The new method of ZnIn2S4 synthesis on the titania nanotubes substrate with enhanced stability and photoelectrochemical performance.

In this work, ZnIn2S4 layers were obtained on fluorine doped tin oxide (FTO) glass and TiO2 nanotubes (TiO2NT) using a hydrothermal process as photoanodes for photoelectrochemical (PEC) water splitting. Then, samples were annealed and the effect of the annealing temperature was investigated. Optimization of the deposition process and annealing of ZnIn2S4 layers made it possible to obtain an FTO-based material generating a photocurrent of 1.2 mA cm-2 at 1.62 V vs. RHE in a neutral medium. In contrast, the highest photocurrent in the neutral electrolyte obtained for the TiO2NT-based photoanode reached 0.5 mA cm-2 at 1.62 V vs. RHE. In addition, the use of a strongly acidic electrolyte allowed the generated photocurrent by the TiO2NT-based photoanode to increase to 3.02 mA cm-2 at 0.31 V vs. RHE. Despite a weaker photoresponse in neutral electrolyte than the optimized FTO-based photoanode, the use of TiO2NT as a substrate allowed for a significant increase in the photoanode's operating time. After 2 h of illumination, the photocurrent response of the TiO2NT-based photoanode was 0.21 mA cm-2, which was 42% of the initial value. In contrast, the FTO-based photoanode after the same time generated a photocurrent of 0.02 mA cm-2 which was only 1% of the initial value. The results indicated that the use of TiO2 nanotubes as a substrate for ZnIn2S4 deposition increases the photoanode's long-term stability in photoelectrochemical water splitting. The proposed charge transfer mechanism suggested that the heterojunction between ZnIn2S4 and TiO2 played an important role in improving the stability of the material by supporting charge separation.

New light on the photocatalytic performance of NH4V4O10 and its composite with rGO.

Solar-driven photocatalysis has shown great potential as a sustainable wastewater treatment technology that utilizes clean solar energy for pollutant degradation. Consequently, much attention is being paid to the development of new, efficient and low-cost photocatalyst materials. In this study, we report the photocatalytic activity of NH4V4O10 (NVO) and its composite with rGO (NVO/rGO). Samples were synthesized via a facile one-pot hydrothermal method and successfully characterized using XRD, FTIR, Raman, XPS, XAS, TG-MS, SEM, TEM, N2 adsorption, PL and UV‒vis DRS. The results indicate that the obtained NVO and NVO/rGO photocatalysts exhibited efficient absorption in the visible wavelength region, a high content of V4+ surface species and a well-developed surface area. Such features resulted in excellent performance in methylene blue photodegradation under simulated solar light illumination. In addition, the composite of NH4V4O10 with rGO accelerates the photooxidation of the dye and is beneficial for photocatalyst reusability. Moreover, it was shown that the NVO/rGO composite can be successfully used not only for the photooxidation of organic pollution but also for the photoreduction of inorganic pollutants such as Cr(VI). Finally, an active species trapping experiment was conducted, and the photodegradation mechanism was discussed.

Examining the Distribution and Impact of Single-Nucleotide Polymorphisms in the Capsular Locus of Streptococcus pneumoniae Serotype 19A.

Streptococcus pneumoniae serotype 19A prevalence has increased after the implementation of the PCV7 and PCV10 vaccines. In this study, we have provided, with high accuracy, the genetic diversity of the 19A serotype in a cohort of Dutch invasive pneumococcal disease patients and asymptomatic carriers obtained in the period from 2004 to 2016. The whole genomes of the 338 pneumococcal isolates in this cohort were sequenced and their capsule (cps) loci compared to examine their diversity and determine the impact on the production of capsular polysaccharide (CPS) sugar precursors and CPS shedding. We discovered 79 types with a unique cps locus sequence. Most variation was observed in the rmlB and rmlD genes of the TDP-Rha synthesis pathway and in the wzg gene, which is of unknown function. Interestingly, gene variation in the cps locus was conserved in multiple alleles. Using RmlB and RmlD protein models, we predict that enzymatic function is not affected by the single-nucleotide polymorphisms as identified. To determine if RmlB and RmlD function was affected, we analyzed nucleotide sugar levels using ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS). CPS precursors differed between 19A cps locus subtypes, including TDP-Rha, but no clear correlation was observed. Also, significant differences in multiple nucleotide sugar levels were observed between phylogenetically branched groups. Because of indications of a role for Wzg in capsule shedding, we analyzed if this was affected. No clear indication of a direct role in shedding was found. We thus describe genotypic variety in rmlB, rmlD, and wzg in serotype 19A in the Netherlands, for which we have not discovered an associated phenotype.

