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Objective The toxin-producing Klebsiella oxytoca causes antibiotic-associated haemorrhagic colitis (AAHC). The disease-relevant cytotoxins tilivalline and tilimycine produced by certain K. oxytoca isolates are encoded by the non-ribosomal peptide synthetase genes A (npsA) and B (npsB). In this study, the new LightMix® Modular kit for detection of relevant K. oxytoca sensu lato (s.l.) toxin genes was evaluated. Methods DNA was extracted on the automated EMAG® platform. Amplification was done on the Light Cycler® 480 II instrument. A total of 130 residual faecal specimens that had been collected from patients with antibiotic-associated diarrhoea were studied to determine the clinical sensitivity and specificity. Toxigenic culture served as reference method. Results With the new kit, the limit of detection was 15 CFU/mL for all targets. For the K. oxytoca s.l. specific pehX target, 65 of 130 clinical specimens were positive while toxin specific targets (npsA/npsB) were positive in 47 of 130. The npsA/npsB PCR targets showed a clinical sensitivity of 100% (95% CI of 80.5% to 100%) and a specificity of 73.5% (95% CI of 64.3% to 81.3%) with a positive predictive value of 16.5% (95% CI of 12.7% to 21.2%) and a negative predictive value of 100%. Conclusion Compared with culture, additional K. oxytoca s.l.-positive clinical specimens were detected with real-time PCR. The specificity of the toxin targets appears moderate due to the inferior sensitivity of the culture-based reference method. Since the developed assay is highly sensitive, it may be used as first-line method to improve AAHC diagnosis.

To search for a new eco-friendly therapy for infectious disease caused by Escherichia coli, Staphylococcus aureus or Klebsiella oxytoca, we collected the vaginal swabs from healthy women, screened for Lactobacillus and found a strain repressing the growth of pathogenic bacteria. The new isolate was identified as L. gasseri by the colony morphology, Gram staining, biochemical reactions and confirmed by the 16S rDNA sequencing. The HMV18 strain inhibited the growth of food-borne pathogens such as E. coli, S. aureus and K. oxytoca. The HMV18 strain was sensitive to penicillin, ampicillin, erythromycin, tetracycline and chloramphenicol. The HMV18 strain produced α-hemolysis. Pathological histology of the mice ileum showed that the mucosa, villi, lamina propria and crypt depth remained intact and there was no inflammation or hyperemia in the L. gasseri HMV18 gavaged group. L. gasseri HMV18 could not up-regulate inflammatory cytokines level of plasma. All the results suggested L. gasseri HMV18 is a candidate probiotic to be an additive for food preservation or drug to prevent food-borne diseases.

In this study, the silver nanoparticles (AgNPs) were extracellularly synthesized using a bioluminescent bacterium, Vibrio campbellii, and characterized their functional properties and morphological nature by UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM–EDS), and atomic force microscopy (AFM). Further, the synthesized AgNPs were analyzed for their antibacterial and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), and hydrogen peroxide) in in vitro method. The antibacterial activity of AgNPs was tested against pathogenic bacteria such as Aeromonas hydrophila MTCC 1739, Klebsiella pneumoniae MTCC 4030, Klebsiella oxytoca MTCC 3030, and Pseudomonas aeruginosa MTCC 1934. Characterization studies revealed that the synthesized AgNPs were poly-dispersed, spherical shaped with various size ranges, and exhibited as crystalline in nature. The assay of antibacterial activity showed the synthesized AgNPs strongly inhibited the tested pathogenic bacterial growth. Also, the AgNPs showed good antioxidant activity by strong scavenging actions on DPPH (61.88%) and hydrogen peroxide (53.48%) free radicals. Overall results demonstrated that AgNPs could be used in the pharmaceutical field due to their good antibacterial and antioxidant activity.

Summary New Delhi metallo-β-lactamase (NDM) gene confers high-level resistance to an array of β-lactams including carbapenems. Short- and long-read sequencing was used to investigate outbreaks of NDM-positive Enterobacterales including a potential horizontal gene transfer (HGT) event of an NDM-positive plasmid between Salmonella enterica and Klebsiella pneumoniae. Genomic analysis demonstrated a high degree of similarity between NDM-carrying plasmids from patient 1 in K. pneumoniae and patient 2 with S. enterica, K. pneumoniae and Klebsiella oxytoca, confirming an inter-species HGT event. The utility of whole-genome sequencing was demonstrated for in-hospital outbreaks, previously undetected using traditional infection-control surveillance.

Aim To isolate and characterize bacteriophage lytic for the opportunistic pathogen Klebsiella oxytoca and their formulation into a range of solid dosage forms for in-vitro testing. Methods and results We report the isolation, genomic and functional characterization of a novel bacteriophage lytic for Klebsiella oxytoca, which does not infect the closely related Klebsiella pneumoniae. This bacteriophage was formulated into suppositories and troches and shown to be released and lyse underlying Klebsiella oxytoca bacteria in an in-vitro model. These bacteriophage formulations were stable for at least 49 days at 4°C. Conclusions The successful in-vitro assay of these formulations here suggests that they could potentially be tested in-vivo to determine whether such a therapeutic approach could modulate the gut microbiome, and control Klebsiella oxytoca overgrowth, during antibiotic therapy regimes. Significance and impact of the study This study reports a novel bacteriophage specific for Klebsiella oxytoca which can be formulated into solid dosage forms appropriate for potential delivery in testing as a therapy to modulate gut microbiome during antibiotic therapies.

Citrus peel is an important source of essential oils (EOs). However, these EOs are not invested, although the annual production of citrus is high in Syria. The current study aimed to investigate chemical composition and antibacterial activity of some citrus peel EOs, namely: lemon (Citrus limon), orange (C. sinensis), grapefruit (C. paradisi), mandarin (C. reticulata) and bitter orange (C. aurantium). Gas chromatography–mass spectrometry (GC/MS) (gas chromatograph type: Agilent 7890A, auto sampler type: Agilent 7683B coupled to mass spectrometer, type Agilent 5975C, using DB–1 capillary column. EOs. concentration 1: 10 v/v in chloroform, injection volume 1 µl, split ratio 1: 80), was used to identify the chemical composition of the EOs, which were extracted by hydrodistillation technique, and chemical composition was expressed as Mean ± SD of three replications using SPSS V17 software. Minimal bactericidal concentration (MBC) was used to determine the antibacterial activity against five Gram-positive bacteria (Bacillus cereus, B. licheniformis, Staphylococcus haemolyticus, S. lugdunensis, Enterococcus faecalis) and five Gram negative bacteria (Klebsiella oxytoca, Citrobacter koseri, Serratia liquefaciens, Pseudomonas fluorescens and P. luteola). Limonene formed the vast majority of EOs (between 62.16 and 95.26% in lemon and orange EOs, respectively), but there were other active components, such as α–Pinene and β–Pinene. Lemon EO was the most effective one, with MBC values ranged between 4 μl.ml–1 (against Bacillus cereus) and 50 μl.ml–1 (against Serratia liquefaciens). Pseudomonas luteola (a Gram-negative bacterium) was the most sensitive species to citrus EOs (MBC values ranged between 4 and 50 μl.ml–1 for lemon and orange EOs, respectively); while S. liquefaciens (a Gram-negative bacterium) was the most resistant bacterium (MBC values were 50 and 150 μl.ml–1 for lemon and mandarin EOs, respectively) among all species studied in the current research.

