Introduction: The aim of this study was to correlate genes involved in carbapenem resistance to MIC levels among clinical ESBL and non-ESBL producing carbapenem resistant Enterobacteriaceae (CRE) ...isolates of Escherichia coli and Klebsiella pneumoniae.
Methodology: E. coli (n = 76) and K. pneumoniae (n = 54), collected between July 2008 and July 2014, were analyzed. The MICs were determined against ertapenem (ERT), imipenem (IMP) and meropenem (MER). PCR was performed on all 130 isolates to amplify
the resistance and outer membrane proteins (OMPs) encoding genes: blaOXA-48, blaNDM-1, blaTEM-1, blaCTX-M-15, ompC and ompF. Sequencing was performed on selected isolates.
Results: The prevalence of blaOXA-48, blaNDM-1, blaTEM-1, and/or blaCTX-M-15 among E. coli isolates were 36%, 12%, 20% and 80%, respectively, while among K. pneumoniae they were 37%, 28%, 28% and 72%, respectively. K. pneumoniae isolates positive for any of these genes had an MIC90 > 32μg/mL against ERT, IMP and MER, while in E. coli isolates there was a variation in the MIC90 values. Porin impermeabilities were due to mutations in ompC and ompF genes in E. coli, and loss of ompC and ompF genes in K. pneumoniae, and increased MIC90 values.
Conclusion: The presence of more than one carbapenem resistance encoding gene and/or ESBL encoding gene did not have an effect on the MIC90 value in K. pneumoniae isolates, while in E. coli it showed higher MIC90 values.
Membrane transport proteins are essential for the transport of a wide variety of molecules across the cell membrane to maintain cellular homeostasis. Generally, these transport proteins can be ...overexpressed in a suitable host (bacteria, yeast, or mammalian cells), and it is well documented that overexpression of membrane proteins alters the global metabolomic and proteomic profiles of the host cells. In the present study, we investigated the physiological consequences of overexpression of a membrane transport protein YdgR that belongs to the POT/PTR family from E. coli by using the lab strain BL21 (DE3)pLysS in its functional and attenuated mutant YdgR-E33Q. We found significant differences between the omics (metabolomics and proteomics) profiles of the cells expressing functional YdgR as compared to cells expressing attenuated YdgR, e.g., upregulation of several uncharacterized y-proteins and enzymes involved in the metabolism of peptides and amino acids. Furthermore, molecular network analysis suggested a relatively higher presence of proline-containing tripeptides in cells expressing functional YdgR. We envisage that an in-depth investigation of physiological alterations due to protein over-expression may be used for the deorphanization of the y-gene transportome.
•Physiological response to membrane protein overexpression depends upon functionality.•Protein functionality tunes the expression of uncharacterized proteins.•Changes in cell shape as a consequence of membrane protein overexpression.
A few commonly used non-antibiotic drugs have recently been associated with changes in gut microbiome composition, but the extent of this phenomenon is unknown. Here, we screened more than 1,000 ...marketed drugs against 40 representative gut bacterial strains, and found that 24% of the drugs with human targets, including members of all therapeutic classes, inhibited the growth of at least one strain in vitro. Particular classes, such as the chemically diverse antipsychotics, were overrepresented in this group. The effects of human-targeted drugs on gut bacteria are reflected on their antibiotic-like side effects in humans and are concordant with existing human cohort studies. Susceptibility to antibiotics and human-targeted drugs correlates across bacterial species, suggesting common resistance mechanisms, which we verified for some drugs. The potential risk of non-antibiotics promoting antibiotic resistance warrants further exploration. Our results provide a resource for future research on drug-microbiome interactions, opening new paths for side effect control and drug repurposing, and broadening our view of antibiotic resistance.
An efficient monitoring and control strategy is the basis for a reliable production process. Conventional optical density (OD) measurements involve superpositions of light absorption and scattering, ...and the results are only given in arbitrary units. In contrast, photon density wave (PDW) spectroscopy is a dilution-free method that allows independent quantification of both effects with defined units. For the first time, PDW spectroscopy was evaluated as a novel optical process analytical technology tool for real-time monitoring of biomass formation in Escherichia coli high-cell-density fed-batch cultivations. Inline PDW measurements were compared to a commercially available inline turbidity probe and with offline measurements of OD and cell dry weight (CDW). An accurate correlation of the reduced PDW scattering coefficient µ
' with CDW was observed in the range of 5-69 g L
(R
= 0.98). The growth rates calculated based on µ
' were comparable to the rates determined with all reference methods. Furthermore, quantification of the reduced PDW scattering coefficient µ
' as a function of the absorption coefficient µ
allowed direct detection of unintended process trends caused by overfeeding and subsequent acetate accumulation. Inline PDW spectroscopy can contribute to more robust bioprocess monitoring and consequently improved process performance.