Nano Tin/Tin Oxide Attached onto Graphene Oxide Skeleton as a Fluorine Free Anode Material for Lithium-Ion Batteries.

Herein, we show a composite formation method of tin/tin oxide nanoparticles with graphene oxide and CMC based on laser ablation technique as an electrode material for energy storage devices. The material exhibited a three-dimensional conducting graphene oxide network decorated with tin or tin oxide nanoparticles. The structure, homogeneous distribution of nanoparticles, and direct contact between inorganic and organic parts were confirmed by scanning electron microscopy and high-resolution transmission electron spectroscopy. Electrochemical performances of composite electrode material showed a reversible capacity of 644 mAh/g at a current density equal to 35 mA/g, and 424 mAh/g at 140 mA/g. The capacity retention of 90% after 250 cycles show that tested electrode material is suitable as a negative electrode for lithium-ion batteries.

The role of complement in innate and adaptive immunity to pneumococcal colonization and sepsis in a murine model.

Streptococcus pneumoniae is an important bacterial cause of sepsis, meningitis, pneumonia and otitis media. Pneumococcal disease is generally preceded by mucosal colonization with the homologous strain; hence, resistance to colonization may be an important aspect of resistance to disease. In humans, complement deficiency is a risk factor for the development of pneumococcal disease. Although many studies have shown protective effects of complement during pneumonia and meningitis, there have been no studies reported that evaluate the role of complement in containment of pneumococcal colonization. To this end, we studied the role of complement in preventing the progression of pneumococcal mucosal colonization to sepsis in a mouse model. Sepsis developed in 60% of complement-depleted mice following intranasal pneumococcal challenge, but not in control or neutrophil-depleted mice. Colonization density in the nasopharynx and local mucosal tissue was similar between complement-depleted and control mice before onset of sepsis. Immunization of complement-depleted mice with an intranasally administered whole cell pneumococcal vaccine (WCV) reduced progression towards sepsis and protected surviving mice against colonization comparably to complement-sufficient mice. We therefore conclude that complement prevents sepsis following pneumococcal colonization in a neutrophil-independent fashion, but and WCV-induced adaptive immunity is complement-independent.

Genetic diversity of the tet(M) gene in tetracycline-resistant clonal lineages of Streptococcus pneumoniae.

The aim of the present study was to examine the stability and evolution of tet(M)-mediated resistance to tetracyclines among members of different clonal lineages of Streptococcus pneumoniae. Thirty-two tetracycline-resistant isolates representing three national (Spanish serotype 14, Spanish serotype 15, and Polish serotype 23F) and one international (Spanish serotype 23F) multidrug-resistant epidemic clones were all found to be tet(M) positive and tet(O), tet(K), and tet(L) negative. These isolates all carried the integrase gene, int, which is associated with the Tn1545-Tn916 family of conjugative transposons. High-resolution restriction analysis of tet(M) products identified six alleles, tet(M)1 to tet(M)6: tet(M)1 to tet(M)3 and tet(M)5 in isolates of the Spanish serotype 14 clone, tet(M)4 in both the Spanish serotype 15 and 23F clones, and tet(M)6, the most divergent allele, in the Polish 23F clone. This indicates that tet(M) variation can occur at the inter- and intraclone levels in pneumococci. Two alleles of int were identified, with int1 being found in all isolates apart from members of the international Spanish 23F clone, which carried int2. Susceptibility to tetracycline, doxycycline, and minocycline was evaluated for all isolates with or without preincubation in the presence of subinhibitory concentrations of tetracyclines. Resistance to tetracyclines was found to be inducible in isolates of all clones; however, the strongest induction was observed in the Spanish serotype 15 and 23F clones carrying tet(M)4. Tetracycline was found to be the strongest inducer of resistance, and minocycline was found to be the weakest inducer of resistance.

Expression of resistance to tetracyclines in strains of methicillin-resistant Staphylococcus aureus.

A diverse collection of methicillin-resistant Staphylococcus aureus (MRSA) isolates resistant to tetracycline was screened by PCR for the presence of the resistance determinants tetK, tetL, tetM or tetO. Twenty-four of 66 isolates had tetM alone, 21 had tetK alone and 21 had both tetK and tetM (tetKM). All isolates were tetL- and tetO-negative. MICs of tetracycline, doxycycline and minocycline were evaluated for all isolates with or without preincubation in the presence of subinhibitory concentrations of tetracycline or minocycline. All isolates with one or more tetracycline resistance determinants were resistant to tetracycline 8 mg/L without induction of resistance. Some MRSA isolates of each of these three genotypes showed an unexpected lack of resistance to tetracyclines when the disc diffusion or agar dilution method was applied to uninduced cells. Resistance to tetracycline and doxycycline was greater (two- to four-fold) in tetK cells preincubated with tetracycline (tetK MRSA isolates were susceptible to minocycline

[Methicillin resistant clinical strains of Staphylococcus aureus isolated from patients in the State Clinical Hospital Nr 2 in Szczecin]. / Oporne na metycyline szczepy Staphylococcus aureus izolowane od chorych w Panstwowym Szpitalu Klinicznym Nr 2 w Szczecinie.

