, characterization of ZnONPs using UV–visible spectroscopy, TEM, XRD, and EDX revealed the important role precursor salts played in influencing the size and shape of ZnONPs, i.e., 20–23 nm spherical (ZA-AN-ZNPs), 55–59 nm triangular (ZN-AN-ZNPs), and 94–97 nm nano-flowers (ZS-AN-ZNPs). FTIR analysis showed the involvement of alkaloids, alcohols, carboxylic acid, and phenolic compounds present in Acacia nilotica extract during the synthesis process. Since different precursor salts showed different morphology of ZnONPs, their biological activities were also variable. ZN-AN-ZNPs showed the highest cytotoxicity towards HepG2 cells with the lowest cell viability (28.92 ± 0.99%), highest ROS/RNS production (3425.3 ± 184.58 relative DHR123 fluorescence), and loss of mitochondrial membrane potential (1645.2 ± 32.12 relative fluorescence unit) as well as induced significant caspase-3 gene expression. In addition to this, studying the zone of inhibitions and minimum bactericidal and inhibitory concentrations of ZnONPs showed their exceptional potential as antibacterial agents. At MIC as low as 8 µg/mL, ZA-AN-ZNPs and ZN-AN-ZNPs exhibited significant bactericidal activities against human pathogens Klebsiella pneumoniae and Listeria monocytogenes, respectively. Furthermore, alkaline phosphatase, DNA/RNA leakage, and phosphate ion leakage studies revealed that a damage to the bacterial cell membrane and cell wall is involved in mediating the antibacterial effects of ZnONPs. [ABSTRACT FROM AUTHOR]

This study presents an enhanced fractional-order mathematical model for analyzing the dynamics of Klebsiella pneumonia infections and antibiotic resistance over time. The model incorporates fractional Caputo derivative operators and kernel, to provide a more comprehensive understanding of the complex temporal dynamics. The model consists of three groups: Susceptible (S), Infected (I), and Resistant (R) individuals, each controlled by a fractional differential equation. The model represents the interaction between infection, recovery from infection, and the possible development of antibiotic resistance in susceptible individuals. The existence, uniqueness, stability, and alignment of the model's prediction to the observed data were analyzed and buttressed with numerical simulations. The results show that imipenem has the highest efficacy compared with ertapenem and meropenem category drugs. The estimated reproduction number and reproduction coefficient illustrate the potential impact of this model in improving treatment strategies, while the memory effects highlight the advantages of fractional differentiation. The model predicts an increased possibility of antibiotic resistance despite effective treatment, suggesting a new treatment approach. [ABSTRACT FROM AUTHOR]

As an alternative to antibiotics in response to antimicrobial-resistant infections, bacteriophages (phages) are garnering renewed interest in recent years. However, the massive preparation of phage is restricted using traditional pathogens as host cells, which incurs additional costs and contamination. In this study, an opportunistic pathogen, Klebsiella pneumoniae used to convert glycerol to 1,3-propanediol (1,3-PDO), was reused to prepare phage after fermentation. The phage infection showed that the fed-batch fermentation broth containing 71.6 g/L 1,3-PDO can be directly used for preparation of phage with a titer of 1 × 108 pfu/mL. Then, the two-step salting-out extraction was adopted to remove most impurities, e.g. acetic acid (93.5%), ethanol (91.5%) and cells (99.4%) at the first step, and obtain 1,3-PDO (56.6%) in the top phase as well as phage (97.4%) in the middle phase at the second step. This integrated process provides a cheap and environment-friendly manner for coproduction of 1,3-PDO and phage. [ABSTRACT FROM AUTHOR]

Background and Aims: Cirrhotic patients presenting with spontaneous bacterial peritonitis (SBP) have elevated risk of short-term mortality. While high Model for End-Stage Liver Disease-Sodium score (MELD-Na) and ascites culture yielding multi-drug resistance (MDR) bacteria are well established risk factors for further aggravating mortality, the impact of individual, causative microorganisms and their respective pathogenesis have not been previously investigated. Methods: This is a retrospective study of 267 cirrhotic patients at two tertiary care hospitals undergoing paracentesis from January 2015 to January 2021 who presented with ascitic PMN count > 250 cells/mm3. The primary outcome was SBP progression defined as death or liver transplantation within 1-month of paracentesis stratified by microorganism type. Results: Of 267 patients with SBP, the ascitic culture yielded causative microorganism in 88 cases [median age 57 years (IQR 52–64)]; 68% male; median MELD-Na 29 (IQR 23–35). The microbes isolated were E. coli (33%), Streptococcus (15%), Klebsiella (13%), Enterococcus (13%), Staphylococcus (9%) and others (18%); 41% were MDR. Cumulative incidence of SBP progression within 1-month was 91% (95% CI 67–100) for Klebsiella, 59% (95% CI 42–76) for E. coli, and 16% (95% CI 4–51) for Streptococcus. After adjusting for MELD-Na and MDR, risk of SBP progression remained elevated for Klebsiella (HR 2.07; 95% CI 0.98–4.24; p-value = 0.06) and decreased for Streptococcus (HR 0.28; 95% CI 0.06–1.21; p-value = 0.09) compared to all other bacteria. Conclusion: Our study found Klebsiella-associated SBP had worse clinical outcomes while Streptococcus-associated SBP had the most favorable outcomes after accounting for MDR and MELD-Na. Thus, identification of the causative microorganism is crucial not only for optimizing the treatment but for prognostication. [ABSTRACT FROM AUTHOR]