Synthetic biology is driving a new era of medicine through the genetic programming of living cells
. This transformative approach allows for the creation of engineered systems that intelligently ...sense and respond to diverse environments, ultimately adding specificity and efficacy that extends beyond the capabilities of molecular-based therapeutics
. One particular area of focus has been the engineering of bacteria as therapeutic delivery systems to selectively release therapeutic payloads in vivo
. Here we engineered a non-pathogenic Escherichia coli strain to specifically lyse within the tumor microenvironment and release an encoded nanobody antagonist of CD47 (CD47nb)
, an anti-phagocytic receptor that is commonly overexpressed in several human cancer types
. We show that delivery of CD47nb by tumor-colonizing bacteria increases activation of tumor-infiltrating T cells, stimulates rapid tumor regression, prevents metastasis and leads to long-term survival in a syngeneic tumor model in mice. Moreover, we report that local injection of CD47nb-expressing bacteria stimulates systemic tumor-antigen-specific immune responses that reduce the growth of untreated tumors, providing proof-of-concept for an abscopal effect induced by an engineered bacterial immunotherapy. Thus, engineered bacteria may be used for safe and local delivery of immunotherapeutic payloads leading to systemic antitumor immunity.
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•Consolidated data on wound healing and wound dressing along with drug delivery mechanism.•The comprehensive wound healing process have been explained.•The therapeutic approach for ...reducing the healing time with nano/micro-fibers based wound dressing.•Classification of Electrospun nanofibers and their effect on the drug delivery efficiency.
Chronic wound healing is an intricate time-consuming process (healing time ∼12 weeks), susceptible to external biological attack such as bacteria (e.g. E. coli, B. subtilis, S. aureus etc.) promoting wound infection and exhibit a negative effect on the immune system, therefore, it is a necessity to form a controlled environment for wound healing with the help of suitable barrier. Over the past few decades, various topical formulations of wound barriers like films, hydrogels, emulsions and nano/micro-fibers have been explored. The drug-embedded fibers are the potential candidate for wound healing as a barrier owing to the large specific surface area (for surface functionalization), enormous porosity ∼60–90% (for oxy-permeability), reticulated nano-porosity (for inhibition of the microorganism) and advanced electrospinning methodology which facilitates sustained drug release. Wound bed exhibits 37 °C temperature and 7.4 pH (typically for blood) condition which triggers the drug release and nano/micro-fiber degradation simultaneously. Drug-embedded nano/micro-fiber consists of a matrix with excellent biocompatibility, appreciable biodegradation rate (e.g. Chitin nanofiber-20% degradation in 15 days) and a drug with a superior antibiotic, antimicrobial property, besides certain drug (e.g. Captopril) also promote vasodilation which increases in-vascular permeability leading to rapid movement of leukocytes into the affected tissue, thereby reducing the healing time. In this review article, we discuss the consolidated recent advanced works on wound healing and wound dressing which implies the significance of wound dressing. In addition, the recent advancements in nano/micro-fiber fabrication methodology for drug release mechanism, and benefits of the fiber-based wound dressings compared to conventional wound dressings have been extensively discussed.
Infections due to multidrug resistant bacteria are a major concern and cause for human mortality worldwide. Materials that can selectively capture, and eliminate these pathogens have turned into a ...priority. Development of excellent point-of-care material/system that can help in the visual detection of the captured bacterial cells in addition to their killing capability can be advantageous. In this study, we demonstrate the synthesis of a hitherto unknown glycosylated gel microspheres that can capture, kill and detect pathogenic bacteria. Silver nanoparticles (AgNPs) loaded glucose/mannose/galactose functionalized microspheres namely; PAM-Glc, PAM-Man and PAM-Gal, were synthesized by inverse emulsion polymerization. The sugar functionalities present on the microspheres interacts with the bacterial cell wall leading to capture of the cells while the antibacterial action was brought about by the AgNPs synthesized in-situ within the microspheres. The highlight of the designed system is visual indication of bacterial capture due to aggregation of gel microspheres and an indicative colour change of AgNPs. The capture kinetics of bacterial cells using PAM-Man was faster compared to PAM-Glc and PAM-Gal. Among the AgNPs loaded glyco microspheres, silver loaded mannose microspheres (Ag@PAM-Man) exhibited greater inhibition against E. coli and antibiotic resistant S. aureus cells. Bacterial cells captured by PAM-Man, exhibited pink coloration upon interaction with Resorufin β-glucuronide; suggesting the destruction of bacteria upon adhesion to microspheres. The plausible mechanistic aspects involved in the capture, detection and killing process is also discussed.
