Selection of resistance by antimicrobial coatings in the healthcare setting.

Antimicrobial touch surfaces have been introduced in healthcare settings with the aim of supporting existing hygiene procedures, and to help combat the increasing threat of antimicrobial resistance. However, concerns have been raised over the potential selection pressure exerted by such surfaces, which may drive the evolution and spread of antimicrobial resistance. This review highlights studies that indicate risks associated with resistance on antimicrobial surfaces by different processes, including evolution by de-novo mutation and horizontal gene transfer, and species sorting of inherently resistant bacteria dispersed on to antimicrobial surfaces. The review focuses on antimicrobial surfaces made of copper, silver and antimicrobial peptides because of the practical application of copper and silver, and the promising characteristics of antimicrobial peptides. The available data point to a potential for resistance selection and a subsequent increase in resistant strains via cross-resistance and co-resistance conferred by metal and antibiotic resistance traits. However, translational studies describing the development of resistance to antimicrobial touch surfaces in healthcare-related environments are rare, and will be needed to assess whether and how antimicrobial surfaces lead to resistance selection in these settings. Such studies will need to consider numerous variables, including the antimicrobial concentrations present in coatings, the occurrence of biofilms on surfaces, and the humidity relevant to dry-surface environments. On-site tests on the efficacy of antimicrobial coatings should routinely evaluate the risk of selection associated with their use.

Bacterial community changes in copper and PEX drinking water pipeline biofilms under extra disinfection and magnetic water treatment.

AIMS: To study the stability of biofilms and water quality in pilot scale drinking water copper and PEX pipes in changing conditions (extra disinfection, magnetic water treatment, MWT). METHODS AND RESULTS: Next-generation sequencing (NGS) of 16S ribosomal RNA genes (rDNA) to describe total bacterial community and ribosomal RNA (rRNA) to describe active bacterial members in addition to traditional microbiological methods were applied. Biofilms from control copper and PEX pipes shared same most abundant bacteria (Methylobacterium spp., Sphingomonas spp., Zymomonas spp.) and average species diversities (Shannon 3·8-4·2) in rDNA and rRNA libraries, whereas few of the taxa differed by their abundance such as lower total Mycobacterium spp. occurrence in copper (<0·02%) to PEX (<0·2%) pipes. Extra disinfection (total chlorine increase from c. 0·5 to 1 mg l-1 ) affected total and active population in biofilms seen as decrease in many bacterial species and diversity (Shannon 2·7, P < 0·01, rRNA) and increase in Sphingomonas spp. as compared to control samples. Furthermore, extra-disinfected copper and PEX samples formed separate clusters in unweighted non-metric multidimensional scaling plot (rRNA) similarly to MWT-treated biofilms of copper (but not PEX) pipes that instead showed higher species diversity (Shannon 4·8, P < 0·05 interaction). CONCLUSIONS: Minor chlorine dose addition increased selection pressure and many species were sensitive to chlorination. Pipe material seemed to affect mycobacteria occurrence, and bacterial communities with MWT in copper but not in PEX pipes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study using rRNA showed that chlorination affects especially active fraction of bacterial communities. Copper and PEX differed by the occurrence of some bacterial members despite similar community profiles.

Copper as an antibacterial material in different facilities.

The present study was performed in real life settings in different facilities (hospital, kindergarten, retirement home, office building) with copper and copper alloy touch surface products (floor drain lids, toilet flush buttons, door handles, light switches, closet touch surfaces, corridor hand rails, front door handles and toilet support rails) in parallel to reference products. Pure copper surfaces supported lower total bacterial counts (16 ± 45 vs 105 ± 430 CFU cm-2 , n = 214, P < 0·001) and a lower occurrence of Staphylococcus aureus (2·6 vs 14%, n = 157, P < 0·01) and Gram-negatives (21 vs 34%, n = 214, P < 0·05) respectively than did reference surfaces, whereas the occurrence of enterococci (15%, n = 214, P > 0·05) was similar. The studied products could be assigned to three categories according to their bacterial loads as follows (P < 0·001): floor drain lids (300 ± 730 CFU cm-2 , n = 32), small area touch surfaces (8·0 ± 7·1 to 62 ± 160 CFU cm-2 , n = 90) and large area touch surfaces (1·1 ± 1·1 to 1·7 ± 2·4 CFU cm-2 , n = 92). In conclusion, copper touch surface products can function as antibacterial materials to reduce the bacterial load, especially on frequently touched small surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: The efficiency of copper as an antimicrobial material has been noted in laboratory studies and in the hospital environment. The present study further shows that copper exerted an antibacterial effect in different facilities, i.e. in a hospital, a kindergarten, an office building and in a retirement home for the elderly. The study suggests that copper has potential use as an antibacterial material and therefore might serve as a means to lower the incidence of transmission of infectious agents from inanimate surfaces in different facilities, with everyday functions.

