Magnetoelectric Properties of Multiferroic Composites Based on BaTiO3 and Nickel-Zinc Ferrite Material

The purpose of the present study was to learn the morphological, structural, ferroelectric, dielectric, electromechanical, magnetoelectric, and magnetic properties, and DC conductivity of BaTiO3-Ni0.64Zn0.36Fe2O4 (BT-F) multiferroic composites compacted via the free sintering method. The influence of the ferrite content in ceramic composite materials on the functional properties is investigated and discussed. X-ray diffraction studies confirmed the presence of two main phases of the composite, with strong reflections originating from BaTiO3 and weak peaks originating from nickel-zinc ferrite. BT-F ceramic composites have been shown to exhibit multiferroism at room temperature. All studied compositions have high permittivity values and low dielectric loss, while the ferroelectric properties of the BT component are maintained at a high level. On the other hand, magnetic properties depend on the amount of the ferrite phase and are the strongest for the composition with 15 wt.% of F (magnetization at RT is 4.12 emu/g). The magnetoelectric coupling between BT and F phases confirmed by the lock-in technique is the largest for 15 wt.% ferrite. In the present work, the process conditions of the free sintering method for obtaining BT-F multiferroic composite with good electrical and magnetic properties (in one material) were optimized. An improved set of multifunctional properties allows the expansion of the possibilities of using multiferroic composites in microelectronics.

Extreme Case of Surgical Port Metastasis in Ovarian Cancer

Ovarian cancer accounts for more deaths than any other malignancy of the female reproductive system. Early diagnosis of this disease is difficult because there are no systematic opportunistic screening methods. At advanced stages, diagnostic laparoscopy is the first step in confirming disease advancement and obtaining samples for genetic and pathologic examination needed to start chemotherapy. Swiftly starting oncological treatment is crucial for increasing the survival rate in these patients. We present the case of a 51-year-old woman with metastatic International Federation of Gynecology and Obstetrics (FIGO) stage IIIC ovarian cancer who had delayed her therapy after initial laparoscopy due to COVID-19 infection and presented with an extreme case of surgical port metastasis.

Electric and Magnetic Properties of the Multiferroic Composites Made Based on Pb(Fe1/2Nb1/2)1-xMnxO3 and the Nickel-Zinc Ferrite

This work presents the electrophysical properties of the multiferroic ceramic composites obtained as a result of combining both magnetic and ferroelectric material. The ferroelectric components of the composite are materials with the following chemical formulas: PbFe_0.5Nb_0.5O₃ (PFN), Pb(Fe_0.495Nb_0.495Mn_0.01)O₃ (PFNM₁), and Pb(Fe_0.49Nb_0.49Mn_0.02)O₃ (PFNM₂), while the magnetic component of the composite is the nickel-zinc ferrite (Ni_0.64Zn_0.36Fe₂O₄ marked as F). The crystal structure, microstructure, DC electric conductivity, and ferroelectric, dielectric, magnetic, and piezoelectric properties of the multiferroic composites are performed. The conducted tests confirm that the composite samples have good dielectric and magnetic properties at room temperature. Multiferroic ceramic composites have a two-phase crystal structure (ferroelectric from a tetragonal system and magnetic from a spinel structure) without a foreign phase. Composites with an admixture of manganese have a better set of functional parameters. The manganese admixture increases the microstructure's homogeneity, improves the magnetic properties, and reduces the electrical conductivity of composite samples. On the other hand, in the case of electric permittivity, a decrease in the maximum values of ε_m is observed with an increase in the amount of manganese in the ferroelectric component of composite compositions. However, the dielectric dispersion at high temperatures (associated with high conductivity) disappears.

The Effect of Postprocessing on the Fatigue Properties of Ti-5Al-5Mo-5V-1Cr-1Fe Produced Using Electron Beam Melting

Despite the significant potential advantages of processing Ti-5Al-5Mo-5V-1Cr-1Fe alloy (Ti-55511) using Electron Beam Melting (PBF-EB/M), when compared to conventional manufacturing technologies, the resulting internal defects are an important characteristic of such additive technologies and can highly decrease mechanical properties. One of the most dangerous defects formed during metal additive manufacturing processes are material discontinuities such as a lack of fusion. Defects of this type, due to their "flat" nature, are difficult to characterize. For cycle-loaded specimens, where the loading force acts perpendicular to the lack-of-fusion plane, defects of this type can significantly reduce fatigue properties. This paper presents the results of research aimed at improving the fatigue properties of Ti55511 alloy by reducing the influence of the lack-of-fusion defect on fatigue damage. The static and fatigue properties of specimens in the as-built state, as well as after hot isostatic pressing (HIP) treatment, were analyzed. The effect of HIP on both the reduction of pores and the degree of sphericity when using the X-ray computed tomography (XCT) system was presented. The change in the microstructure after HIP was analyzed in terms of the change in the size of individual phases, as well as the change in the phase ratio. This paper also contains a fractographic analysis of the samples after tensile and fatigue tests.

