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Epidemiology and Infection Jan 2019Non-cholera Vibrio (NCV) species are important causes of disease. These pathogens are thermophilic and climate change could increase the risk of NCV infection. The El...
Non-cholera Vibrio (NCV) species are important causes of disease. These pathogens are thermophilic and climate change could increase the risk of NCV infection. The El Niño Southern Oscillation (ENSO) is a 'natural experiment' that may presage ocean warming effects on disease incidence. In order to evaluate possible climatic contributions to observed increases in NCV infection, we obtained NCV case counts for the United States from publicly available surveillance data. Trends and impacts of large-scale oceanic phenomena, including ENSO, were evaluated using negative binomial and distributed non-linear lag models (DNLM). Associations between latitude and changing risk were evaluated with meta-regression. Trend models demonstrated expected seasonality (P < 0.001) and a 7% (6.1%-8.1%) annual increase in incidence from 1999 to 2014. DNLM demonstrated increased vibriosis risk following ENSO conditions over the subsequent 12 months (relative risk 1.940, 95% confidence interval (CI) 1.298-2.901). The 'relative-relative risk' (RRR) of annual disease incidence increased with latitude (RRR per 10° increase 1.066, 95% CI 1.027-1.107). We conclude that NCV risk in the United States is impacted by ocean warming, which is likely to intensify with climate change, increasing NCV risk in vulnerable populations.
Topics: Animals; Centers for Disease Control and Prevention, U.S.; Cholera; Climate Change; Databases, Factual; Disease Outbreaks; El Nino-Southern Oscillation; Humans; Incidence; Nonlinear Dynamics; Retrospective Studies; Risk; Risk Assessment; Seasons; United States; Vibrio Infections; Vibrio cholerae
PubMed: 31364581
DOI: 10.1017/S0950268819001316 -
MSphere Jun 2019The azithromycin resistance conferred by phosphotransferase is encoded in the gene (A). This gene has been discovered in and reported for many bacterial species. We...
The azithromycin resistance conferred by phosphotransferase is encoded in the gene (A). This gene has been discovered in and reported for many bacterial species. We examined the prevalence of azithromycin resistance in (AR-VF) isolated during 2014 to 2015 from the hospitalized acute diarrheal patients in Kolkata, India. Most of the isolates are identified as the sole pathogen (54%). The prevalence of AR-VF was higher in 2015 (19 [68%]) than in 2014 (9 [32%]). Among AR-VF isolates, the azithromycin MICs ranged from 4 to >256 mg/liter. Twenty-eight of the 48 (58%) isolates harbored the gene (A) and phenotypically resistant to azithromycin. All the AR-VF isolates remained susceptible to doxycycline. In addition to azithromycin, other antimicrobial resistance-encoding genes of AR-VF were also characterized. All the AR-VF isolates were positive for class 1 integron, and most of them (17/28) carried the gene cassettes. Only one isolate was positive for the gene, which encodes resistance to erythomycin. The majority of the isolates were resistant to β-lactam antibiotics ( [96%], [93%], and [68%]) and aminoglycoside actetyltransferase, conferring resistance to ciprofloxacin-modifying enzyme [] (96%). Analyses by pulsed-field gel electrophoresis (PFGE) showed that the AR-VF isolates belonged to different genetic lineages. This is the first study to report azithromycin resistance and the presence of the (A) gene in isolates. Circulation of AR-VF isolates with high azithromycin MICs is worrisome, since it may limit the treatment options for diarrheal infections. The progressive rise in antibiotic resistance among enteric pathogens in developing countries is becoming a big concern. India is one of the largest consumers of antibiotics, and their use is not well regulated. is increasingly recognized as an emerging diarrheal pathogen of public health importance. Here we report the emergence of azithromycin resistance in isolates from diarrheal patients in Kolkata, India. Azithromycin has been widely used in the treatment of various infections, both in children and in adults. Resistance to azithromycin is encoded in the gene (A). Emerging azithromycin resistance in is a major public health challenge, and future studies should be focused on identifying ways to prevent the dissemination of this antibiotic resistance gene.
Topics: Anti-Bacterial Agents; Azithromycin; Child; Child, Preschool; Diarrhea; Drug Resistance, Multiple, Bacterial; Female; Humans; India; Male; Microbial Sensitivity Tests; Phosphotransferases; Vibrio
PubMed: 31189560
DOI: 10.1128/mSphere.00215-19 -
The FEBS Journal Oct 2019The biodegradation of the nylon-6 precursor caprolactam by a strain of Pseudomonas jessenii proceeds via ATP-dependent hydrolytic ring opening to 6-aminohexanoate. This...