Over a fivefold increase, from 11% to 58%, in the prevalence of methicillin-resistance was observed in 1994-95 amongst clinical isolates of Staphylococcus aureus in the State Clinical Hospital No 2 in Szczecin, one of the largest hospitals in the West Pomeranian region of Poland. The aim of this study was to see if any one particular strain was responsible for this apparent outbreak. Fifty-six randomly selected isolates were typed by SmaI macrorestriction analysis using PFGE and by analysis of antimicrobial susceptibility patterns. Results indicate the presence of two epidemic multi-drug resistant MRSA strains. Over 85% of typed MRSA belonged to the first strain, which was probably present in the hospital long before 1994. MRSA of this strain were isolated from patients in 8 hospital wards. The second strain was introduced into two wards of the hospital in the last year of the study.

Outbreak of mupirocin-resistant staphylococci in a hospital in Warsaw, Poland, due to plasmid transmission and clonal spread of several strains.

An outbreak of mupirocin-resistant (MuR) staphylococci was investigated in two wards of a large hospital in Warsaw, Poland. Fifty-three MuR isolates of Staphylococcus aureus, S. epidermidis, S. haemolyticus, S. xylosus, and S. capitis were identified over a 17-month survey which was carried out after introduction of the drug for the treatment of skin infections. The isolates were collected from patients with infections, environmental samples, and carriers; they constituted 19.5% of all staphylococcal isolates identified in the two wards during that time. Almost all the MuR isolates were also resistant to methicillin (methicillin-resistant S. aureus and methicillin-resistant coagulase-negative staphylococci). Seven of the outbreak isolates expressed a low-level-resistance phenotype (MuL), whereas the remaining majority of isolates were found to be highly resistant to mupirocin (MuH). The mupA gene, responsible for the MuH phenotype, has been assigned to three different polymorphic loci among the strains in the collection analyzed. The predominant polymorph, polymorph I (characterized by a mupA-containing EcoRI DNA fragment of about 16 kb), was located on a specific plasmid which was widely distributed among the entire staphylococcal population. All MuR S. aureus isolates were found to represent a single epidemic strain, which was clonally disseminated in both wards. The S. epidermidis population was much more diverse; however, at least four clusters of closely related isolates were identified, which suggested that some strains of this species were also clonally spread in the hospital environment. Six isolates of S. epidermidis were demonstrated to express the MuL and MuH resistance mechanisms simultaneously, and this is the first identification of such dual MuR phenotype-bearing strains. The outbreak was attributed to a high level and inappropriate use of mupirocin, and as a result the dermatological formulation of the drug has been removed from the hospital formulary.

Multidrug-resistant Streptococcus pneumoniae in Poland: identification of emerging clones.

Penicillin resistance among Streptococcus pneumoniae isolates has rapidly emerged in Poland during the last decade and has reached prevalence levels of up to 14.4% in 1997. In order to investigate the nature of this increase, a molecular epidemiological analysis of non-penicillin-susceptible multidrug-resistant pneumococci isolated in 1995 and 1996 was conducted. Thirty-seven patients who suffered mainly from upper respiratory tract infections and pneumococcal pneumonia were enrolled in this study. The medical centers to which the patients were admitted were located in 16 Polish towns across the country. Eight distinct BOX PCR types were observed, representing 14 subtypes. Restriction fragment end labeling (RFEL) analysis divided the pneumococcal strains into 16 distinct types. By combining the BOX PCR and RFEL data, four genetically distinct clusters of strains were identified. Two clusters represented the genetic clones 23F and 9V, which have recently emerged all over the world. The two other genetic clusters, which represented serotypes 23F and 6B, clearly predominated in the analyzed collection of Polish non-penicillin-susceptible pneumococcal strains. Since the latter clusters did not match any of the 133 RFEL types of non-penicillin-susceptible pneumococci collected in 15 other countries, their Polish clonal origin is most likely.

Clonal distribution of methicillin-resistant Staphylococcus aureus in Poland.