Influence of the AlSi7Mg0.6 Aluminium Alloy Powder Reuse on the Quality and Mechanical Properties of LPBF Samples

Additive manufacturing (AM) is dynamically developing and finding applications in different industries. The quality of input material is a part of the process and of the final product quality. That is why understanding the influence of powder reuse on the properties of bulk specimens is crucial for ensuring the repeatable AM process chain. The presented study investigated the possibility of continuous reuse of AlSi7Mg0.6 powder in the laser powder bed fusion process (LPBF). To date, there is no study of AlSi7Mg0.6 powder reuse in the LPBF process to be found in the literature. This study aims to respond to this gap. The five batches of AlSi7Mg0.6 powder and five bulk LPBF samples series were characterised using different techniques. The following characteristics of powders were analysed: the powder size distribution (PSD), the morphology (scanning electron microscopy—SEM), the flowability (rotating drum analysis), and laser light absorption (spectrophotometry). Bulk samples were characterised for microstructure (SEM), chemical composition (X-ray fluorescence spectrometry—XRF), porosity (computed tomography—CT) and mechanical properties (tensile, hardness). The powder was reused in subsequent processes without adding (recycling/rejuvenation) virgin powder (collective ageing powder reuse strategy). All tested powders (powders P0–P4) and bulk samples (series S0–S3) show repeatable properties, with changes observed within error limits. Samples manufactured within the fifth reuse cycle (series S4) showed some mean value changes of measured characteristics indicating initial degradation. However, these changes also mostly fit within error limits. Therefore, the collective ageing powder reuse strategy is considered to give repeatable LPBF process results and is recommended for the AlSi7Mg0.6 alloy within at least five consecutive LPBF processes.

Interatomic Potential for InP

Classical modeling of structural phenomena occurring in InP crystal, for example plastic deformation caused by contact force, requires an interatomic interaction potential that correctly describes not only the elastic properties of indium phosphide but also the pressure-induced reversible phase transition B3↔B1. In this article, a new parametrization of the analytical bond-order potential has been developed for InP. The potential reproduces fundamental physical properties (lattice parameters, cohesive energy, stiffness coefficients) of the B3 and B1 phases in good agreement with first-principles calculations. The proposed interaction model describes the reversibility of the pressure-induced B3↔B1 phase transition as well as the formation of native point defects in the B3 phase.

Influence of Dissolving Fe-Nb-B-Dy Alloys in Zirconium on Phase Structure, Microstructure and Magnetic Properties

This paper refers to the structural and magnetic properties of [(Fe₈₀Nb₆B₁₄)_0.88Dy_0.12]_1-xZr_x (x = 0; 0.01; 0.02; 0.05; 0.1; 0.2; 0.3; 0.5) alloys obtained by the vacuum mold suction casting method. The analysis of the phase contribution indicated a change in the compositions of the alloys. For x < 0.05, occurrence of the dominant Dy₂Fe₁₄B phase was observed, while a further increase in the Zr content led to the increasing contribution of the Fe-Zr compounds and, simultaneously, separation of crystalline Dy. The dilution of (Fe₈₀Nb₆B₁₄)_0.88Dy_0.12 in Zr strongly influenced the magnetization processes of the examined alloys. Generally, with the increasing x parameter, we observed a decrease in coercivity; however, the unexpected increase in magnetic saturation and remanence for x = 0.2 and x = 0.3 was shown and discussed.

