Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 28
Filter
1.
New Microbiol ; 47(2): 164-171, 2024 Jul.
Article in English | MEDLINE | ID: mdl-39023526

ABSTRACT

The study objective is to examine epidemiological and microbiological aspects of aerobic vaginitis in female patients admitted to University Hospital of Campania "L. Vanvitelli" over five years. The most represented strains were E. coli (n = 153), Citrobacter spp. increasing from 2020, E. faecalis (n = 149), S. haemolitycus (n = 61), and Candida albicans (n = 87). The susceptibility patterns of a selection of gram-negative and gram-positive representative bacterial isolates were examined. Carbapenems, aminoglycosides, and fosfomycin were most effective against gram-negative bacteria, whereas vancomycin, daptomycin, and linezolid exhibited greater efficacy against gram-positive bacteria. None of the E. coli and Citrobacter spp. isolates produced extended-spectrum beta-lactamases, and the S. haemolyticus strains were methicillin-resistant. In gram-positive isolates, gentamicin susceptibility increased in 2020 and 2021 compared to clindamycin; erythromycin showed high resistance rates in 2020. Our findings indicate that integrating proper microbiological cultures into clinical practice could improve the management of aerobic vaginitis. Moreover, they highlight the necessity of establishing a nationwide surveillance guideline to mitigate antimicrobial resistance. Improvement actions in antimicrobial diagnostic stewardship must be considered when seeking the appropriate diagnosis and treatment for aerobic vaginitis.


Subject(s)
Anti-Bacterial Agents , Antimicrobial Stewardship , Microbial Sensitivity Tests , Female , Humans , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Adult , Drug Resistance, Bacterial , Middle Aged , Vaginosis, Bacterial/microbiology , Vaginosis, Bacterial/drug therapy , Vaginosis, Bacterial/diagnosis , Young Adult , Vaginitis/microbiology , Vaginitis/drug therapy
2.
New Microbiol ; 46(1): 29-36, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36853815

ABSTRACT

Bloodstream infections (BSIs) monitoring and antibiotic susceptibility assumes a priority relevance to guide antibiotic treatment strategies and prevention programs. The study aims to identify the most common causative agents of BSIs, seasonal distribution and variation of antimicrobial susceptibility rates during a 6-year period in a in a Level II EAD Southern Italian Hospital. The study was conducted from 2016 to 2021 at Hospital of National Relevance (AORN) Sant'Anna and San Sebastiano, Caserta, Campania Region in Italy. BSIs Gram positive causative pathogens were S. aureus and Enterococci; Gram negative pathogens were E. coli, K. pneumoniae, P. aeruginosa and A. baumannii. Seasonal distribution showed the main incidence in April-June for Gram positive BSIs pathogens and in July-September months for Gram negative. Antimicrobial susceptibility fluctuations rates from 2016-2018 to 2019-2021 highlighted a significant decrease in S. aureus oxacillin resistance rates. Enterococci incremented resistance was reported for gentamicin. Gram negative pathogens antimicrobial susceptibility revealed decreased carbapenem-resistance rates for K. pneumoniae (-21.5%) and P. aeruginosa (-19.7%). A. baumannii colistin resistance had a significant increase in 2019-2021. K. pneumoniae and E. coli isolates showed decreased trend of extended-spectrum -lactamase-producing (ESBL) and carbapenem-resistant (CRE) resistance profiles. Our finding reflects the success of our Istitution regarding antimicrobial stewardship program and highlights the need to know the trend of antimicrobial resistance characterization focus on local pathogens' profile. In this way, in conjunction with infection control strategies, il could be possible to constantly reduce the spread of Multi Drug Resistant organisms.