4-Hydroxybenzoic acid (4-HBA) is a common organic compound that is prevalent in the environment, and the persistence of 4-HBA residues results in exertion of pollution-related detrimental effects. Bioremediation is an effective method for the removal of 4-HBA from the environment. In this study, two bacterial strains FZ-5 and FZ-8 capable of utilizing 4-HBA as the sole carbon and energy source under anaerobic conditions were isolated from marine sediment samples. Phylogenetic analysis identified the two strains FZ-5 and FZ-8 as Acinetobacter johnsonii and Klebsiella oxytoca, respectively. The strains FZ-5 and FZ-8 degraded 2000 mg·L−1 4-HBA in 72 h with degradation rates of 71.04% and 80.10%, respectively. The optimum culture conditions for degradation by the strains and crude enzymes were also investigated. The strains FZ-5 and FZ-8 also exhibited the ability to degrade other lignin-derived compounds, such as protocatechuic acid, cinnamic acid, and vanillic acid. Immobilization of the two strains showed that they could be used for the bioremediation of 4-HBA in an aqueous environment. Soils inoculated with the strains FZ-5 and FZ-8 showed higher degradation of 4-HBA than the uninoculated soil, and the strains could survive efficiently in anaerobic soil. This is the first report of 4-HBA-degrading bacteria, belonging to the two genera, which showed degradation ability under anaerobic conditions. This study expound the strains could efficiently degrade 4-HBA in anaerobic soil and will help in the development of 4-HBA anaerobic bioremediation systems.

Eradication of Helicobacter pylori has contributed to the treatment of peptic ulcers and mucosa-associated lymphoid tissue lymphoma. Moreover, it has possibly decreased the prevalence of gastric cancer. However, eradication therapy is associated with various adverse effects, of which diarrhea is the most common. The incidence of diarrhea after eradication treatment varies from 8% to 48%. In particular, the incidence is higher in patients who receive first-line standard triple therapy compared with those who receive second-line therapy. Both antibiotics and proton pump inhibitors, components of eradication therapy, have short-term and long-term impacts on gut microbiota. The alterations of gut microbiota may not recover until 1 year after eradication therapy. Most cases of diarrhea that occur after eradication therapy are antibiotic-associated diarrhea caused by the destruction of the normal gut microbiota. In some cases, Clostridioides difficile-associated diarrhea occurs after eradication therapy. If bloody diarrhea occurs after eradication therapy and the Clostridioides difficile toxin is not detected, antibiotic-associated hemorrhagic colitis associated with Klebsiella oxytoca infection should be suspected. It is crucial to explain the possibility of diarrhea before initiating eradication therapy to increase compliance. Furthermore, probiotics may be administered to reduce diarrhea. If severe diarrhea or symptoms other than the usual antibiotic-associated diarrhea occur during or after eradication therapy, antibiotics should be discontinued. In addition, appropriate tests to determine the cause of diarrhea should be performed. This review summarizes the alteration of the gut microbiota, the causes of diarrhea after Helicobacter pylori eradication therapy, and its management.

Early diagnosis and probabilistic antibiotic therapy based on known bacterial ecology and antibiotic sensibility can reduce mortality and morbidity in pathologies caused by a bacterial infection. This study aimed at determining the prevalence and risk factors of extended-spectrum β-lactamases (ESBLs)-producing Escherichia coli isolated from blood cultures of neonates and infants population. We conducted a cross-sectional study during which pathogenic bloodstream isolates were identified. Antibiotic susceptibility test was performed on Escherichia coli isolates and phenotypic confirmation of ESBL production by Escherichia coli was performed by a double-disc synergy test. Over the course of this study, 298 blood cultures were performed and 129 (43.3%) positive cultures were obtained. Of the 129 bacterial isolates, 90 (69.7%) were Escherichia coli and 39 (30.2%) were other bacteria strains that included Klebsiella oxytoca, Streptococcus pneumonia, and Coagulase-negative staphylococci. Antibiotic susceptibility test indicated that Escherichia coli isolates were resistant to cephalosporin, penicillin, sulfonamide, and aminoglycoside antibiotic families. Further analysis indicated that 31 (34.4%) Escherichia coli strains were ESBL producers and risk factors for bloodstream infection by ESBL-producing Escherichia coli were prior to exposure to antibiotics and immune system depression. These findings clearly extend our understanding of the type of resistant initiated by ESBL-producing Escherichia coli in bloodstream infection of neonates, and infants and also provides useful information that can guide the establishment of an efficient therapeutic strategy for the community- and hospital-acquired bloodstream infection.

Background: To explore the prevalence of urinary tract infections (UTIs) among female patients in the Najran region of Saudi Arabia and determine their antimicrobial resistance pattern. Methods: This study was conducted on 136 urine samples collected from outpatient departments (OPDs) of the different government hospitals in the Najran region of Saudi Arabia. Over one year, the results of susceptibility testing reports of outpatient midstream urine samples from three government hospitals were prospectively evaluated. Results: Of 136 urine samples, only 123 (90.45%) were found to show significant growth for UTIs, from which 23 different uropathogens were identified. Escherichia coli (58.5%) was the most commonly isolated organism, followed by Klebsiella pneumoniae (8.1%). The isolated microorganism showed increased resistance patterns from 3.3% to 62.6%, with an overall resistance of 27.19%. Meropenem was the most effective antimicrobial, followed by amikacin and ertapenem (0.47%, 0.91%, and 1.5% resistance, respectively). At the same time, ampicillin and cephazolin were the least (62.6% and 59.5% resistance, respectively) effective. Overall, eleven (8.94%) uropathogens isolates were ESBLs, among which there were eight (6.5%) Escherichia coli, one (0.81%) Klebsiella pneumoniae, one (0.81%) Klebsiella oxytoca, and one (0.81%) Citrobacter amalonaticus. Conclusions: E. coli remains the most commonly isolated causative uropathogens, followed by Klebsiella species. The prevalence of pathogenic E. coli and Klebsiella species underscores the importance of developing cost-effective, precise, and rapid identification systems to minimize public exposure to uropathogens. Antibiotic susceptibility data revealed that most of the isolates were resistant to the majority of the antibiotics. The patients with UTIs in the Najran region of Saudi Arabia are at a high risk of antibiotic resistance, leading to significant problems in outpatient department (OPD) treatment outcomes and raising the alarm for the physician to change their empiric treatment.

Purpose Klebsiella oxytoca is an opportunistic pathogen causing nosocomial infections. This study was designed to characterize the genomic features of a carbapenem-resistant K. oxytoca strain and analyze its molecular characteristics. Materials and Methods The strain wzx-IMP was isolated from the blood of a 2-year-old girl diagnosed with acute myeloid leukemia-M7. Species identification was performed, and the minimal inhibitory concentration of the strain was measured. Multilocus sequence typing was performed to identify the subtypes of K. oxytoca. The transfer capacity of the blaIMP-4-harboring plasmid was investigated by conjugation experiments, and the genome characteristics of the strain were examined using whole-genome sequencing. Results wzx-IMP belongs to the ST85 type and is resistant to imipenem and meropenem, which harbored the blaIMP-4 gene. The blaIMP-4 gene was located in an IS26-associated class 1 integron of pwzx_IMP, which contains conserved IncN1-type backbone regions with a replication gene and its accessory structure for plasmid replication. The blaIMP-4-carrying plasmid in wzx-IMP was successfully transferred to Escherichia coli EC600 by conjugation. Whole-genome sequencing showed that the wzx-IMP isolate included the blaOXY-1-1 gene, accompanied by OmpK36 absence. Conclusion We report an ST85-type carbapenem-resistant K. oxytoca strain, which produces blaIMP-4 located in an IncN1-type plasmid and accompanied by OmpK36 porin deficiency.

International audience; Type II secretion systems (T2SS) allow Gram-negative bacteria to transport toxins and enzymes from the periplasm to the external milieu, and are thus important for the pathogenicity of bacteria. To drive secretion, T2SS assemble filaments called pseudopili closely related to bacterial type IV pili. These filaments are non-covalent polymers of proteins that are assembled by an inner membrane complex called the assembly platform connected to a cytoplasmic ATPase motor. In the Klebsiella oxytoca T2SS, the PulL protein from the assembly platform is essential for pseudopilus assembly and protein secretion. However, its role in these processes is not well understood. To decipher the molecular basis of PulL function, we used solution NMR to study its structure and interactions with other components of the machinery. Here as a first step, we report the 1 H, 15 N and 13 C backbone and side-chain chemical shift assignments of the C-terminal periplasmic domain of PulL and its secondary structure based on NMR data.