In this study, antibacterial activity of the essential oil (EO) and the hydrosol (HY) of Thymbra spicata L. were tested on K. pneumoniae and S. aureus. Since antimicrobial agent resistance is an important problem in infectious diseases, it was discussed the DRA (Dehydrogenase Relative Activity), DNA, and protein leakage during the inhibition period of bacteria exposed the EO. In addition, the effect of hydrosol interacted with UV on bacteria inoculated to artificial skin surface was studied. The main compounds of T. spicata EO were found as carvacrol (60.65%), γ-terpinene (23.03%), p-cymene (5.05%) by GC/MS (Gas Chromatography-Mass Spectrometry) analysis while HY's main components were detected as carvacrol (91.23%) and thymol (5.43%). No antimicrobial effect of the hydrosol alone was observed for S. aureus and K. pneumoniae in this study. Inactivation of the bacteria by UV-activated hydrosol was performed on 1cm2-lab skin surface. The 0.02 CFU/cm2 and 0.07 CFU/cm2 log reductions were observed in K. pneumoniae at 5 and 15 minutes, respectively, while 0.6 CFU/cm2 and 1.2 CFU/cm2 log reductions were observed in S. aureus at 5 and 15 minutes, respectively, on the lab skin. The inhibition zones (IZ) of the EO were 34.32 mm and 10.02 mm for K. pneumoniae and for S. aureus, respectively. After treatment by T. spicata EO at MIC, the increase in the water-soluble proteins of bacteria exposed to the EO was between 0.57% and 0.6% for K. pneumoniae, 0.01% and 0.3% for S. aureus within 15 min. In S. aureus supernatant, DRA was between 67.32% and 66.4% within 15 min, while DRA dropped to 21% from 28.1% in K. pneumonia treated with the EO. The increase in DNA leakage of the bacteria exposed to the EO was 0.09%-0.12% for K. pneumoniae, 0.08%-0.1% for S. aureus within 15 min. The findings may have provided a broader perspective on working mechanisms of antibacterials and directed the industrial use of UV-activated hydrosol to become widespread. [ABSTRACT FROM AUTHOR]

Environmental pollution by toxic heavy metals because of mining, metallurgic processes, and irrigation with primary treated sewage water is a global problem. This study was designed to investigate bioremediation of mercury by bacterial mixtures. The bacterial strains were isolated from the mercury mine and microbial fertilizer using the serial dilution and plate streaking. The following parameters were monitored during the experiment: growth curve, pH, time, inoculation quantity and resistance to mercury best. The mechanism of adsorption was examined utilizing FTIR, XRD and SEM–EDS studies. The obtained results revealed that three bacterial strains were identified as Klebsiella pneumonia, Bacillus toyonensis and Bacillus subtilis based on their morphology, biochemical characteristics and 16S ribosomal DNA gene. Compared to the single culture, the bacterial mixtures showed higher resistance to mercury. Klebsiella pneumoniae and Bacillus toyonensis grew normally when the mercury concentration was 0 ~ 30 mg L−1 and pH 4 ~ 8. Synergistic effects on the remediation of mercury (10 mg L−1) via the bacterial mixtures were observed after 72 h, and 80 ~ 83% remediation efficiency of mercury was recorded. Compared with single-strain cultures (40 ~ 50% remediation efficiency), the bacterial mixtures demonstrated greater resistance and efficiency for mercury remediation. This work proves that bacterial mixtures are useful in the bioremediation of heavy metals in the contaminated environment. [ABSTRACT FROM AUTHOR]