Subject(s)
Anti-Bacterial Agents , Sepsis , Humans , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Escherichia coli , Staphylococcus aureus , Carbapenems , Hospitals , Italy/epidemiology , Klebsiella pneumoniae , Pseudomonas aeruginosa
3.
New Microbiol ; 46(3): 264-270, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37747471

ABSTRACT

Carbapenemase-producing Enterobacteriaceae (CPE) are an increasing threat to global public health. Treatment of CPE isolates, like New Delhi metallo-ß-lactamase (NDM), is limited and often necessitates combination therapies. The aim of this study was to evaluate the synergistic meropenem/fosfomycin combination against K.pneumoniae-producing NDM isolates. Fosfomycin/meropenem, fosfomycin/colistin and meropenem/colistin were tested alone and in combination, using e-test and time-kill assay against 20 clinical carbapenemase-producing K. pneumonia (CPKp NDM) isolates collected from September 2022 to December 2022. K. pneumoniae strains were resistant to meropenem, ceftazidime/avibactam and ceftolozano/tazobactam, 75% and 80% of isolates were susceptible for cefiderocol and for colistin respectively. Fosfomycin/meropenem combination was synergic in 95% (n=19) strains. Fosfomycin/colistin and colistin/meropenem combination showed only 10% synergistic combination strains. In 16 isolates (80%) indifference action for fosfomycin/colistin and colistin/meropenem was reported. For 0.8% of CpKP NDM isolates colistin/meropenem and fosfomycin/colistin combinations found to be antagonistic. In this study, time kill assay showed combination therapies action versus K.pneumoniae metallo-b-lactamase producing (NDM) strains and confirmed the synergistic action of fosfomycin/meropenem combination. In vitro synergy testing should be routinely performed in multidrug resistance infections and combo therapies can be used as a possible alternative in targeted patients with the goal of reducing overall antibiotic costs.


Subject(s)
Carbapenem-Resistant Enterobacteriaceae , Fosfomycin , Humans , Meropenem/pharmacology , Fosfomycin/pharmacology , Colistin/pharmacology , Klebsiella pneumoniae
4.
Nucleic Acids Res ; 48(D1): D704-D715, 2020 01 08.
Article in English | MEDLINE | ID: mdl-31701156

ABSTRACT

In biology and biomedicine, relating phenotypic outcomes with genetic variation and environmental factors remains a challenge: patient phenotypes may not match known diseases, candidate variants may be in genes that haven't been characterized, research organisms may not recapitulate human or veterinary diseases, environmental factors affecting disease outcomes are unknown or undocumented, and many resources must be queried to find potentially significant phenotypic associations. The Monarch Initiative (https://monarchinitiative.org) integrates information on genes, variants, genotypes, phenotypes and diseases in a variety of species, and allows powerful ontology-based search. We develop many widely adopted ontologies that together enable sophisticated computational analysis, mechanistic discovery and diagnostics of Mendelian diseases. Our algorithms and tools are widely used to identify animal models of human disease through phenotypic similarity, for differential diagnostics and to facilitate translational research. Launched in 2015, Monarch has grown with regards to data (new organisms, more sources, better modeling); new API and standards; ontologies (new Mondo unified disease ontology, improvements to ontologies such as HPO and uPheno); user interface (a redesigned website); and community development. Monarch data, algorithms and tools are being used and extended by resources such as GA4GH and NCATS Translator, among others, to aid mechanistic discovery and diagnostics.


Subject(s)
Computational Biology/methods , Genotype , Phenotype , Algorithms , Animals , Biological Ontologies , Databases, Genetic , Exome , Genetic Association Studies , Genetic Variation , Genomics , Humans , Internet , Software , Translational Research, Biomedical , User-Computer Interface
5.
New Microbiol ; 45(4)2022 May 10.
Article in English | MEDLINE | ID: mdl-36066216

ABSTRACT

Viral hepatitis still represents a significant worldwide public health issue, being an important cause of morbidity and mortality. The aim of our study is to evaluate the prevalence of Hepatitis B virus (HBV) markers from serologic analysis of hospitalized patients at University Hospital of Campania "Luigi Vanvitelli" and also to investigate the prevalence of HBV/HCV coinfection. We screened serum Anti-Hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), antibody to hepatitis B core antigen (anti-HBc), and antibody to Hepatitis C Virus (Anti-HCV) Anti-HCV from January to December 2020. Analyses of HBV serological profile based on age showed that the 51-60 age group was the most numerous and with the highest cases of HBsAg. The 61-70 age group recorded the highest prevalence of anti-HBc while age groups 0-10 years and 31-40 years the highest cases of anti-HBs. Antibody levels decline with time. In subjects older than 20 years, compared to vaccinated cohort individuals, anti-HBc seropositive prevalence increased linearly. This study underlined, in our geographic region, the decreased incidence of hepatitis B and high immunogenicity in the young population. Therefore, administration of HBV vaccine booster dose should be considered for the population rather than vaccination in the first year of life. In conclusion, our findings reaffirm the importance of health surveillance in hospitalized subjects, stressing the need to improve immunized subjects to increase the general population's health.