In this work, the antibiotic resistance of 218 isolates to 9 different antibiotics was analyzed with minimum inhibitory concentration method. All Lactobacillus pentosus strains were found to be resistant to streptomycin sulfate and ciprofloxacin hydrochloride. Lactococcus lactis strains were resistant to streptomycin sulfate. Specifically, 90% Klebsiella oxytoca and all Citrobacter freundii strains were resistant to ampicillin sodium. 30% K. oxytoca strains were resistant to ciprofloxacin hydrochloride. All Bacillus albus strains were resistant to erythromycin and 80% strains were resistant to ampicillin sodium. Results from PCR analysis revealed that 90 isolates carried the aadE gene. The tetM gene was detected in four L. pentosus isolates. And the streptomycin resistant gene aadA was detected in one L. pentosus isolate. Metagenome analysis revealed that 74.7% genes associated with antibiotic resistance were antibiotic resistance genes. The tetM and aadA genes, detected in PCR analysis, were also retrieved from the paocai metagenome. In brief, this study generated the antibiotic resistance profile of some paocai-originated bacteria strains. L. pentosus found in the final edible paocai were inherently resistant to antibiotics, such as streptomycin and ciprofloxacin. Results in this work reminds us to carefully choose the LAB strains for traditional Chinese paocai production to avoid potential spreading of antibiotic resistant genes.

The aim of this study was to analyze the extended spectrum β-lactamases (ESBLs) production and antibiotic susceptibility profile of urinary tract infected bacterial pathogens such as Escherichia coli and Klebsiella spp. A total of 143 Gram-negative bacteria were isolated from people suffering from urinary tract infections (UTIs) were included in this study. Among them, Escherichia coli (75%) were the predominantly isolated bacterial pathogen followed by Klebsiella oxytoca (14.6%) and K. pneumoniae (10.4%). Approximately 65% (n=93) of isolates were positive for ESBL production and E.coli was found to be the highest ESBL producer (67.6%) followed by K. oxytoca (57.1%) and K. pneumoniae (53.3%). E. coli showed high level of 86.1% resistance to cefotaxime and cefuroxime and 100% sensitive to imipenem and meropenem, whereas, K. oxytoca showed high level of 90.5% resistance to cefuroxime and 100% sensitive to amikacin, imipenem and meropenem. Similarly, K. pneumoniae showed high level of 73.3% resistance to nitrofurantoin and 93.3% sensitive to imipenem. This study reveals that majority of UTIs caused bacteria are ESBL producing multidrug-resistant bacteria and showing broad spectrum antibiotic resistance profile.

The rapid detection and characterization of carbapenemases in isolates of Enterobacterales are crucial for precise antibiotic administration and infection control. This article reports the findings from a parallel evaluation of the NG-Test Carba 5 (NG Biotech, Guipry, France) and Xpert Carba-R (Cepheid, Sunnyvale, CA) assays in the detection and differentiation of five carbapenemases [imipenem-resistant phenotype (IMP), Klebsiella pneumoniae carbapenemase, New Delhi metallo-β-lactamase (NDM), oxacillin-hydrolyzing β-lactamase (OXA)-48-like, and Verona integron-encoded metallo-β-lactamase] or the genes that encode them. A total of 122 isolates recovered from blood cultures and 106 positive blood culture broth (BCB) specimens, including 134 Klebsiella pneumoniae, 54 Escherichia coli, 27 Enterobacter cloacae, 8 Klebsiella oxytoca, 2 Klebsiella aerogenes, and 3 Citrobacter freundii, were collected from two tertiary hospitals (Xi'an, China). Using PCR sequencing techniques, 89 isolates and 29 BCB specimens were determined to be Enterobacterales harboring carbapenem-resistance genes. In comparison to the PCR sequencing results, the specificities with both the NG-Test Carba 5 and Xpert Carba-R assays were 100%; the sensitivities were 92.1% and 100%, respectively, for recovered isolates and 79.3% and 100% for BCB specimens. The NG-Test Carba 5 missed eight NDM, four OXA-48-like, and one IMP β-lactamases in specimens containing two or three carbapenemase types. In summary, the NG-Test Carba 5 assay may yield false-negative results if isolates or BCB specimens contain two or three carbapenemases.

2,3-Butanediol (2,3-BDO) is a promising commodity chemical with various industrial applications. While petroleum-based chemical processes currently dominate the industrial production of 2,3-BDO, fermentation-based production of 2,3-BDO provides an attractive alternative to chemical-based processes with regards to economic and environmental sustainability. The achievement of high 2,3-BDO titer, yield, and productivity in microbial fermentation is a prerequisite for the production of 2,3-BDO at large scales. Also, enantiopure production of 2,3-BDO production is desirable because 2,3-BDO stereoisomers have unique physicochemical properties. Pursuant to these goals, many metabolic engineering strategies to improve 2,3-BDO production from inexpensive sugars by Klebsiella oxytoca, Bacillus species, and Saccharomyces cerevisiae have been developed. This review summarizes the recent advances in metabolic engineering of non-pathogenic microorganisms to enable efficient and enantiopure production of 2,3-BDO. KEY POINTS: • K. oxytoca, Bacillus species, and S. cerevisiae have been engineered to achieve efficient 2,3-BDO production. • Metabolic engineering of non-pathogenic microorganisms enabled enantiopure production of 2,3-BDO. • Cost-effective 2,3-BDO production can be feasible by using renewable biomass.

s Abundance and diversity of cultivated bacteria in saprotrophic soil complexes were monitored for two years on the territory of one of the large industrial cities of the European North of Russia, Syktyvkar. The analysis was carried out before and after quarantine due to the COVID-19 pandemic. The city of Syktyvkar is characterized by a high population and intensive anthropogenic pressure. According to the total indicators of the current state of the environmental components, it should belong to the tense category, by environmental standards. Studies were conducted in 2019–2020. Topsoils (0–10 cm) of urbanozems and horizon A in the park area in the urban space, as well as zonal undisturbed podzolic soil, were analyzed. Comparison of the two-year monitoring results demonstrated a marked increase in the number and diversity of saprotrophic bacterial complexes in 2020 in both urban and control soils (topsoil, 0–10 cm). Due to a sharp and prolonged decrease in the anthropogenic impact on the environment during quarantine measures, content of the bacteria of the families Enterobacteriaceae including sanitary-indicative (Escherichia coli, Enterococcus faecalis) and opportunistic and allergenic (Enterobacter agglomerans, Citrobacter europaeus, Klebsiella oxytoca, Serratia marcescens, etc.) in the urbanozems decreased. This can be considered as a manifestation of the soil’s ability to “self-remediate” during a decrease in anthropogenic impact on the environment.

Necrotizing fasciitis (NF) is a rare, fulminant, lethal soft-tissue infection result in fascial necrosis, it is rarer in the head and neck area. Infection caused by Klebsiella oxytoca is much less common. Therefore, we reported a case of NF in the maxillofacial region, neck and upper mediastinum caused by Klebsiella oxytoca as the main cause recently treated in our department. The patient is a middle-aged male with a 10-year history of diabetes with unstable insulin control. The main symptoms were pain on left side with dysphagia and fever and the situation was getting worse. The patient had limited ability to have mouth open and had hyperemia, swelling on the left pharynx, maxillofacial area, and upper left neck and skin tenderness, and all symptoms were getting worse quick. The CT mainly found out that left oropharyngeal wall, parotid gland area, bilateral submaxilla, left neck, and superior mediastinum are swelling with gas. The blood test result: leukocytes count 16.64×109 /L, neutrophils percentage 85.8%; C-Pr 320 mg/L; urinary routine: urine glucose (+++++), ketone bodies (+++++); fasting glucose metabolism: glucose 21.33 mmol/L, glycosylated albumin 47.67%. Three incisions of facial and neck were performed to drain pus. Result of bacteria culture: Klebsiella oxytoca and Streptococcus constellatus During treatment of DKA and reduce patient glucose level, we also treated patient with neck and trachea incisions to drain pus and cleaned daily wound area and used different antibiotics according to the bacteria culture and CT results. And finally, the patient was cured and discharged from hospital. This case of NF was very rare not only the bacteria in this case but also the pathological changes related. (involving the mediastinum). The report of his diagnosis and treatment can provide experience for future treatments.