We report on a study of 158 methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates obtained from 1990 to 1996 in 18 different hospitals in Poland. All isolates were recovered from infection and carriage sites of patients, carriage sites of health care personnel, and hospital environment samples. Fifty-seven MRSA strains described here were studied previously and these were divided into two different clusters according to the degree of heterogeneity of methicillin resistance expression. The aim of this study was to extend the correlation between the two clusters and identify the clonal identities among all isolates by a combination of different methodologies: (i) analysis of mecA polymorphs and Tn554 insertion patterns and (ii) determination of pulsed-field gel electrophoresis patterns of chromosomal SmaI digests. Ninety-seven of 158 strains showed a heterogeneous expression of resistance to methicillin. Among these, 75 (77.3%) were ClaI-mecA type I, ClaI-Tn554 type NH (NH, no homology with transposon Tn554), and pulsed-field gel electrophoresis (PFGE) pattern A (I::NH::A); 10 isolates were III::B::M (10.3%); and the remaining clones included a few or single isolates. The isolates with homogeneous expression of resistance to methicillin (n = 61) were predominantly ClaI-mecA type III (49 of 61 [80.3%]) but had great variability in their ClaI-Tn554 and PFGE patterns. This study confirmed the existence of two main clusters of MRSA in Poland.

Use of glycopyrrolate and other anticholinergic medications for sialorrhea in children with cerebral palsy.

Fifty-four parents/caretakers of children with cerebral palsy were surveyed regarding their use of antisialorrheic medication for excessive drooling. Glycopyrrolate was used by 37 of 41 respondents, with significant improvement in drooling noted in the vast majority (95%) of cases as indicated by a five-point rating scale. Side effects (dry mouth, thick secretions, urinary retention, or flushing) surfaced in almost half (44%) of the patients but necessitated discontinuation of pharmacologic treatment in less than a third. While larger clinical studies are needed, our preliminary data indicate a trial of glycopyrrolate should be considered in children with cerebral palsy where drooling is a significant problem.

Comparison of genetic characteristics of MRSA strains present in a Warsaw hospital in 1992 and 1996.

Nine isolates of methicillin-resistant Staphylococcus aureus (MRSA) collected in a Warsaw hospital in 1996 were typed by phenotypic (resistograms) and genotypic (PFGE and plasmid restriction analysis-REAP) methods. Twenty-four (MRSA) strains collected in this hospital during a period of the same duration in 1992 and typed earlier using resistograms and PFGE were also typed by REAP. Comparison of typing results obtained for isolates from 1992 and 1996 showed that strains characterised by PFGE patterns of two distinct types described as specific of the two clonally related groups of Polish MRSA in a multicentre study in 1992 are continuously present in the hospital. However, MRSA strains representing PFGE patterns not observed before were also found within the collection from 1996. REAP typing has proved to have a discriminatory power similar to that of PFGE analysis. Nevertheless, due to the lack of plasmids or difficulties in plasmid DNA isolation in 3 out of 33 studied strains, the typability of REAP turned out to be lower than that of PFGE.

[The use of molecular biology in the modeling of Pseudomonas aeruginosa strains recovered from nosocomial infections]. / Zastosowanie metod biologii molekularnej do typowania szczepów Pseudomonas aeruginosa izolowanych z zakazen szpitalnych.

Different methods of molecular typing (ribotyping, genomic DNA RFLP and RAPD) were tested on Pseudomonas aeruginosa strains isolated in Polish hospitals in order to elaborate a reliable typing scheme for epidemiological investigations. The combined RAPD analysis with the use of two different primers, RAPD-4 and RAPD-7, was found to have the highest discriminatory power which considering also the easiness and low time-consumption has suggested its high usefulness in studies of outbreaks caused by P. aeruginosa. Ribotyping was shown to be the least discriminatory, however, especially with the use of the PvuII restriction enzyme, this method can be very useful in revealing the genetic structure of P. aeruginosa populations persisting in hospital environments over longer periods. Clonal relations within populations of strains isolated in four different hospitals were revealed. In two of the hospitals P. aeruginosa populations demonstrated a very high diversity which suggested that infections had been caused by strains of different origins, probably introduced from other environments. P. aeruginosa strains from two remaining hospitals were found to form some clonally related clusters what revealed that in these hospitals epidemic strains of this microorganism have been circulating for prolonged periods and infecting predisposed patients.

[Susceptibility of Pseudomonas aeruginosa isolated from hospital infections to antibiotics]. / Wrazliwosc na leki szczepów pseudomonas aeruginosa izolowanych z zakazen szpitalnych.