The Effect of Pore Size Distribution and l-Lysine Modified Apatite Whiskers (HAP) on Osteoblasts Response in PLLA/HAP Foam Scaffolds Obtained in the Thermally Induced Phase Separation Process

In this research, we prepared foam scaffolds based on poly(l-lactide) (PLLA) and apatite whiskers (HAP) using thermally induced phase separation technique supported by the salt leaching process (TIPS-SL). Using sodium chloride having a size of (a) 150-315 μm, (b) 315-400 μm, and (c) 500-600 μm, three types of foams with different pore sizes have been obtained. Internal structure of the obtained materials has been investigated using SEM as well as μCT. The materials have been studied by means of porosity, density, and compression tests. As the most promising, the composite prepared with salt size of 500-600 μm was prepared also with the l-lysine modified apatite. The osteoblast hFOB 1.19 cell response for the scaffolds was also investigated by means of cell viability, proliferation, adhesion/penetration, and biomineralization. Direct contact cytotoxicity assay showed the cytocompatibility of the scaffolds. All types of foam scaffolds containing HAP whiskers, regardless the pore size or l-lysine modification induced significant stimulatory effect on the cal-cium deposits formation in osteoblasts. The PLLA/HAP scaffolds modified with l-lysine stimulated hFOB 1.19 osteoblasts proliferation. Compared to the scaffolds with smaller pores (150-315 µm and 315-400 µm), the PLLA/HAP foams with large pores (500-600 µm) promoted more effective ad-hesion of osteoblasts to the surface of the biomaterial.

Multidrug-Resistant Micro-Organisms Associated with Urinary Tract Infections in Orthopedic Patients: A Retrospective Laboratory-Based Study

Background: The risk of healthcare-associated infections (HAIs) in surgical wards remains closely related to the type of surgery and procedures performed on patients. Those factors also condition the risk of various forms of clinical infections, especially urinary tract infections (UTIs). UTIs are most frequently (70–80% of cases) caused by the use of bladder catheter in the perioperative period. The aim of this study was to perform an epidemiological and microbiological analysis of UTIs in orthopedic patients, with an emphasis on multidrug-resistant (MDR) micro-organisms. Methods: The study was conducted in a 38-bed Department of Orthopedic-Traumatic Surgery in Sosnowiec, Poland. 5239 patients, operated on in 2013–2015, were included in the study. The urinary catheter use rate was 30.7%. Laboratory-based study used the UTI definition of the HAI-Net program. A micro-organism was declared MDR if it was resistant to at least one antibiotic from three or more groups of antibacterial drugs, and extensively drug-resistant (XDR) if it was sensitive to antibiotics from no more than two groups of drugs. Results: The UTI incidence was 3.2% (168 cases), the CA-UTI incidence density was 9.6/1000 catheter days. The highest risk of UTI was found in patients aged 75 or older. Monomicrobial cultures were detected in 163 specimens (78% of all microbiologically confirmed UTIs). Gram-negative flora prevailed among the micro-organisms, the predominantly isolated Enterobacteriaceae being Escherichiacoli and Klebsiellapneumoniae. In 16 patients (7.7% of microbiologically confirmed UTIs), yeast infection was confirmed. Isolated micro-organisms were fully sensitive to carbapenems. Gram-negative bacilli showed the lowest sensitivity to extended substrate spectrum penicillins and fluoroquinolones (37–64%), as well as to trimethoprim-sulfamethoxazole (50%). The MDR prevalence was 24.4%. Conclusions: The presented data indicates that UTIs are a significant problem in the studied population, so is antimicrobial resistance, especially to quinolones, and extended-spectrum cephalosporins, which are often used as first-line therapy. To tackle the problem of high UTI incidence and MDR prevalence, reducing the UTI risk factors should be prioritized.

Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound

We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd_0.4Tb_0.6Co₂ compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔS_M) was determined for many values of the magnetic field change (Δμ₀H), which varied from 0.1 to 7 T. In each case, the ΔS_M had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (J_RR), R-Co (J_RCo), and Co-Co (J_CoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near T_C the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.

From Atomic Level to Large-Scale Monte Carlo Magnetic Simulations

This paper refers to Monte Carlo magnetic simulations for large-scale systems. We propose scaling rules to facilitate analysis of mesoscopic objects using a relatively small amount of system nodes. In our model, each node represents a volume defined by an enlargement factor. As a consequence of this approach, the parameters describing magnetic interactions on the atomic level should also be re-scaled, taking into account the detailed thermodynamic balance as well as energetic equivalence between the real and re-scaled systems. Accuracy and efficiency of the model have been depicted through analysis of the size effects of magnetic moment configuration for various characteristic objects. As shown, the proposed scaling rules, applied to the disorder-based cluster Monte Carlo algorithm, can be considered suitable tools for designing new magnetic materials and a way to include low-level or first principle calculations in finite element Monte Carlo magnetic simulations.