Infections with hypervirulent Klebsiella pneumoniae (hvKp) commonly presents with primary liver infection, bacteremia, and metastatic abscesses. Here, we present 2 cases of severe community-acquired pulmonary infections by hvKp in patients in the Netherlands without recent travel history. Both bacterial isolates are closely related to an archetype ST23 hvKp reference isolate. Based on these findings, surveillance programs on hvKp may consider to include isolates from community-acquired pneumonia by K. pneumoniae. [ABSTRACT FROM AUTHOR]

Background: The serine carbapenemase enzymes (KPC) which produce from bacteria klebsiella pneumoniae today have been emerged as one of the β-lactamase enzymes that is capable to inactivating the last line of carbapenems. The gene encoding the K. pneumonia (blaKPC) belongs to gene carried on plasmid among Enterobacteriaceae family, which has modulation for the infections control so this study is aimed to spot the presence and evaluate blaKPC gene expression by real-time PCR in local isolates of K. pneumonia. Methods: Forty-seven of K. pneumonia isolates were isolated from different clinical samples (blood, sputum, urine, wounds and burns) from patients in separate hospitals in Baghdad., Antimicrobial sensitivity test was carried out by vitik-2 system and Kirby- Bauer method. The PCR was employed to detect carbapenemase gene. Results: The results of this study showed that all explored isolates were resistant to Ertapenem, Meropenem and imipenem 47(100%). Phenotypically, all the isolates had carbapenemase which hydrolyzed the carbapenem antibiotics. Furthermore, the isolates showed (100%) resistance to Cefazolin, Ampicillin and Amoxicillin/ Clavulic acid. However, the most effective antibiotic was Levofloxacin (91.5%). The results of conventional PCR technique for the detection of blaKPC gene showed that 38 (80.9%) isolates of carbapenem-resistant K. pneumoniae harboured blaKPC gene (1010 bp), while none carried other carbapenemase genes including blaNDM1, blaVIM and blaIMP genes. High levels of carbapenem resistance was clarified by the imipenem and meropenem MICs determination. All 38 isolates were positive in CNPT. Furthermore, the 38 isolates showed over expression of blaKPC gene compared with housekeeping rpo gene in Real-Time PCR. Conclusions: According to these results, the resistant isolates to carbapenem were belong to the present and high level expression of blaKPC gene in our local isolates. [ABSTRACT FROM AUTHOR]

Increasing environmental concerns have brought natural surfactant produced by microorganisms into limelight due to their lesser toxicity, biodegradable nature, and retention of activity at extreme conditions. In the present investigation, the surfactant production perspective of capsulated Gram-negative bacilli Klebsiella pneumoniae ssp. ozaenae BK34 was explored. It was identified on the basis of PCR amplification of conserved region of 16SrRNA using species specific primers. Highest oil displacement and emulsification (E24) index of 6.8 cm and 20% along with 4.38-fold increase in biomass were attained using olive oil (2% (v/v)) as substrate. Incorporation of urea at 0.5% (w/v) concentration increased the oil displacement, E24 index, and drop diameter to 9.2 cm, 77.50%, and 0.80 cm, respectively, accompanied by 5.38-fold increase in biomass production. Biosurfactant level was recorded maximum at 30 °C as apparent from the oil displacement of 9.3 cm and E24 index of 75%. Reduction in incubation temperature to 25 °C abated oil displacement (5.2 cm) and E24 index (17.66%). Biosurfactant production was also appeared to be pH sensitive as shifting pH from 7.0 to 6.0 or 8.0 reduced the E24 index from 75 to 35% and 25%, respectively. Inoculum of stationary phase bacterial biomass at the proportion of 0.05% (w/v) was found adequate in triggering maximum biosurfactant production while the log phase biomass delayed the production significantly. Acid precipitation method was able to yield 7 g/L biosurfactant at pH 2. The surfactant was allocated to glycolipopeptide class on the basis of FTIR spectroscopy. [ABSTRACT FROM AUTHOR]