6.
New Microbiol ; 45(4): 338-343, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36538299

ABSTRACT

The aim of this study was to describe the prevalence and epidemiology distribution of K. pneumoniae isolated at University Hospital of Campania "Luigi Vanvitelli," including the susceptibility evolution profile. Data on resistant phenotype strains, such as extended-spectrum-ß-lactamase (ESBL) producers and carbapenem-resistant K. pneumoniae (CRE) isolates, were also reported. K. pneumoniae strains were collected at the Complex Operative Unit (UOC) of Virology and Microbiology from different colonization and infection sites from January 2016 to December 2020. The highest rates of isolation were in urinary samples and in respiratory and wound swabs. Antibiotics susceptibility patterns showed more than 50% of the isolates resistant to cephalosporins, fluoroquinolones and penicillin. On the other hand, from 20% to 40% of K. pneumoniae strains were resistant to carbapenems and aminoglycosides. Based on our analysis, fosfomycin, ceftazidime/avibactam and ceftolozane/tazobactam are still therapeutic alternatives. Data analysis on carbapenem class evolution in 2016-2020 showed a significant increase in resistance rates (p<0.05). Increased rates in CRE and ESBL producing K. pneumoniae since 2017 were reported. Providing information on clinical characteristics and epidemiology data on contemporary K. pneumoniae evolution could help mitigate the spread of these isolates in our hospital and avert the endemic levels that have been observed in Southern Italy and in other European countries.


Subject(s)
Fosfomycin , Klebsiella Infections , Humans , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Klebsiella pneumoniae/genetics , Drug Resistance, Bacterial , Carbapenems/pharmacology , Microbial Sensitivity Tests , beta-Lactamases/genetics , Klebsiella Infections/epidemiology , Klebsiella Infections/drug therapy
7.
Nucleic Acids Res ; 47(D1): D1018-D1027, 2019 01 08.
Article in English | MEDLINE | ID: mdl-30476213

ABSTRACT

The Human Phenotype Ontology (HPO)-a standardized vocabulary of phenotypic abnormalities associated with 7000+ diseases-is used by thousands of researchers, clinicians, informaticians and electronic health record systems around the world. Its detailed descriptions of clinical abnormalities and computable disease definitions have made HPO the de facto standard for deep phenotyping in the field of rare disease. The HPO's interoperability with other ontologies has enabled it to be used to improve diagnostic accuracy by incorporating model organism data. It also plays a key role in the popular Exomiser tool, which identifies potential disease-causing variants from whole-exome or whole-genome sequencing data. Since the HPO was first introduced in 2008, its users have become both more numerous and more diverse. To meet these emerging needs, the project has added new content, language translations, mappings and computational tooling, as well as integrations with external community data. The HPO continues to collaborate with clinical adopters to improve specific areas of the ontology and extend standardized disease descriptions. The newly redesigned HPO website (www.human-phenotype-ontology.org) simplifies browsing terms and exploring clinical features, diseases, and human genes.


Subject(s)
Biological Ontologies , Computational Biology/methods , Congenital Abnormalities/genetics , Genetic Predisposition to Disease/genetics , Knowledge Bases , Rare Diseases/genetics , Congenital Abnormalities/diagnosis , Databases, Genetic , Genetic Variation , Humans , Internet , Phenotype , Rare Diseases/diagnosis , Whole Genome Sequencing/methods
8.
New Microbiol ; 43(2): 96-98, 2020 Apr.
Article in English | MEDLINE | ID: mdl-32310303

ABSTRACT

Infections caused by Campylobacter jejuni are rarely associated with extraintestinal complications. C. jejuni bacteremia is difficult to detect in patients with hematological malignancies undergoing chemotherapy where the choice of appropriate antibiotic treatment is extremely important. We report two cases of C. jejuni bacteremia in Italian pediatric patients affected by acute lymphoblastic leukemia (ALL). Agreeing with the most recent epidemiological data, both clinical isolates showed a typical phenotypic antimicrobial resistance patterns with combined resistance to ciprofloxacin and tetracycline. To our knowledge, this is the first report of C. jejuni isolation from the blood of ALL pediatric patients in Italy, and it provides important epidemiological information on this rare infection.