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Soils in household environments in low- and middle-income countries may play an important role in the persistence, proliferation, and transmission of
Our goal was to investigate the risk factors for ...detection, survival, and growth of
in soils collected from household plots.
was enumerated in soil and fecal samples from humans, chickens, and cattle from 52 households in rural Bangladesh. Associations between
concentrations in soil, household-level risk factors, and soil physicochemical characteristics were investigated. Susceptibility to 16 antibiotics and the presence of intestinal pathotypes were evaluated for 175
isolates. The growth and survival of
in microcosms using soil collected from the households were also assessed.
was isolated from 44.2% of the soil samples, with an average of 1.95 log
CFU/g dry soil. Soil moisture and clay content were associated with
concentrations in soil, whereas no household-level risk factor was significantly correlated. Antibiotic resistance and pathogenicity were common among
isolates, with 42.3% resistant to at least one antibiotic, 12.6% multidrug resistant (≥3 classes), and 10% potentially pathogenic. Soil microcosms demonstrate growth and/or survival of
, including an enteropathogenic extended-spectrum beta-lactamase (ESBL)-producing isolate, in some, but not all, of the household soils tested. In rural Bangladesh, defined soil physicochemical characteristics appear more influential for
detection in soils than household-level risk factors. Soils may act as reservoirs in the transmission of antibiotic-resistant and potentially pathogenic
and therefore may impact the effectiveness of water, sanitation, and hygiene interventions.
Soil may represent a direct source or act as an intermediary for the transmission of antibiotic-resistant and pathogenic
strains, particularly in low-income and rural settings. Thus, determining risk factors associated with detection, growth, and long-term survival of
in soil environments is important for public health. Here, we demonstrate that household soils in rural Bangladesh are reservoirs for antibiotic-resistant and potentially pathogenic
strains and can support
growth and survival, and defined soil physicochemical characteristics are drivers of
survival in this environment. In contrast, we found no evidence that household-level factors, including water, sanitation, and hygiene indicators, were associated with
contamination of household soils.
Antibiotic resistance plasmids can be disseminated between different Enterobacteriaceae in the gut. Here, we investigate how closely related Enterobacteriaceae populations with similar nutrient needs ...can co-bloom in the same gut and thereby facilitate plasmid transfer. Using different strains of Salmonella Typhimurium (S.Tm SL1344 and ATCC14028) and mouse models of Salmonellosis, we show that the bloom of one strain (i.e., recipient) from very low numbers in a gut pre-occupied by the other strain (i.e., donor) depends on strain-specific utilization of a distinct carbon source, galactitol or arabinose. Galactitol-dependent growth of the recipient S.Tm strain promotes plasmid transfer between non-isogenic strains and between E. coli and S.Tm. In mice stably colonized by a defined microbiota (OligoMM12), galactitol supplementation similarly facilitates co-existence of two S.Tm strains and promotes plasmid transfer. Our work reveals a metabolic strategy used by Enterobacteriaceae to expand in a pre-occupied gut and provides promising therapeutic targets for resistance plasmids spread.
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•Strain-specific traits enable discrete Salmonella strains to co-bloom in the mouse gut•Salmonella can use galactitol or arabinose during co-colonization with a different strain•Single-carbon usage fuels plasmid transfer between different Enterobacteriaceae strains•Carbon metabolic capacity enables gut-luminal co-blooming of distinct Enterobacteriaceae
Gül et al. reveal that the ability to exclusively utilize a single-carbon source (e.g., galactitol or arabinose) enables Salmonella to bloom from low numbers in a gut pre-colonized by another Enterobacteriaceae population. This metabolic strategy promotes the transfer of antibiotic resistance plasmids in the mouse gut.
An efficient genome-scale editing tool is required for construction of industrially useful microbes. We describe a targeted, continual multigene editing strategy that was applied to the Escherichia ...coli genome by using the Streptococcus pyogenes type II CRISPR-Cas9 system to realize a variety of precise genome modifications, including gene deletion and insertion, with a highest efficiency of 100%, which was able to achieve simultaneous multigene editing of up to three targets. The system also demonstrated successful targeted chromosomal deletions in Tatumella citrea, another species of the Enterobacteriaceae, with highest efficiency of 100%.
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