Microbial fuel cells (MFCs) have been developed impressively over recent years. In order to take this technology from research to application, the performance of these systems needs to be further investigated and optimized. The electrode materials and operating conditions play a vital role in MFCs performance. In the current work, dual chamber MFC was used to investigate the performance of different electrode materials under stationary and flow conditions. Microorganism solution of Klebsiella oxytoca and Citrobacter Freundii inoculum was used in the anode chamber. Three electrode materials were investigated, namely activated carbon, graphite, and titanium. High current density and power output were obtained by activated carbon electrode and graphite, while titanium showed poor performance for bio-electricity production. The low flow velocity (or Reynolds number) in catholyte was found to enhance the energy production, while the high velocity caused a reduction in the produced current. The aeration of the cathode chamber had a negative effect on the produced current due to the transfer of dissolved oxygen to the microorganism chamber. Activated carbon showed high performance due to its high surface area with the achieved maximum power density of 462.74 mW/m2 at Reynolds number of 7030.

The present study evaluated the toxicity of different bacterial strains isolated from the outer surface of adult flies associated with carrions at Al – Mansoureya, Giza Governorate, Egypt against Culex pipiens larvae. 11 different bacterial strains were isolated and identified from the adults of Musca domestica, Chrysomya albiceps and Lucilia sericata. Only five strains caused mortality in C. pipiens larvae more than 50 %. The highest larval mortality was caused by the bacterial strains; Klebsiella oxytoca and Staphylococcus sciuri. The results indicated that entomopathogenic bacterial strains could have the potential for the biological control of mosquitoes.

Cellulases are enzymes produced by many organisms and cellulose hydrolysis. They are well-known for their widely distributed industrial and medical uses. In this work, 84 bacterial strains were recovered from agar plates and 24 demonstrated hydrolyzing areas from carboxymethyl cellulose-containing agar dishes following Congo-Red staining. Among the 24 strains, three isolates Z7, Z9 and Z63 have shown increased activity of carboxymethyl cellulase (CMCase). It was shown that the three strains, Bacillus and Klebsiella, belonged to 2 separate genera. The isolates have been morphologically, physiologically, biochemically determined and validated by their 16S rRNA gene sequence. The 16S rRNA sequence of Z7, Z9 and Z63 has been submitted with GenBank under the accession codes (KT693283, KT693282 and KT693284). The sequences have been identified as Bacillus cereus strain Z7, Bacillus licheniformis strain Z9 and Klebsiella oxytoca strain Z63. This study gave appropriate information on the variety of rhizospheric isolated cellulose-degrading bacteria.

Edible insects are presented as a source of protein, fat and micronutrients. Consequently, they are an attractive growing environment for microorganisms. Although, professionals in this sector in Sub-Saharan Africa use traditional harvesting, processing and marketing techniques, there is little scientific data on the microorganisms that infest edible insects. The aim of this study was to identify the microorganisms present in the Cirina forda supply chain, the most commercially marketed insect species in Togo. A total of 300 samples of fresh, processed and commercial C. forda caterpillars were collected and analyzed using standard microbiological microorganism identification techniques. The caterpillar was 90% contaminated with Staphylococcus spp, 60% by Escherichia coli, 40% by Enterobacter spp, 40% by Aspergillus niger, 30% by Klebsiella pneumoniae and 10% by Mucor spp, Klebsiella oxytoca, Proteus spp, Serratia spp and Aspergillus flavus. Pathogenic microorganisms are found in all samples at all stages of the supply chain, so caterpillars handled using traditional methods are detrimental to the health of the consumer. The presence of germs indicative of contamination of the caterpillar analyzed exposes consumers to the risk of food poisoning. Keywords: Cirina forda, marketing, microorganisms, Togo

The Morus plants with a wide range of features and properties are widely used for their edible fruits, medicinal and other ornamental purposes worldwide. In summer and spring of 2016, a wetwood disease was observed on Morus trees (Black mulberry, White mulberry and Red mulberry), in municipal lands and parks of Rafsanjan city (Kerman Province), Iran. Typical symptoms were wetwood symptoms characterized by canker, stem weeping and liquid exudates on trunk of infected trees. The causative agent of wetwood disease from the infected samples was identified as Klebsiella oxytoca based on its biochemical and phenotypic feature and confirmed using sequence analysis of atpD gene. Artificial inoculation of the isolated bacterial strain (predominant) on 1-year-old mulberry seedlings produced the necrotic symptoms on the inner bark of seedlings. To fulfill Koch’s postulates, the same bacteria were re-isolated from the diseased tissues and identified as Klebsiella based on colony morphology, phenotypic, and biochemical tests. Here, we described the characteristics of K. oxytoca strains as the causal agent of wetwood disease of Red mulberry (Morus rubra), White mulberry (Morus alba), and Black mulberry (Morus nigra) for the first time.

Quantifying the passage of the large peptide protamine (Ptm) across CymA, a passive channel for cyclodextrin uptake, is in the focus of this study. Using a reporter‐pair‐based fluorescence membrane assay we detected the entry of Ptm into liposomes containing CymA. The kinetics of the Ptm entry was independent of its concentration suggesting that the permeation through CymA is the rate‐limiting factor. Furthermore, we reconstituted single CymA channels into planar lipid bilayers and recorded the ion current fluctuations in the presence of Ptm. To this end, we were able to resolve the voltage‐dependent entry of single Ptm peptide molecules into the channel. Extrapolation to zero voltage revealed about 1–2 events per second and long dwell times, in agreement with the liposome study. Applied‐field and steered molecular dynamics simulations added an atomistic view of the permeation events. It can be concluded that a concentration gradient of 1 μm Ptm leads to a translocation rate of about one molecule per second and per channel., Surprisingly, large peptides (Protamine, 5.1 kDa) can permeate through bacterial outer membrane channels. The use of fluorescence, electrophysiology, and all‐atom modeling allows to quantify the flux. This approach can be transferred to related problems.

This study aims to analyze the contamination and biofilm formation of foodborne and opportunistic pathogens in yellow-feathered chicken carcasses sampled in different seasons and to prove the relationship between biofilm-forming ability and bacterial extracellular polysaccharide (EPS) production. A total of 78 strains were isolated from chicken samples. The strains consisted of 30.8% Escherichia coli, 14.1% Pseudomonas aeruginosa, 12.8% Salmonella enteritidis, 12.8% Klebsiella pnenmoniae, 10.2% Enterobacter cloacae, 8.9% Proteus mirabilis, 5.1% Klebsiella oxytoca, 1.3% Staphylococcus aureus, and 1.3% Citrobacter braakii. Crystal violet staining assay revealed six strains with strong biofilm-forming ability, namely, E. coli S7, K. oxytoca B12, K. pnenmoniae B6, S. enteritidis H4, P. aeruginosa M5, and S. aureus G1, which showed had high abilities of cell motility and EPS production. Confocal laser scanning microscopy and scanning electron microscopy showed that all six strains can form mature biofilm architectures after 5 d of cultivation. This study may serve as a reference to control the contamination of foodborne pathogens in yellow-feathered chicken and enhance the quality and shelf life of these chicken products.