Diversity of ribosomal 16S DNA- and RNA-based bacterial community in an office building drinking water system.

AIMS: Next-generation sequencing of 16S ribosomal RNA genes (rDNA) and ribosomal RNA (rRNA) was used to characterize water and biofilm microbiome collected from a drinking water distribution system of an office building after its first year of operation. METHODS AND RESULTS: The total bacterial community (rDNA) and active bacterial members (rRNA) sequencing databases were generated by Illumina MiSeq PE250 platform. As estimated by Chao1 index, species richness in cold water system was lower (180-260) in biofilms (Sphingomonas spp., Methylobacterium spp., Limnohabitans spp., Rhizobiales order) than in waters (250-580), (also Methylotenera spp.) (P = 0·005, n = 20). Similarly species richness (Chao1) was slightly higher (210-580) in rDNA libraries compared to rRNA libraries (150-400; P = 0·054, n = 24). Active Mycobacterium spp. was found in cross-linked polyethylene (PEX), but not in corresponding copper pipeline biofilm. Nonpathogenic Legionella spp. was found in rDNA libraries but not in rRNA libraries. CONCLUSIONS: Microbial communities differed between water and biofilms, between cold and hot water systems, locations in the building and between water rRNA and rDNA libraries, as shown by clear clusters in principal component analysis (PcoA). By using the rRNA method, we found that not all bacterial community members were active (e.g. Legionella spp.), whereas other members showed increased activity in some locations; for example, Pseudomonas spp. in hot water circulations' biofilm and order Rhizobiales and Limnohabitans spp. in stagnated locations' water and biofilm. SIGNIFICANCE AND IMPACT OF THE STUDY: rRNA-based methods may be better than rDNA-based methods for evaluating human health implications as rRNA methods can be used to describe the active bacterial fraction. This study indicates that copper as a pipeline material might have an adverse impact on the occurrence of Mycobacterium spp. The activity of Legionella spp. maybe questionable when detected solely by using DNA-based methods.

Penetrating trauma; experience from Southwest Finland between 1997 and 2011, a retrospective descriptive study.

BACKGROUND: (1) There is lack of epidemiological data on penetrating trauma in European countries. (2) In Finland most acts of violence are performed under the influence of alcohol. The aim of this study was to determine the incidence and types of injury, treatment and survival of patients with penetrating injuries to the thorax and abdomen. METHODS: This study includes two trauma centers with combined catchment area of approximately 720,000 patients. Patients were identified from patient records using ICD-10 codes. RESULTS: Patients were predominantly young males and they were stab victims. The average yearly incidence for penetrating trauma was 0.9/100,000 inhabitants. Thirteen percent of patients admitted gave a negative toxicology screen or breathalyzer test for alcohol. Twenty two percent of wounds were self-inflicted. Fifty five percent of patients received a chest tube and 30 patients (23%) underwent emergent thoracotomy after sustaining critical injury to the thorax. A considerable proportion (12%) of the study group also later died due to alcohol and/or violence, highlighting the psychosocial co-morbidity among penetrating trauma victims. DISCUSSION: Chest tube insertion is a skill to be mastered by any on-call physician. This simple procedure can be potentially life-saving. There is also a call for assessment of psychosocial well-being among penetrating trauma victims.

Planning, performing and analyzing X-ray Raman scattering experiments.

A compilation of procedures for planning and performing X-ray Raman scattering (XRS) experiments and analyzing data obtained from them is presented. In particular, it is demonstrated how to predict the overall shape of the spectra, estimate detection limits for dilute samples, and how to normalize the recorded spectra to absolute units. In addition, methods for processing data from multiple-crystal XRS spectrometers with imaging capability are presented, including a super-resolution method that can be used for direct tomography using XRS spectra as the contrast. An open-source software package with these procedures implemented is also made available.

Temperature dependence of CO2 and N2 core-electron excitation spectra at high pressure.

We report a study on the temperature dependence of the core-electron excitation spectra of CO2 and N2, performed using non-resonant inelastic X-ray scattering spectroscopy. The spectra were measured at two temperatures (300 K and 850 K) and at high pressure (40 bar). For CO2 a clear temperature dependence was observed at the C and O near-edge regions. The spectra of CO2 were simulated by density functional theory calculations, and the temperature was accounted for by sampling the initial state molecular geometries using the Metropolis algorithm. This model is able to account for the experimentally observed temperature dependence of the spectrum. The experiment fortifies the status of the non-resonant inelastic X-ray scattering spectroscopy as a valuable technique for physics and chemistry for in situ studies under extreme sample conditions. Especially in the case of gas phase the sample conditions of considerably elevated temperature and pressure are unfeasible for many other spectroscopic techniques.