Due to potential antimicrobial application of chitosan nanoparticles (CNPs), alone or in combination with other natural or artificial compounds, we describe the preparation, characterization, and potent antimicrobial activity of kanamycin (KAN) and gentamicin (GM) that were chemically loaded to glucose-conjugated chitosan nanoparticles (g-CNPs). Successfully prepared CNPs, g-CNPs, and encapsulated drugs into g-CNPs backbones were evaluated by Fourier-transform infrared spectroscopy (FT-IR). Surface topology of CNPs was evaluated by X-ray diffraction pattern (XRD). Particle size and morphology of CNPs and drug-loaded nanoparticles were confirmed using transmission electron microscopy (TEM) and scanning electron microscope (SEM). Antibacterial potential of aminoglycoside loaded to g-CNPs was evaluated using minimum inhibitory concentration (MIC), as well as dynamic curves in the exposed strain to the nanoparticles were also investigated and result showed the appropriate antimicrobial activity against clinical strain of Klebsiella pneumonia. The used concentrations of 32 to 64 μg mL−1 of each KAN—g-CNPs and GM—g-CNPs showed bacteriostatic effect as well as entirely inhibitory impact on bacterial growth, respectively. In well diffusion assay, drugs loaded g-CNPs showed more antimicrobial activity with zone of inhibition (ZOI) 26.00 and 28.00 mm, compare to free nanoparticles and antimicrobial drugs with ZOI 21.00 and 10.00 mm, respectively. Furthermore, antibiofilm activity of KAN and GM loaded g-CNPs was studied using crystal violet assay and results indicated that there was a direct correlation with concentration of nanoparticles as well as anti-biofilm activity. The cell membrane integrity in the presence of KAN and GM loaded g-CNPs were evaluated and result indicated that there was an amount of released nucleic acids and proteins in environment. The inhibitory effect of KAN—g-CNPs and GM—g-CNPs on bacterial efflux pump (EP) was evaluated and result showed that all strains were sensitive to moderate concentration of nanoparticles and high sensitive to concentration of 0.5 and 0.8 μg mL−1 of ethidium bromide (EtBr) and 64 to 128 μg mL−1 of KAN—g-CNPs and GM—g-CNPs. The results clearly demonstrated that there was an inhibitory effect of the drugs loaded g-CNPs on efflux pump performances. Therefore, it can be assumed that this uniquely designed structure (KAN—g-CNPs and GM—g-CNPs) can serve as a potent next-generation antimicrobial compounds, but further studies should be performed on antimicrobial activity, in particular the mechanism of nanoparticles effect on bacterial cells. [ABSTRACT FROM AUTHOR]

Immunoinformatics or vaccine informatics focuses on applying computational approaches to advance vaccine research and development (R&D). It is also considered as an emerging field of research capable of improving immunization programs. Urinary tract infections (UTIs) are induced by exogenous organisms, including Klebsiella pneumonia, Proteus mirabilis, and extra-intestinal pathogenic Escherichia coli (ExPEC), which are closely related strains. Bacterial colonization in the urinary tract causes UTI. The purpose of this study was to design the cross-reactive epitope vaccine for stimulating the immune system (CD8 + and CD4 + T cells) against ExPEC, Klebsiella pneumonia, and Proteus mirabilis. In this study, protective vaccine antigens from the genome of ExPEC were used. Immunological predictions based on informatics were performed using available data to design vaccine candidates for inducing potentially cross-protective T-cells against UTI pathogens. Two vaccine candidates, comprising highly conserved and experimentally verified immunogenic epitopes, were designed. Epitope prediction and selection were performed for nine candidate proteins. The particular fusion of proper linkers, carriers, and epitopes was done, and constructs were designed. Physicochemical characteristics assessment of solubility, allergenicity, and antigenicity; reverse translation and codon optimization; second and third structure predictions were utilized for both vaccine candidates. Finally, the designed constructs with particular conserved epitopes with linkers and carriers were structurally approved. These vaccine candidates could be used as a broad immune system inducer, and its cross-protective immunity in UTI would confirm in the future. [ABSTRACT FROM AUTHOR]

Objective: Glycerol-based biosynthesis of 3-hydroxypropionic acid (3-HP) in Klebsiella pneumoniae involves two reactions: glycerol conversion to 3-hydroxypropionaldehyde (3-HPA) by glycerol dehydratase, and 3-HPA conversion to 3-HP by aldehyde dehydrogenase (ALDH). The ALDH catalysis consumes a lot of cofactor nicotinamide adenine dinucleotide (NAD+), which constrains 3-HP production. Results: Here we report that intensifying niacin-based biosynthesis of NAD+ can substantially enhance 3-HP production. We constructed tac promoter-driven NAD+ synthesis pathway in K. pneumoniae. The strain only overexpressing nicotinate phosphoribosyltransferase (PncB) showed 14.24% increase in the production of NAD+ relative to the stain harboring an empty vector. When PncB was coexpressed with PuuC (one of native ALDHs), the recombinant strain exhibited increased ALDH activity but slightly reduced 3-HP production due to plasmid burden. When 30 mg niacin l−1 (a substrate for biosynthesis of NAD+) was added into shake flask, the strain produced 0.55 g 3-HP l−1, which was 2.75 times that of the control. In a 5-L bioreactor, replenishment of niacin led to 36.43% increase of 3-HP production. Conclusions: These results indicated that intensifying niacin-based biosynthesis of NAD+ boosts 3-HP production. [ABSTRACT FROM AUTHOR]