Herein, we report a novel green phytosynthesis for silver nanoparticles (AgNPs) using Echinochloa stagnina (Retz.) P. Beauv. (Burgu) extract and assess their potential activities. The phytosynthesized AgNPs were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform infrared (FTIR) spectroscopy. The surface plasmon resonance was peaked at 405 nm indicating the formation of AgNPs. Morphologically, AgNPs were spherical in shape with a diameter of 30 nm and monodispersed. Structurally, XRD data indicated that AgNPs were highly nanocrystalline in nature. FTIR spectral analysis demonstrated the presence of phytochemicals which could be responsible for the reduction of Ag ions and capping of AgNPs. The phytosynthesized AgNPs showed antibacterial activity with MIC of 12.5 and 6.25 μg/mL against multidrug-resistant (MDR) Klebsiella oxytoca (ATCC 51983) and Pseudomonas aeruginosa (ATCC MP-23), respectively. The time-kill kinetics profile of AgNPs against MDR Klebsiella oxytoca (ATCC 51983) and Pseudomonas aeruginosa (ATCC MP-23) revealed a time- and dose-dependent reduction manner. The inhibition concentrations of AgNPs that inhibits 50% (IC50) of Vero and HepG2 cells were 89.01 and 35.1 μg/mL, respectively. The LC50 and LC90 concentrations were (87.669 and 538.017 mg/mL) for Anopheles pharoensis and (51.338 and 311.227 mg/mL) for Culex pipiens, respectively. Collectively, our data suggest that plant-mediated synthesis of AgNPs is more feasible to synthesis AgNPs with improved properties.

Background: Food-borne diseases can cause many problems and harm consumers and societies. Dairy products are an important part of the food pyramid. In addition, dairy products provide many nutritional needs to humans and can also be contaminated with bacteria and cause gastrointestinal diseases and food poisoning. Objective: The purpose of the present research was to evaluate bacterial contamination rate in cheese, raw and pasteurized milk. Methods: For this purpose, 100 samples, including 35 samples of raw milk samples, 35 samples of pasteurized milk and 30samples of cheese, were evaluated. Cultures, biochemical and phenotypic tests were performed. Finally, statistical analysis was performed. Results: Our finding demonstrates that Enterococcus spp was the highest rate in cheese samples, E.coli was the highest rate in raw milk samples, and citrobacter freundii, klebsiella oxytoca and enterococcus spp were of the same rate in pasteurized milk samples. Conclusion: The results obtained in this study demonstrated that some dairy products in Ilam province, were contaminated. So, we suggested that the pasteurized milk and dairy products be done with complete care and raw dairy products should not be used.

Coke oven sector emanates phenol and cyanide as the eminent virulent compounds due to abrupt industrialization which is detrimental in aqueous state, and its severity is increased on simultaneous coexistence even at low concentrations that eventually causes extensive damage to the peripheral ecosystem. The efficacy of isolated mixed bacterial culture comprising of Alcaligenes faecalis JF339228 and Klebsiella oxytoca KF303807 in wastewater treatment was investigated following a batch study. The impact of initial concentration of phenol (100–1500 mg L−1) and cyanide (10–150 mg L−1) on the growth and treatment by the mixed microbial cultures were evaluated over a time period of 72 h. The biodegradation mechanism was explained by Monod, Haldane, Aiba and Edward kinetic models. The maximum specific growth rate was reported to be 0.096 h−1 and 0.126 h−1 for phenol and cyanide respectively. The substrate inhibitory effect became eminent after a concentration of 450 mg L−1 for phenol and 45 mg L−1 for cyanide. Based on the lower sum of squared error (SSE) values, Haldane model for phenol and Edward model for cyanide was found to be favourable for substrate inhibition kinetics. The fate of the secondary intermediates produced after microbial degradation was assessed by phytotoxicity studies using Vigna radiata. The interactive binding of the pernicious pollutants and resultant biodegraded compounds with the DNA (herring sperm DNA) was examined following spectrofluorometric and spectrophotometric anatomization. Toxicity studies revealed that biological treatment was viable for eco benign disposal and results also depicted that both the strains have potential in remediation of phenol and cyanide from coke oven wastewater.

We analyzed the prevalence and genetic characteristics of the extended-spectrum β-lactamases (ESBLs)-producing Enterobacterales isolated from adult patients hospitalized in the oncological center in 2019. Out of 9372 patients admitted to the hospital, 1373 had been in various medical facilities during the last year, which was an indication to perform a screening test for ESBL-producing Enterobacterales colonizing their gastrointestinal tract. In eighty-three patients (6.1%), 85 ESBL producers were detected. These isolates included the following: Escherichia coli (n = 67; 78.8%), Klebsiella pneumoniae (n = 14; 16.5%), Enterobacter cloacae cplx (n = 3; 3.5%), and Klebsiella oxytoca (n = 1; 1.2%). CTX-M-1-like enzymes were the most common ESBLs (n = 67; 78.8%). Two K. pneumoniae isolates (2/85; 2.4%) additionally produced New Delhi-metallo-β-lactamases (NDM). All isolates, except for K. oxytoca, were typed by pulsed-field gel electrophoresis (PFGE) and demonstrated high genetic diversity. The most prevalent phylogroups of E. coli were B2 group (n = 30; 44.8%), followed by A group (n = 25; 37.3%). These observations have motivated us to investigate the link between ESBL-E colonization and infection among patients with solid tumors.

The present work aimed to investigate the efficiency of kinetic modeling and Response Surface Methodology (RSM), by employing a Central Composite Rotatable Design (CCRD) and to evaluate the effects of carbon and nitrogen sources, inoculation volume, and bioprocess time on an exopolysaccharide (EPS) producer, Klebsiella oxytoca ICCF 419, in batch fermentation with shaken flasks. Among the kinetic models tested, logistic equations were found to fit accordingly, with a correlation coefficient (R2 ) of 0.999. The interaction between glucose and corn steep liquor was found to have a significant impact on the EPS production, and glucose (2% w/v), and a 5% v/v inoculum of 24 hours age, are sufficiently to positively affect the bioprocess, if it is desired only a maximum cell growth, but not associated with the polymer synthesis. The optimal formula predicted by the RSM design was experimentally validated by the following results: 12.16 g EPS/L and 1.65 dry biomass/L, after 48 hours fermentation.

Background and Purpose: Klebsiella species are amongst the most common causes of a variety of community-acquired and hospital-acquired infections (HAI), characterized by high morbidity and mortality rates. Most infections caused by Klebsiella species are usually treated using antibiotics. The aim of this study was to determine the antimicrobial resistance profile of Klebsiella species isolated from in-patients and out-patients at the Yaounde University Teaching Hospital. The data generated will go a long way to improve on the choice of an adequate empiric antibiotic treatment for infections caused by Klebsiella species. Methodology: A cross-sectional descriptive study was carried out over a period of 6 months, spanning from February 2019 to July 2019 with a sample size of 37 isolates, obtained from 6 different clinical specimens. Identification of isolates was done using API 20E identification system (Biomerieux SA, Lyon, France). Susceptibility to antibiotics was tested as described by Kirby-Bauer in 1956. Inhibition diameters were interpreted according to recommendations from the European Committee on Antimicrobial Susceptibility Testing (EUCAST, 2019). Results and Conclusion: Among the 37 Klebsiella isolates identified, Klebsiella pneumoniae was the most prevalent species isolated with a percentage of 54.1%, followed by Klebsiella rhinoscleromatis 18.9%, Klebsiella ozaenae 16.2% and Klebsiella oxytoca, 10.8%. The resistance pattern of Klebsiella to amoxicillin, amoxicillin/clavulanate, tircacillin, tircacillin + clavulanic acid, piperacillin, piperacillin + tazobactam, cefalotin, cefuroxim, ceftazidime, cefotaxime, ceftriaxone, cefepime, imipenem, meropenem, aztreonam, amikacin, gentamicin, tobramycin, trimethoprim/ sulfamethoxazole, nalidixic acid, pipemidic acid, norfloxacin, ciprofloxacin, levofloxacin, ofloxacin, and moxifoxacin was as follows; 100%, 86.5%, 97.3%, 83.6%, 86.5%, 16.2%, 86.5%, 83.8%, 78.4%, 32.4%, 78.4%, 76.7%, 2.7%, 2.7%, 76.7%, 13.5%, 75.7%, 73.0%, 91.9%, 51.4%, 48.6%, 64.9%, 48.6%, 48.6%, 73.0% and 62.2% respectively. Multidrug resistance was observed in 94.6% of the Klebsiella isolates. Conclusion: This study shows that the level of multidrug resistance is high. The isolates expressed good sensitivity to carbapenems, piperacillin + tazobactam, amikacin and high resistance to all other antimicrobials tested. Therefore, antimicrobial susceptibility testing prior to prescriptions should be encouraged and sensitization of the population about consequences of inappropriate antibiotic treatment and auto medication should be enforced as a means to curb antimicrobial resistance.