Antibiotic Stewardship in Staphylococcus aureus Bloodstream Infection Treatment-Analysis Based on 29,747 Patients from One Hospital

Some of the most serious healthcare-associated infections (HAI) are highly deadly bloodstream infections (BSIs) caused by Staphylococcus aureus. The aim of the study was to analyse compliance of treatment practice with clinical guidelines in patients with S. aureus BSIs. The study was conducted at the Sosnowiec Hospital, Poland in 2019. During the study, 29,747 patients were hospitalized and 41 S. aureus BSIs (only HAIs) episodes were observed. According to local clinical practice guidelines, each case of BSI required blood cultures, echocardiography and control culture after the implementation of the targeted therapy. Incidence rate of S. aureus BSI was 0.8/1000 admissions; the greatest department admission rates were in the ICU (19.3/1000 admissions) and in the Nephrology Department (8.7/1000 admissions). Only 2 patients were treated following the protocol (4.8%); the most common errors were the use of an inappropriate drug or incorrect duration of antibiotic treatment. No patient underwent echocardiography, and control cultures were performed in 70% of cases. The case fatality rate was 7.3%. A satisfactorily low case fatality rate was found despite the poor antibiotic stewardship. Lack of discipline concerning antibiotic use can strongly impact the observed high drug resistance in HAIs and high Clostridioides difficile incidence rate in the studied hospital.

[Bacteraemia caused by ochrobactrum anthropi - unusual behavior]

O. anthropi, formerly known as Achromobacter, is an aerobic, Gram-negative bacillus, widespread in the environment, in various ecological niches. Currently, it is an emerging opportunistic microorganism associated with health care, as well as infections in people with immunodeficiency, mainly in children and newborns. The authors of the presented work present a case of a 13-year-old female patient with a neurodegenerative disorder in which O. anthropi was isolated from blood cultures. She was hospitalized in the Social Society of the Cordis Hospice in Katowice, and after discharge from the hospice she was covered by long-term home care under the supervision of a family doctor. Clinical picture O. anthropi can be very different, causes serious infections, such as blood infections. Due to difficulties in identification, Ochrobactrum anthropi can be a diagnostic and therapeutic challenge. The difficulty in differentiating Ochrobactrum spp. Is also related to the lack of a clear clinical picture of infection with bactera O.anthropi. In addition, this microorganism is difficult to treat due to the natural broad spectrum of antibiotic resistance.

Application of Ti6Al7Nb Alloy for the Manufacture of Biomechanical Functional Structures (BFS) for Custom-Made Bone Implants

Unlike conventional manufacturing techniques, additive manufacturing (AM) can form objects of complex shape and geometry in an almost unrestricted manner. AM’s advantages include higher control of local process parameters and a possibility to use two or more various materials during manufacture. In this work, we applied one of AM technologies, selective laser melting, using Ti6Al7Nb alloy to produce biomedical functional structures (BFS) in the form of bone implants. Five types of BFS structures (A1, A2, A3, B, C) were manufactured for the research. The aim of this study was to investigate such technological aspects as architecture, manufacturing methods, process parameters, surface modification, and to compare them with such functional properties such as accuracy, mechanical, and biological in manufactured implants. Initial in vitro studies were performed using osteoblast cell line hFOB 1.19 (ATCC CRL-11372) (American Type Culture Collection). The results of the presented study confirm high applicative potential of AM to produce bone implants of high accuracy and geometric complexity, displaying desired mechanical properties. The experimental tests, as well as geometrical accuracy analysis, showed that the square shaped (A3) BFS structures were characterized by the lowest deviation range and smallestanisotropy of mechanical properties. Moreover, cell culture experiments performed in this study proved that the designed and obtained implant’s internal porosity (A3) enhances the growth of bone cells (osteoblasts) and can obtain predesigned biomechanical characteristics comparable to those of the bone tissue.

Antibiotic consumption versus the prevalence of multidrug-resistant Acinetobacter baumannii and Clostridium difficile infections at an ICU from 2014-2015

BACKGROUND

Acinetobacter baumannii strains are currently the most commonly isolated non-fermenting rods at Polish intensive care units (ICUs), and they are the dominant aetiological agents of pneumonia. This study aimed to evaluate the prevalence of A. baumannii isolated from patients who were hospitalised at Sosnowiec Hospital's ICU. We also investigated the drug sensitivity of A. baumannii in relation to antibiotic consumption expressed as the defined daily dose (DDD) and Clostridium difficile infection (CDI).