M18 strain of Streptococcus salivarius is a bacterial replacement probiotic that has been suggested for use in the oral cavity. Here, we have shown that S. salivarius M18 cell-free supernatant reduced the growth of the two most common human pathogens Pseudomonas aeruginosa and Klebsiella pneumonia and sensitized the pathogenic bacteria to antibiotic. Besides, the supernatant inhibited biofilm formation of P. aeruginosa drastically. For pinpointing the biomolecular changes that occurred in P. aeruginosa incubated with the probiotic supernatant, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used. Unsupervised learning algorithms, principal component analysis (PCA) and hierarchical cluster analysis (HCA), and intensity analyses of individual spectral bands exhibited comprehensive alterations in the polysaccharide and lipid contents and compositions of P. aeruginosa cultivated with S. salivarius M18 cell-free supernatant. These results indicate that S. salivarius M18 has the potential for the prevention or alleviation of different pathogen-induced infections along with the infections of oral pathogens. [ABSTRACT FROM AUTHOR]

The pathogenic bacterium Klebsiella pneumoniae (KP) is the major causative agent of pyogenic liver abscess (PLA). But reports about the prognosis of KP-caused PLA (KPLA) are rare. This study aimed to ascertain the recurrence rate of KPLA after initial treatment and its contributing factors. A total of 110 patients who had first-time episodes of KPLA were included into the study. The average follow-up time was 3.65 ± 2.18 years. Twenty (18.18%) KPLA patients experienced recurrence. Those in the recurrence group had a significantly greater incidence of extended-spectrum β-lactamase (ESBL) production compared with the non-recurrence group (30.0% vs 8.89%, P = 0.018). Diabetes, biliary tract disease, and history of malignancy were not associated with recurrence (all P > 0.05). No difference in the CT characteristics of KPLA (including abscess size, location, whether multilocular, gas production of KPLA, and thrombophlebitis) was found between the two groups. Multivariate regression analysis showed that ESBL production (OR, 6.3; 95% CI, 1.02–38.59; P = 0.04) was an independent risk factor for the recurrence of KPLA. Our findings emphasize that KPLA has a high recurrence rate and ESBL production is an independent risk factor for recurrent KPLA. [ABSTRACT FROM AUTHOR]

The present study investigated the clinical course, treatment pattern, prognostic factors, and outcome of patients with pun-drug resistant (PDR) infections. This was a retrospective single-center cohort study including consecutive eligible patients with a PDR infection hospitalized at the University Hospital of Heraklion, Crete, Greece, between January 2010 and June 2018. In total, 65 patients with infections due to PDR gram-negative pathogens were identified. The median age was 64 years (interquartile range, IQR: 45.5–74.5) and the median Charlson comorbidity index 3.0 (IQR: 1.0–5.75). Of the 65 PDR isolates, 31 (48%) were Klebsiella pneumoniae, 28 (43%) Acinetobacter baumannii, and 6 (9%) Pseudomonas aeruginosa. The most common empirical therapy was colistin-based combination (n = 32; 49%), followed by non-colistin, non-tigecycline combination (n = 25; 39%), and carbapenemes + tigecycline (n = 8; 12%). The empirical therapy was effective in 50%, 37.5%, and 8% of patients receiving colistin combination, carbapenemes – tigecycline, and non-colistin, non-tigecycline combination, respectively (p value = 0.003). The infection-related in-hospital mortality was 32% (95% confidence interval, CI: 21–45%). Three factors were significantly associated with infection-related in-hospital mortality in multivariate analysis: Charlson comorbidity index (odds ratio, OR: 1.5, 95% CI: 1.0–2.3, p value = 0.030), prior steroid use (OR: 4.1, 95% CI: 1.0–17.0, p value = 0.049), and empirical treatment with non-colistin, non-tigecycline combination (OR: 7.5; 95% CI: 1.7–32.8, p value = 0.008). Infections due to PDR pathogens are associated with considerable mortality. Our results support the use of colistin and/or tigecycline-based combinations as empirical therapy when infection due to PDR pathogens is suspected. [ABSTRACT FROM AUTHOR]