Subject(s)
Bacteremia , Campylobacter Infections , Campylobacter jejuni , Precursor Cell Lymphoblastic Leukemia-Lymphoma , Anti-Bacterial Agents , Bacteremia/complications , Campylobacter Infections/complications , Campylobacter Infections/diagnosis , Campylobacter jejuni/isolation & purification , Child , Drug Resistance, Bacterial , Humans , Italy , Microbial Sensitivity Tests , Precursor Cell Lymphoblastic Leukemia-Lymphoma/complications
9.
Intervirology ; 62(1): 15-22, 2019.
Article in English | MEDLINE | ID: mdl-31117080

ABSTRACT

Epstein-Barr virus (EBV) is a common herpesvirus that may cause asymptomatic infection or various diseases, such as mononucleosis, lymphoproliferative disorders and several cancers. Our objective was to estimate the prevalence of EBV among patients hospitalized in "Luigi Vanvitelli" University Hospital in the last 10 years. Our results showed that EBV seroprevalence in our geographical area was 65%. Seroprevalence increased gradually with age with no significant difference between females (49.42%) and males (50.58%). The seropositivity for primary infection was higher in patients about 5 years old, while seropositivity for past infection was predominant in patients of about 35 years old. These results underline that children in our country are still exposed to EBV. The development and the deeper use of an EBV vaccine in the early years of life could represent the solution for this infection.


Subject(s)
Antibodies, Viral/blood , Asymptomatic Infections/epidemiology , Epstein-Barr Virus Infections/epidemiology , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Child , Child, Preschool , Epstein-Barr Virus Infections/diagnosis , Female , Herpesvirus 4, Human , Hospitals, University , Humans , Infant , Infant, Newborn , Italy/epidemiology , Male , Middle Aged , Prevalence , Retrospective Studies , Seroepidemiologic Studies , Young Adult
10.
J Am Chem Soc ; 140(32): 10131-10134, 2018 08 15.
Article in English | MEDLINE | ID: mdl-30059213

ABSTRACT

Thin layers of viologen-based oligomers with thicknesses between 3 and 14 nm were deposited on gold electrodes by electrochemical reduction of a diazonium salt, and then a Ti/Au top contact was applied to complete a solid-state molecular junction (MJ). MJs show symmetric J- V curves and highly efficient long-range transport, with an attenuation factor as small as 0.25 nm-1. This is attributed both to the fact that the viologen LUMO energy lies between the energies of the Fermi levels of the two contacts and to strong electronic coupling between molecules and contacts. As a consequence, resonant tunneling is likely to be the dominant transport mechanism within these MJs, but the temperature dependence of the transport properties suggests that activated redox hopping plays a role at high temperature.

11.
J Am Chem Soc ; 139(34): 11913-11922, 2017 08 30.
Article in English | MEDLINE | ID: mdl-28780873

ABSTRACT

Thin layers of oligomers with thickness between 7 and 9 nm were deposited on flat gold electrode surfaces by electrochemical reduction of diazonium reagents, then a Ti(2 nm)/Au top contact was applied to complete a solid-state molecular junction. The molecular layers investigated included donor molecules with relatively high energy HOMO, molecules with high HOMO-LUMO gaps and acceptor molecules with low energy LUMO and terminal alkyl chain. Using an oligo(bisthienylbenzene) based layer, a molecule whose HOMO energy level in a vacuum is close to the Fermi level of the gold bottom electrode, the devices exhibit robust and highly reproducible rectification ratios above 1000 at low voltage (2.7 V). Higher current is observed when the bottom gold electrode is biased positively. When the molecular layer is based on a molecule with a high HOMO-LUMO gap, i.e., tetrafluorobenzene, no rectification is observed, while the direction of rectification is reversed if the molecular layer consists of naphtalene diimides having low LUMO energy level. Rectification persisted at low temperature (7 K), and was activationless between 7 and 100 K. The results show that rectification is induced by the asymmetric contact but is also directly affected by orbital energies of the molecular layer. A "molecular signature" on transport through layers with thicknesses above those used when direct tunneling dominates is thus clearly observed, and the rectification mechanism is discussed in terms of Fermi level pinning and electronic coupling between molecules and contacts.