Antimicrobial resistance (AMR) is a global threat to public health and particularly to children. This study aimed to determine the prevalence of multidrug resistance of fecal Klebsiella spp on selected beta lactam (3rd generation cephalosporins and carbapenems) and fluoroquinolone classes of drugs in four health facilities serving the slum communities of Nairobi city in Kenya. Additionally, determine the genetic basis for the multidrug resistance observed. A cross sectional laboratory based study was undertaken where a total of 1171 children below 16 years were selected, from whom stool samples were collected, tested and analyzed. 395 (33.73%) Klebsiella spp were isolated, consisting of 365 (92.4%) Klebsiella pneumoniae and 30 (7.6%) Klebsiella oxytoca were isolated. The proportion of multi-drug resistance (MDR) K. pneumoniae and MDR K. oxytoca was 64.1% (234/365) and 96.67% (29/30) respectively. Third generation cephalosporins, cefotaxime ceftriaxone and ceftazidime showed the highest resistance of 30.7%, 29.9% and 27.4% respectively, whereas carbapenems including imipenem and meropenem had the least resistance of 1.6%, each, to K. pneumoniae. A significant association was observed in diarrheic children (OR = 1.88; p = 0.01) and those below 50 months (OR = 0.43; p = 0.002) and carrying K. pneumoniae resistance to one or more third generation cephalosporins. Genes associated with resistance included bla TEM 100%, bla CTX-M 95.2%, bla SHV 57.1%, bla OXA-1 66.7%, qnrS 54.1%, qnrB 47.6% and bla NDM 7.1%. In conclusion, there’s need for more effective infection control measures, antimicrobial stewardship to reduce emergence of antimicrobial resistance, improved drinking water, sanitation and hygiene (WASH) practices.

Background: As many as 150 million people worldwide have experienced urinary tract infections. Bacteria and fungi are agents that cause urinary tract infections that can be found in the urine of a person who is indicated to have a urinary tract infection. Objective: To determine the pattern of germs as well as the sensitivity and resistance of antibiotics to bacteria that cause urinary tract infections in Sanglah Hospital, Denpasar. Methods: This research is a descriptive study. The research subjects were obtained from the profile of the patient's urine culture supporting examination data at Sanglah General Hospital Denpasar Bali, December 2019 - June 2020. Results: A total of 327 samples were tested, 207 (63.3%) women and 120 men (36.7%). the mean age of the samples was 55.04 SD. The bacteria in urine culture with a colony count of 105 that most commonly caused urinary tract infections were E. coli as much as 130 (39.76%), Klebsiella pneumoniae ssp. pneumoniae as much as 36 (11.01%), Acinetobacter baumannii as much as 22 (6.73%), Proteus mirabilis as much as 15 (4.59%), Klebsiella oxytoca as much as 15 (4.59%). Conclusion: Several considerations of antibiotics as a therapeutic option in microorganisms are as follows. E. coli with the antibiotic nitrofurantoin, Klebsiella pneumoniae ssp. Pneumoniae with the antibiotic meropenem, Acinetobacter baumannii with trimethoprin/sulfamethoxazole antibiotics, Proteus mirabilis with the antibiotic ceftriaxone, and Klebsiella oxytoca with the antibiotic gentamicin.

Pyruvate is an important platform material widely used in food, pharmaceutical, and chemical industries. Pyruvate-tolerant Klebsiella oxytoca PDL-0 was chosen as a chassis for pyruvate production via metabolic engineering. Genes related to by-product generation were knocked out to decrease the production of 2,3-butantediol, acetate, ethanol, and succinate. The NADH oxidase encoding gene nox was inserted into the locus of the lactate dehydrogenase encoding gene ldhD in the genome of K. oxytoca to simultaneously block lactate production and regenerate NAD+. The pyruvate importers CstA and YjiY were identified, and their encoding genes were deleted to increase pyruvate accumulation. The engineered strain K. oxytoca PDL-YC produced 71.0 g/L pyruvate from glucose. Furthermore, K. oxytoca PDL-YC can use whey powder, an abundant by-product of the cheese making process, as substrate for pyruvate production. Pyruvate production with a concentration of 62.3 g/L and a productivity of 1.60 g/[L·h] was realized using whey powder as substrate.

Background At Canadian Blood Services, platelet concentrate (PC) shelf life was extended to 7 days with a large-volume, delayed-sampling bacterial screening algorithm. We present the development study and postimplementation results. Study design and methods In the development study, PCs inoculated with five bacteria (various concentrations) were incubated for 7 days with daily sampling for BacT/ALERT cultures and bacterial quantification. After implementation, from August 2017 to December 2019, a total of 223 156 pools and 39 725 apheresis units and 5310 outdated PCs were screened. Since March 2018, cocomponents associated to false-positive results have been released to inventory. Results In the development study, Klebsiella pneumoniae, Serratia marcescens, and Staphylococcus aureus were detected at concentrations of at least 0.01 colony-forming units (CFUs)/mL at 24 hours postinoculation. However, Staphylococcus epidermidis was detected at concentrations of less than 0.16 CFUs/mL only more than 48 hours postinoculation. After implementation, 776 (0.35%) and 303 (0.77%) initial-positive results and 201 (0.09%) and 16 (0.04%) confirmed-positive results were obtained for pools and apheresis units, respectively, predominantly with Cutibacterium acnes. Other organisms included staphylococci, streptococci, Klebsiella oxytoca and Pseudomonas aeruginosa. One nonfatal reaction involving a 7-day pool contaminated with S. epidermidis occurred. Approximately, 1-in-1000 false-negative screening results were obtained during testing of outdated PCs. Approximately 1000 cocomponents associated with false-positive results were released into inventory. Combined PC outdating at Canadian Blood Services and hospitals was reduced from 18.9% to 13.1%. Conclusion Screening of 7-day PCs increased bacterial detection mainly of anaerobes and reduced outdating. The incidence of septic transfusion events has decreased approximately threefold. A longer surveillance period is needed to evaluate the value of anaerobic cultures and residual safety risk.

A sol containing biogenic ferrihydrite nanoparticles is obtained by cultivating Klebsiella oxytoca microorganisms. Data on the physical properties of the biogenic ferrihydrite and its effect on the organism of laboratory animals are obtained using a model of experimental hemolytic anemia, according to indicators of the functional activity of erythrocytes and morphological descriptions of organs.