1,3-Propanediol (1,3-PDO) has numerous industrial applications in the synthesis of the monomer of the widely used fiber polytrimethylene terephthalate. In this work, the production of 1,3-PDO by Klebsiella pneumoniae is increased by dual-substrate cultivation and fed-batch fermentation. Experimental results indicate that the production of 1,3-PDO can be elevated to 16.09 g/L using a dual substrate ratio (of glucose to crude glycerol) of 1/30 and to 20.73 g/L using an optimized dual-substrate ratio of 1/20. Ultimately, the optimal dual-substrate feeding for a 5 L scale fed-batch fermenter that maximizes 1,3-PDO production (29.69 g/L) is determined. This production yield is better than that reported in most related studies. Eventually, the molecular weight and chemical structure of 1,3-PDO were obtained by FAB-MS, 1H-NMR, and 13C-NMR. Also, in demonstrating the effectiveness of the fermentation strategy in increasing the production and production yield of 1,3-PDO, experimental results indicate that the fermentation of 1,3-PDO is highly promising for commercialization. [ABSTRACT FROM AUTHOR]

In the last few years, gold nanoparticle biosensors have been developed for rapid, precise, easy and inexpensive with high specificity and sensitivity detection of human, plant and animal pathogens. Klebsiella pneumoniae serotype K2 is one of the common gram-negative pathogens with high prevalence. Therefore, it is essential to provide the effective and exclusive method to detect the bacteria. Klebsiella pneumoniae serotype K2 strain ATCC9997 genomic DNA was applied to establish the detection protocol either with thiol-capped oligonucleotide probes and gold nanoparticles or polymerase chain reaction based on K2A gene sequence. In the presence of the genomic DNA and oligonucleotide probes, a change in the color of gold nanoparticles and maximum changes in wavelength at 550-650 nm was achieved. In addition, the result showed specificity of 15 × 105 CFU/mL and 9 pg/μL by gold nanoparticles probes. The lower limit of detection obtained by PCR method was 1 pg/μL. Moreover, results demonstrated a great specificity of the designed primers and probes for colorimetric detection assay and PCR. Colorimetric detection using gold nanoparticle probe with advantages such as the lower time required for detection and no need for expensive detection instrumentation compared to the biochemical and molecular methods could be introduced for rapid, accurate detection of the bacteria. [ABSTRACT FROM AUTHOR]

Pneumonia-induced sepsis is responsible for about 50% of cases in the world. Patients who develop severe sepsis and septic shock present organ dysfunction and elevated plasma cytokine levels, which may lead to death. Clinical scores are important to evaluate the framework of septic patients and are used to predict the syndrome progress, prognostics, and mortality. The objective of the present study was to verify the applicability of a murine clinical score system to experimental sepsis (pneumonia-induced sepsis in male mice) and to correlate it with mortality and bacterial dissemination in different organs. Results demonstrated that animals which present higher clinical scores (>3) are more likely to die. Animals presenting high clinical scores exhibited transient bacteremia and displayed bacterial spreading to different organs such as heart, kidney, liver, and brain. There is a correlation between clinical score and bacterial dissemination and consequently greater risk of death. In addition, animals which showed bacterial dissemination in more than three organs and high clinical scores presented high levels of cytokines (TNF-α, MCP-1, IL-6, and IL-10) in plasma, lung, heart, liver, kidney, and brain. Therefore, our study suggests that (1) severity scores have predictive power in experimental models of sepsis and (2) high concentrations of tissue cytokines may contribute to localized inflammation and be one of the factors responsible for the systemic inflammatory syndrome of sepsis. [ABSTRACT FROM AUTHOR]

Objectives: To improve 1,3-propanediol (1,3-PD) production and reduce byproduct concentration during the fermentation of Klebsiella pneumonia. Results: Klebsiella. pneumonia 2-1Δ ldhA, K. pneumonia 2-1Δ aldH and K. pneumonia 2-1Δ ldhAΔ aldH mutant strains were obtained through deletion of the ldhA gene encoding lactate dehydrogenase required for lactate synthesis and the aldH gene encoding acetaldehyde dehydrogenase involved in the synthesis of ethanol. After fed-batch fermentation, the production of 1,3-PD from glycerol was enhanced and the concentrations of byproducts were reduced compared with the original strain K. pneumonia 2-1. The maximum yields of 1,3-PD were 85.7, 82.5 and 87.5 g/l in the respective mutant strains. Conclusion: Deletion of either aldH or ldhA promoted 1,3-PD production in K. pneumonia. [ABSTRACT FROM AUTHOR]