12.
Proc Natl Acad Sci U S A ; 110(14): 5326-30, 2013 Apr 02.
Article in English | MEDLINE | ID: mdl-23509271

ABSTRACT

In this work, we bridge the gap between short-range tunneling in molecular junctions and activated hopping in bulk organic films, and greatly extend the distance range of charge transport in molecular electronic devices. Three distinct transport mechanisms were observed for 4.5-22-nm-thick oligo(thiophene) layers between carbon contacts, with tunneling operative when d < 8 nm, activated hopping when d > 16 nm for high temperatures and low bias, and a third mechanism consistent with field-induced ionization of highest occupied molecular orbitals or interface states to generate charge carriers when d = 8-22 nm. Transport in the 8-22-nm range is weakly temperature dependent, with a field-dependent activation barrier that becomes negligible at moderate bias. We thus report here a unique, activationless transport mechanism, operative over 8-22-nm distances without involving hopping, which severely limits carrier mobility and device lifetime in organic semiconductors. Charge transport in molecular electronic junctions can thus be effective for transport distances significantly greater than the 1-5 nm associated with quantum-mechanical tunneling.


Subject(s)
Electronics/methods , Hot Temperature , Nanotechnology/methods , Semiconductors , Carbon/chemistry , Ion Exchange , Quantum Theory
13.
Sci Data ; 11(1): 220, 2024 Feb 19.
Article in English | MEDLINE | ID: mdl-38374088

ABSTRACT

Tuberculosis (TB) is one of the deadliest infectious disorders in the world. To effectively TB manage, an essential step is to gain insight into the lineage of Mycobacterium tuberculosis (MTB) and the distribution of drug resistance. Although the Campania region is declared a cluster area for the infection, to contribute to the effort to understand TB evolution and transmission, still poorly known, we have generated a dataset of 159 genomes of MTB strains, from Campania region collected during 2018-2021, obtained from the analysis of whole genome sequence. The results show that the most frequent MTB lineage is the 4 according for 129 strains (81.11%). Regarding drug resistance, 139 strains (87.4%) were classified as multi susceptible, while the remaining 20 (12.58%) showed drug resistance. Among the drug-resistance strains, 8 were isoniazid-resistant MTB, 4 multidrug-resistant MTB, while only one was classified as pre-extensively drug-resistant MTB. This dataset expands the existing available knowledge on drug resistance and evolution of MTB, contributing to further TB-related genomics studies to improve the management of this disease.


Subject(s)
Mycobacterium tuberculosis , Tuberculosis, Multidrug-Resistant , Humans , Antitubercular Agents/pharmacology , Drug Resistance, Multiple, Bacterial/genetics , Isoniazid/pharmacology , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/genetics , Tuberculosis, Multidrug-Resistant/microbiology
14.
J Am Chem Soc ; 135(28): 10218-21, 2013 Jul 17.
Article in English | MEDLINE | ID: mdl-23805821

ABSTRACT

Quantum interference in cross-conjugated molecules embedded in solid-state devices was investigated by direct current-voltage and differential conductance transport measurements of anthraquinone (AQ)-based large area planar junctions. A thin film of AQ was grafted covalently on the junction base electrode by diazonium electroreduction, while the counter electrode was directly evaporated on top of the molecular layer. Our technique provides direct evidence of a large quantum interference effect in multiple CMOS compatible planar junctions. The quantum interference is manifested by a pronounced dip in the differential conductance close to zero voltage bias. The experimental signature is well developed at low temperature (4 K), showing a large amplitude dip with a minimum >2 orders of magnitude lower than the conductance at higher bias and is still clearly evident at room temperature. A temperature analysis of the conductance curves revealed that electron-phonon coupling is the principal decoherence mechanism causing large conductance oscillations at low temperature.