METHODS

We performed a retrospective, laboratory-based study, which comprised consecutive, non-repetitive A. baumannii isolates from bloodstream infections and patients with pneumonia who were hospitalised from 2014-2015.

RESULTS

In the analysed period, 187 A. baumannii strains constituted 13.5% of all pathogens from clinical samples. A total of 76.5% of these strains were extensively drug resistant. Resistance of A. baumannii to fluoroquinolones, amikacin, and trimethoprim/sulfamethoxazole exceeded 90%. A total of 95% of strains were resistant to imipenem and meropenem, and 100% were resistant to cephalosporins and tetracyclines. Antibiotic consumption was 191.54 DDD for 100 patient-days, and the highest use of antibiotics involved ampicillin with sulbactam. The cumulative CDI incidence rate was 2.4%.

CONCLUSIONS

In our ICU, all of the strains were extensively drug resistant and sensitive to colistin. The significantly high consumption of carbapenems, fluoroquinolones, and aminoglycosides should be reduced because the high CDI incidence is probably related to extensive antibiotic consumption.

Severe infections caused by multidrug-resistant non-fermentative bacilli in southern Poland

BACKGROUND

The impact of multidrug-resistant organisms (MDROs), including non-fermentative bacilli (NFBs), is rising and underestimated, especially in intensive care units (ICUs). The growing prevalence of multidrug resistance (MDR) and extensive drug resistance (XDR) is challenging for clinicians, as the treatment options are limited.

OBJECTIVES

The purpose of this study was to analyze the extent of the epidemiological problem of multidrugresistant, extensively drug-resistant and pandrug-resistant (PDR) non-fermentative bacilli isolated from pneumonia and bloodstream infections (BSIs) in patients hospitalized in southern Poland.

MATERIAL AND METHODS

This study included 253 NFBs belonging to Acinetobacter sp. (ACI), Pseudomonas sp. (PAR), and Stenotrophomonas sp. (STM). The microorganisms were identified, and susceptibility testing was performed using a semi-automatic system. The different patterns of resistance were defined as MDR, XDR, or PDR strains. Epidemiological typing of A. baumannii from ICUs was performed by repetitive polymerase chain reaction (rep-PCR).

RESULTS

More than half of the strains (57.7%) were isolated within ICUs. ACI-strains came significantly more often from ICU wards. The highest prevalence of ACI and PAR was found in pneumonia, whereas STM dominated in BSIs. ACIs were more frequently resistant than other pathogens to all studied antibiotics except colistin (n = 76; 58.9%), and they belonged to the XDR category. DiversiLab demonstrated the presence of 2 dominant clones in the ACI group, both classified as European Clone 2 (EUII).

CONCLUSIONS

Our results indicate serious potential therapeutic problems related to high antibiotic resistance of ACI isolates. The stratification of drug resistance (MDR/XDR/PDR) may become an important tool for the assessment of public health epidemiology and microbiological hazards at the local, national, and international level. It allows clear presentation of the issues concerning the epidemiology of highly resistant bacilli, and the exchange of information between medical staff and local representatives of public health for the implementation of effective measures to reduce drug resistance.

Virulence and antimicrobial resistance of Staphylococcus aureus isolated from bloodstream infections and pneumonia in Southern Poland

OBJECTIVES

Staphylococcus aureus remains the most important cause of infections in hospitals and long-term care facilities. The aim of this study was to analyse the resistance, virulence, and epidemiological and genetic relationships of S. aureus from bloodstream infections (BSIs) and pneumonia from patients in Southern Poland.

METHODS

All strains were tested for antimicrobial susceptibility using the disk diffusion method. Etest was also performed for vancomycin, teicoplanin, tigecycline, oxacillin, cefoxitin and penicillin. PCR amplification was used to detect selected virulence genes. The genetic similarity of methicillin-resistant S. aureus (MRSA) isolates was determined by spa typing and pulsed-field gel electrophoresis (PFGE). Using the BURP algorithm and the Ridom SpaServer database, spa types were clustered into different clonal complexes (spa-CCs).

RESULTS AND CONCLUSIONS

MRSA strains were observed at a prevalence of 26.7%, but 88.6% of hospital-acquired infections were MRSA, with no difference between BSIs and pneumonia. The highest resistance was observed to erythromycin and tobramycin. None of the strains were resistant to linezolid, glycopeptides or tigecycline. The strains had no significant virulence factors and the number of virulence genes present did not correlate with the degree of drug resistance. PFGE typing showed relatively high diversity of strains. The majority of isolates belonged to spa type t003 (CC5).