To date, few studies have focused on reducing the toxic by-product acetate during 1,3-propanediol production by Klebsiella pneumoniae. In this study, the effects of deleting the poxB, pta, and ackA genes, which are involved in the two main acetate synthesis pathways, on cell growth and 1,3-propanediol production were investigated. Although acetate synthesis via pyruvate oxidase (PoxB, encoded by poxB) generally seems unnecessary and wasteful, PoxB was shown to play an important role in K. pneumoniae. Deletion of poxB severely inhibited cell growth, and the poxB mutant exhibited an anomalously high accumulation of acetate in aerobic cultures and failed to produce an endogenous supply of carbon dioxide (CO) in anaerobic cultures. It is interesting that both the aerobic and anaerobic growth defects of the poxB mutant were corrected by further deleting pta and ackA, which blocked the other main acetate synthesis pathway. The poxB-pta-ackA mutant excreted less acetate and showed an excellent ability to produce 1,3-propandiol. The final 1,3-propanediol yield and concentration in a 2-L fed-batch fermentation reached 0.66 (mol/mol) and 76.8 g/L, respectively, which were 16 and 15 % greater, respectively, than those of the parent strain. [ABSTRACT FROM AUTHOR]

The facultative aerobic bacteria isolated from the mucosa of rectum in the zone of malignant tumor and neighboring normal mucosa in patients with colorectal cancer were studied using molecular genetic methods. The species attribution of bacteria was implemented using the cultural morphological analysis and sequencing of the 16S rRNA locus. The microorganisms with intraepithelial invasion to rectal mucosa were identified as the representatives of adherent-invasive (AIEC) subgroup of Escherichia coli and species Klebsiella pneumonia. The molecular analysis by genetic determinants controlling adhesive, hemolytic, and toxigenic activity revealed that some bacterial isolates were able to produce toxins with potential cancerogenic activity (e.g., colibactin and cytotoxic necrotizing factor 1). Certain bacterial species isolated from malignant and normal rectal epithelium of the same patient demonstrated no difference between analyzed factors of toxigenicity. [ABSTRACT FROM AUTHOR]

Microbial fermentation under anaerobic and microaerobic conditions has been used for the production of 1,3-propanediol (1,3-PD), a monomer used to produce polymers such as polytrimethylene terephthalate. In this study, we screened microorganisms using the high throughput screening method and isolated the Klebsiella pneumoniae AJ4 strain, which is able to produce 1,3-PD under aerobic conditions. To obtain the maximum 1,3-PD concentration from glycerol, the response surface methodology based on a central composite design was chosen to show the statistical significance of the effects of glycerol, peptone, and (NH)SO on 1,3-PD production by K. pneumoniae AJ4. The optimal culture medium factors for achieving maximum concentrations of 1,3-PD included glycerol, 108.5 g/L; peptone, 2.72 g/L; and (NH)SO 4.38 g/L. Under this optimum condition, the maximum concentration of 1,3-PD, 54.76 g/L, was predicted. A concentration of about 52.59 g/L 1,3-PD was obtained using the optimized medium during 26-h batch fermentation, a finding that agreed well with the predicted value. [ABSTRACT FROM AUTHOR]

The composition and the antibacterial activity of the essential oil, isolated by hydrodistillation from the wood burl parts of Tetraclinis articulata from Morocco, were analyzed by GC and GC/MS. Fifteen compounds accounting for about 96% of the oil were positively identified. Cedrene (23%), thymol (22%), 3-tert-butyl-4-methoxyphenol (19%), cedrenol (9.6%), muurolene (5.4%), and sclarene (3%) were found to be the main constituents. The essential oil was tested for antimicrobial activity against four different genera of bacteria: Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae and Streptococcus D. and exhibited considerable inhibitory effects against all bacteria tested with MIC and MIB close to 1.25 μl/mL. The findings of the present study suggest that Tetraclinis articulata oil from hydro-distillation of sawdust from burl wood collected from artisans, has a potential to be used as bactericide. [ABSTRACT FROM AUTHOR]

The production of 1,3-propanediol (1,3-PD) was investigated with Klebsiella pneumoniae DSM 4799 using raw glycerol without purification obtained from a biodiesel production process. Fed-batch cultures with suspended cells revealed that 1,3-PD production was more effective when utilizing raw glycerol than pure glycerol (productivity after 47 h of fermentation, 0.84 gL-1h-1 versus 1.51 gL-1h-1 with pure and raw glycerol, respectively). In addition, more than 80 g/L of 1,3-PD was produced using raw glycerol; this is the highest 1,3-PD concentration reported thus far for K. pneumoniae using raw glycerol. Repeated fed-batch fermentation with cell immobilization in a fixed-bed reactor was performed to enhance 1,3-PD production. Production of 1,3-PD increased with the cycle number (1.06 gL-1h-1 versus 1.61 gL-1h-1 at the first and fourth cycle, respectively) due to successful cell immobilization. During 46 cycles of fed-batch fermentation taking place over 1,460 h, a stable and reproducible 1,3-PD production performance was observed with both pure and raw glycerol. Based on our results, repeated fed batch with immobilized cells is an efficient fermentor configuration, and raw glycerol can be utilized to produce 1,3-PD without inhibitory effects caused by accumulated impurities. [ABSTRACT FROM AUTHOR]