Subject(s)
Anthraquinones/chemistry , Quantum Theory , Models, Molecular , Molecular Structure
15.
ACS Nano ; 17(19): 18924-18931, 2023 Oct 10.
Article in English | MEDLINE | ID: mdl-37585336

ABSTRACT

Two-dimensional (2D) ferroelectric (FE) materials are promising compounds for next-generation nonvolatile memories due to their low energy consumption and high endurance. Among them, α-In2Se3 has drawn particular attention due to its in- and out-of-plane ferroelectricity, whose robustness has been demonstrated down to the monolayer limit. This is a relatively uncommon behavior since most bulk FE materials lose their ferroelectric character at the 2D limit due to the depolarization field. Using angle resolved photoemission spectroscopy (ARPES), we unveil another unusual 2D phenomenon appearing in 2H α-In2Se3 single crystals, the occurrence of a highly metallic two-dimensional electron gas (2DEG) at the surface of vacuum-cleaved crystals. This 2DEG exhibits two confined states, which correspond to an electron density of approximately 1013 electrons/cm2, also confirmed by thermoelectric measurements. Combination of ARPES and density functional theory (DFT) calculations reveals a direct band gap of energy equal to 1.3 ± 0.1 eV, with the bottom of the conduction band localized at the center of the Brillouin zone, just below the Fermi level. Such strong n-type doping further supports the quantum confinement of electrons and the formation of the 2DEG.

16.
J Am Chem Soc ; 134(1): 154-7, 2012 Jan 11.
Article in English | MEDLINE | ID: mdl-22148633

ABSTRACT

Molecular junctions were fabricated with the combined use of electrochemistry and conventional CMOS tools. They consist of a 5-10 nm thick layer of oligo(1-(2-bisthienyl)benzene) between two gold electrodes. The layer was grafted onto the bottom electrode using diazonium electroreduction, which yields a stable and robust gold-oligomer interface. The top contact was obtained by direct electron-beam evaporation on the molecular layers through masks defined by electron-beam lithography. Transport mechanisms across such easily p-dopable layers were investigated by analysis of current density-voltage (J-V) curves. Application of a tunneling model led to a transport parameter (thickness of ~2.4 nm) that was not consistent with the molecular thickness measured using AFM (~7 nm). Furthermore, for these layers with thicknesses of 5-10 nm, asymmetric J-V curves were observed, with current flowing more easily when the grafted electrode was positively polarized. In addition, J-V experiments at two temperatures (4 and 300 K) showed that thermal activation occurs for such polarization but is not observed when the bias is reversed. These results indicate that simple tunneling cannot describe the charge transport in these junctions. Finally, analysis of the experimental results in term of "organic electrode" and redox chemistry in the material is discussed.

17.
Pathogens ; 11(11)2022 Oct 28.
Article in English | MEDLINE | ID: mdl-36365001

ABSTRACT

Bacterial co-infection in COVID-19 patients significantly contributes to the worsening of the prognosis based on morbidity and mortality. Information on the co-infection profile in such patients could help to optimize treatment. The purpose of this study was to describe bacterial co-infections associated with microbiological, clinical, and laboratory data to reduce or avoid a secondary infection. A retrospective cohort study was conducted at Sant'Anna and San Sebastiano Hospital from January 2020 to December 2021. Bacterial co-infection was detected in 14.3% of the COVID-19-positive patients. The laboratory findings on admission showed significant alterations in the median D-dimer, C-reactive protein, interleukin-6, and lactate dehydrogenase values compared to normal values. All inflammatory markers were significantly elevated. The most common pathogens isolated from blood cultures were E. faecalis and S. aureus. Instead, the high prevalence of respiratory tract infections in the COVID-19 patients was caused by P. aeruginosa (41%). In our study, 220 (82.4%) of the COVID-19 patients received antimicrobial treatment. Aminoglycosides and ß-lactams/ß-lactamase inhibitors showed the highest resistance rates. Our results showed that older age, underlying conditions, and abnormal laboratory parameters can be risk factors for co-infection in COVID-19 patients. The antibiotic susceptibility profile of bacterial pathogen infection provides evidence on the importance, for the clinicians, to rationalize and individualize antibiotic usage.