The biodegradation of the nylon-6 precursor caprolactam by a strain of Pseudomonas jessenii proceeds via ATP-dependent hydrolytic ring opening to 6-aminohexanoate. This non-natural ω-amino acid is converted to 6-oxohexanoic acid by an aminotransferase (PjAT) belonging to the fold type I pyridoxal 5'-phosphate (PLP) enzymes. To understand the structural basis of 6-aminohexanoatate conversion, we solved different crystal structures and determined the substrate scope with a range of aliphatic and aromatic amines. Comparison with the homologous aminotransferases from Chromobacterium violaceum (CvAT) and Vibrio fluvialis (VfAT) showed that the PjAT enzyme has the lowest K values (highest affinity) and highest specificity constant (k /K ) with the caprolactam degradation intermediates 6-aminohexanoate and 6-oxohexanoic acid, in accordance with its proposed in vivo function. Five distinct three-dimensional structures of PjAT were solved by protein crystallography. The structure of the aldimine intermediate formed from 6-aminohexanoate and the PLP cofactor revealed the presence of a narrow hydrophobic substrate-binding tunnel leading to the cofactor and covered by a flexible arginine, which explains the high activity and selectivity of the PjAT with 6-aminohexanoate. The results suggest that the degradation pathway for caprolactam has recruited an aminotransferase that is well adapted to 6-aminohexanoate degradation. DATABASE: The atomic coordinates and structure factors P. jessenii 6-aminohexanoate aminotransferase have been deposited in the PDB as entries 6G4B (E∙succinate complex), 6G4C (E∙phosphate complex), 6G4D (E∙PLP complex), 6G4E (E∙PLP-6-aminohexanoate intermediate), and 6G4F (E∙PMP complex).
Topics: Amino Acid Sequence; Aminocaproic Acid; Bacterial Proteins; Caprolactam; Crystallography, X-Ray; Models, Molecular; Phylogeny; Pseudomonas; Pyridoxal Phosphate; Sequence Homology; Substrate Specificity; Transaminases
PubMed: 31162815
DOI: 10.1111/febs.14950 -
Frontiers in Microbiology 2019Food safety has become an important public health issue worldwide. However, conventional methods for detection of food-borne pathogens are complicated, and...
Food safety has become an important public health issue worldwide. However, conventional methods for detection of food-borne pathogens are complicated, and labor-intensive. Moreover, the sensitivity is often low, and it is difficult to achieve high-throughput detection. This study developed a TaqMan real-time polymerase chain reaction (PCR) assay for the simultaneous detection and quantification of 12 common pathogens in a single reaction, including , β hemolyticus, spp., , and in food and drinking water. Based on published sequence data, specific primers, and fluorescently-labeled hybridization probes were designed targeting based on the virulence genes of the 12 pathogens, and these primers and probes were optimized to achieve consistent reaction conditions. The assay was evaluated using 106 pure bacterial culture strains. There was no cross-reaction among the different pathogens. The analytical sensitivity was 1 copy/μL for , β spp., , and , 10 copies/μL for , and , respectively. The limit of detection (LOD) was 296, 500, 177, 56, 960, 830, 625, 520, 573, 161, 875, and 495 CFU/mL for , β spp., , and , respectively. The limit of detection for the assay in meat samples was 10 CFU/g for and 10 CFU/g for other 11 strains. Together, these results indicate that the optimized TaqMan real-time PCR assay will be useful for routine detection of pathogenic bacteria due to its rapid analysis, low cost, high-throughput, high specificity, and sensitivity.
PubMed: 30814987
DOI: 10.3389/fmicb.2019.00222 -
The Canadian Journal of Infectious... 2018Cell phones may be an ideal habitat for colonization by bacterial pathogens, especially in hot climates, and may be a reservoir or vehicle in transmitting nosocomial...
Cell phones may be an ideal habitat for colonization by bacterial pathogens, especially in hot climates, and may be a reservoir or vehicle in transmitting nosocomial infections. We investigated bacterial contamination on cell phones of healthcare workers in three hospitals in Saudi Arabia and determined antibacterial resistance of selected bacteria. A questionnaire was submitted to 285 healthcare workers in three hospitals, and information was collected on cell phone usage at the work area and in the toilet, cell phone cleaning and sharing, and awareness of cell phones being a source of infection. Screening on the Vitek 2 Compact system (bioMérieux Inc., USA) was done to characterize bacterial isolates. Of the 60 samples collected from three hospitals, 38 (63.3%) were positive with 38 bacterial isolates (4 Gram-negative and 34 Gram-positive bacteria). We found 38.3% of cell phones were contaminated with coagulase-negative staphylococci, particularly (10 isolates). Other bacterial agents identified were , , , , and . Antimicrobial susceptibility testing showed that most coagulase-negative staphylococci were resistant to benzylpenicillin, erythromycin, and rifampicin. Eight isolates were resistant to oxacillin, specifically (3), (2), and (2). , a cause of acute otitis media showed multidrug resistance. One isolate, a confirmed hetero-vancomycin intermediate-resistant , was resistant to antibiotics, commonly used to treat skin infection. There was a significant correlation between the level of contamination and usage of cell phone at toilet and sharing. Our findings emphasize the importance of hygiene practices in cell phone usage among healthcare workers in preventing the transmission of multidrug-resistant microbes.