Efficacy and safety of imipenem/cilastatin in neonatal Klebsiella pneumonia sepsis was investigated in 45 infants compared to 39 control infants on conventional antibiotic regimen. Sensitivity to imipenem was 94% followed by cephoxitin (88%), quinolons (80%), and amikacin (52%) according to susceptibility results in the study group. Treatment duration of surviving infants was 16.5 +/- 4.6 and 20.3 +/- 6.4 days in the study and control groups respectively (p < 0.05). Five infants (11%) vs 27 (69%) were unresponsive (septic deaths) to treatment in the study and control groups respectively (p < 0.001). The cure rates were 73% and 28% respectively (p < 0.001). Sequelae free discharge rates were 67% and 23% respectively (p < 0.001). The most frequent adverse effects of imipenem/cilastatin were Candida albicans superinfection (20%); Candida albicans colonisation (10%); impairment of liver and renal functions (19% and 10% respectively); seizures (5%); thrombocytosis (3%); thrombophlebitis (3%); urine discoloration (3%); and Staphylococcus epidermidis colonisation (2%). Imipenem is considered a good alternative for neonatal Klebsiella pneumonia sepsis with these results, however, one must be aware of the increased risk of Candida albicans superinfection. [ABSTRACT FROM AUTHOR]

In Klebsiella pneumonia, regulation of the NifF protein (involved in N2-fixation) was not disscussed at the post-translational level until the recent discovery in Esherichia coli. Using a new K. pneumoniae strain MF, expressing high levels of NifF protein, we report a post-translational modification of NifF, which is different from that of E.coli. K. pneumoniae MF cultivated in L-broth and induced by IPTG had two forms of NifF protein (NifFα and NifFβ) that behaved similarly to the two forms of E. coli 71–18 NifF proteins (NifFI and NifFII) in non-SDS-PAGE. However, they behaved differently in response to the reduction by β-mercaptoethanol. NifFβ in the strain MF could not be reduced to NifFα, while NifFII from E. coli could be reduced to NifFI. Detection of NifF protein in different N2-fixing cells of K. pneumonia showed that only NifFβ existed, suggesting that this is the active form during N2-fixation. We conclude that post-translational control system of NifF during N2-fixation in K. pneumoniae is possibly different from that of E. coli. © Rapid Science Ltd. 1998 [ABSTRACT FROM AUTHOR]

Recurrent pregnancy loss is a disease of grave psychological and economic concern. The etiology in the vast majority of the cases is unknown or at best poorly understood. Although Klebsiella pneumonia infections have been reported in humans and animals during pregnancy, there is hardly any information to indicate whether or not these infections may be responsible for early pregnancy loss. We present a review of literature and report for the first time in humans, Klebsiella pneumonia infection in placenta of a 38-year-old secondary recurrent aborter (parity 2+3). [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to compare in vivo activity between cefquinome (CEQ)-loaded poly lactic-co-glycolic acid (PLGA) microspheres (CEQ-PLGA-MS) and CEQ injection (CEQ-INJ) against Klebsiella pneumonia in a rat lung infection model. Methods: Forty-eight rats were divided into control group (sham operated without infection and drug treatment), Klebsiella pneumonia model group (KPD + Saline), CEQ-PLGA-MS and CEQ-INJ therapy groups (KPD + CEQ-PLGA-MS and KPD + INJ, respectively). In the KPD + Saline group, rats were infected with Klebsiella pneumonia ATCC 10031. In the KPD + CEQ-PLGA-MS and KPD + INJ groups, infected rats were intravenously injected with 12.5 mg/kg body weight CEQ-PLGA-MS and CEQ-INJ, respectively. Results: Compared to CEQ-INJ treatment group, CEQ-PLGA-MS treatment further decreased the number of bacteria colonies (decreased to 1.94 lg CFU/g) in lung tissues and the levels of inflammatory cytokine including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-4 (p < 0.05 or p < 0.01) in bronchoalveolar lavage fluid at 48 h. Consistently, a significant decreases of scores of inflammation severity were showed at 48 h in the KPD + CEQ-PLGA-MS treatment group, compared to the KPD + CEQ-INJ treatment group. Conclusion: Our results reveal that CEQ-PLGA-MS has the better therapeutic effect than CEQ-INJ for Klebsiella pneumonia lung infections in rats. The vehicle of CEQ-PLGA-MS as the promising alternatives to control the lung infections with the important pathogens. [ABSTRACT FROM AUTHOR]