Bad to the Bone: On In Vitro and Ex Vivo Microbial Biofilm Ability to Directly Destroy Colonized Bone Surfaces without Participation of Host Immunity or Osteoclastogenesis

Bone infections are a significant public health burden associated with morbidity and mortality in patients. Microbial biofilm pathogens are the causative agents in chronic osteomyelitis. Research on the pathogenesis of osteomyelitis has focused on indirect bone destruction by host immune cells and cytokines secondary to microbial insult. Direct bone resorption by biofilm pathogens has not yet been seriously considered. In this study, common osteomyelitis pathogens (Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Streptococcus mutans) were grown as biofilms in multiple in vitro and ex vivo experiments to analyze quantitative and qualitative aspects of bone destruction during infection. Pathogens were grown as single or mixed species biofilms on the following substrates: hydroxyapatite, rat jawbone, or polystyrene wells, and in various media. Biofilm growth was evaluated by scanning electron microscopy and pH levels were monitored over time. Histomorphologic and quantitative effects of biofilms on tested substrates were analyzed by microcomputed tomography and quantitative cultures. All tested biofilms demonstrated significant damage to bone. Scanning electron microscopy indicated that all strains formed mature biofilms within 7 days on all substrate surfaces regardless of media. Experimental conditions impacted pH levels, although this had no impact on biofilm growth or bone destruction. Presence of biofilm led to bone dissolution with a decrease of total volume by 20.17±2.93% upon microcomputed tomography analysis, which was statistically significant as compared to controls (p <0.05, ANOVA). Quantitative cultures indicated that media and substrate did not impact biofilm formation (Kruskall-Wallis test, post-hoc Dunne's test; p <0.05). Overall, these results indicate that biofilms associated with osteomyelitis have the ability to directly resorb bone. These findings should lead to a more complete understanding of the etiopathogenesis of osteomyelitis, where direct bone resorption by biofilm is considered in addition to the well-known osteoclastic and host cell destruction of bone.

Molecular Epidemiology and Drug Resistance of Acinetobacter baumannii Isolated from Hospitals in Southern Poland: ICU as a Risk Factor for XDR Strains

The objectives of the present study were to investigate the carbapenemase and metallo-beta-lactamase genes of Acinetobacter baumannii clinical isolates by polymerase chain reaction (PCR) and real time PCR and to determine the molecular epidemiology of the strains using the DiversiLab tool. From these data, correlations between drug resistance, resistance genes, and epidemiological clones may be revealed. The study was conducted on 125 A. baumannii collected over the 2013 year. The majority of the isolates from both intensive care unit (ICU) and non-ICU cases originated from pneumonia infections (79.2%), isolates from blood infections accounted for 17.6% and 3.2% were from meningitis infections. In the ICU cases compared with the non-ICU cases, bloodstream infections were more frequently diagnosed (19.2% vs. 11.5%). Sixty percent of A. baumannii strains were resistant to all the antimicrobials tested with the exception of colistin. All strains were susceptible to colistin and polymyxin B. Extensively drug-resistant (XDR) strains accounted for 80.8% of the isolates tested and these XDR strains were more frequently isolated from ICU cases than from non-ICU cases (93.9% vs. 30.8%). Among the 101 isolates of A. baumannii exhibiting the XDR pattern of resistance, 80 possessed the blaOXA-24 gene and 29 had the blaOXA-23 gene. Only two isolates possessed the blaVIM gene. The presence of the ISAba1element was confirmed among 10 strains from patients hospitalized in the ICU. Using repetitive extragenic palindromic sequence PCR (DiversiLab typing), six clones and 12 unique strains were identified, of which two clones dominated. Most isolates belonging to clone 1 (66.7%) and clone 2 (85.5%) were susceptible only to colistin. In summary, it is clear from our findings and those of other studies that carbapenem resistance among A. baumannii strains presents a serious clinical problem worldwide. Furthermore, the presence of XDR international clone II in ICUs poses a potential risk for future outbreaks of A. baumannii infection and controlling A. baumannii infections in hospitals presents a serious challenge.

The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm

In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements.