Hepatic artery pseudoaneurysm is a rare but potentially life-threatening condition that usually occurs after trauma. Early recognition and prompt management are essential for preventing catastrophic consequences, such as hemoperitoneum. We report a rare case of liver abscess caused by Klebsiella oxytoca resulting in hepatic artery pseudoaneurysm without iatrogenic injury. The unique feature of the present case is that the abscess cavity itself became a pseudoaneurysm as a result of fistula formation with the hepatic artery. Vascular complications should be considered in patients with unfavorable clinical course even in the absence of iatrogenic injury. Endovascular treatment is safe and effective.

Cerastoderma glaucum, a marine bivalve inhabiting Lake Timsah, is surrounded by different pathogenic organisms. The present study evaluates the antimicrobial activities, cytotoxicity and characterization of C. glaucum extracts. Chloroform, methanol and acidic tissue extracts were prepared from C. glaucum collected during winter and summer seasons. Winter acidic extract exhibits potent antimicrobial activities against 21 bacterial, 2 yeast and 2 viral strains. The inhibition zone of this extract ranges from 10 mm against Klebsiella oxytoca, Pseudomonas stutzeri, Globicatella sulfidifaciens and Bacillus (B. badius, B. amyloliquefaciens and B. pumilus) to 24 mm against Shigella flexneri. Also, the inhibition viral activities of this extract at a concentration of 62.5 µg ml−1 against Hepatitis A virus and Herpes simplex virus type 1 (HSV-1) are 62.383% and 57.035%, respectively, with low cytotoxicity of 24.030%. Furthermore, winter acidic extract of C. glaucum has the highest total protein contents (9.8 mg ml−1) compared with the other extracts. Moreover, the sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) indicates the presence of four clear low molecular weight peptides bands; 8.588, 7.237, 4.423 and 2.692 kDa. Fourier transform-infrared (FT-IR) analysis indicates the presence of 12 functional groups of proteins in winter acidic extract of C. glaucum at appropriate wavelengths.

The degradation of phenol by microorganisms in the soil is an important method through which these materials are removed from the environment, thus reducing environmental pollution. Biodegradation by bacterial species provides unique opportunities to destroy or convert phenolic compounds into other less toxic compounds. In this study, two Klebsiella oxytoca isolates were selected from petroleum contaminated soils using mineral salts medium supporting with phenol as the only carbon source.The isolates were identified by microscopic, morphological, and biochemical approaches, and their capabilities of biodegrading phenol were analyzed by 4-aminoantipyrine assay. The results showed that the selected Klebsiella oxytoca isolates were able to remove 100% of phenol even at a the highest used concentration(500 mg / L).The results of the current study indicate the possibility of using Klebsiella oxytoca in bioremediation of phenol contaminated environments.

In this study, K. oxytoca KMS004 (ΔadhE Δpta-ackA) was further reengineered by the deletion of frdABCD and pflB genes to divert carbon flux through D-(−)-lactate production. During fermentation of high glucose concentration, the resulted strain named K. oxytoca KIS004 showed poor in growth and glucose consumption due to its insufficient capacity to generate acetyl-CoA for biosynthesis. Evolutionary adaptation was thus employed with the strain to overcome impaired growth and acetate auxotroph. The evolved K. oxytoca KIS004-91T strain exhibited significantly higher glucose-utilizing rate and D-(−)-lactate production as a primary route to regenerate NAD+. D-(−)-lactate at concentration of 133 g/L (1.48 M), with yield and productivity of 0.98 g/g and 2.22 g/L/h, respectively, was obtained by the strain. To the best of our knowledge, this strain provided a relatively high specific productivity of 1.91 g/gCDW/h among those of other previous works. Cassava starch was also used to demonstrate a potential low-cost renewable substrate for D-(−)-lactate production. Production cost of D-(−)-lactate was estimated at $3.72/kg. Therefore, it is possible for the KIS004-91T strain to be an alternative biocatalyst offering a more economically competitive D-(−)-lactate production on an industrial scale. • KIS004-91T produced optically pure D-(−)-lactate up to 1.48 M in a low salts medium. • It possessed the highest specific D-(−)-lactate productivity than other reported strains. • Cassava starch as a cheap and renewable substrate was used for D-(−)-lactate production. • Costs related to media, fermentation, purification, and waste disposal were reduced.

Background Bacterial keratitis can threaten vision through permanent corneal scarring and even perforation, resulting in loss of the eye. Klebsiella oxytoca is resistant to several antibiotics because it produces extended-spectrum β-lactamase encapsulated with polysaccharide. Thus, this article is aimed at reporting a rare case of Klebsiella oxytoca-induced keratitis in Jimma University Medical Centre, Jimma, Ethiopia. Case presentation TA 25-year-old female patient presented with photophobia, redness, and purulent discharge from the right eye. She had matted cilia of the eyelid, conjunctiva injection, corneal ulcer, and deep fibrinous anterior chamber reaction. She had light perception (LP) visual acuity for the same eye and it was firm when examined digitally. The cornea-scleral repair was performed one month earlier, due to open globe injury. The patient had taken empirical fortified antibiotics before the identification of the specific pathogen. Culture and drug sensitivity test was performed in order to identify the aetiology. The result of the test revealed that the identified pathogen was multi-drug-resistant Klebsiella oxytoca. Based on this result and drug availability, high dose topical fluoroquinolones eye drops (Ciprofloxacin eye drop 0.3% and Ofloxacin 0.3%) were given. Besides, dexamethasone 0.1% eye drop was added to the aforementioned antibiotics. After four months of treatment, the visual outcome was changed from LP to hand motion. Conclusion A rare case of multi-drug resistant Klebsiella oxytoca induced keratitis which was isolated in a biochemical test was successfully treated with a high dose of fluoroquinolones.

Biofertilizers are recently used on a large scale to reduce chemical fertilizers and their pollutant effect on soils and water. In this work, a pot experiment was carried out to evaluate the effect of Azotobacter chroococcum, Azospirillum lipoferum and Klebsiella oxytoca with different levels of nitrogenous fertilizer on the growth and yield of canola (Brassica napus L.) and microbial population in the soil during the winter season, 2018. Results reveal that used bacterial species as biofertilizers have a great effect on morphological and yield traits of canola plants, where the plants treated with Azotobacter, Azopirillum and Klebsiella were characterized by increases in plant heights, plant weights as well as numbers of branches and pods. Also, Azotobacter and Azospirillum increased nitrogen, whereas Klebsiella oxytoca increased phosphorus in plants and seeds. The results showed that using triple inoculum (Az. chroococcum, Azosp. lipoferum and K. oxytoca) with 75% of nitrogenous fertilizer (33.75 kg N/feddan) achieved the highest seed yield per plant (24.35 g/plant), while oil percent in seeds was 46.86%, which was not the highest but very close to oil percentage in plants treated with the recommended dose of nitrogen, which was 47.47%. On the other side, using bacterial inoculum stimulate microbial population and increased total bacteria, diazotrophs (Azotobacter and Azospirillum) and phosphate dissolving bacteria counts in the rhizosphere of canola plants.

This study aims to investigate the feasibility of treating olive mill waste water (OMWW) by activated sludge pilot (AS) after its high dilution (1%) by urban waste water (UWW) and to study the effect of polyphenol compounds on the biomass during the treatment. Specific oxygen uptake rate (SOUR), mixed liquor volatile suspended solids (MLVSS), chemical oxygen demand (COD) and total polyphenols, were followed up over 100 days. In spite of the polyphenols' high concentration (up to 128 mg·L−1), successful biomass growth of 7.12 g MLVSS.L −1 and activity were achieved. Most of the bacteria (Pseudomonas sp., Klebsiella oxytoca, Citrobacter fereundii, Escherichia coli and Staphylococcus sp.) and fungi (Trichoderma sp., Rhizopus sp., Aspergillus niger, Penicillium sp., Fusarium sp., Alternaria) identified in the aerobic basin during the stabilization stage were known to be resistant to OMWW and showed effective adaptation of the biomass to polyphenols in high concentration. COD and polyphenols were highly eliminated (90%, 92% respectively). The sludge volume index in the pilot settling tank was almost constant at around 120 mL.g −1. This suggests the possibility of managing OMWW by simple injection at a given percentage in already functioning conventional AS treating UWW.