A total of 674 clinical isolates of Pseudomonas aeruginosa were collected from 30 different hospitals located in 26 cities of Poland. These were 12 big regional hospitals, 7 large teaching hospitals, 4 specialised hospitals curing patients from the whole country, 6 small local hospitals and one regional paediatric hospital. The majority of strains were collected from patients hospitalised at ICUs (25.7%), surgical (21.7%), and internal medicine wards (9.9%). The isolates were recovered from different types of infections, mostly from respiratory tract infections (33.7%), wound infections (22.3%), and urinary tract infections (22.0%). All the isolates were subjected to antimicrobial susceptibility testing by MIC values evaluation. MICs of 13 different antibiotics (beta-lactams, aminoglycosides, chinolones) were determined by the agar dilution method. The general level of resistance of P.aeruginosa observed in the study was high, especially when compared to results of surveys obtained in other countries. Out of the antimicrobials used the highest activity in vitro was observed with meropenem, imipenem, piperacillin--tazobactam and ceftazidime. The high in vitro activity of ceftazidime was striking considering the long time of the use of this antibiotic in Polish hospitals. The highest levels of resistance were observed to some of the aminoglycosides. Populations of strains isolated in different wards or hospitals of different size were characterised by different susceptibility patterns.

Simultaneous persistence of methicillin-resistant and methicillin-susceptible clones of Staphylococcus aureus in a neonatal ward of a Warsaw hospital.

Fifty-seven methicillin-resistant Staphylococcus aureus (MRSA) isolates from babies (N = 31), carriers amongst health care workers (N = 16; 10% of all staff members) and the environment (N = 10); 39 MSSA isolates, from babies (N = 18), health care workers (N = 5) and environment (N = 16) were analysed. The strains were from the neonatal ward of a teaching hospital in Warsaw and were collected over a period of 16 months (1993/1994). The isolates were characterized by phage-typing, arbitrary-primed polymerase chain reaction (AP PCR), DNA repeat polymorphism within the protein A gene and the resistance pattern to antimicrobial agents. The presence of the mecA gene was determined by PCR. MRSA were classified as heterogeneously resistant to methicillin, susceptible to other antimicrobial agents and, except for three isolates, appeared to be genotypically almost identical. The first example of mupirocin resistant MRSA in Poland was documented. Amongst MSSA isolates, increased variability was seen, however, the persistence of one predominate clone of MSSA was shown. In this particular hospital environment, several different strains of both MRSA and MSSA were capable of maintaining persistent colonization.

Phenotyping methods in epidemiological analysis of epidemic Staphylococcus aureus strains.

One hundred and fifty hospital Staphylococcus aureus strains isolated on Polish hospitals during an outbreaks were used to evaluate usefulness of S. aureus phenotyping methods. According to the expression of resistance to methicillin (a marker of resistance to all beta-lactam antibiotics) all strains were classified as homogeneously of heterogeneously resistant to methicillin (methicillin resistant S. aureus--MRSA) and as susceptible to this antibiotic (methicillin-susceptible S. aureus--MSSA). All strains were analysed according to the resistance patterns to fifteen antistaphylococcal drugs, results of crystal violet test, phage patterns and results of biochemical fingerprinting by PhenePlate (PhP) System (BioSys inova). All MSSA analysed were resistant to penicillin and 22% to tetracycline, and only occasionally resistant to other antimicrobials. They showed sensitive to phages of all international and additional lytic groups. Heterogeneous MRSA were widely susceptible to almost all antimicrobials except tetracycline and were lysed by phages of Ist, IIIrd international groups and additional phages. All these strains produced penicillinases. Homogeneous MRSA were multi-drug resistant and were not typable by phages of Ist and IInd lytic groups and weakly typable by phages of IIIrd and additional groups. PhP Systems divided all used strains into 13 common (with two dominating) and 50 single strain PhP-types. The combination of various phenotyping methods may be useful in epidemiological investigation of hospitals.

Characterization of two different clusters of clonally related methicillin-resistant Staphylococcus aureus strains by conventional and molecular typing.

The DNA fragments of 28 distinct isolates of methicillin-resistant Staphylococcus aureus (MRSA) originating from different hospitals in Warsaw and Lodz, were studied. They were obtained by cleavage with restriction endonuclease SmaI and subsequently analysed by pulsed-field electrophoresis. Sixteen different patterns were seen and clusters of related strains were clearly distinguishable. Minor differences in fragment patterns within these clusters and among epidemiologically related strains, revealed genomic rearrangements in the course of clonal dissemination of particular strains. The isolates were also checked for the expression of methicillin resistance. Isolates with heterogenous and homogeneous phenotypes, fell into clearly distinct clusters and thus formed two clonally related MRSA strains. Differences were also seen with phage and biochemical typing, and antimicrobial resistance patterns.