Inelastic X-ray scattering and vibrational effects at the K-edges of gaseous N2, N2O, and CO2.

We report non-resonant inelastic X-ray scattering experiments of several gaseous samples in the inner-shell excitation energy range. The experimental near-edge spectra from all the K-edges of N(2), N(2)O, and CO(2) including the momentum transfer dependence are presented. The results are analyzed using density functional theory calculations that accurately reproduce the experimental spectral features. We observe vibrational effects in the measured spectrum and in the calculations the atomic motion is modeled using the Franck-Condon approximation and the linear coupling model. Our findings show that vibrational effects cannot be neglected in the analysis of high resolution inelastic X-ray scattering spectroscopy. The results also support the validity of the transition potential approximation for calculating core excited state potential energy surfaces.

Direct effect of thyroxine on pig sphincter of Oddi contractility.

Sphincter of Oddi (SO) motility has an important role in the regulation of bile flow. SO function disturbances (stenosis or dyskinesia) may prevent normal bile flow and thus enhance the probability of common bile duct (CBD) stone formation. Previously we have shown that there is an increased prevalence of diagnosed hypothyroidism in CBD stone patients, compared with gallbladder stone patients or age-, sex-, and hospital-admission-adjusted controls. The present study was done to test the hypothesis that thyroxine directly effects the SO. The specificity of the effects of thyroxine were studied by comparing with triiodothyronine (T3), progesterone, cortisone, estrogen, and testosterone. For ex vivo studies three or four successive 1 to 1.5-mm SO rings were prepared from each pig and placed between two hooks in oxygenated physiologic salt solution at 37 degrees C. SO contraction was measured with isometric force displacement transducers and registered on a polygraph. Each SO ring was stimulated with KCl (125 mM), acetylcholine (ACh; 10 or 100 microM) and histamine (Hist; 10 or 100 microM) with and without thyroxine (10(-10) or 10(-8) M), T3 (10(-9) or 10(-7) M), progesterone (1 microM), cortisone (1 microM), estrogen (1 microM), or testosterone (1 nM) in the medium. KCI, ACh, and Hist induced strong contractions in the SO rings. The addition of thyroxine did not influence significantly the KCl-induced contractions, but the ACh- and Hist-induced contractions decreased by a mean of 37-44% (P < 0.001) and 54-56% (P < 0.001), respectively, as compared to the contractions without thyroxine. Triiodothyronine had a similar inhibitory effect to thyroxine, whereas cortisone, estrogen, and testosterone had no effect. Progesterone decreased the KCl-, ACh-, and Hist-induced SO contractions. In conclusion, physiological concentrations of thyroxine have an inhibitory effect on receptor-mediated ACh and Hist, but not on the nonspecific KCl-induced SO contraction ex vivo. The inhibitory effect is similar in thyroxine and triiodothyronine. Of the steroid hormones, only progesterone nonspecifically ameliorates SO contractions ex vivo. Because the effect of thyroxine on the SO is prorelaxing, the lack of thyroxine may result in an increased tension of the SO.

Association between common bile duct stones and treated hypothyroidism.

BACKGROUND/AIMS: The purpose of this study was to investigate the frequency of diagnosed hypothyroidism in patients with common bile duct stones. METHODOLOGY: The common bile duct stone group (Group I) consisted of all the patients who had verified gallstones in the common bile duct in endoscopic retrograde cholangiopancreatography during 1995. The control group (Group II) was matched for age, sex, and hospital admission. These patients did not have diagnosed gallbladder or common duct stones. In both groups there were 86 patients (56 women and 30 men). The median age in these groups was 73 (range: 22-92) years at the time of common bile duct stone diagnosis. Medical records of all patients were reviewed. RESULTS: In Group I the prevalence of previously diagnosed hypothyroidism was 7/86 (8%) compared with 1/86 (1%) in Group II (P = 0.01). Hypothyroidism was previously diagnosed only in the common bile duct stone patients (Group I) of over 60 years of age, where the prevalence was 7/66 (11%). In addition, we studied 36 consecutive gallbladder stone patients (Group III) of over 60 years, who had no evidence of common bile duct stones. Hypothyroidism had been diagnosed in them less frequently (2/36 = 6%) than in the age and hospital admission matched common bile duct stone patients (P = 0.01). Other diagnosed endocrine disorders did not differ between the study groups. CONCLUSIONS: There is a significant association between the common bile duct stones and previously diagnosed hypothyroidism. There stronger association between the common bile duct stones and hypothyroidism compared to gallbladder stones and hypothyroidism suggests a mechanism other than merely the cholesterol metabolism mediated mechanism. The 11% prevalence of previously diagnosed hypothyroidism in the common bile duct stone patients of over 60 years of age suggests all patients with common bile duct stones be screened for current thyroid dysfunction.