PubMed: 30675320
DOI: 10.1155/2018/6598918 -
Applied and Environmental Microbiology Feb 2019Inappropriate and disproportionate use of antibiotics is contributing immensely to the development of antibiotic resistance in bacterial species associated with food...
Inappropriate and disproportionate use of antibiotics is contributing immensely to the development of antibiotic resistance in bacterial species associated with food contamination. The use of natural products in combination can be a potent alternative hurdle strategy to inactivate foodborne pathogens. Here, we explored the pro-oxidant properties of essential oil inalool and itamin C in combination with opper (LVC) in combating the foodborne pathogens and subsp. serovar Typhi using a three-dimensional (3D) checkerboard microdilution assay. Antibacterial activity in terms of the MIC revealed that the triple combination exerted a synergistic effect compared to the effects of the individual constituents. The bactericidal effect of the triple combination was confirmed by a live/dead staining assay. Reactive oxygen species (ROS) measurements with the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling assay and scanning electron microscopy imaging strongly suggested that the increase in ROS production is the underlying mechanism of the enhanced antibacterial potency of the LVC combination (linalool [1.298 mM], vitamin C [8 mM], copper [16.3 μM]). In addition, the hypersensitivity of oxidative stress regulator mutants (, , , and mutants) toward LVC corroborated the involvement of ROS in cell death. Live/dead staining and changes in cellular morphology revealed that oxidative stress did not transform the cells into the viable but nonculturable (VBNC) state; rather, killing was associated with intracellular and extracellular oxidative burst. Furthermore, the LVC combination did not display toxicity to human cells, while it effectively reduced the pathogen levels in acidic fruit juices by 3 to 4 log CFU/ml without adversely altering the organoleptic properties. This study opens a new outlook for combinatorial antimicrobial therapy. There is a need to develop effective antibacterial therapies for mitigating bacterial pathogens in food systems. We used a 3D checkerboard assay to ascertain a safe synergistic combination of food-grade components: vitamin C, copper, and the essential oil linalool. Individually, these constituents have to be added in large amounts to exert their antibacterial effect, which leads to unwanted organoleptic properties. The triple combination could exceptionally inhibit foodborne Gram-negative pathogens like and subsp. serovar Typhi at low concentrations (linalool, 1.298 mM; vitamin C, 8 mM; copper, 16.3 μM) and displayed potent microbial inhibition in acidic beverages. We found increased susceptibility in deletion mutants of oxidative stress regulators (, , , and mutants) due to ROS generation by Fenton's chemistry. The results of this study show that it may be possible to use plant-based antimicrobials in synergistic combinations to control microbial contaminants.
Topics: Acyclic Monoterpenes; Anti-Bacterial Agents; Ascorbic Acid; Copper; DNA Damage; Drug Combinations; Drug Synergism; Escherichia coli; Humans; Microbial Sensitivity Tests; Microbial Viability; Oils, Volatile; Reactive Oxygen Species; Salmonella enterica; Vibrio
PubMed: 30552187
DOI: 10.1128/AEM.02487-18 -
Journal of Infection in Developing... Aug 2018We describe an unusual case of a urinary tract infection (UTI) in a 52-year-old woman caused by Vibrio fluvialis. To our knowledge, this is the first report of this...
We describe an unusual case of a urinary tract infection (UTI) in a 52-year-old woman caused by Vibrio fluvialis. To our knowledge, this is the first report of this organism causing such an infection. The source of the organism could be the highly contaminated water she is using at home.
Topics: Ciprofloxacin; Female; Humans; Microbial Sensitivity Tests; Middle Aged; Urinary Tract Infections; Vibrio; Vibrio Infections
PubMed: 31958331
DOI: 10.3855/jidc.9709 -
Scientific Reports Jul 2018Omega (ω)-transaminase catalyzes the transfer of an amino group from a non-α position amino acid, or an amine compound with no carboxylic group, to an amino acceptor,...