The ability of S.aureus to form biofilm on the Ti-6Al-7Nb scaffolds produced by Selective Laser Melting and subjected to the different types of surface modifications

The Gram-positive coccus, Staphylococcus aureus, is the leading etiologic agent of limb and life-threatening biofilm-related infections in the patients following the orthopaedic implantations. The aim of the present paper is to estimate the ability of S. aureus to form biofilm on titanium alloy (Ti-6Al-7Nb) scaffolds produced by Selective Laser Melting (SLM) and subjected to the different types of surface modifications, including ultrasonic cleaning and chemical polishing. The results obtained indicate significantly the decreased ability of S.aureus to form biofilm on the surface of scaffolds subjected to the chemical polishing in comparison to the scaffolds cleaned ultrasonically. The data provided can be useful for future applications of the SLM technology in production of Ti-6Al-7Nb medical implants.

Differences in metabolic profiles of planktonic and biofilm cells in Staphylococcus aureus - (1)H Nuclear Magnetic Resonance search for candidate biomarkers

Staphylococcus aureus is responsible for many types of infections related to biofilm presence. As the early diagnostics remains the best option for prevention of biofilm infections, the aim of the work presented was to search for differences in metabolite patterns of S. aureus ATCC6538 biofilm vs. free-swimming S. aureus planktonic forms. For this purpose, Nuclear Magnetic Resonance (NMR) spectroscopy was applied. Data obtained were supported by means of Scanning Electron Microscopy, quantitative cultures and X-ray computed microtomography. Metabolic trends accompanying S. aureus biofilm formation were found using Principal Component Analysis (PCA). Levels of isoleucine, alanine and 2,3-butanediol were significantly higher in biofilm than in planktonic forms, whereas level of osmoprotectant glycine-betaine was significantly higher in planktonic forms of S. aureus. Results obtained may find future application in clinical diagnostics of S. aureus biofilm-related infections.

The risk related to surgical site infections after hip endoarthroplasty--surveillance outcome analysis in two Polish orthopaedic centres

BACKGROUND

Surgical Site Infections (SSIs) are a major infection control problem in modern hospitals. The aim of this study was to carry out an epidemiological analysis of surgical site infections diagnosed in patients after hip endoarthroplasty in two clinical centres in 2005.

MATERIAL AND METHODS

Surveillance of hospital infections was performed according to the definitions and criteria of the National Nosocomial Infections Surveillance System (NNIS). 187 and 479 surgical procedures were performed in two hospital wards.

RESULTS

Incidence was found to be 7.5% and 2.3%, respectively. Deep infections were the dominant type in Clinical Centre I and superficial infections predominated in Clinical Centre II. In one of the centres, an effective post-discharge infection registration system was implemented (63.6% of the cases); the second centre registered SSI cases predominantly during the patients' stay on the ward. Gram-positive cocci were the most common aetiological factor for all types of SSIs. All Staphylococcus aureus strains isolated were MSSA and the main therapeutic problem was multi-resistant coagulase-negative staphylococci.

CONCLUSIONS

The results of the study point to a significantly higher SSI incidence in the population of patients in Clinical Centre I. Prolonged preoperative hospital stay was shown to raise the risk for SSI. The technical skill of the surgeons, expressed as the number of procedures carried out at each centre, was another significant factor. Drug resistance of isolates points to the problem of multi-resistant coagulase-negative staphylococci infections in the study population.

[Registration of hospital infections: effects of 5 years observation of peritonitis]

In connection with a great availability of antibiotics, many negative side effects have been observed. A registration program of hospital infections' occurrence and drug-sensitiveness has been conducted for five years in all wards of Mining Hospital in Sosnowiec. This paper presents our first data and conclusions after examinations of the biological materials coming from patients suffering from different kinds of the peritonitis.