18.
Sci Rep ; 12(1): 19216, 2022 Nov 10.
Article in English | MEDLINE | ID: mdl-36357414

ABSTRACT

A standard experimental setup for Inelastic Electron Tunneling Spectroscopy (IETS) performs the measurement of the second derivative of the current with respect to the voltage ([Formula: see text]) using a small AC signal and a lock-in based second harmonic detection. This avoids noise arising from direct differentiation of the current-voltage characteristics (I-V) by standard numerical methods. Here we demonstrate a noise-filtering algorithm based on Tikhonov Regularization to obtain IET spectra (i.e. [Formula: see text] vs. V) from measured DC I-V curves. This leads to a simple and effective numerical method for IETS extraction. We apply the algorithm to I-V data from a molecular junction and a metal-insulator-semiconductor tunneling device, demonstrating that the computed first/second derivatives have a workable match with those obtained from our lock-in measurements; the computed IET spectral peaks also correlate well with reported experimental ones. Finally, we present a scheme for automated tuning of the algorithm parameters well-suited for the use of this numerical protocol in real applications.

19.
Nanoscale ; 14(35): 12692-12702, 2022 Sep 15.
Article in English | MEDLINE | ID: mdl-35993375

ABSTRACT

We present a bias-controlled spin-filtering mechanism in spin-valves including a hybrid organic chain/graphene interface. Wet growth conditions of oligomeric molecular chains would usually lead, during standard CMOS-compatible fabrication processes, to the quenching of spintronics properties of metallic spin sources due to oxidation. We demonstrate by X-ray photoelectron spectroscopy that the use of a protective graphene layer fully preserves the metallic character of the ferromagnetic surface and thus its capability to deliver spin polarized currents. We focus here on a small aromatic chain of controllable lengths, formed by nitrobenzene monomers and derived from the commercial 4-nitrobenzene diazonium tetrafluoroborate, covalently attached to the graphene passivated spin sources thanks to electroreduction. A unique bias dependent switch of the spin signal is then observed in complete spin valve devices, from minority to majority spin carriers filtering. First-principles calculations are used to highlight the key role played by the spin-dependent hybridization of electronic states present at the different interfaces. Our work is a first step towards the exploration of spin transport using different functional molecular chains. It opens the perspective of atomic tailoring of magnetic junction devices towards spin and quantum transport control, thanks to the flexibility of ambient electrochemical surface functionalization processes.

20.
Antibiotics (Basel) ; 10(5)2021 May 03.
Article in English | MEDLINE | ID: mdl-34063711

ABSTRACT

Ocular bacterial infections represent a serious problem that affecting people of all age and genders. These infections can lead to visual impairment and blindness if not properly treated. The current study evaluates the antimicrobial resistance profiles and the resistance trend of both Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CoNS), the main pathogens involved in eye infections. A total of 322 isolates of S. aureus and CoNS, were collected from patients with bacterial conjunctivitis and keratitis at the "Luigi Vanvitelli" University Hospital of Campania in Naples, Italy, between 2017 and 2020. The isolated bacteria showed a high percentage of resistance to methicillin and other antibiotics commonly used for the treatment of ocular infections. Trends in antibiotic resistance were not encouraging, recording-especially among CoNS strains-an increase of more than 20% in resistance to methicillin and aminoglycosides during the study period. Instead, the resistance rates to tetracycline had a significant decrease in CoNS isolates while no changes in their susceptibility to fluoroquinolones and macrolides were observed. However, all isolates showed no resistance to trimethoprim/sulfamethoxazole and chloramphenicol. In this scenario, preventive identification of the infection causative agents and the evaluation of the antimicrobial susceptibility patterns are essential to set up an ocular infection effective drug treatment and also prevent antibiotic resistance.

SELECTION OF CITATIONS
SEARCH DETAIL