Omega (ω)-transaminase catalyzes the transfer of an amino group from a non-α position amino acid, or an amine compound with no carboxylic group, to an amino acceptor, and has been studied intensively because of its high potential utility in industry and pharmatheutics. The ω-transaminase from Vibrio fluvialis JS17 (Vfat) is an amine:pyruvate transaminase capable of the stereo-selective transamination of arylic chiral amines. This enzyme exhibits extraordinary enantio-selectivity, and has a rapid reaction rate for chiral amine substrates. In this study, we report the crystal structure of the apo form of Vfat. The overall structure of Vfat was typical of other class III aminotransferase exhibiting an N-terminal helical domain, a small domain, and a large domain. Interestingly, the two subunits of apo Vfat in the asymmetric unit had different structures. A comparison of the overall structure to other transaminases, revealed that the structures of the N-terminal helical domain and the large domain can be affected by cofactor occupancy, but the structural rearrangement in these regions can occur independently.
Topics: Catalytic Domain; Coenzymes; Crystallography, X-Ray; Protein Multimerization; Protein Structure, Secondary; Protein Subunits; Structural Homology, Protein; Substrate Specificity; Transaminases; Vibrio
PubMed: 30061559
DOI: 10.1038/s41598-018-29846-0 -
Journal of Biotechnology Sep 2018The amine transaminase from Vibrio fluvialis (Vf-ATA) is an attractive enzyme with applications within Biocatalysis for the preparation of chiral amines. Various...
The amine transaminase from Vibrio fluvialis (Vf-ATA) is an attractive enzyme with applications within Biocatalysis for the preparation of chiral amines. Various catalytic properties of Vf-ATA have been investigated, but a biophysical characterization of its stability has been lacking. Today, the industrial application of Vf-ATA is limited by its low operational stability. In order to enhance the knowledge regarding the structural stability of ATAs, general characterizations of different ATAs are required. In this work, the stability of Vf-ATA was explored. First, the affinity between enzyme and pyridoxal-5'-phosphate (PLP) (K value of 7.9 μM) was determined. Addition of PLP to enzyme preparations significantly improved the enzyme thermal stability by preventing enzyme unfolding. With the aim to understand if this was due to the PLP phosphate group coordination into the phosphate group binding cup, the effect of phosphate buffer on the enzyme stability was compared to HEPES buffer. Low concentrations of phosphate buffer showed a positive effect on the enzyme initial activity, while higher phosphate buffer concentrations prevented cofactor dissociation. Additionally, the effects of various amine or ketone substrates on the enzyme stability were explored. All tested amines caused a concentration dependent enzyme inactivation, while the corresponding ketones showed no or stabilizing effects. The enzyme inactivation due to the presence of amine can be connected to the formation of PMP, which forms in the presence of amines in the absence of ketone. Since PMP is not covalently bound to the enzyme, it could readily leave the enzyme upon formation. Exploring the different stability effects of cofactor, substrates, additives and buffer system on ATAs seems to be important in order to understand and improve the general performance of ATAs.
Topics: Amines; Bacterial Proteins; Enzyme Stability; Escherichia coli; Ketones; Pyridoxal Phosphate; Transaminases; Transition Temperature; Vibrio
PubMed: 29906477
DOI: 10.1016/j.jbiotec.2018.06.309 -
Frontiers in Microbiology 2018, an emerging foodborne pathogen of increasing public health concern, contains two distinct gene clusters encoding type VI secretion system (T6SS), the most newly...
, an emerging foodborne pathogen of increasing public health concern, contains two distinct gene clusters encoding type VI secretion system (T6SS), the most newly discovered secretion pathway in Gram-negative bacteria. Previously we have shown that one of the two T6SS clusters, namely VflT6SS2, is active and associates with anti-bacterial activity. However, how its activity is regulated is not completely understood. Here, we report that the global regulator integration host factor (IHF) positively modulates the expression and thus the function of VflT6SS2 through co-regulating its major cluster and 22 (also known as ) orphan clusters. Specifically, reporter gene activity assay showed that IHF transactivates the major and orphan clusters of VflT6SS2, while deletion of either or , the genes encoding the IHF subunits, decreased their promoter activities and mRNA levels of 2, , and 2 for the selected major cluster genes and 2 and 2 for the selected orphan cluster genes. Subsequently, the direct bindings of IHF to the promoter regions of the major and orphan clusters were confirmed by electrophoretic mobility shift assay (EMSA). Site-directed mutagenesis combined with reporter gene activity assay or EMSA pinpointed the exact binding sites of IHF in the major and orphan cluster promoters, with two sites in the major cluster promoter, consisting with its two observed shifted bands in EMSA. Functional studies showed that the expression and secretion of hemolysin-coregulated protein (Hcp) and the VflT6SS2-mediated antibacterial virulence were severely abrogated in the deletion mutants of Δ and Δ, but restored when their trans-complemented plasmids were introduced, suggesting that IHF mostly contributes to environmental survival of . by directly binding and modulating the transactivity and function of VflT6SS2.
PubMed: 29867866
DOI: 10.3389/fmicb.2018.00962