Cerebrospinal meningitis with the presence of Acinetobacter spp

The study was conducted on 16 strains of Acinetobacter sp. which were isolated from cerebrospinal fluid. The diagnostic material was analysed with the use of automatic BacT/Alert system (Organon Teknika). The analysis was performed in the Department of Microbiology, Medical University in Bydgoszcz. API 20NE system (bioMérieux) enabled the identification of 14 strains (87.5%) as A. baumannii, 1 strain as A. haemolyticus and 1 strain as A. lwoffii. The micro-organisms were isolated from patients whose age ranged between 4 and 66 years. These patients were treated in the departments of Neurosurgery (75.0%), Neurology (18.8%) and Intensive Therapy (6.2%). The infection of cerebrospinal fluid was caused by injury and subsequent exposure to the bacteria present in external environment. Antibiotic-sensitivity of these micro-organisms was evaluated with the help of disc-diffusion method, observing standardisation conditions outlined by NCCLS. All the strains proved sensitive to carbapenems, 15 strains were sensitive to netilmicin, 7 strains--to tobramycin and 7 strains--to amikacin. All the strains displayed multiple resistance. The only exception was A. haemolyticus. The use of two-discs allowed for the detection of ESBLs in 7 A. baumannii strains. Positive results were most frequently obtained after the combination of sublactam and aztreonam. Due to microscopic resemblance between Acinetobacter spp., and bacteria of Neisseria, Moraxella and Haemophilus genus, microbiological diagnostics should not be restricted to microscopic assessment of cerebrospinal fluid and quick serological tests evaluating the antigens of the most frequent aetiological factors. Considering multiple resistance of Acinetobacter spp. to antibiotics, the treatment should be based on sensitivity tests and the ability of a given antibiotic to penetrate into cerebrospinal fluid. In our opinion, both reasonable antibiotic policy as well as observing the principles of hygiene and monitoring infections play equally important roles in the prevention of infections with Acinetobacter spp. Such combined measures may help to prevent the spreading of multiple resistant strains in hospital environment.

[Occurrence and susceptibility of hospital strains producing enzymes with a wide spectrum of substrate profiles]

In connection with more and more frequent occurrence of extended spectrum beta-lactamases an effort has been made to detect their presence in the biological materials coming from the patients of different wards of Mining Hospital in Sosnowiec from January to September 1995. Among 38 diagnostic materials, from which the strains in question were isolated, the following materials have been examined: bronchial lavage (52.6%), surgical wounds (18.4%), urines (15.8%) and others (13.2%). The examined diagnostic materials came from Intensive Care Unit (87.0%), Casualty and Orthopaedic Surgery Clinic (5.0%) and General Surgery Clinic (3.0%). The most frequently isolated microorganisms were Klebsiella pneumoniae. (47.4%), Serratia marcescens (36.8%), Enterobacter cloacae (10.5%) and others (5.3%). Half of the examined strains constituted those producing extended spectrum beta-lactamases and probably possessing an extra resistance mechanism: (Serratia marcescens--74%, Enterobacter cloacae--21%, Enterobacter aerogenes--5.0%) and 50% were those producing extended--spectrum beta-lactamases. (Klebsiella pneumoniae--95%, Escherichia coli--5%). Susceptibility of the examined strains to anti-microbial antibiotics was diverse. Full susceptibility of the analysed strains has been observed exclusively in case of Karbapenems (Imipenem, Meropenem and Cefamycyn). In case of beta-lactamase with beta-lactamase inhibitor combinations susceptibility was diverse and dependent on the species of the examined microorganism.

[Phage and serological types of bacteria infecting patients in anesthesiology and intensive therapy (1988-1990)]

1736 of biological materials, being taken from 264 patients, were investigated since 1988 to 1990. 1410 kinds of microorganisms were cultured from 999 biological materials, in which the growth of bacterial flora was noticed. Following species were isolated most frequently: Pseudomonas aeruginosa 15.39%, Proteus mirabilis 12.91%, Klebsiella pneumoniae 10.43% and Staphylococcus aureus 10.43%. The most frequent serological type according to Fisher's scheme was Pseudomonas aeruginosa--immunotype T 3.7 and according to Habs scheme--immunotype P 16. Strains of Staphylococcus aureus were most frequently sensitive to phages the group II. In case of Klebsiella sp. bacilli, the most predominant strains were not typed either by basic or extended phage sets.

Differences in metabolic profiles of planktonic and biofilm cells in Staphylococcus aureus - (1)H Nuclear Magnetic Resonance search for candidate biomarkers

Staphylococcus aureus is responsible for many types of infections related to biofilm presence. As the early diagnostics remains the best option for prevention of biofilm infections, the aim of the work presented was to search for differences in metabolite patterns of S. aureus ATCC6538 biofilm vs. free-swimming S. aureus planktonic forms. For this purpose, Nuclear Magnetic Resonance (NMR) spectroscopy was applied. Data obtained were supported by means of Scanning Electron Microscopy, quantitative cultures and X-ray computed microtomography. Metabolic trends accompanying S. aureus biofilm formation were found using Principal Component Analysis (PCA). Levels of isoleucine, alanine and 2,3-butanediol were significantly higher in biofilm than in planktonic forms, whereas level of osmoprotectant glycine-betaine was significantly higher in planktonic forms of S. aureus. Results obtained may find future application in clinical diagnostics of S. aureus biofilm-related infections.