Objective The production of β-lactamase enzymes such as AmpC β-lactamases and extended-spectrum β-lactamases (ESBLs) is among the main mechanisms for resistance to expanded-spectrum cephalosporins. The present study was conducted to investigate the prevalence and molecular epidemiology of plasmid-mediated AmpC beta (β)-lactamase in ESBL co-producing Escherichia coli (E. coli) and Klebsiella spp. (Klebsiella pneumoniae and Klebsiella oxytoca) clinical isolates in the northeast of Iran. Methods A total of 602 E. coli and Klebsiella spp. clinical isolates were collected from three hospitals in Mashhad (northeast of Iran). A combination disk test (CDT) was performed for the phenotypic detection of ESBLs. Screening for the detection of AmpC β-lactamases was performed by a susceptibility test to a cefoxitin disc among ESBL producing isolates. A confirmatory test for AmpC β-lactamases was performed using the Mast® D68C test. Identification of plasmid-mediated AmpC cluster genes was done by multiplex polymerase chain reaction (PCR). Results Among 336 ESBL-producing strains, 230 (68.4%) isolates were resistant to cefoxitin. Results of the Mast® D68C test showed that 30% (69/230) of cefoxitin-resistant isolates simultaneously exhibited ESBL and AmpC activity and 22% (51/230) of isolates probably showed multi-drug resistant (MDR) phenotype. Results of multiplex PCR among ESBL-positive isolates showed that, 16.7% (56/336) of isolates were positive for plasmid-borneampC cluster genes, and CMY (38%) was the most frequent genotype of plasmid mediated AmpC. Conclusion Findings of the study revealed that an increase in the prevalence of ESBL and AmpC co-producer in E. coli and Klebsiella spp. strains may become an important public health issue. Therefore, there is a vital need for surveillance of spread of these clinical isolates.

The use of profenofos (PFF) increased due to its effectiveness against pests resistant to other organophosphates (OP). Its presence in the environment could produce acute or chronic poisoning for people who use it for daily agricultural activities as well as for people who get in contact with polluted soil, water, air or food. In this context, proposing alternatives to accelerate OP degradation processes is important. Therefore, the objective of the present study was to evaluate for 28 days the degradation process of PFF in soils with 50 mg PFF/kg (pH = 7.20 + / - 0.31) using Eisenia foetida (EF) and native bacteria (NB). The "control group" showed a PFF degradation of 52.95 +/- 1.69% in sterilized soils. NB achieved a degradation of 63.60 +/- 3.27%, EF degraded PFF by 72.65 +/- 1.92% and the combination of EF and NB, 79.21 +/- 1.79%. Bacteria with potential PFF degradation capacity were isolated and identified as Klebsiella oxytoca and Pseudomonas aeruginosa. It was shown that EF play an important role by accelerating the degradation of PFF in soils, presenting a possible synergy with Klebsiella oxytoca and Pseudomonas aeruginosa.

Objectives The aim of this study was to investigate the molecular mechanisms of imipenem resistance in Enterobacteriaceae and to assess the antimicrobial activities of ceftazidime/avibactam (CAZ/AVI) and aztreonam/avibactam (ATM/AVI) against imipenem-resistant clinical isolates in a tertiary hospital in China. Methods A total of 91 imipenem-resistant Enterobacteriaceae were collected and genes encoding carbapenemases, ESBLs, AmpC β-lactamases and porins were detected using PCR. MICs and susceptibility were determined using in-house-prepared broth microdilution panels and were interpreted according to CLSI breakpoints. Results Imipenem-resistant isolates comprising 54 Klebsiella pneumoniae, 18 Escherichia coli, 8 Enterobacter cloacae, 6 Serratia marcescens, 3 Klebsiella oxytoca and 2 Klebsiella aerogenes were collected independently. Five different carbapenemase genes were identified, namely blaKPC-2 (n = 60), blaNDM-5 (n = 14), blaNDM-1 (n = 11), blaKPC-3 (n = 4) and blaIMP-4 (n = 1). Among the 91 carbapenem-resistant Enterobacteriaceae (CRE), 85 isolates harboured at least one ESBL and/or AmpC gene, including 5 strains without carbapenemase-encoding genes. Moreover, 31 K. pneumoniae carried ompK35 and/or ompK36 mutations. MLST results showed that the K. pneumoniae belonged to 12 different STs, with ST11 being predominant (29/54; 53.7%). Overall, 17.6%, 25.3%, 41.8%, 65.9% and 100% of the CRE strains were susceptible to amikacin, trimethoprim/sulfamethoxazole, tetracycline, CAZ/AVI and ATM/AVI, respectively. Conclusion This study revealed that CRE isolates differ significantly in their species, STs, porins and carbapenemase genes in a single Chinese hospital. ATM/AVI exhibited potent activity against CRE isolates, even for the most notorious double-carbapenemase-producers with porin defects, whereas CAZ/AVI was active against all the non-metallo-β-lactamase-producing isolates.

Background: The aim of this study was to determine the occurrence and antibiotic susceptibility profile of enterobacteria isolated from ready-to-eat foods within Benin metropolis, Nigeria.Methods: This was a descriptive study of 210 ready-to-eat food samples comprising fried rice, jollof rice, moi-moi, salad, oil beans, non-oil beans, and African salad obtained from roadside food vendors between January and June 2017. Isolation and identification of enterobacteria isolates were carried out using standard bacteriological and molecular methods. Antibiotic susceptibility profile was carried out using the disc diffusion method.Results: The mean mesophilic bacterial count expressed in log10 CFU/g from the ready-to-eat foods ranged from oil beans (4.3±0.52) to African salad (7.2±1.38). Escherichia coli count ranged between oil beans (1.8±0.16) and African salad (4.1±0.10). Salmonella species count ranged from non-oil beans (2.3±0.17) to African salad (5.2±0.09). Significant differences were observed from the population count of the ready-to-eat foods (p < 0.05). Bacterial isolates recovered from the ready-to-eat foods include Pseudomonas aeruginosa, Citrobacter freundii, Enterobacter cloacae, Salmonella enterica, Escherichia coli, Klebsiella oxytoca. The highest occurrence of the bacterial isolates was Escherichia coli 23(41.07%) while the least was Citrobacter freundii 3(5.36%) and Enterobacter cloacae 3(5.36%). The antimicrobial susceptibility profile of the bacterial isolates revealed that all bacterial isolates were 100% resistant to cefepime, ceftazidime, cefuroxime, ertapenem, and meropenem; with considerable sensitivity to kanamycin and gentamycin.Conclusion: The occurrence of these bacterial isolates in the foods constitutes public health risk to consumers as these pathogens have been associated with foodborne infections. Keywords: Antibiotic-resistant; Enterobacteria; Foodborne pathogens; Microbial quality; Public health; Street foods

Leupeptin is a bacterial small molecule that is used worldwide as a protease inhibitor. However, its biosynthesis and genetic distribution remain unknown. We identified a family of leupeptins in gammaproteobacterial pathogens, including Photorhabdus, Xenorhabdus, and Klebsiella species, amongst others. Through genetic, metabolomic, and heterologous expression analyses, we established their construction by discretely expressed ligases and accessory enzymes. In Photorhabdus species, a hypothetical protein required for colonizing nematode hosts was established as a new class of proteases. This enzyme cleaved the tripeptide aldehyde protease inhibitors, leading to the formation of "pro-pyrazinones" featuring a hetero-tricyclic architecture. In Klebsiella oxytoca, the pathway was enriched in clinical isolates associated with respiratory tract infections. Thus, the bacterial production and proteolytic degradation of leupeptins can be associated with animal colonization phenotypes.